Process–Property Relationships and Mechanical Tunability of MEX-Fabricated Polycaprolactone for Bioresorbable Stent Materials

Process–Property Relationships and Mechanical Tunability of MEX-Fabricated Polycaprolactone for Bioresorbable Stent Materials | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Process–Property Relationships and Mechanical Tunability of MEX-Fabricated Polycaprolactone for Bioresorbable Stent Materials Kuang Yee Ng, Noorhafiza Muhammad, Siti Noor Fazliah Mohd Noor, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9089947/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Material extrusion (MEX) has emerged as a promising method for fabricating bioresorbable stents (BRS); however, a systematic understanding of how process parameters regulate material-level compressive and flexural behaviour of polycaprolactone (PCL) under different loading modes remains limited. In this study, the effects of extrusion temperature (T E ), material deposition speed (v D ) and extrusion multiplier (M E ) on the compressive and flexural responses of MEX-fabricated PCL were investigated using a response surface methodology framework. Distinct parameter sensitivities were observed between loading modes, with M E identified as the dominant factor governing both strength and modulus through its control of volumetric material delivery and consolidation quality, while T E and v D acted as secondary modulators. Regression-based statistical models were developed to capture the nonlinear process–property relationships and were subsequently employed to define compression-focused, flexural-focused and multi-objective optimisation pathways, reflecting the clinically relevant trade-off between radial support and conformability in coronary stent design. Microstructural observations from cross-sectional SEM imaging provided mechanistic support for the parameter-dependent trends by revealing variations in material continuity, void distribution and defect suppression. By isolating material behaviour from geometric effects, this work establishes a tunable, geometry-independent mechanical window for MEX-fabricated PCL, offering a quantitative material baseline to support future design and optimisation of BRS architectures. Material extrusion (MEX) Polycaprolactone (PCL) Bioresorbable stents (BRS) Process–property relationships Mechanical tunability Figures Figure 1 Figure 2 Figure 3 Figure 4 1.0 Introduction Coronary artery disease (CAD) remains one of the leading causes of morbidity worldwide, and vascular stents have become an essential intervention to restore luminal patency [ 1 – 3 ]. Once deployed, a stent must withstand a complex mechanical environment, including continuous radial compression from vascular recoil and pulsatile blood pressure, as well as significant bending deformation during crimping, delivery and navigation through tortuous coronary anatomy [ 4 , 5 ]. These loading conditions place stringent mechanical requirements on stent materials and structures, necessitating sufficient radial strength to resist collapse while simultaneously providing adequate flexural flexibility to ensure trackability and conformability within curved vessels [ 6 – 8 ]. Achieving an optimal balance between these mechanical demands is fundamental to the performance and long-term reliability of coronary stents. To meet these demanding mechanical requirements, increasing attention has turned toward bioresorbable materials and advanced fabrication strategies for bioresorbable stents (BRS). Such stents provide temporary mechanical support and gradually degrade over time, thereby mitigating the long-term complications associated with permanent metallic implants [ 9 , 10 ]. Among existing bioresorbable polymers, polycaprolactone (PCL) stands out as an attractive candidate due to its excellent biocompatibility and biodegradability, favourable flexibility and ductility and history of Food and Drug Administration (FDA) approval for use in implantable medical devices [ 11 – 14 ]. Concurrently, the growing adoption of additive manufacturing has positioned material extrusion (MEX) as a promising technique for producing patient-specific stents, offering precise geometric control and on-demand customisation [ 15 – 17 ]. However, the mechanical performance of MEX-fabricated components is highly sensitive to process parameters, leading to significant variations in the resulting material behaviour [ 18 ]. Accordingly, it is crucial to determine how MEX process parameters affect the inherent mechanical properties of PCL to ensure the mechanical performance of the fabricated stent. Recent studies have increasingly examined how MEX process parameters influence the mechanical behaviour of PCL-based stent structures, with particular attention to radial and flexural performance—two properties that are fundamental to coronary stent function [ 6 – 8 ]. Guerra and Ciurana [ 19 ] investigated the effects of nozzle temperature, flow rate and printing speed by evaluating the recoil ratio of PCL stent samples, showing that flow rate above 100% produced wider struts and hinges that enabled greater radial expansion. Wang et al. [ 20 ] adopted a more comprehensive mechanical characterisation approach, including three-point bending, radial compression and expansion tests, to examine how extruder rotational speed alters key geometric features such as connector length and beam width, ultimately demonstrating that higher extrusion speeds increase strut width, thereby improving radial strength while reducing bending flexibility. Singh et al. [ 21 ] employed a response surface methodology (RSM) to systematically study the influence of layer thickness (t L ) and printing speed on the bending and compression behaviour of solvent-cast PCL-based composite stents, identifying parameter combinations that reduce dimensional shrinkage and enhance overall mechanical stability. Similarly, Kandi and Pandey [ 22 ] evaluated tubular PCL-based scaffolds under varying infill density, t L and print speed, showing that increased infill improves radial load capacity and ductility, whereas faster speed and thicker t L reduce mechanical performance; their optimisation study further established a parameter set that maximises radial compression load. Collectively, these findings demonstrate that MEX parameters exert clear and measurable effects on the mechanical behaviour of fabricated PCL-based stent structures. However, meaningful comparison across existing studies remains challenging as their experimental methodologies and sample structures differ substantially. Although prior work consistently shows that radial and flexural behaviours can be modulated through MEX parameters, the mechanical testing protocols used in these studies vary widely, making their findings difficult to reconcile. For instance, Guerra and Ciurana [ 19 ] quantified radial performance by expanding samples to their maximum dilation, whereas Wang et al. [ 20 ] evaluated recoil only at fixed expansion levels of 10% and 20%, resulting in fundamentally non-comparable measurements. Likewise, the radial compression tests conducted by Kandi and Pandey [ 22 ] and by Singh et al. [ 21 ] used different compression ranges and loading conditions, raising uncertainty as to whether discrepancies in their reported optimal parameters reflect true processing effects or merely differences in testing procedures. Such inconsistencies underscore the need for more uniform and standardised mechanical evaluation methods. Beyond differences in testing methodology, the stent geometries employed across these studies also vary considerably, introducing an additional layer of complexity [ 23 ]. Each investigation utilised distinct structural patterns, connector or strut dimensions—factors that may exert dominant effects on mechanical performance. In this context, computational and experimental studies in stent mechanics consistently demonstrate that variations in cell topology, strut geometry, or connector architecture can lead to fundamentally different radial strength, bending flexibility and optimal design strategies [ 24 – 28 ]. Recent review articles further emphasise that stent performance is highly geometry-dependent, such that even small structural modifications can shift the balance between radial support and flexibility, ultimately requiring different optimisation routes for different designs [ 5 , 29 , 30 ]. Under these circumstances, it becomes exceedingly difficult to determine whether the “optimal” process parameters reported in previous studies are genuinely material- or process-driven, or whether they are simply a consequence of the specific stent architectures being tested. Together, these methodological and geometric inconsistencies highlight a critical gap in current research: the field lacks a geometry-independent, standardised framework for understanding how MEX process parameters influence the intrinsic mechanical response of PCL for coronary stent applications. This motivates the need to decouple material–process effects from sample structural effects, thereby enabling a more controlled and generalisable investigation. Efforts to clarify these parameter–property relationships using a more standardised approach have been limited, particularly for PCL. A few studies have characterised the compressive or flexural behaviour of PCL using standardised mechanical tests or ASTM-inspired specimen geometries, including selective laser sintering (SLS) scaffolds [ 31 , 32 ] and PCL–cellulose structures [ 33 ]. These works provide useful baseline measurements of PCL mechanical behaviour. However, most of these studies did not involve the MEX process, nor did they discuss it in the context of the demand for coronary stents. Moreover, they do not investigate how process parameters systematically influence the intrinsic mechanical response of PCL. In contrast, standard-based and DOE-driven analyses of MEX process parameters are well established for other polymers such as polylactic acid (PLA) [ 34 – 37 ] and polyethylene terephthalate glycol (PETG) [ 35 , 38 ], yet corresponding studies for PCL, particularly those linking parameter effects to stent-relevant compressive and flexural properties, remain notably scarce. This gap is especially important as radial strength and flexural flexibility constitute an inherent mechanical trade-off in stent design [ 5 , 20 , 39 ], and different clinical scenarios prioritise these properties differently [ 40 , 41 ]. A reliable, geometry-independent mechanical characterisation of MEX-fabricated PCL is therefore essential as a foundational input for future structure-level optimisation and patient-specific stent development. Accordingly, there is a clear need for studies that employ standardised specimen designs, controlled MEX parameter schemes and systematic analytical frameworks to isolate and quantify the material–process relationships of PCL. Therefore, this study aims to establish a geometry-independent mechanical characterisation of MEX-fabricated PCL by using ASTM-standard compression (D695) and flexural (D790) specimens to eliminate the influence of stent geometry. A central composite design (CCD) based on RSM is implemented to systematically evaluate the effects of T E , v D and M E on the compressive and flexural strength and modulus of PCL. By developing statistically validated response models and identifying parameter conditions that optimise radial- and flexural-analogous behaviours, this work provides a fundamental material-level framework that can serve as a transferable input for future stent-structure optimisation and patient-specific device design. 2.0 Materials and Methods 2.1 Materials and MEX Fabrication PCL filament (Fabbxible Technology) with a diameter of 1.75 mm was used for specimen fabrication. All specimens were produced using a MEX system (Artillery® Genius Pro) equipped with a 0.4 mm extrusion nozzle. Specimen designs were created in CAD software (SolidWorks 2022®) and exported in .stl format for slicing (Ultimaker Cura, version 5.2.2). Three key MEX parameters (T E , v D and M E ) were selected as the experimental factors, and the ranges of these parameters used in this study (Table 1 ) were defined based on a combination of reported values in the literature [ 19 – 22 ] and preliminary processability trials. This broad parameter space was intentionally adopted to encompass the full span of processing conditions previously employed for MEX-fabricated PCL stents, thereby enabling as comprehensive and systematic an identification as possible of the dominant process–property relationships and facilitating the reconciliation of inconsistencies among prior studies. The other process parameters were maintained at the slicing software default settings. No additional post-processing was performed on the specimens after fabrication, in order to preserve the as-fabricated microstructural features induced by the selected process parameters and to isolate their intrinsic effects on mechanical behaviour. This approach enables direct attribution of the measured mechanical responses to variations in MEX processing conditions rather than to secondary surface modification steps. Table 1 The levels of the three key MEX parameters studied. Process Parameter T E (℃) v D (mm/s) M E (%) Low Level 80 5 70 High Level 250 50 150 2.2 Specimen Preparation Two types of standardised solid specimens were prepared in compliance with ASTM D695 and ASTM D790 for compression and flexural testing, respectively. The compression specimens were cylindrical (12.7 mm in diameter and 25.4 mm in height), while the flexural specimens were rectangular bars (127 mm × 12.7 mm × 3.2 mm). To eliminate geometric influences and focus solely on the effects of process parameters, standardised solid specimens were employed in this study instead of the stent-like geometries used previously. 2.3 Experimental Design To systematically evaluate the effects of the selected parameters, a statistical design of experiments approach was adopted. A CCD within the framework of RSM was employed to investigate the combined effects of T E , v D and M E . A face-centred CCD (α = 1) was selected to maintain all factor levels within the feasible operating range, resulting in a total of 17 experimental runs, with three centre-point runs included to monitor experimental stability. Five replicates (n = 5) were produced and examined for each parameter combination. 2.4 Mechanical Testing Mechanical testing was conducted to evaluate the compressive and flexural performance of the fabricated PCL specimens. All tests were performed using a computer-controlled electronic universal testing machine (Shimadzu AGS-X) under ambient laboratory conditions (25°C). Compression testing followed the procedures of ASTM D695, using the cylindrical specimens described in Section 2.2 . The samples were compressed between two parallel plates at a crosshead speed of 1.0 mm/min using a 50 kN load cell, and the test was terminated once 50% strain was reached. The compressive modulus was determined from the initial linear region (3–6% strain). As slight variations in the final termination strain occurred when applying the nominal 50% strain limit to as-fabricated specimens, the stress value at 49.5% strain was used as a consistent reference for compressive strength evaluation across all parameter conditions. Flexural testing was conducted in accordance with ASTM D790, using the rectangular specimens specified in Section 2.2 . Tests were performed in a three-point bending configuration with a support span of 51.2 mm at a crosshead speed of 1.3 mm/min using a 50 kN load cell. The tests were terminated at 5% strain. The flexural modulus was determined from the initial linear region (1–4% strain). Similarly, flexural strength was reported at 4.5% strain to ensure consistent data extraction prior to the strain-controlled termination limit, enabling unbiased comparison across the investigated parameter conditions. 2.5 Microstructural Characterisation Microstructural analysis was performed to examine how MEX process parameters influence the internal morphology of the fabricated PCL specimens. Dedicated specimens were sectioned to expose their cross-sectional surfaces, which were then sputter-coated with a thin layer of platinum using an ion sputter coater (COXEM SPT-20). The coated surfaces were imaged using a tabletop scanning electron microscope (Hitachi TM3000) at an accelerating voltage of 10 kV and a magnification of 100×. The SEM images were used to assess interlayer bonding quality and the presence of internal voids or porosity associated with different processing conditions, as these microstructural features are known to play a critical role in the resulting compressive and flexural behaviour. 2.6 Data Analysis and Optimisation Statistical analyses were performed using statistical software (Minitab®, version 21.4) based on RSM. A second-order (quadratic) regression model was fitted to describe the relationships between T E , v D and M E with the compressive and flexural responses. The model significance was evaluated through ANOVA (p < 0.05). Single- and multi-response optimisation was conducted using the desirability function approach to maximise the compressive- and flexural-related properties. 3.0 Results and Discussion 3.1 Mechanical Behaviour under Compression and Flexure In the present study, T E , v D and M E were selected as the process parameters of interest, as they are widely recognised as the primary MEX variables dominating the effective mechanical response of fabricated parts in the context of PCL-based BRS fabrication [ 19 – 22 ]. Meanwhile, compressive and flexural strength and modulus were adopted as the mechanical evaluation metrics, as they capture the fundamental material responses that govern radial support and deformation resistance in coronary stent applications. Strength reflects the load-bearing capacity before failure, while modulus reflects the stiffness that resists radial and bending deformation—both of which directly underpin a stent’s ability to maintain lumen patency. Although the loading configurations differ, radial and flexural behaviour is fundamentally governed by the intrinsic elastic modulus and strength of the material [ 24 , 42 , 43 ]. Accordingly, optimising these key parameters offers a direct means to enhance the radial- and flexural-load-bearing capability of fabricated PCL at the material level, complementing geometry-based strategies commonly used to improve stent mechanical performance. Based on this framework, a CCD-based RSM was implemented to systematically explore the effects of T E , v D and M E on the compressive and flexural behaviour of MEX-fabricated PCL specimens. The resulting stress–strain responses obtained from ASTM-standard compression and flexural tests are presented in Fig. 1 . Table 2 summarises the complete CCD matrix, together with the corresponding experimentally measured strength and modulus values extracted from the stress–strain curves. Table 2 CCD of RSM used in the DOE. Results of strength and modulus obtained from the PCL compressive and flexural tests are shown. Set Process Parameters Compressive Response Flexural Response T E (℃) v D (mm/s) M E (%) Strength (MPa) Modulus (MPa) Strength (MPa) Modulus (MPa) 1 80 5 70 7.37 ± 1.12 73.39 ± 3.85 7.53 ± 0.52 180.63 ± 11.81 2 250 5 70 7.02 ± 0.95 51.90 ± 9.91 5.67 ± 1.65 133.52 ± 41.67 3 80 50 70 7.48 ± 0.79 60.60 ± 5.84 7.42 ± 0.45 176.00 ± 11.97 4 250 50 70 8.28 ± 0.62 69.02 ± 13.28 4.84 ± 0.49 113.67 ± 11.22 5 80 5 150 29.27 ± 1.65 227.43 ± 14.64 7.50 ± 0.57 175.62 ± 13.65 6 250 5 150 36.38 ± 1.02 233.79 ± 13.49 14.80 ± 0.83 353.78 ± 20.09 7 80 50 150 29.95 ± 1.27 241.78 ± 28.24 12.50 ± 5.30 288.01 ± 128.59 8 250 50 150 39.82 ± 0.44 276.33 ± 21.48 15.67 ± 0.82 375.15 ± 19.74 9 80 27.5 110 25.60 ± 1.36 229.71 ± 13.49 18.05 ± 1.02 431.08 ± 21.82 10 250 27.5 110 27.25 ± 0.95 201.67 ± 8.20 14.80 ± 0.59 351.11 ± 9.75 11 165 5 110 26.28 ± 1.23 209.68 ± 13.08 15.65 ± 0.78 367.96 ± 19.90 12 165 50 110 27.77 ± 0.75 206.70 ± 7.77 15.22 ± 0.39 358.91 ± 10.88 13 165 27.5 70 9.40 ± 0.38 78.67 ± 4.18 6.70 ± 0.83 155.10 ± 21.02 14 165 27.5 150 35.75 ± 0.40 273.67 ± 11.73 17.35 ± 2.39 406.22 ± 58.31 15 165 27.5 110 28.35 ± 0.24 185.20 ± 16.61 18.47 ± 0.48 434.26 ± 11.75 16 165 27.5 110 28.89 ± 0.21 219.62 ± 11.51 17.60 ± 0.59 418.32 ± 15.58 17 165 27.5 110 28.48 ± 0.35 199.05 ± 13.93 16.48 ± 0.45 387.87 ± 11.91 (a) Effects of Extrusion Temperature Figure 2 presents the main effects of T E , v D and M E on the compressive and flexural strength and modulus of the fabricated PCL specimens. With respect to T E , T E generally enhances both compressive and flexural strength, although the responses are non-monotonic across the investigated range. Strength values increase with T E up to an intermediate optimum before slightly declining at higher T E , whereas the elastic modulus exhibits only minor variation, indicating a comparatively weak sensitivity to thermal input. Despite the presence of non-linear trends, the overall influence of T E across the full range from 80 to 250°C remains moderate, with compressive and flexural strength increasing by approximately 15.38% and 3.43%, respectively, while changes in compressive and flexural modulus are limited (0.018% and 3.93%, respectively). These results suggest that T E primarily influences failure-related strength, particularly under compression, rather than elastic response, while further increases in T E beyond an intermediate level provide limited additional benefit. This behaviour is consistent with the thermorheological characteristics of semi-crystalline polymers such as PCL. Increasing T E typically improves melt fluidity and interlayer fusion, promoting more effective load transfer under mechanical loading, whereas excessive thermal input may offset these benefits through material degradation or geometric instability. Similar temperature-dependent strengthening trends have been widely reported for MEX-fabricated thermoplastics including PLA, PETG and high-performance polymers such as polyetheretherketone (PEEK), where enhanced melt mobility and reduced interlayer separation lead to improved mechanical integrity [ 38 , 44 , 45 ]. The present results confirm that this general mechanism also applies to PCL, whose low melting temperature and high viscosity sensitivity render its mechanical performance particularly responsive to thermal conditions during deposition. (b) Effects of Material Deposition Speed Figure 2 also illustrates the main effects of v D on the compressive and flexural strength and modulus of the fabricated PCL specimens. In contrast to T E , the influence of v D on all four mechanical responses is comparatively moderate and exhibits a shallow non-monotonic trend across the investigated range. As v D increases from 5 mm/s, both compressive and flexural strength gradually increase, reaching maximum values at intermediate speeds (≈ 30–35 mm/s), before showing a slight decline at higher v D . A similar response is observed for the corresponding moduli, with only limited variation across the full range. When comparing the extreme conditions, increasing v D from 5 to 50 mm/s results in modest net changes of approximately 5–6% for both the compressive and flexural strength and modulus, indicating that v D exerts a secondary influence on mechanical performance relative to other process parameters. The presence of an intermediate optimal v D suggests a balance between deposition continuity and thermal–temporal interaction during extrusion. At low v D , prolonged residence time may promote thermal dissipation and material over-softening, while at excessively high v D , insufficient inter-path contact time may limit interlayer consolidation. The relatively flat response profiles observed here indicate that PCL exhibits a broad processing window with respect to v D , within which mechanical properties remain comparatively stable. Although prior studies on materials such as PLA, PETG and PEEK frequently report monotonic reductions in strength with increasing v D [ 37 , 38 , 45 ], the present results highlight that the rate sensitivity of PCL is less pronounced. This discrepancy is likely associated with the low melting temperature and high thermal diffusivity of PCL, which mitigate the adverse effects of reduced deposition time at elevated v D . (c) Effects of Extrusion Multiplier Figure 2 further illustrates the main effects of M E on the compressive and flexural strength and modulus of the fabricated PCL specimens. Among the investigated process parameters, M E exerts the most pronounced influence on all four mechanical responses, with substantially larger variations observed across the studied range compared with T E and v D . As M E increases, compressive strength and modulus increase monotonically, indicating a strong sensitivity of compressive load-bearing capacity to deposited material volume. In contrast, the flexural responses exhibit a non-monotonic dependence on M E , increasing up to an intermediate optimum before declining at higher M E . When evaluated across the full M E range from 70% to 150%, the overall changes are substantial, with compressive strength and modulus increasing by approximately 271% and 239%, respectively, while flexural strength and modulus increase by approximately 83% and 84%. These magnitudes are markedly larger than those associated with T E and v D , confirming that M E is the dominant parameter governing the mechanical behaviour of MEX-fabricated PCL within the investigated design space. The pronounced sensitivity to M E underscores the importance of deposited material volume in governing internal porosity, inter-bead contact and effective load-bearing cross-sectional area. Although direct investigations of M E in MEX are limited, similar mechanisms have been widely discussed in studies on infill density, where increased material content reduces void fraction and enhances stress-transfer continuity [ 37 , 38 , 46 , 47 ]. In this context, the present findings suggest that M E serves as an effective process-level control of material volume, while excessive flow may compromise geometric fidelity and bending stress distribution, leading to reduced flexural performance at high M E . (d) Statistical Significance and Relative Influence of Process Parameters The statistical significance and relative influence of T E , v D and M E were evaluated using ANOVA based on the developed response surface models. Separate analyses were conducted for compressive strength, compressive modulus, flexural strength and flexural modulus, and the key statistical metrics are summarised in Table 3 . For the compressive responses, M E is identified as the overwhelmingly dominant parameter. In the case of compressive strength, M E exhibits an exceptionally high F-value (8760.63, p < 0.001) and accounts for 97.67% of the total contribution among the main factors, whereas T E and v D contribute only marginally (2.05% and 0.28%, respectively), despite both being statistically significant (p < 0.001). A similar trend is observed for compressive modulus, where M E remains the sole statistically significant parameter (p < 0.001) and contributes 99.60% of the total variation, while the effects of T E and v D are negligible. A comparable dominance of M E is also evident in the flexural responses. For flexural strength, M E shows the highest F-value (170.10, p 0.05). Likewise, for flexural modulus, M E again governs the response, contributing 97.81% with a statistically significant effect (p < 0.001), while the contributions of T E and v D remain minor and statistically insignificant. These statistical trends are consistent with the main effect plots in Fig. 2 , where variations in M E induce substantially larger response amplitudes than those associated with T E and v D across all mechanical metrics. Thus, the ANOVA results demonstrate that, within the investigated design space, the mechanical behaviour of MEX-fabricated PCL is predominantly governed by M E , irrespective of the loading mode. In contrast, T E and v D play secondary roles, with limited contributions and inconsistent statistical significance across responses. This finding highlights the critical importance of volumetric material deposition in controlling load-bearing capacity and elastic modulus, and motivates a microstructural examination of how variations in M E influence void distribution, filament bonding and interlayer morphology. Table 3 ANOVA results showing F-values, p -values and percentage contribution of T E , v D and M E to compressive strength, compressive modulus, flexural strength and flexural modulus based on the response surface models. Response Factor F-value p-value Contribution (%) Compressive strength T E 184.22 0.000 2.05 v D 24.74 0.000 0.28 M E 8760.63 0.000 97.67 Compressive modulus T E 0.00 0.993 0.00 v D 6.48 0.013 0.40 M E 1614.47 0.000 99.60 Flexural strength T E 1.04 0.311 0.60 v D 2.72 0.103 1.57 M E 170.1 0.000 97.84 Flexural modulus T E 1.31 0.255 0.80 v D 2.29 0.134 1.39 M E 160.97 0.000 97.81 3.2 Microstructural Evidence and Mechanistic Interpretation Cross-sectional SEM imaging at 100× magnification was employed to qualitatively assess consolidation-related morphological features associated with the parameter-dependent mechanical responses discussed in Section 3.1 . At this magnification, the analysis focuses on material continuity, underfilled regions, void-like features and inter-layer consolidation, rather than fine-scale fracture mechanisms. Extreme parameter levels (low and high T E , v D and M E ) were selected to maximise observable morphological contrast and to elucidate the dominant mechanisms governing mechanical performance in MEX-fabricated PCL. For T E , specimens fabricated at low T E (80°C) and high T E (250°C) exhibit broadly similar macroscopic surface morphologies, characterised by relatively smooth cross-sections with limited large-scale voids (Fig. 3 a, b and Fig. 4 a, b). However, low-T E samples occasionally display subtle discontinuities and less uniform material regions, consistent with restricted melt mobility and reduced inter-road fusion. In contrast, high-T E samples show more continuous and homogeneous cross-sections, indicative of improved melt flow and consolidation. The modest nature of these morphological differences aligns with the comparatively weak sensitivity of elastic modulus to T E and the non-monotonic strength trends observed in Section 3.1 . Variations in v D similarly produce only subtle changes in cross-sectional morphology at the examined scale (Fig. 3 c, d and Fig. 4 c, d). Low-v D specimens exhibit relatively uniform material distribution, while high-v D conditions show slightly increased surface irregularity, reflecting reduced interaction time between deposited filaments. The absence of pronounced microstructural disruption supports the statistical findings that v D exerts a secondary influence on both compressive and flexural responses within the investigated range. In contrast, changes in M E give rise to pronounced and readily observable morphological differences. Low-M E specimens (70%) display clear underfilled regions, sparse material packing and prominent void-like features within the cross-section (Fig. 3 e and Fig. 4 e), indicative of insufficient volumetric material delivery. Conversely, high-M E specimens (150%) exhibit dense, continuous material regions with markedly reduced defect prevalence (Fig. 3 f and Fig. 4 f). These consolidation-related differences directly support the strong and dominant influence of M E on both strength and modulus identified in the ANOVA and main effect analyses. Taken together, the SEM observations provide a coherent microstructural basis for the statistical significance trends reported in Section 3.1 . While T E and v D primarily modulate melt mobility and deposition stability with relatively subtle morphological manifestations, M E governs volumetric packing efficiency and defect suppression, emerging as the principal determinant of mechanical integrity in MEX-fabricated PCL. The convergence of morphological and statistical evidence confirms that consolidation quality, controlled predominantly by material flow rate, underpins the observed mechanical behaviour. 3.3 Statistical Modelling, Optimisation and Relevance to Stent Design Building on the mechanistic insights established in Sections 3.1 and 3.2 , this section translates the identified parameter–microstructure–mechanics relationships into quantitative predictive models and clinically relevant optimisation frameworks. Due to the fact that clinical implantation does not require a single mechanical profile, but rather a context-dependent balance between radial strength and flexural compliance, three optimisation pathways were defined in this study: (1) A compression-focused optimisation prioritises maximal compressive strength and modulus to represent scenarios where enhanced radial support is required. (2) A flexural-focused optimisation targets high flexural strength while minimising flexural modulus, corresponding to applications demanding improved conformability and resistance to fracture under bending. (3) In addition, a multi-objective optimisation was implemented to balance all four mechanical responses simultaneously, explicitly capturing the trade-off between radial rigidity and vascular compliance that underpins contemporary stent design. Regression models obtained from RSM ( Eqs. 1–4 ) were used to generate predictive relationships between T E , v D and M E and the resulting mechanical responses. Table 4 summarises the optimised parameter sets obtained under different optimisation strategies. Although the optimised points coincided with previously tested design points, their corresponding experimental responses were used to validate the model predictions. The small prediction errors observed across all responses confirm that the regression models provide reliable estimates of PCL mechanical behaviour within the investigated parameter space. Compressive strength (MPa) = -47.14 + 0.0190 T E + 0.0495 v D + 0.9597 M E − 0.000213 T E * T E − 0.001866 v D * v D − 0.003370 M E * M E + 0.000255 T E * v D + 0.000608 T E * M E + 0.000383 v D * M E (1) Compressive modulus (MPa) = -286.1–0.323 T E − 0.356 v D + 7.204 M E + 0.000000 T E * T E − 0.01481 v D * v D − 0.02470 M E * M E + 0.00380 T E * v D + 0.001984 T E * M E + 0.00730 v D * M E (2) Flexural strength (MPa) = -28.14–0.0083 T E + 0.1717 v D + 0.6987 M E − 0.000121 T E * T E − 0.00369 v D * v D − 0.003300 M E * M E − 0.000317 T E * v D + 0.000549 T E * M E + 0.000944 v D * M E (3) Flexural modulus (MPa) = -656–0.461 T E + 4.02 v D + 16.74 M E − 0.00235 T E * T E − 0.0881 v D * v D − 0.07962 M E * M E − 0.00694 T E * v D + 0.01378 T E * M E + 0.02198 v D * M E (4) Table 4 Optimised MEX process parameter sets obtained under different optimisation strategies, together with RSM-predicted values, experimentally measured responses and corresponding prediction errors for compressive and flexural properties of PCL. No.* T E (℃) v D (mm/s) M E (%) Optimisation results Optimised responses* Predicted value (MPa) Actual value (MPa) Error (%) 1 250 50 150 σ C 39.062 39.82 ± 0.44 1.90 E C 279.81 276.33 ± 21.48 1.26 2 80 50 150 σ F 12.712 12.50 ± 5.30 1.70 E F 294.5 288.01 ± 128.59 2.25 3 250 50 150 σ C 39.062 39.82 ± 0.44 1.90 E C 279.81 276.33 ± 21.48 1.26 σ F 15.787 15.67 ± 0.82 0.75 E F 376.8 375.15 ± 19.74 0.44 *No. indicate the optimisation strategies: 1 is compression-focused, 2 is flexural-focused and 3 is a multi-objective optimisation strategy. *σ C refers to compressive strength, E C refers to compressive modulus, σ F refers to flexural strength, E F refers to flexural modulus. It should be emphasised that the optimised parameter sets identified in this study represent material-level extrema within the investigated design space rather than directly applicable processing conditions for stent fabrication. In particular, although a high M E (150%) maximises compressive and flexural performance by enhancing volumetric material delivery and consolidation, such conditions are expected to compromise dimensional fidelity and surface quality, especially for fine stent struts. Similarly, despite the ability to fabricate specimens at elevated T E (250°C) with enhanced strength, the observed non-monotonic dependence of mechanical responses on T E suggests that excessive thermal input may offset consolidation benefits through degradation or geometric instability. Accordingly, the present optimisation defines an upper bound of achievable material-level mechanical performance under MEX processing, while future multi-objective optimisation should integrate mechanical, morphological and biological performance requirements to identify clinically viable processing windows. To contextualise the optimised mechanical responses, the results were compared against reported ranges for solid PCL specimens fabricated using different manufacturing methods and tested under standardised compression or flexural configurations. Published compressive moduli for bulk PCL typically fall within the range of 300–325 MPa, with compressive strengths reported in the range of 34–39 MPa for injection-moulded and SLS-fabricated specimens [ 31 , 32 , 48 ]. The compression-optimised condition identified in the present study yields compressive modulus and strength values approaching the upper region of these reported ranges. A similarly broad distribution is evident in reported flexural properties of PCL, with flexural strength values spanning approximately 11–24 MPa and flexural moduli ranging from 109 to 423 MPa, largely depending on manufacturing process, molecular weight and porosity [ 49 – 53 ]. The flexural-optimised condition obtained in this work likewise falls well within the broad envelope defined by existing PCL reports. Considering that alternative manufacturing routes, such as SLS and injection moulding, generally produce highly consolidated structures with minimal void content, the ability of MEX-fabricated PCL to attain comparable modulus and strength after parameter optimisation underscores the substantial influence of extrusion-based processing conditions on material consolidation and load transfer. As the compressive and flexural strength in this study were evaluated at strain levels of 49.5% and 4.5%, respectively (as defined in Section 2.4 ), comparisons with literature values reported at nominally 50% (compression) and 5% (flexure) strain are intended to indicate general trends and ranges rather than exact numerical equivalence. Notably, the multi-objective condition also achieved a balanced mechanical response across both compressive and flexural loading, indicating that the mechanical behaviour of MEX-fabricated PCL can be systematically tuned through process-parameter selection rather than being confined to a narrow range associated with default fabrication settings. Although stent-level radial and flexural performance arise from the combined contributions of material properties and geometric design [ 28 ], the present study intentionally isolates the material component by characterising PCL under standardised ASTM compression and flexural testing. By excluding geometry-dependent effects such as strut thickness, cell topology and hinge mechanics, this approach provides a generalisable assessment of how MEX process parameters regulate the intrinsic modulus and strength of the polymer itself. These material-level properties correspond to the modulus-dependent term in stent mechanical descriptors such as radial stiffness and bending compliance [ 54 ], and therefore define the baseline upon which any specific stent geometry must operate. When viewed within this material-centric framework, the optimised PCL responses can be positioned relative to established BRS backbone materials. Commercial BRS platforms such as Absorb, DESolve and MeRes100 predominantly employ poly(L-lactic acid) (PLLA), which typically exhibits moduli on the order of 2–4 GPa and strengths of 50–70 MPa [ 42 , 55 , 56 ]. While these values reflect bulk material properties rather than assembled stent performance, they define a widely accepted strength and modulus hierarchy for stent backbones. The optimised PCL obtained in the present study exhibits compressive and flexural moduli in the sub-GPa range, positioning it well below PLLA but above highly compliant soft polymers, and firmly within a low-modulus domain associated with next-generation flexible stent concepts [ 57 ]. From a design perspective, the three optimisation pathways delineate distinct material states that map directly onto clinically relevant deployment scenarios. The compression-optimised condition represents a stiffer, higher load-bearing material state suitable for applications where enhanced radial support is required, such as moderately calcified or recoil-prone lesions. In contrast, the flexural-optimised condition corresponds to a more compliant material state, favouring navigation through tortuous or highly curved vessels. The multi-objective solution occupies an intermediate region of the design space, reflecting the practical compromise between radial rigidity and vascular conformability inherent to modern stent design. Crucially, these material states were achieved solely through process-parameter modulation, demonstrating that MEX-fabricated PCL spans a clinically meaningful mechanical spectrum rather than possessing a single intrinsic strength and modulus profile. This tunable material window provides a foundational design space upon which future geometry-driven optimisation strategies may be layered. Therefore, the optimised PCL windows identified in the present study do not function as final stent specifications but as strength and modulus regimes that future stent architectures may selectively leverage depending on the targeted lesion environment. This establishes a direct and clinically grounded link between MEX parameter selection, material-level mechanics and the broader performance envelope required of next-generation BRS. 4.0 Conclusion This study elucidated the process–structure–property relationships governing the compressive and flexural behaviour of MEX-fabricated PCL, establishing a quantitative, material-level framework relevant to BRS development. Statistical modelling coupled with microstructural observations identified M E as the primary determinant of mechanical performance, while T E and v D acted as secondary modulators of consolidation quality. These findings demonstrate that the mechanical response of MEX-fabricated PCL is governed predominantly by volumetric material delivery rather than thermal or kinematic parameters alone, defining a tunable mechanical window that can be systematically accessed through process optimisation. By decoupling material behaviour from structural geometry, this work provides a robust baseline for future stent-level design and geometry-driven optimisation strategies. Declarations Conflict of interests The authors have no relevant financial or non-financial interests to disclose. Funding information This work was funded by the Fundamental Research Grant Scheme (FRGS) under a grant number of FRGS/1/2021/TK0/UNIMAP/02/19 from Ministry of Higher Education Malaysia. Availability of data and materials The datasets generated and analysed during the current study are included in this article. Additional data are available from the corresponding author on request. References Okereke MI, Khalaj R, Tabriz AG, et al (2023) Development of 3D printable bioresorbable drug eluting coronary stents: An experimental and computational investigation. J Drug Deliv Sci Technol 79:103952. https://doi.org/10.1016/j.jddst.2022.103952 Wu H, Yang L, Luo R, et al (2024) A drug-free cardiovascular stent functionalized with tailored collagen supports in-situ healing of vascular tissues. Nat Commun 15:735. https://doi.org/10.1038/s41467-024-44902-2 Dinc R, Ekingen E (2025) Biodegradable Stents in the Treatment of Arterial Stenosis. J Clin Med 14:532. https://doi.org/10.3390/jcm14020532 Xu J, Yang J, Huang N, et al (2016) Mechanical response of cardiovascular stents under vascular dynamic bending. Biomed Eng Online 15:21. https://doi.org/10.1186/s12938-016-0135-8 Ahadi F, Azadi M, Biglari M, et al (2023) Evaluation of coronary stents: A review of types, materials, processing techniques, design, and problems. Heliyon 9:e13575. https://doi.org/10.1016/j.heliyon.2023.e13575 Pan C, Han Y, Lu J (2021) Structural design of vascular stents: A review. Micromachines (Basel). 12 Fang S (2024) Assessing the functional mechanical properties of polycaprolactone stents post-processed by ultrasonic strengthening. J Manuf Process 118:154–162. https://doi.org/10.1016/j.jmapro.2024.03.052 Yasmin F, Vafadar A, Tolouei‐Rad M (2025) Application of Additive Manufacturing in the Development of Polymeric Bioresorbable Cardiovascular Stents: A Review. Adv Mater Technol 10:. https://doi.org/10.1002/admt.202400210 Gallinoro E, Almendarez M, Alvarez-Velasco R, et al (2022) Bioresorbable stents: Is the game over? Int J Cardiol 361:20–28. https://doi.org/10.1016/j.ijcard.2022.05.024 Kapoor A, Jepson N, Bressloff NW, et al (2024) The road to the ideal stent: A review of stent design optimisation methods, findings, and opportunities. Mater Des 237:112556. https://doi.org/10.1016/j.matdes.2023.112556 Tidwell K, Harriet S, Barot V, et al (2021) Design and Analysis of a Biodegradable Polycaprolactone Flow Diverting Stent for Brain Aneurysms. Bioengineering 8:183. https://doi.org/10.3390/bioengineering8110183 Sousa AM, Amaro AM, Piedade AP (2022) 3D Printing of Polymeric Bioresorbable Stents: A Strategy to Improve Both Cellular Compatibility and Mechanical Properties. Polymers (Basel) 2022:1099. https://doi.org/10.3390/polym Zhao J, Song G, Zhao Q, et al (2023) Development of three‐dimensionally printed vascular stents of bioresorbable poly(l‐lactide‐co‐caprolactone). J Biomed Mater Res B Appl Biomater 111:656–664. https://doi.org/10.1002/jbm.b.35184 Jeong Y-J, Choi B, Kim S, et al (2024) Fully bioresorbable, all-polymer-based, 3D-printed scaffolds with prolonged radiopacity and enhanced durability. Chemical Engineering Journal 494:152851. https://doi.org/10.1016/j.cej.2024.152851 Szymczyk-Ziółkowska P, Łabowska MB, Detyna J, et al (2020) A review of fabrication polymer scaffolds for biomedical applications using additive manufacturing techniques. Biocybern. Biomed. Eng. 40:624–638 Jiang W, Zhao W, Zhou T, et al (2022) A Review on Manufacturing and Post-Processing Technology of Vascular Stents. Micromachines (Basel). 13 Li Y, Shi Y, Lu Y, et al (2023) Additive manufacturing of vascular stents. Acta Biomater. 167:16–37 Patel R, Jani S, Joshi A (2023) Review on multi-objective optimization of FDM process parameters for composite materials. International Journal on Interactive Design and Manufacturing (IJIDeM) 17:2115–2125. https://doi.org/10.1007/s12008-022-01111-9 Guerra AJ, Ciurana J (2018) 3D-printed bioabsordable polycaprolactone stent: The effect of process parameters on its physical features. Mater Des 137:430–437. https://doi.org/10.1016/j.matdes.2017.10.045 Wang C, Zhang L, Fang Y, Sun W (2021) Design, Characterization, and 3D Printing of Cardiovascular Stents with Zero Poisson’s Ratio in Longitudinal Deformation. Engineering 7:979–990. https://doi.org/10.1016/j.eng.2020.02.013 Singh J, Singh G, Pandey PM (2021) Multi-objective optimization of solvent cast 3D printing process parameters for fabrication of biodegradable composite stents. International Journal of Advanced Manufacturing Technology 115:3945–3964. https://doi.org/10.1007/s00170-021-07423-6 Kandi R, Pandey PM (2021) Statistical modelling and optimization of print quality and mechanical properties of customized tubular scaffolds fabricated using solvent-based extrusion 3D printing process. Proc Inst Mech Eng H 235:1421–1438. https://doi.org/10.1177/09544119211032012 Brunelli M, Perrault CM, Lacroix D (2017) Mechanical response of 3D Insert® PCL to compression. J Mech Behav Biomed Mater 65:478–489. https://doi.org/10.1016/j.jmbbm.2016.08.038 Wang Q, Fang G, Zhao Y-H, Zhou J (2018) Improvement of Mechanical Performance of Bioresorbable Magnesium Alloy Coronary Artery Stents through Stent Pattern Redesign. Applied Sciences 8:2461. https://doi.org/10.3390/app8122461 Wei Y, Wang M, Zhao D, et al (2019) Structural Design of Mechanical Property for Biodegradable Polymeric Stent. Advances in Materials Science and Engineering 2019:1–14. https://doi.org/10.1155/2019/2960435 Samant S, Wu W, Zhao S, et al (2021) Computational and experimental mechanical performance of a new everolimus-eluting stent purpose-built for left main interventions. Sci Rep 11:8728. https://doi.org/10.1038/s41598-021-87908-2 Wang Y, Wu H, Fan S, et al (2023) Structure design and mechanical performance analysis of three kinds of bioresorbable poly-lactic acid (PLA) stents. Comput Methods Biomech Biomed Engin 26:25–37. https://doi.org/10.1080/10255842.2022.2045485 Carbonaro D, Ferro N, Mezzadri F, et al (2024) Easy-to-use formulations based on the homogenization theory for vascular stent design and mechanical characterization. Comput Methods Programs Biomed 257:108467. https://doi.org/10.1016/j.cmpb.2024.108467 Wang L, Jiao L, Pang S, et al (2021) The development of design and manufacture techniques for bioresorbable coronary artery stents. Micromachines (Basel) 12:. https://doi.org/10.3390/mi12080990 Bai C, Feng X, Lan L, et al (2025) Recent advances and perspectives in bioresorbable metal coronary drug-eluting stents. Biomedical Materials 20:032001. https://doi.org/10.1088/1748-605X/adc058 Eshraghi S, Das S (2010) Mechanical and microstructural properties of polycaprolactone scaffolds with one-dimensional, two-dimensional, and three-dimensional orthogonally oriented porous architectures produced by selective laser sintering. Acta Biomater 6:2467–2476. https://doi.org/10.1016/j.actbio.2010.02.002 Eshraghi S, Das S (2012) Micromechanical finite-element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone–hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering. Acta Biomater 8:3138–3143. https://doi.org/10.1016/j.actbio.2012.04.022 Alemán‐Domínguez ME, Giusto E, Ortega Z, et al (2019) Three‐dimensional printed polycaprolactone‐microcrystalline cellulose scaffolds. J Biomed Mater Res B Appl Biomater 107:521–528. https://doi.org/10.1002/jbm.b.34142 Wang S, Ma Y, Deng Z, et al (2020) Effects of fused deposition modeling process parameters on tensile, dynamic mechanical properties of 3D printed polylactic acid materials. Polym Test 86:106483. https://doi.org/10.1016/j.polymertesting.2020.106483 Hsueh M-H, Lai C-J, Wang S-H, et al (2021) Effect of Printing Parameters on the Thermal and Mechanical Properties of 3D-Printed PLA and PETG, Using Fused Deposition Modeling. Polymers (Basel) 13:1758. https://doi.org/10.3390/polym13111758 Kamaal M, Anas M, Rastogi H, et al (2021) Effect of FDM process parameters on mechanical properties of 3D-printed carbon fibre–PLA composite. Progress in Additive Manufacturing 6:63–69. https://doi.org/10.1007/s40964-020-00145-3 Al-Tamimi AA, Pandžić A, Kadrić E (2023) Investigation and Prediction of Tensile, Flexural, and Compressive Properties of Tough PLA Material Using Definitive Screening Design. Polymers (Basel) 15:4169. https://doi.org/10.3390/polym15204169 Valvez S, Silva AP, Reis PNB (2022) Optimization of Printing Parameters to Maximize the Mechanical Properties of 3D-Printed PETG-Based Parts. Polymers (Basel) 14:2564. https://doi.org/10.3390/polym14132564 He S, Chen Q, Li Z (2025) Influence of Stent Structure on Mechanical and Degradation Properties of Poly (Lactic Acid) Vascular Stent. J Funct Biomater 16:248. https://doi.org/10.3390/jfb16070248 Noad RL, Hanratty CG, Walsh SJ (2011) Clinical Impact of Stent Design. Interventional Cardiology Review 9:89. https://doi.org/10.15420/icr.2011.9.2.89 Park J, Kwak HS, Kim J-W (2020) Bench-Top Comparison of Three Different Types of Stents Used for Treatment of Intracranial Atherosclerotic Stenosis. Neurointervention 15:117–125. https://doi.org/10.5469/neuroint.2020.00248 Ang HY, Huang YY, Lim ST, et al (2017) Mechanical behavior of polymer-based vs. metallic-based bioresorbable stents. J Thorac Dis 9:S923–S934. https://doi.org/10.21037/jtd.2017.06.30 Gautam AJ, Wairkar S (2024) 3D-printed bioresorbable vascular stents: emerging frontiers in personalized cardiac care. Polymer Bulletin 81:10533–10560. https://doi.org/10.1007/s00289-024-05237-6 Tang C, Liu J, Yang Y, et al (2020) Effect of process parameters on mechanical properties of 3D printed PLA lattice structures. Composites Part C: Open Access 3:. https://doi.org/10.1016/j.jcomc.2020.100076 Wang P, Zou B, Ding S, et al (2021) Effects of FDM-3D printing parameters on mechanical properties and microstructure of CF/PEEK and GF/PEEK. Chinese Journal of Aeronautics 34:236–246. https://doi.org/10.1016/j.cja.2020.05.040 Fernandez-Vicente M, Calle W, Ferrandiz S, Conejero A (2016) Effect of Infill Parameters on Tensile Mechanical Behavior in Desktop 3D Printing. 3D Print Addit Manuf 3:183–192. https://doi.org/10.1089/3dp.2015.0036 Samykano M, Selvamani SK, Kadirgama K, et al (2019) Mechanical property of FDM printed ABS: influence of printing parameters. The International Journal of Advanced Manufacturing Technology 102:2779–2796. https://doi.org/10.1007/s00170-019-03313-0 Sagar A, Nehme C, Saigal A, James TP (2020) Stress–Strain Relationship of Polycaprolactone in Liquid Nitrogen for Finite Element Simulation of Cryogenic Micropunching Process. J Eng Sci Med Diagn Ther 3:. https://doi.org/10.1115/1.4047461 Abdul Haq RH, Saidin W, Mat UW (2013) Improvement of Mechanical Properties of Polycaprolactone (PCL) by Addition of Nano-Montmorillonite (MMT) and Hydroxyapatite (HA). Applied Mechanics and Materials 315:815–819. https://doi.org/10.4028/www.scientific.net/AMM.315.815 Jiao Z, Luo B, Xiang S, et al (2019) 3D printing of HA / PCL composite tissue engineering scaffolds. Advanced Industrial and Engineering Polymer Research 2:196–202. https://doi.org/10.1016/j.aiepr.2019.09.003 Siqueira DD, Luna CBB, Araújo EM, et al (2019) Biocomposites based on PCL and macaiba fiber. Detailed characterization of main properties. Mater Res Express 6:095335. https://doi.org/10.1088/2053-1591/ab3496 Abbas A, Park EJ, Guo J, et al (2024) Performance of bioresorbable peptide incorporated polymers produced for fused deposition modelling (FDM). Next Materials 5:100223. https://doi.org/10.1016/j.nxmate.2024.100223 Toorani S, Sohrabian M, Sameezadeh M, Khalafi M (2025) Optimized Fabrication and Enhanced Flexural Properties of PCL/F-BG Nanocomposites for Hard Tissue Engineering. J Polym Environ 33:5130–5148. https://doi.org/10.1007/s10924-025-03710-5 Brand M, Sharon N (2025) Analytical Modeling and Validation of Radial Stiffness in Zigzag‐Shaped Stents: Experimental and Numerical Approaches. J Biomed Mater Res B Appl Biomater 113:. https://doi.org/10.1002/jbm.b.35574 Katagiri Y, Stone G, Onuma Y, Serruys P (2017) State of the art: the inception, advent and future of fully bioresorbable scaffolds. EuroIntervention 13:734–750. https://doi.org/10.4244/EIJ-D-17-00499 Farhan M, Hasan G, Sobhi A, et al (2025) Bioresorbable scaffolds advances, challenges, and future directions. Annals of Medicine & Surgery 87:4173–4183. https://doi.org/10.1097/MS9.0000000000003424 Xu D, Harvey T, Begiristain E, et al (2022) Measuring the elastic modulus of soft biomaterials using nanoindentation. J Mech Behav Biomed Mater 133:105329. https://doi.org/10.1016/j.jmbbm.2022.105329 Supplementary Files GraphicalAbstract.pdf Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 18 Mar, 2026 Reviewers invited by journal 18 Mar, 2026 Editor assigned by journal 17 Mar, 2026 First submitted to journal 15 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9089947","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":608261177,"identity":"0d937a07-9909-4e07-9059-c281f793bedf","order_by":0,"name":"Kuang Yee Ng","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAElEQVRIiWNgGAWjYBACCRiDTf5h44MPIAY7sVr4GZIPG84AaWEmVotkQ1qaMA+IRUiL5IzkZw+/ttnIGRw4Y8Zs82ubPB8zA+OHjzm4tUhLpJkby7alGRsc7DF7nNt327CNmYFZcuY23FrkJBLMpCXbDiduOMxjbpzbc5sRqIWNmRevlvRvQC3/6zcc4zGTtuy5bU9Qi7REjpnkx7YDCZI9bGnSDD9uJxLUItnzpkya4VyyYb8E82HD3obbyW3MjM14/SJxPH2b5I8yO3k2CcbGBz/+3Lad39588MNHPFpAgJmXDcpibAOTDfjVg5T8+ANj/sGnbhSMglEwCkYqAAAOeU9B8McP+AAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-8679-4360","institution":"University Malaysia Perlis: Universiti Malaysia Perlis","correspondingAuthor":true,"prefix":"","firstName":"Kuang","middleName":"Yee","lastName":"Ng","suffix":""},{"id":608261178,"identity":"f07808b1-6dfc-4237-8232-40cb1c8ac44c","order_by":1,"name":"Noorhafiza Muhammad","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Noorhafiza","middleName":"","lastName":"Muhammad","suffix":""},{"id":608261179,"identity":"b9751af7-8cf1-483c-bcee-97ce0c6e31da","order_by":2,"name":"Siti Noor Fazliah Mohd Noor","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Siti","middleName":"Noor Fazliah Mohd","lastName":"Noor","suffix":""},{"id":608261180,"identity":"27c7ebc7-caca-447d-8bb0-fe308a6c4fd0","order_by":3,"name":"Mohd Shuhidan Saleh","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Mohd","middleName":"Shuhidan","lastName":"Saleh","suffix":""},{"id":608261181,"identity":"5bb8c6c8-628d-48df-88f9-e3c8c75ab060","order_by":4,"name":"Kamalakanta Muduli","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Kamalakanta","middleName":"","lastName":"Muduli","suffix":""}],"badges":[],"createdAt":"2026-03-11 04:59:01","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9089947/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9089947/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105198177,"identity":"abee7b7f-b558-4a7d-aeb3-29265a79cd6e","added_by":"auto","created_at":"2026-03-23 10:42:21","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":76766,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative stress–strain responses of MEX-fabricated PCL specimens under (a) compression and (b) flexure. Each curve corresponds to a distinct process parameter set (Set 1–Set 17) generated using the CCD-based response surface design.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9089947/v1/7b2889336fa536e0786f6936.png"},{"id":105198193,"identity":"70463279-de19-4d22-bd87-d105465c92a8","added_by":"auto","created_at":"2026-03-23 10:42:24","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":64274,"visible":true,"origin":"","legend":"\u003cp\u003eMain effect plots of T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE \u003c/sub\u003eon (a) compressive strength, (b) compressive modulus, (c) flexural strength and (d) flexural modulus.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9089947/v1/7154f30753c2e58380c7d528.png"},{"id":105198191,"identity":"d78e71a1-7d75-4e22-b26a-8d55f17935c1","added_by":"auto","created_at":"2026-03-23 10:42:24","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":581895,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative cross-sectional SEM micrographs of MEX-fabricated PCL specimens for compression testing acquired at 100× magnification, illustrating the effects of extreme process parameters on consolidation-related morphology. (a) Low T\u003csub\u003eE\u003c/sub\u003e (80 °C); (b) high T\u003csub\u003eE\u003c/sub\u003e (250 °C); (c) low v\u003csub\u003eD\u003c/sub\u003e (5 mm/s); (d) high v\u003csub\u003eD\u003c/sub\u003e (50 mm/s); (e) low M\u003csub\u003eE\u003c/sub\u003e (70%); and (f) high M\u003csub\u003eE\u003c/sub\u003e (150%).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9089947/v1/7e627427666a75463cecf549.png"},{"id":105198140,"identity":"58f8eee8-5dde-4631-b97c-20598f8417fc","added_by":"auto","created_at":"2026-03-23 10:42:04","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":567982,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative cross-sectional SEM micrographs of MEX-fabricated PCL specimens for flexural testing acquired at 100× magnification, illustrating the effects of extreme process parameters on consolidation-related morphology. (a) Low T\u003csub\u003eE\u003c/sub\u003e (80 °C); (b) high T\u003csub\u003eE\u003c/sub\u003e (250 °C); (c) low v\u003csub\u003eD\u003c/sub\u003e (5 mm/s); (d) high v\u003csub\u003eD\u003c/sub\u003e (50 mm/s); (e) low M\u003csub\u003eE\u003c/sub\u003e (70%); and (f) high M\u003csub\u003eE\u003c/sub\u003e (150%).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-9089947/v1/cf3bd16c4713417384576fe1.png"},{"id":105198319,"identity":"bf5416a0-fe1a-4bbf-ab69-93f0a6aa7819","added_by":"auto","created_at":"2026-03-23 10:43:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2536625,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9089947/v1/135858b2-b86b-4ee2-b7b2-6894a3a44f81.pdf"},{"id":105198131,"identity":"11dff660-8487-42e1-91de-13bf5fbe36e4","added_by":"auto","created_at":"2026-03-23 10:42:02","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":84435,"visible":true,"origin":"","legend":"","description":"","filename":"GraphicalAbstract.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9089947/v1/229cb5bfacb0ed2bca948ea7.pdf"}],"financialInterests":"","formattedTitle":"Process–Property Relationships and Mechanical Tunability of MEX-Fabricated Polycaprolactone for Bioresorbable Stent Materials","fulltext":[{"header":"1.0 Introduction","content":"\u003cp\u003eCoronary artery disease (CAD) remains one of the leading causes of morbidity worldwide, and vascular stents have become an essential intervention to restore luminal patency [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Once deployed, a stent must withstand a complex mechanical environment, including continuous radial compression from vascular recoil and pulsatile blood pressure, as well as significant bending deformation during crimping, delivery and navigation through tortuous coronary anatomy [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. These loading conditions place stringent mechanical requirements on stent materials and structures, necessitating sufficient radial strength to resist collapse while simultaneously providing adequate flexural flexibility to ensure trackability and conformability within curved vessels [\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Achieving an optimal balance between these mechanical demands is fundamental to the performance and long-term reliability of coronary stents.\u003c/p\u003e \u003cp\u003eTo meet these demanding mechanical requirements, increasing attention has turned toward bioresorbable materials and advanced fabrication strategies for bioresorbable stents (BRS). Such stents provide temporary mechanical support and gradually degrade over time, thereby mitigating the long-term complications associated with permanent metallic implants [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Among existing bioresorbable polymers, polycaprolactone (PCL) stands out as an attractive candidate due to its excellent biocompatibility and biodegradability, favourable flexibility and ductility and history of Food and Drug Administration (FDA) approval for use in implantable medical devices [\u003cspan additionalcitationids=\"CR12 CR13\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Concurrently, the growing adoption of additive manufacturing has positioned material extrusion (MEX) as a promising technique for producing patient-specific stents, offering precise geometric control and on-demand customisation [\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. However, the mechanical performance of MEX-fabricated components is highly sensitive to process parameters, leading to significant variations in the resulting material behaviour [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Accordingly, it is crucial to determine how MEX process parameters affect the inherent mechanical properties of PCL to ensure the mechanical performance of the fabricated stent.\u003c/p\u003e \u003cp\u003eRecent studies have increasingly examined how MEX process parameters influence the mechanical behaviour of PCL-based stent structures, with particular attention to radial and flexural performance\u0026mdash;two properties that are fundamental to coronary stent function [\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Guerra and Ciurana [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] investigated the effects of nozzle temperature, flow rate and printing speed by evaluating the recoil ratio of PCL stent samples, showing that flow rate above 100% produced wider struts and hinges that enabled greater radial expansion. Wang et al. [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] adopted a more comprehensive mechanical characterisation approach, including three-point bending, radial compression and expansion tests, to examine how extruder rotational speed alters key geometric features such as connector length and beam width, ultimately demonstrating that higher extrusion speeds increase strut width, thereby improving radial strength while reducing bending flexibility. Singh et al. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] employed a response surface methodology (RSM) to systematically study the influence of layer thickness (t\u003csub\u003eL\u003c/sub\u003e) and printing speed on the bending and compression behaviour of solvent-cast PCL-based composite stents, identifying parameter combinations that reduce dimensional shrinkage and enhance overall mechanical stability. Similarly, Kandi and Pandey [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] evaluated tubular PCL-based scaffolds under varying infill density, t\u003csub\u003eL\u003c/sub\u003e and print speed, showing that increased infill improves radial load capacity and ductility, whereas faster speed and thicker t\u003csub\u003eL\u003c/sub\u003e reduce mechanical performance; their optimisation study further established a parameter set that maximises radial compression load. Collectively, these findings demonstrate that MEX parameters exert clear and measurable effects on the mechanical behaviour of fabricated PCL-based stent structures.\u003c/p\u003e \u003cp\u003eHowever, meaningful comparison across existing studies remains challenging as their experimental methodologies and sample structures differ substantially. Although prior work consistently shows that radial and flexural behaviours can be modulated through MEX parameters, the mechanical testing protocols used in these studies vary widely, making their findings difficult to reconcile. For instance, Guerra and Ciurana [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] quantified radial performance by expanding samples to their maximum dilation, whereas Wang et al. [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] evaluated recoil only at fixed expansion levels of 10% and 20%, resulting in fundamentally non-comparable measurements. Likewise, the radial compression tests conducted by Kandi and Pandey [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] and by Singh et al. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] used different compression ranges and loading conditions, raising uncertainty as to whether discrepancies in their reported optimal parameters reflect true processing effects or merely differences in testing procedures. Such inconsistencies underscore the need for more uniform and standardised mechanical evaluation methods.\u003c/p\u003e \u003cp\u003eBeyond differences in testing methodology, the stent geometries employed across these studies also vary considerably, introducing an additional layer of complexity [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Each investigation utilised distinct structural patterns, connector or strut dimensions\u0026mdash;factors that may exert dominant effects on mechanical performance. In this context, computational and experimental studies in stent mechanics consistently demonstrate that variations in cell topology, strut geometry, or connector architecture can lead to fundamentally different radial strength, bending flexibility and optimal design strategies [\u003cspan additionalcitationids=\"CR25 CR26 CR27\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Recent review articles further emphasise that stent performance is highly geometry-dependent, such that even small structural modifications can shift the balance between radial support and flexibility, ultimately requiring different optimisation routes for different designs [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Under these circumstances, it becomes exceedingly difficult to determine whether the \u0026ldquo;optimal\u0026rdquo; process parameters reported in previous studies are genuinely material- or process-driven, or whether they are simply a consequence of the specific stent architectures being tested.\u003c/p\u003e \u003cp\u003eTogether, these methodological and geometric inconsistencies highlight a critical gap in current research: the field lacks a geometry-independent, standardised framework for understanding how MEX process parameters influence the intrinsic mechanical response of PCL for coronary stent applications. This motivates the need to decouple material\u0026ndash;process effects from sample structural effects, thereby enabling a more controlled and generalisable investigation. Efforts to clarify these parameter\u0026ndash;property relationships using a more standardised approach have been limited, particularly for PCL. A few studies have characterised the compressive or flexural behaviour of PCL using standardised mechanical tests or ASTM-inspired specimen geometries, including selective laser sintering (SLS) scaffolds [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] and PCL\u0026ndash;cellulose structures [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. These works provide useful baseline measurements of PCL mechanical behaviour. However, most of these studies did not involve the MEX process, nor did they discuss it in the context of the demand for coronary stents. Moreover, they do not investigate how process parameters systematically influence the intrinsic mechanical response of PCL. In contrast, standard-based and DOE-driven analyses of MEX process parameters are well established for other polymers such as polylactic acid (PLA) [\u003cspan additionalcitationids=\"CR35 CR36\" citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e] and polyethylene terephthalate glycol (PETG) [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e], yet corresponding studies for PCL, particularly those linking parameter effects to stent-relevant compressive and flexural properties, remain notably scarce.\u003c/p\u003e \u003cp\u003eThis gap is especially important as radial strength and flexural flexibility constitute an inherent mechanical trade-off in stent design [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e], and different clinical scenarios prioritise these properties differently [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. A reliable, geometry-independent mechanical characterisation of MEX-fabricated PCL is therefore essential as a foundational input for future structure-level optimisation and patient-specific stent development. Accordingly, there is a clear need for studies that employ standardised specimen designs, controlled MEX parameter schemes and systematic analytical frameworks to isolate and quantify the material\u0026ndash;process relationships of PCL. Therefore, this study aims to establish a geometry-independent mechanical characterisation of MEX-fabricated PCL by using ASTM-standard compression (D695) and flexural (D790) specimens to eliminate the influence of stent geometry. A central composite design (CCD) based on RSM is implemented to systematically evaluate the effects of T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e on the compressive and flexural strength and modulus of PCL. By developing statistically validated response models and identifying parameter conditions that optimise radial- and flexural-analogous behaviours, this work provides a fundamental material-level framework that can serve as a transferable input for future stent-structure optimisation and patient-specific device design.\u003c/p\u003e"},{"header":"2.0 Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials and MEX Fabrication\u003c/h2\u003e \u003cp\u003ePCL filament (Fabbxible Technology) with a diameter of 1.75 mm was used for specimen fabrication. All specimens were produced using a MEX system (Artillery\u0026reg; Genius Pro) equipped with a 0.4 mm extrusion nozzle. Specimen designs were created in CAD software (SolidWorks 2022\u0026reg;) and exported in .stl format for slicing (Ultimaker Cura, version 5.2.2). Three key MEX parameters (T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e) were selected as the experimental factors, and the ranges of these parameters used in this study (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) were defined based on a combination of reported values in the literature [\u003cspan additionalcitationids=\"CR20 CR21\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] and preliminary processability trials. This broad parameter space was intentionally adopted to encompass the full span of processing conditions previously employed for MEX-fabricated PCL stents, thereby enabling as comprehensive and systematic an identification as possible of the dominant process\u0026ndash;property relationships and facilitating the reconciliation of inconsistencies among prior studies. The other process parameters were maintained at the slicing software default settings. No additional post-processing was performed on the specimens after fabrication, in order to preserve the as-fabricated microstructural features induced by the selected process parameters and to isolate their intrinsic effects on mechanical behaviour. This approach enables direct attribution of the measured mechanical responses to variations in MEX processing conditions rather than to secondary surface modification steps.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe levels of the three key MEX parameters studied.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProcess Parameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eT\u003csub\u003eE\u003c/sub\u003e (℃)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ev\u003csub\u003eD\u003c/sub\u003e (mm/s)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eM\u003csub\u003eE\u003c/sub\u003e (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLow Level\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHigh Level\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e250\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Specimen Preparation\u003c/h2\u003e \u003cp\u003eTwo types of standardised solid specimens were prepared in compliance with ASTM D695 and ASTM D790 for compression and flexural testing, respectively. The compression specimens were cylindrical (12.7 mm in diameter and 25.4 mm in height), while the flexural specimens were rectangular bars (127 mm \u0026times; 12.7 mm \u0026times; 3.2 mm). To eliminate geometric influences and focus solely on the effects of process parameters, standardised solid specimens were employed in this study instead of the stent-like geometries used previously.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Experimental Design\u003c/h2\u003e \u003cp\u003eTo systematically evaluate the effects of the selected parameters, a statistical design of experiments approach was adopted. A CCD within the framework of RSM was employed to investigate the combined effects of T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e. A face-centred CCD (α\u0026thinsp;=\u0026thinsp;1) was selected to maintain all factor levels within the feasible operating range, resulting in a total of 17 experimental runs, with three centre-point runs included to monitor experimental stability. Five replicates (n\u0026thinsp;=\u0026thinsp;5) were produced and examined for each parameter combination.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Mechanical Testing\u003c/h2\u003e \u003cp\u003eMechanical testing was conducted to evaluate the compressive and flexural performance of the fabricated PCL specimens. All tests were performed using a computer-controlled electronic universal testing machine (Shimadzu AGS-X) under ambient laboratory conditions (25\u0026deg;C).\u003c/p\u003e \u003cp\u003eCompression testing followed the procedures of ASTM D695, using the cylindrical specimens described in Section \u003cspan refid=\"Sec4\" class=\"InternalRef\"\u003e2.2\u003c/span\u003e. The samples were compressed between two parallel plates at a crosshead speed of 1.0 mm/min using a 50 kN load cell, and the test was terminated once 50% strain was reached. The compressive modulus was determined from the initial linear region (3\u0026ndash;6% strain). As slight variations in the final termination strain occurred when applying the nominal 50% strain limit to as-fabricated specimens, the stress value at 49.5% strain was used as a consistent reference for compressive strength evaluation across all parameter conditions.\u003c/p\u003e \u003cp\u003eFlexural testing was conducted in accordance with ASTM D790, using the rectangular specimens specified in Section \u003cspan refid=\"Sec4\" class=\"InternalRef\"\u003e2.2\u003c/span\u003e. Tests were performed in a three-point bending configuration with a support span of 51.2 mm at a crosshead speed of 1.3 mm/min using a 50 kN load cell. The tests were terminated at 5% strain. The flexural modulus was determined from the initial linear region (1\u0026ndash;4% strain). Similarly, flexural strength was reported at 4.5% strain to ensure consistent data extraction prior to the strain-controlled termination limit, enabling unbiased comparison across the investigated parameter conditions.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Microstructural Characterisation\u003c/h2\u003e \u003cp\u003eMicrostructural analysis was performed to examine how MEX process parameters influence the internal morphology of the fabricated PCL specimens. Dedicated specimens were sectioned to expose their cross-sectional surfaces, which were then sputter-coated with a thin layer of platinum using an ion sputter coater (COXEM SPT-20). The coated surfaces were imaged using a tabletop scanning electron microscope (Hitachi TM3000) at an accelerating voltage of 10 kV and a magnification of 100\u0026times;. The SEM images were used to assess interlayer bonding quality and the presence of internal voids or porosity associated with different processing conditions, as these microstructural features are known to play a critical role in the resulting compressive and flexural behaviour.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Data Analysis and Optimisation\u003c/h2\u003e \u003cp\u003eStatistical analyses were performed using statistical software (Minitab\u0026reg;, version 21.4) based on RSM. A second-order (quadratic) regression model was fitted to describe the relationships between T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e with the compressive and flexural responses. The model significance was evaluated through ANOVA (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Single- and multi-response optimisation was conducted using the desirability function approach to maximise the compressive- and flexural-related properties.\u003c/p\u003e \u003c/div\u003e"},{"header":"3.0 Results and Discussion","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1 Mechanical Behaviour under Compression and Flexure\u003c/h2\u003e\n \u003cp\u003eIn the present study, T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e were selected as the process parameters of interest, as they are widely recognised as the primary MEX variables dominating the effective mechanical response of fabricated parts in the context of PCL-based BRS fabrication [\u003cspan additionalcitationids=\"CR20 CR21\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Meanwhile, compressive and flexural strength and modulus were adopted as the mechanical evaluation metrics, as they capture the fundamental material responses that govern radial support and deformation resistance in coronary stent applications. Strength reflects the load-bearing capacity before failure, while modulus reflects the stiffness that resists radial and bending deformation\u0026mdash;both of which directly underpin a stent\u0026rsquo;s ability to maintain lumen patency. Although the loading configurations differ, radial and flexural behaviour is fundamentally governed by the intrinsic elastic modulus and strength of the material [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. Accordingly, optimising these key parameters offers a direct means to enhance the radial- and flexural-load-bearing capability of fabricated PCL at the material level, complementing geometry-based strategies commonly used to improve stent mechanical performance. Based on this framework, a CCD-based RSM was implemented to systematically explore the effects of T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e on the compressive and flexural behaviour of MEX-fabricated PCL specimens. The resulting stress\u0026ndash;strain responses obtained from ASTM-standard compression and flexural tests are presented in Fig. \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e summarises the complete CCD matrix, together with the corresponding experimentally measured strength and modulus values extracted from the stress\u0026ndash;strain curves.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\u0026nbsp;\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eCCD of RSM used in the DOE. Results of strength and modulus obtained from the PCL compressive and flexural tests are shown.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003eSet\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\n \u003cp\u003eProcess Parameters\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\n \u003cp\u003eCompressive Response\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\n \u003cp\u003eFlexural Response\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003eT\u003csub\u003eE\u003c/sub\u003e (℃)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003ev\u003csub\u003eD\u003c/sub\u003e (mm/s)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c4\"\u003e\n \u003cp\u003eM\u003csub\u003eE\u003c/sub\u003e (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colname=\"c6\"\u003e\n \u003cp\u003eStrength (MPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c7\"\u003e\n \u003cp\u003eModulus (MPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c8\"\u003e\n \u003cp\u003eStrength (MPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c9\"\u003e\n \u003cp\u003eModulus\u003c/p\u003e\n \u003cp\u003e(MPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e7.37\u0026thinsp;\u0026plusmn;\u0026thinsp;1.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e73.39\u0026thinsp;\u0026plusmn;\u0026thinsp;3.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e7.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e180.63\u0026thinsp;\u0026plusmn;\u0026thinsp;11.81\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e7.02\u0026thinsp;\u0026plusmn;\u0026thinsp;0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e51.90\u0026thinsp;\u0026plusmn;\u0026thinsp;9.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e5.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e133.52\u0026thinsp;\u0026plusmn;\u0026thinsp;41.67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e7.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e60.60\u0026thinsp;\u0026plusmn;\u0026thinsp;5.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e7.42\u0026thinsp;\u0026plusmn;\u0026thinsp;0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e176.00\u0026thinsp;\u0026plusmn;\u0026thinsp;11.97\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e8.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e69.02\u0026thinsp;\u0026plusmn;\u0026thinsp;13.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e4.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e113.67\u0026thinsp;\u0026plusmn;\u0026thinsp;11.22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e29.27\u0026thinsp;\u0026plusmn;\u0026thinsp;1.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e227.43\u0026thinsp;\u0026plusmn;\u0026thinsp;14.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e7.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e175.62\u0026thinsp;\u0026plusmn;\u0026thinsp;13.65\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e36.38\u0026thinsp;\u0026plusmn;\u0026thinsp;1.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e233.79\u0026thinsp;\u0026plusmn;\u0026thinsp;13.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e14.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e353.78\u0026thinsp;\u0026plusmn;\u0026thinsp;20.09\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e29.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e241.78\u0026thinsp;\u0026plusmn;\u0026thinsp;28.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e12.50\u0026thinsp;\u0026plusmn;\u0026thinsp;5.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e288.01\u0026thinsp;\u0026plusmn;\u0026thinsp;128.59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e39.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e276.33\u0026thinsp;\u0026plusmn;\u0026thinsp;21.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e15.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e375.15\u0026thinsp;\u0026plusmn;\u0026thinsp;19.74\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e25.60\u0026thinsp;\u0026plusmn;\u0026thinsp;1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e229.71\u0026thinsp;\u0026plusmn;\u0026thinsp;13.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e18.05\u0026thinsp;\u0026plusmn;\u0026thinsp;1.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e431.08\u0026thinsp;\u0026plusmn;\u0026thinsp;21.82\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e27.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e201.67\u0026thinsp;\u0026plusmn;\u0026thinsp;8.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e14.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e351.11\u0026thinsp;\u0026plusmn;\u0026thinsp;9.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e26.28\u0026thinsp;\u0026plusmn;\u0026thinsp;1.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e209.68\u0026thinsp;\u0026plusmn;\u0026thinsp;13.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e15.65\u0026thinsp;\u0026plusmn;\u0026thinsp;0.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e367.96\u0026thinsp;\u0026plusmn;\u0026thinsp;19.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e27.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e206.70\u0026thinsp;\u0026plusmn;\u0026thinsp;7.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e15.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e358.91\u0026thinsp;\u0026plusmn;\u0026thinsp;10.88\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e9.40\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e78.67\u0026thinsp;\u0026plusmn;\u0026thinsp;4.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e6.70\u0026thinsp;\u0026plusmn;\u0026thinsp;0.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e155.10\u0026thinsp;\u0026plusmn;\u0026thinsp;21.02\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e35.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e273.67\u0026thinsp;\u0026plusmn;\u0026thinsp;11.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e17.35\u0026thinsp;\u0026plusmn;\u0026thinsp;2.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e406.22\u0026thinsp;\u0026plusmn;\u0026thinsp;58.31\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e28.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e185.20\u0026thinsp;\u0026plusmn;\u0026thinsp;16.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e18.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e434.26\u0026thinsp;\u0026plusmn;\u0026thinsp;11.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e28.89\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e219.62\u0026thinsp;\u0026plusmn;\u0026thinsp;11.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e17.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e418.32\u0026thinsp;\u0026plusmn;\u0026thinsp;15.58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c6\"\u003e\n \u003cp\u003e28.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c7\"\u003e\n \u003cp\u003e199.05\u0026thinsp;\u0026plusmn;\u0026thinsp;13.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c8\"\u003e\n \u003cp\u003e16.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\"±\" colname=\"c9\"\u003e\n \u003cp\u003e387.87\u0026thinsp;\u0026plusmn;\u0026thinsp;11.91\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(a) Effects of Extrusion Temperature\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e presents the main effects of T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e on the compressive and flexural strength and modulus of the fabricated PCL specimens. With respect to T\u003csub\u003eE\u003c/sub\u003e, T\u003csub\u003eE\u003c/sub\u003e generally enhances both compressive and flexural strength, although the responses are non-monotonic across the investigated range. Strength values increase with T\u003csub\u003eE\u003c/sub\u003e up to an intermediate optimum before slightly declining at higher T\u003csub\u003eE\u003c/sub\u003e, whereas the elastic modulus exhibits only minor variation, indicating a comparatively weak sensitivity to thermal input.\u003c/p\u003e\n \u003cp\u003eDespite the presence of non-linear trends, the overall influence of T\u003csub\u003eE\u003c/sub\u003e across the full range from 80 to 250\u0026deg;C remains moderate, with compressive and flexural strength increasing by approximately 15.38% and 3.43%, respectively, while changes in compressive and flexural modulus are limited (0.018% and 3.93%, respectively). These results suggest that T\u003csub\u003eE\u003c/sub\u003e primarily influences failure-related strength, particularly under compression, rather than elastic response, while further increases in T\u003csub\u003eE\u003c/sub\u003e beyond an intermediate level provide limited additional benefit.\u003c/p\u003e\n \u003cp\u003eThis behaviour is consistent with the thermorheological characteristics of semi-crystalline polymers such as PCL. Increasing T\u003csub\u003eE\u003c/sub\u003e typically improves melt fluidity and interlayer fusion, promoting more effective load transfer under mechanical loading, whereas excessive thermal input may offset these benefits through material degradation or geometric instability. Similar temperature-dependent strengthening trends have been widely reported for MEX-fabricated thermoplastics including PLA, PETG and high-performance polymers such as polyetheretherketone (PEEK), where enhanced melt mobility and reduced interlayer separation lead to improved mechanical integrity [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. The present results confirm that this general mechanism also applies to PCL, whose low melting temperature and high viscosity sensitivity render its mechanical performance particularly responsive to thermal conditions during deposition.\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(b) Effects of Material Deposition Speed\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e also illustrates the main effects of v\u003csub\u003eD\u003c/sub\u003e on the compressive and flexural strength and modulus of the fabricated PCL specimens. In contrast to T\u003csub\u003eE\u003c/sub\u003e, the influence of v\u003csub\u003eD\u003c/sub\u003e on all four mechanical responses is comparatively moderate and exhibits a shallow non-monotonic trend across the investigated range.\u003c/p\u003e\n \u003cp\u003eAs v\u003csub\u003eD\u003c/sub\u003e increases from 5 mm/s, both compressive and flexural strength gradually increase, reaching maximum values at intermediate speeds (\u0026asymp;\u0026thinsp;30\u0026ndash;35 mm/s), before showing a slight decline at higher v\u003csub\u003eD\u003c/sub\u003e. A similar response is observed for the corresponding moduli, with only limited variation across the full range. When comparing the extreme conditions, increasing v\u003csub\u003eD\u003c/sub\u003e from 5 to 50 mm/s results in modest net changes of approximately 5\u0026ndash;6% for both the compressive and flexural strength and modulus, indicating that v\u003csub\u003eD\u003c/sub\u003e exerts a secondary influence on mechanical performance relative to other process parameters.\u003c/p\u003e\n \u003cp\u003eThe presence of an intermediate optimal v\u003csub\u003eD\u003c/sub\u003e suggests a balance between deposition continuity and thermal\u0026ndash;temporal interaction during extrusion. At low v\u003csub\u003eD\u003c/sub\u003e, prolonged residence time may promote thermal dissipation and material over-softening, while at excessively high v\u003csub\u003eD\u003c/sub\u003e, insufficient inter-path contact time may limit interlayer consolidation. The relatively flat response profiles observed here indicate that PCL exhibits a broad processing window with respect to v\u003csub\u003eD\u003c/sub\u003e, within which mechanical properties remain comparatively stable.\u003c/p\u003e\n \u003cp\u003eAlthough prior studies on materials such as PLA, PETG and PEEK frequently report monotonic reductions in strength with increasing v\u003csub\u003eD\u003c/sub\u003e [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e], the present results highlight that the rate sensitivity of PCL is less pronounced. This discrepancy is likely associated with the low melting temperature and high thermal diffusivity of PCL, which mitigate the adverse effects of reduced deposition time at elevated v\u003csub\u003eD\u003c/sub\u003e.\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(c) Effects of Extrusion Multiplier\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e further illustrates the main effects of M\u003csub\u003eE\u003c/sub\u003e on the compressive and flexural strength and modulus of the fabricated PCL specimens. Among the investigated process parameters, M\u003csub\u003eE\u003c/sub\u003e exerts the most pronounced influence on all four mechanical responses, with substantially larger variations observed across the studied range compared with T\u003csub\u003eE\u003c/sub\u003e and v\u003csub\u003eD\u003c/sub\u003e.\u003c/p\u003e\n \u003cp\u003eAs M\u003csub\u003eE\u003c/sub\u003e increases, compressive strength and modulus increase monotonically, indicating a strong sensitivity of compressive load-bearing capacity to deposited material volume. In contrast, the flexural responses exhibit a non-monotonic dependence on M\u003csub\u003eE\u003c/sub\u003e, increasing up to an intermediate optimum before declining at higher M\u003csub\u003eE\u003c/sub\u003e.\u003c/p\u003e\n \u003cp\u003eWhen evaluated across the full M\u003csub\u003eE\u003c/sub\u003e range from 70% to 150%, the overall changes are substantial, with compressive strength and modulus increasing by approximately 271% and 239%, respectively, while flexural strength and modulus increase by approximately 83% and 84%. These magnitudes are markedly larger than those associated with T\u003csub\u003eE\u003c/sub\u003e and v\u003csub\u003eD\u003c/sub\u003e, confirming that M\u003csub\u003eE\u003c/sub\u003e is the dominant parameter governing the mechanical behaviour of MEX-fabricated PCL within the investigated design space.\u003c/p\u003e\n \u003cp\u003eThe pronounced sensitivity to M\u003csub\u003eE\u003c/sub\u003e underscores the importance of deposited material volume in governing internal porosity, inter-bead contact and effective load-bearing cross-sectional area. Although direct investigations of M\u003csub\u003eE\u003c/sub\u003e in MEX are limited, similar mechanisms have been widely discussed in studies on infill density, where increased material content reduces void fraction and enhances stress-transfer continuity [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e]. In this context, the present findings suggest that M\u003csub\u003eE\u003c/sub\u003e serves as an effective process-level control of material volume, while excessive flow may compromise geometric fidelity and bending stress distribution, leading to reduced flexural performance at high M\u003csub\u003eE\u003c/sub\u003e.\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(d) Statistical Significance and Relative Influence of Process Parameters\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eThe statistical significance and relative influence of T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e were evaluated using ANOVA based on the developed response surface models. Separate analyses were conducted for compressive strength, compressive modulus, flexural strength and flexural modulus, and the key statistical metrics are summarised in Table \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003eFor the compressive responses, M\u003csub\u003eE\u003c/sub\u003e is identified as the overwhelmingly dominant parameter. In the case of compressive strength, M\u003csub\u003eE\u003c/sub\u003e exhibits an exceptionally high F-value (8760.63, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and accounts for 97.67% of the total contribution among the main factors, whereas T\u003csub\u003eE\u003c/sub\u003e and v\u003csub\u003eD\u003c/sub\u003e contribute only marginally (2.05% and 0.28%, respectively), despite both being statistically significant (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). A similar trend is observed for compressive modulus, where M\u003csub\u003eE\u003c/sub\u003e remains the sole statistically significant parameter (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and contributes 99.60% of the total variation, while the effects of T\u003csub\u003eE\u003c/sub\u003e and v\u003csub\u003eD\u003c/sub\u003e are negligible.\u003c/p\u003e\n \u003cp\u003eA comparable dominance of M\u003csub\u003eE\u003c/sub\u003e is also evident in the flexural responses. For flexural strength, M\u003csub\u003eE\u003c/sub\u003e shows the highest F-value (170.10, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and contributes 97.84% of the total variation, whereas neither T\u003csub\u003eE\u003c/sub\u003e nor v\u003csub\u003eD\u003c/sub\u003e reaches statistical significance (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Likewise, for flexural modulus, M\u003csub\u003eE\u003c/sub\u003e again governs the response, contributing 97.81% with a statistically significant effect (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), while the contributions of T\u003csub\u003eE\u003c/sub\u003e and v\u003csub\u003eD\u003c/sub\u003e remain minor and statistically insignificant. These statistical trends are consistent with the main effect plots in Fig. \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, where variations in M\u003csub\u003eE\u003c/sub\u003e induce substantially larger response amplitudes than those associated with T\u003csub\u003eE\u003c/sub\u003e and v\u003csub\u003eD\u003c/sub\u003e across all mechanical metrics.\u003c/p\u003e\n \u003cp\u003eThus, the ANOVA results demonstrate that, within the investigated design space, the mechanical behaviour of MEX-fabricated PCL is predominantly governed by M\u003csub\u003eE\u003c/sub\u003e, irrespective of the loading mode. In contrast, T\u003csub\u003eE\u003c/sub\u003e and v\u003csub\u003eD\u003c/sub\u003e play secondary roles, with limited contributions and inconsistent statistical significance across responses. This finding highlights the critical importance of volumetric material deposition in controlling load-bearing capacity and elastic modulus, and motivates a microstructural examination of how variations in M\u003csub\u003eE\u003c/sub\u003e influence void distribution, filament bonding and interlayer morphology.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\u0026nbsp;\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eANOVA results showing F-values, \u003cem\u003ep\u003c/em\u003e-values and percentage contribution of T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e to compressive strength, compressive modulus, flexural strength and flexural modulus based on the response surface models.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003eResponse\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003eFactor\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003eF-value\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c4\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c5\"\u003e\n \u003cp\u003eContribution (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\n \u003cp\u003eCompressive strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003eT\u003csub\u003eE\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e184.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e2.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003ev\u003csub\u003eD\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e24.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e0.28\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003eM\u003csub\u003eE\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e8760.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e97.67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\n \u003cp\u003eCompressive modulus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003eT\u003csub\u003eE\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003ev\u003csub\u003eD\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e6.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.013\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e0.40\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003eM\u003csub\u003eE\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e1614.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e99.60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\n \u003cp\u003eFlexural strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003eT\u003csub\u003eE\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e1.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.311\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003ev\u003csub\u003eD\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e2.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.103\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e1.57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003eM\u003csub\u003eE\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e170.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e97.84\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\n \u003cp\u003eFlexural modulus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003eT\u003csub\u003eE\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e1.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.255\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e0.80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003ev\u003csub\u003eD\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e2.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.134\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e1.39\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003eM\u003csub\u003eE\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e160.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e97.81\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2 Microstructural Evidence and Mechanistic Interpretation\u003c/h2\u003e\n \u003cp\u003eCross-sectional SEM imaging at 100\u0026times; magnification was employed to qualitatively assess consolidation-related morphological features associated with the parameter-dependent mechanical responses discussed in Section \u003cspan refid=\"Sec10\" class=\"InternalRef\"\u003e3.1\u003c/span\u003e. At this magnification, the analysis focuses on material continuity, underfilled regions, void-like features and inter-layer consolidation, rather than fine-scale fracture mechanisms. Extreme parameter levels (low and high T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e) were selected to maximise observable morphological contrast and to elucidate the dominant mechanisms governing mechanical performance in MEX-fabricated PCL.\u003c/p\u003e\n \u003cp\u003eFor T\u003csub\u003eE\u003c/sub\u003e, specimens fabricated at low T\u003csub\u003eE\u003c/sub\u003e (80\u0026deg;C) and high T\u003csub\u003eE\u003c/sub\u003e (250\u0026deg;C) exhibit broadly similar macroscopic surface morphologies, characterised by relatively smooth cross-sections with limited large-scale voids (Fig. \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, b and Fig. \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, b). However, low-T\u003csub\u003eE\u003c/sub\u003e samples occasionally display subtle discontinuities and less uniform material regions, consistent with restricted melt mobility and reduced inter-road fusion. In contrast, high-T\u003csub\u003eE\u003c/sub\u003e samples show more continuous and homogeneous cross-sections, indicative of improved melt flow and consolidation. The modest nature of these morphological differences aligns with the comparatively weak sensitivity of elastic modulus to T\u003csub\u003eE\u003c/sub\u003e and the non-monotonic strength trends observed in Section \u003cspan refid=\"Sec10\" class=\"InternalRef\"\u003e3.1\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003eVariations in v\u003csub\u003eD\u003c/sub\u003e similarly produce only subtle changes in cross-sectional morphology at the examined scale (Fig. \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec, d and Fig. \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec, d). Low-v\u003csub\u003eD\u003c/sub\u003e specimens exhibit relatively uniform material distribution, while high-v\u003csub\u003eD\u003c/sub\u003e conditions show slightly increased surface irregularity, reflecting reduced interaction time between deposited filaments. The absence of pronounced microstructural disruption supports the statistical findings that v\u003csub\u003eD\u003c/sub\u003e exerts a secondary influence on both compressive and flexural responses within the investigated range.\u003c/p\u003e\n \u003cp\u003eIn contrast, changes in M\u003csub\u003eE\u003c/sub\u003e give rise to pronounced and readily observable morphological differences. Low-M\u003csub\u003eE\u003c/sub\u003e specimens (70%) display clear underfilled regions, sparse material packing and prominent void-like features within the cross-section (Fig. \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee and Fig. \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ee), indicative of insufficient volumetric material delivery. Conversely, high-M\u003csub\u003eE\u003c/sub\u003e specimens (150%) exhibit dense, continuous material regions with markedly reduced defect prevalence (Fig. \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef and Fig. \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ef). These consolidation-related differences directly support the strong and dominant influence of M\u003csub\u003eE\u003c/sub\u003e on both strength and modulus identified in the ANOVA and main effect analyses.\u003c/p\u003e\n \u003cp\u003eTaken together, the SEM observations provide a coherent microstructural basis for the statistical significance trends reported in Section \u003cspan refid=\"Sec10\" class=\"InternalRef\"\u003e3.1\u003c/span\u003e. While T\u003csub\u003eE\u003c/sub\u003e and v\u003csub\u003eD\u003c/sub\u003e primarily modulate melt mobility and deposition stability with relatively subtle morphological manifestations, M\u003csub\u003eE\u003c/sub\u003e governs volumetric packing efficiency and defect suppression, emerging as the principal determinant of mechanical integrity in MEX-fabricated PCL. The convergence of morphological and statistical evidence confirms that consolidation quality, controlled predominantly by material flow rate, underpins the observed mechanical behaviour.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n \u003ch2\u003e3.3 Statistical Modelling, Optimisation and Relevance to Stent Design\u003c/h2\u003e\n \u003cp\u003eBuilding on the mechanistic insights established in Sections \u003cspan refid=\"Sec10\" class=\"InternalRef\"\u003e3.1\u003c/span\u003e and \u003cspan refid=\"Sec11\" class=\"InternalRef\"\u003e3.2\u003c/span\u003e, this section translates the identified parameter\u0026ndash;microstructure\u0026ndash;mechanics relationships into quantitative predictive models and clinically relevant optimisation frameworks. Due to the fact that clinical implantation does not require a single mechanical profile, but rather a context-dependent balance between radial strength and flexural compliance, three optimisation pathways were defined in this study: (1) A compression-focused optimisation prioritises maximal compressive strength and modulus to represent scenarios where enhanced radial support is required. (2) A flexural-focused optimisation targets high flexural strength while minimising flexural modulus, corresponding to applications demanding improved conformability and resistance to fracture under bending. (3) In addition, a multi-objective optimisation was implemented to balance all four mechanical responses simultaneously, explicitly capturing the trade-off between radial rigidity and vascular compliance that underpins contemporary stent design.\u003c/p\u003e\n \u003cp\u003eRegression models obtained from RSM (\u003cstrong\u003eEqs.\u0026nbsp;1\u0026ndash;4\u003c/strong\u003e) were used to generate predictive relationships between T\u003csub\u003eE\u003c/sub\u003e, v\u003csub\u003eD\u003c/sub\u003e and M\u003csub\u003eE\u003c/sub\u003e and the resulting mechanical responses. Table \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e summarises the optimised parameter sets obtained under different optimisation strategies. Although the optimised points coincided with previously tested design points, their corresponding experimental responses were used to validate the model predictions. The small prediction errors observed across all responses confirm that the regression models provide reliable estimates of PCL mechanical behaviour within the investigated parameter space. \u0026nbsp;\u003c/p\u003e\u003cbr\u003e\n \u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003eCompressive strength (MPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003e=\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e-47.14\u0026thinsp;+\u0026thinsp;0.0190 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e + 0.0495 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e + 0.9597 \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.000213 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.001866 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.003370 \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e + 0.000255 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e + 0.000608 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e + 0.000383 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c4\"\u003e\n \u003cp\u003e(1)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003eCompressive modulus (MPa)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003e=\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e-286.1\u0026ndash;0.323 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.356 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e + 7.204 \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e + 0.000000 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.01481 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.02470 \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e + 0.00380 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e + 0.001984 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e + 0.00730 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cp\u003e(2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003eFlexural strength (MPa)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003e=\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e-28.14\u0026ndash;0.0083 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e + 0.1717 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e + 0.6987 \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.000121 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.00369 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.003300 \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.000317 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e + 0.000549 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e + 0.000944 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cp\u003e(3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003eFlexural modulus (MPa)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003e=\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003e-656\u0026ndash;0.461 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e + 4.02 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e + 16.74 \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.00235 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.0881 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.07962 \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e \u0026minus;\u0026thinsp;0.00694 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e + 0.01378 \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e + 0.02198 \u003cem\u003ev\u003c/em\u003e\u003csub\u003e\u003cem\u003eD\u003c/em\u003e\u003c/sub\u003e*\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eE\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cp\u003e(4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv\u003eTable 4 Optimised MEX process parameter sets obtained under different optimisation strategies, together with RSM-predicted values, experimentally measured responses and corresponding prediction errors for compressive and flexural properties of PCL.\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003cbr\u003e\u003c/div\u003e\u0026nbsp;\u003ctable float=\"No\" id=\"Taba\" border=\"1\" class=\"fr-table-selection-hover\"\u003e\n \u003ccolgroup cols=\"10\"\u003e\u003c/colgroup\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003eNo.*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003eT\u003csub\u003eE\u003c/sub\u003e (℃)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003ev\u003csub\u003eD\u003c/sub\u003e (mm/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003eM\u003csub\u003eE\u003c/sub\u003e (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\" nameend=\"c10\" namest=\"c7\"\u003e\n \u003cp\u003eOptimisation results\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cp\u003eOptimised responses*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c8\"\u003e\n \u003cp\u003ePredicted value (MPa)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c9\"\u003e\n \u003cp\u003eActual value (MPa)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c10\"\u003e\n \u003cp\u003eError (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003e250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cp\u003e\u0026sigma;\u003csub\u003eC\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c8\"\u003e\n \u003cp\u003e39.062\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c9\"\u003e\n \u003cp\u003e39.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c10\"\u003e\n \u003cp\u003e1.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cp\u003eE\u003csub\u003eC\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c8\"\u003e\n \u003cp\u003e279.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c9\"\u003e\n \u003cp\u003e276.33\u0026thinsp;\u0026plusmn;\u0026thinsp;21.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c10\"\u003e\n \u003cp\u003e1.26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cp\u003e\u0026sigma;\u003csub\u003eF\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c8\"\u003e\n \u003cp\u003e12.712\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c9\"\u003e\n \u003cp\u003e12.50\u0026thinsp;\u0026plusmn;\u0026thinsp;5.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c10\"\u003e\n \u003cp\u003e1.70\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cp\u003eE\u003csub\u003eF\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c8\"\u003e\n \u003cp\u003e294.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c9\"\u003e\n \u003cp\u003e288.01\u0026thinsp;\u0026plusmn;\u0026thinsp;128.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c10\"\u003e\n \u003cp\u003e2.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\" morerows=\"3\" rowspan=\"4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\" morerows=\"3\" rowspan=\"4\"\u003e\n \u003cp\u003e250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\" morerows=\"3\" rowspan=\"4\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\" morerows=\"3\" rowspan=\"4\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\" morerows=\"3\" rowspan=\"4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cp\u003e\u0026sigma;\u003csub\u003eC\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c8\"\u003e\n \u003cp\u003e39.062\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c9\"\u003e\n \u003cp\u003e39.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c10\"\u003e\n \u003cp\u003e1.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cp\u003eE\u003csub\u003eC\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c8\"\u003e\n \u003cp\u003e279.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c9\"\u003e\n \u003cp\u003e276.33\u0026thinsp;\u0026plusmn;\u0026thinsp;21.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c10\"\u003e\n \u003cp\u003e1.26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cp\u003e\u0026sigma;\u003csub\u003eF\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c8\"\u003e\n \u003cp\u003e15.787\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c9\"\u003e\n \u003cp\u003e15.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c10\"\u003e\n \u003cp\u003e0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cp\u003eE\u003csub\u003eF\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c8\"\u003e\n \u003cp\u003e376.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c9\"\u003e\n \u003cp\u003e375.15\u0026thinsp;\u0026plusmn;\u0026thinsp;19.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c10\"\u003e\n \u003cp\u003e0.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e*No. indicate the optimisation strategies: 1 is compression-focused, 2 is flexural-focused and 3 is a multi-objective optimisation strategy.\u003c/p\u003e\n \u003cp\u003e*\u0026sigma;\u003csub\u003eC\u003c/sub\u003e refers to compressive strength, E\u003csub\u003eC\u003c/sub\u003e refers to compressive modulus, \u0026sigma;\u003csub\u003eF\u003c/sub\u003e refers to flexural strength, E\u003csub\u003eF\u003c/sub\u003e refers to flexural modulus.\u003c/p\u003e\n \u003cp\u003eIt should be emphasised that the optimised parameter sets identified in this study represent material-level extrema within the investigated design space rather than directly applicable processing conditions for stent fabrication. In particular, although a high M\u003csub\u003eE\u003c/sub\u003e (150%) maximises compressive and flexural performance by enhancing volumetric material delivery and consolidation, such conditions are expected to compromise dimensional fidelity and surface quality, especially for fine stent struts. Similarly, despite the ability to fabricate specimens at elevated T\u003csub\u003eE\u003c/sub\u003e (250\u0026deg;C) with enhanced strength, the observed non-monotonic dependence of mechanical responses on T\u003csub\u003eE\u003c/sub\u003e suggests that excessive thermal input may offset consolidation benefits through degradation or geometric instability. Accordingly, the present optimisation defines an upper bound of achievable material-level mechanical performance under MEX processing, while future multi-objective optimisation should integrate mechanical, morphological and biological performance requirements to identify clinically viable processing windows.\u003c/p\u003e\n \u003cp\u003eTo contextualise the optimised mechanical responses, the results were compared against reported ranges for solid PCL specimens fabricated using different manufacturing methods and tested under standardised compression or flexural configurations. Published compressive moduli for bulk PCL typically fall within the range of 300\u0026ndash;325 MPa, with compressive strengths reported in the range of 34\u0026ndash;39 MPa for injection-moulded and SLS-fabricated specimens [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. The compression-optimised condition identified in the present study yields compressive modulus and strength values approaching the upper region of these reported ranges. A similarly broad distribution is evident in reported flexural properties of PCL, with flexural strength values spanning approximately 11\u0026ndash;24 MPa and flexural moduli ranging from 109 to 423 MPa, largely depending on manufacturing process, molecular weight and porosity [\u003cspan additionalcitationids=\"CR50 CR51 CR52\" citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e]. The flexural-optimised condition obtained in this work likewise falls well within the broad envelope defined by existing PCL reports.\u003c/p\u003e\n \u003cp\u003eConsidering that alternative manufacturing routes, such as SLS and injection moulding, generally produce highly consolidated structures with minimal void content, the ability of MEX-fabricated PCL to attain comparable modulus and strength after parameter optimisation underscores the substantial influence of extrusion-based processing conditions on material consolidation and load transfer. As the compressive and flexural strength in this study were evaluated at strain levels of 49.5% and 4.5%, respectively (as defined in Section \u003cspan refid=\"Sec6\" class=\"InternalRef\"\u003e2.4\u003c/span\u003e), comparisons with literature values reported at nominally 50% (compression) and 5% (flexure) strain are intended to indicate general trends and ranges rather than exact numerical equivalence. Notably, the multi-objective condition also achieved a balanced mechanical response across both compressive and flexural loading, indicating that the mechanical behaviour of MEX-fabricated PCL can be systematically tuned through process-parameter selection rather than being confined to a narrow range associated with default fabrication settings.\u003c/p\u003e\n \u003cp\u003eAlthough stent-level radial and flexural performance arise from the combined contributions of material properties and geometric design [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e], the present study intentionally isolates the material component by characterising PCL under standardised ASTM compression and flexural testing. By excluding geometry-dependent effects such as strut thickness, cell topology and hinge mechanics, this approach provides a generalisable assessment of how MEX process parameters regulate the intrinsic modulus and strength of the polymer itself. These material-level properties correspond to the modulus-dependent term in stent mechanical descriptors such as radial stiffness and bending compliance [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e], and therefore define the baseline upon which any specific stent geometry must operate.\u003c/p\u003e\n \u003cp\u003eWhen viewed within this material-centric framework, the optimised PCL responses can be positioned relative to established BRS backbone materials. Commercial BRS platforms such as Absorb, DESolve and MeRes100 predominantly employ poly(L-lactic acid) (PLLA), which typically exhibits moduli on the order of 2\u0026ndash;4 GPa and strengths of 50\u0026ndash;70 MPa [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]. While these values reflect bulk material properties rather than assembled stent performance, they define a widely accepted strength and modulus hierarchy for stent backbones. The optimised PCL obtained in the present study exhibits compressive and flexural moduli in the sub-GPa range, positioning it well below PLLA but above highly compliant soft polymers, and firmly within a low-modulus domain associated with next-generation flexible stent concepts [\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eFrom a design perspective, the three optimisation pathways delineate distinct material states that map directly onto clinically relevant deployment scenarios. The compression-optimised condition represents a stiffer, higher load-bearing material state suitable for applications where enhanced radial support is required, such as moderately calcified or recoil-prone lesions. In contrast, the flexural-optimised condition corresponds to a more compliant material state, favouring navigation through tortuous or highly curved vessels. The multi-objective solution occupies an intermediate region of the design space, reflecting the practical compromise between radial rigidity and vascular conformability inherent to modern stent design. Crucially, these material states were achieved solely through process-parameter modulation, demonstrating that MEX-fabricated PCL spans a clinically meaningful mechanical spectrum rather than possessing a single intrinsic strength and modulus profile. This tunable material window provides a foundational design space upon which future geometry-driven optimisation strategies may be layered. Therefore, the optimised PCL windows identified in the present study do not function as final stent specifications but as strength and modulus regimes that future stent architectures may selectively leverage depending on the targeted lesion environment. This establishes a direct and clinically grounded link between MEX parameter selection, material-level mechanics and the broader performance envelope required of next-generation BRS.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4.0 Conclusion","content":"\u003cp\u003eThis study elucidated the process\u0026ndash;structure\u0026ndash;property relationships governing the compressive and flexural behaviour of MEX-fabricated PCL, establishing a quantitative, material-level framework relevant to BRS development. Statistical modelling coupled with microstructural observations identified M\u003csub\u003eE\u003c/sub\u003e as the primary determinant of mechanical performance, while T\u003csub\u003eE\u003c/sub\u003e and v\u003csub\u003eD\u003c/sub\u003e acted as secondary modulators of consolidation quality. These findings demonstrate that the mechanical response of MEX-fabricated PCL is governed predominantly by volumetric material delivery rather than thermal or kinematic parameters alone, defining a tunable mechanical window that can be systematically accessed through process optimisation. By decoupling material behaviour from structural geometry, this work provides a robust baseline for future stent-level design and geometry-driven optimisation strategies.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of interests\u003c/h2\u003e \u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding information\u003c/h2\u003e \u003cp\u003eThis work was funded by the Fundamental Research Grant Scheme (FRGS) under a grant number of FRGS/1/2021/TK0/UNIMAP/02/19 from Ministry of Higher Education Malaysia.\u003c/p\u003e\u003ch2\u003eAvailability of data and materials\u003c/h2\u003e \u003cp\u003eThe datasets generated and analysed during the current study are included in this article. Additional data are available from the corresponding author on request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eOkereke MI, Khalaj R, Tabriz AG, et al (2023) Development of 3D printable bioresorbable drug eluting coronary stents: An experimental and computational investigation. J Drug Deliv Sci Technol 79:103952. https://doi.org/10.1016/j.jddst.2022.103952\u003c/li\u003e\n\u003cli\u003eWu H, Yang L, Luo R, et al (2024) A drug-free cardiovascular stent functionalized with tailored collagen supports in-situ healing of vascular tissues. Nat Commun 15:735. https://doi.org/10.1038/s41467-024-44902-2\u003c/li\u003e\n\u003cli\u003eDinc R, Ekingen E (2025) Biodegradable Stents in the Treatment of Arterial Stenosis. J Clin Med 14:532. https://doi.org/10.3390/jcm14020532\u003c/li\u003e\n\u003cli\u003eXu J, Yang J, Huang N, et al (2016) Mechanical response of cardiovascular stents under vascular dynamic bending. Biomed Eng Online 15:21. https://doi.org/10.1186/s12938-016-0135-8\u003c/li\u003e\n\u003cli\u003eAhadi F, Azadi M, Biglari M, et al (2023) Evaluation of coronary stents: A review of types, materials, processing techniques, design, and problems. Heliyon 9:e13575. https://doi.org/10.1016/j.heliyon.2023.e13575\u003c/li\u003e\n\u003cli\u003ePan C, Han Y, Lu J (2021) Structural design of vascular stents: A review. Micromachines (Basel). 12\u003c/li\u003e\n\u003cli\u003eFang S (2024) Assessing the functional mechanical properties of polycaprolactone stents post-processed by ultrasonic strengthening. J Manuf Process 118:154\u0026ndash;162. https://doi.org/10.1016/j.jmapro.2024.03.052\u003c/li\u003e\n\u003cli\u003eYasmin F, Vafadar A, Tolouei‐Rad M (2025) Application of Additive Manufacturing in the Development of Polymeric Bioresorbable Cardiovascular Stents: A Review. Adv Mater Technol 10:. https://doi.org/10.1002/admt.202400210\u003c/li\u003e\n\u003cli\u003eGallinoro E, Almendarez M, Alvarez-Velasco R, et al (2022) Bioresorbable stents: Is the game over? Int J Cardiol 361:20\u0026ndash;28. https://doi.org/10.1016/j.ijcard.2022.05.024\u003c/li\u003e\n\u003cli\u003eKapoor A, Jepson N, Bressloff NW, et al (2024) The road to the ideal stent: A review of stent design optimisation methods, findings, and opportunities. Mater Des 237:112556. https://doi.org/10.1016/j.matdes.2023.112556\u003c/li\u003e\n\u003cli\u003eTidwell K, Harriet S, Barot V, et al (2021) Design and Analysis of a Biodegradable Polycaprolactone Flow Diverting Stent for Brain Aneurysms. Bioengineering 8:183. https://doi.org/10.3390/bioengineering8110183\u003c/li\u003e\n\u003cli\u003eSousa AM, Amaro AM, Piedade AP (2022) 3D Printing of Polymeric Bioresorbable Stents: A Strategy to Improve Both Cellular Compatibility and Mechanical Properties. Polymers (Basel) 2022:1099. https://doi.org/10.3390/polym\u003c/li\u003e\n\u003cli\u003eZhao J, Song G, Zhao Q, et al (2023) Development of three‐dimensionally printed vascular stents of bioresorbable poly(l‐lactide‐co‐caprolactone). J Biomed Mater Res B Appl Biomater 111:656\u0026ndash;664. https://doi.org/10.1002/jbm.b.35184\u003c/li\u003e\n\u003cli\u003eJeong Y-J, Choi B, Kim S, et al (2024) Fully bioresorbable, all-polymer-based, 3D-printed scaffolds with prolonged radiopacity and enhanced durability. Chemical Engineering Journal 494:152851. https://doi.org/10.1016/j.cej.2024.152851\u003c/li\u003e\n\u003cli\u003eSzymczyk-Zi\u0026oacute;łkowska P, Łabowska MB, Detyna J, et al (2020) A review of fabrication polymer scaffolds for biomedical applications using additive manufacturing techniques. Biocybern. Biomed. Eng. 40:624\u0026ndash;638\u003c/li\u003e\n\u003cli\u003eJiang W, Zhao W, Zhou T, et al (2022) A Review on Manufacturing and Post-Processing Technology of Vascular Stents. Micromachines (Basel). 13\u003c/li\u003e\n\u003cli\u003eLi Y, Shi Y, Lu Y, et al (2023) Additive manufacturing of vascular stents. Acta Biomater. 167:16\u0026ndash;37\u003c/li\u003e\n\u003cli\u003ePatel R, Jani S, Joshi A (2023) Review on multi-objective optimization of FDM process parameters for composite materials. International Journal on Interactive Design and Manufacturing (IJIDeM) 17:2115\u0026ndash;2125. https://doi.org/10.1007/s12008-022-01111-9\u003c/li\u003e\n\u003cli\u003eGuerra AJ, Ciurana J (2018) 3D-printed bioabsordable polycaprolactone stent: The effect of process parameters on its physical features. Mater Des 137:430\u0026ndash;437. https://doi.org/10.1016/j.matdes.2017.10.045\u003c/li\u003e\n\u003cli\u003eWang C, Zhang L, Fang Y, Sun W (2021) Design, Characterization, and 3D Printing of Cardiovascular Stents with Zero Poisson\u0026rsquo;s Ratio in Longitudinal Deformation. Engineering 7:979\u0026ndash;990. https://doi.org/10.1016/j.eng.2020.02.013\u003c/li\u003e\n\u003cli\u003eSingh J, Singh G, Pandey PM (2021) Multi-objective optimization of solvent cast 3D printing process parameters for fabrication of biodegradable composite stents. International Journal of Advanced Manufacturing Technology 115:3945\u0026ndash;3964. https://doi.org/10.1007/s00170-021-07423-6\u003c/li\u003e\n\u003cli\u003eKandi R, Pandey PM (2021) Statistical modelling and optimization of print quality and mechanical properties of customized tubular scaffolds fabricated using solvent-based extrusion 3D printing process. Proc Inst Mech Eng H 235:1421\u0026ndash;1438. https://doi.org/10.1177/09544119211032012\u003c/li\u003e\n\u003cli\u003eBrunelli M, Perrault CM, Lacroix D (2017) Mechanical response of 3D Insert\u0026reg; PCL to compression. J Mech Behav Biomed Mater 65:478\u0026ndash;489. https://doi.org/10.1016/j.jmbbm.2016.08.038\u003c/li\u003e\n\u003cli\u003eWang Q, Fang G, Zhao Y-H, Zhou J (2018) Improvement of Mechanical Performance of Bioresorbable Magnesium Alloy Coronary Artery Stents through Stent Pattern Redesign. Applied Sciences 8:2461. https://doi.org/10.3390/app8122461\u003c/li\u003e\n\u003cli\u003eWei Y, Wang M, Zhao D, et al (2019) Structural Design of Mechanical Property for Biodegradable Polymeric Stent. Advances in Materials Science and Engineering 2019:1\u0026ndash;14. https://doi.org/10.1155/2019/2960435\u003c/li\u003e\n\u003cli\u003eSamant S, Wu W, Zhao S, et al (2021) Computational and experimental mechanical performance of a new everolimus-eluting stent purpose-built for left main interventions. Sci Rep 11:8728. https://doi.org/10.1038/s41598-021-87908-2\u003c/li\u003e\n\u003cli\u003eWang Y, Wu H, Fan S, et al (2023) Structure design and mechanical performance analysis of three kinds of bioresorbable poly-lactic acid (PLA) stents. Comput Methods Biomech Biomed Engin 26:25\u0026ndash;37. https://doi.org/10.1080/10255842.2022.2045485\u003c/li\u003e\n\u003cli\u003eCarbonaro D, Ferro N, Mezzadri F, et al (2024) Easy-to-use formulations based on the homogenization theory for vascular stent design and mechanical characterization. Comput Methods Programs Biomed 257:108467. https://doi.org/10.1016/j.cmpb.2024.108467\u003c/li\u003e\n\u003cli\u003eWang L, Jiao L, Pang S, et al (2021) The development of design and manufacture techniques for bioresorbable coronary artery stents. Micromachines (Basel) 12:. https://doi.org/10.3390/mi12080990\u003c/li\u003e\n\u003cli\u003eBai C, Feng X, Lan L, et al (2025) Recent advances and perspectives in bioresorbable metal coronary drug-eluting stents. Biomedical Materials 20:032001. https://doi.org/10.1088/1748-605X/adc058\u003c/li\u003e\n\u003cli\u003eEshraghi S, Das S (2010) Mechanical and microstructural properties of polycaprolactone scaffolds with one-dimensional, two-dimensional, and three-dimensional orthogonally oriented porous architectures produced by selective laser sintering. Acta Biomater 6:2467\u0026ndash;2476. https://doi.org/10.1016/j.actbio.2010.02.002\u003c/li\u003e\n\u003cli\u003eEshraghi S, Das S (2012) Micromechanical finite-element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone\u0026ndash;hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering. Acta Biomater 8:3138\u0026ndash;3143. https://doi.org/10.1016/j.actbio.2012.04.022\u003c/li\u003e\n\u003cli\u003eAlem\u0026aacute;n‐Dom\u0026iacute;nguez ME, Giusto E, Ortega Z, et al (2019) Three‐dimensional printed polycaprolactone‐microcrystalline cellulose scaffolds. J Biomed Mater Res B Appl Biomater 107:521\u0026ndash;528. https://doi.org/10.1002/jbm.b.34142\u003c/li\u003e\n\u003cli\u003eWang S, Ma Y, Deng Z, et al (2020) Effects of fused deposition modeling process parameters on tensile, dynamic mechanical properties of 3D printed polylactic acid materials. Polym Test 86:106483. https://doi.org/10.1016/j.polymertesting.2020.106483\u003c/li\u003e\n\u003cli\u003eHsueh M-H, Lai C-J, Wang S-H, et al (2021) Effect of Printing Parameters on the Thermal and Mechanical Properties of 3D-Printed PLA and PETG, Using Fused Deposition Modeling. Polymers (Basel) 13:1758. https://doi.org/10.3390/polym13111758\u003c/li\u003e\n\u003cli\u003eKamaal M, Anas M, Rastogi H, et al (2021) Effect of FDM process parameters on mechanical properties of 3D-printed carbon fibre\u0026ndash;PLA composite. Progress in Additive Manufacturing 6:63\u0026ndash;69. https://doi.org/10.1007/s40964-020-00145-3\u003c/li\u003e\n\u003cli\u003eAl-Tamimi AA, Pandžić A, Kadrić E (2023) Investigation and Prediction of Tensile, Flexural, and Compressive Properties of Tough PLA Material Using Definitive Screening Design. Polymers (Basel) 15:4169. https://doi.org/10.3390/polym15204169\u003c/li\u003e\n\u003cli\u003eValvez S, Silva AP, Reis PNB (2022) Optimization of Printing Parameters to Maximize the Mechanical Properties of 3D-Printed PETG-Based Parts. Polymers (Basel) 14:2564. https://doi.org/10.3390/polym14132564\u003c/li\u003e\n\u003cli\u003eHe S, Chen Q, Li Z (2025) Influence of Stent Structure on Mechanical and Degradation Properties of Poly (Lactic Acid) Vascular Stent. J Funct Biomater 16:248. https://doi.org/10.3390/jfb16070248\u003c/li\u003e\n\u003cli\u003eNoad RL, Hanratty CG, Walsh SJ (2011) Clinical Impact of Stent Design. Interventional Cardiology Review 9:89. https://doi.org/10.15420/icr.2011.9.2.89\u003c/li\u003e\n\u003cli\u003ePark J, Kwak HS, Kim J-W (2020) Bench-Top Comparison of Three Different Types of Stents Used for Treatment of Intracranial Atherosclerotic Stenosis. Neurointervention 15:117\u0026ndash;125. https://doi.org/10.5469/neuroint.2020.00248\u003c/li\u003e\n\u003cli\u003eAng HY, Huang YY, Lim ST, et al (2017) Mechanical behavior of polymer-based vs. metallic-based bioresorbable stents. J Thorac Dis 9:S923\u0026ndash;S934. https://doi.org/10.21037/jtd.2017.06.30\u003c/li\u003e\n\u003cli\u003eGautam AJ, Wairkar S (2024) 3D-printed bioresorbable vascular stents: emerging frontiers in personalized cardiac care. Polymer Bulletin 81:10533\u0026ndash;10560. https://doi.org/10.1007/s00289-024-05237-6\u003c/li\u003e\n\u003cli\u003eTang C, Liu J, Yang Y, et al (2020) Effect of process parameters on mechanical properties of 3D printed PLA lattice structures. Composites Part C: Open Access 3:. https://doi.org/10.1016/j.jcomc.2020.100076\u003c/li\u003e\n\u003cli\u003eWang P, Zou B, Ding S, et al (2021) Effects of FDM-3D printing parameters on mechanical properties and microstructure of CF/PEEK and GF/PEEK. Chinese Journal of Aeronautics 34:236\u0026ndash;246. https://doi.org/10.1016/j.cja.2020.05.040\u003c/li\u003e\n\u003cli\u003eFernandez-Vicente M, Calle W, Ferrandiz S, Conejero A (2016) Effect of Infill Parameters on Tensile Mechanical Behavior in Desktop 3D Printing. 3D Print Addit Manuf 3:183\u0026ndash;192. https://doi.org/10.1089/3dp.2015.0036\u003c/li\u003e\n\u003cli\u003eSamykano M, Selvamani SK, Kadirgama K, et al (2019) Mechanical property of FDM printed ABS: influence of printing parameters. The International Journal of Advanced Manufacturing Technology 102:2779\u0026ndash;2796. https://doi.org/10.1007/s00170-019-03313-0\u003c/li\u003e\n\u003cli\u003eSagar A, Nehme C, Saigal A, James TP (2020) Stress\u0026ndash;Strain Relationship of Polycaprolactone in Liquid Nitrogen for Finite Element Simulation of Cryogenic Micropunching Process. J Eng Sci Med Diagn Ther 3:. https://doi.org/10.1115/1.4047461\u003c/li\u003e\n\u003cli\u003eAbdul Haq RH, Saidin W, Mat UW (2013) Improvement of Mechanical Properties of Polycaprolactone (PCL) by Addition of Nano-Montmorillonite (MMT) and Hydroxyapatite (HA). Applied Mechanics and Materials 315:815\u0026ndash;819. https://doi.org/10.4028/www.scientific.net/AMM.315.815\u003c/li\u003e\n\u003cli\u003eJiao Z, Luo B, Xiang S, et al (2019) 3D printing of HA / PCL composite tissue engineering scaffolds. Advanced Industrial and Engineering Polymer Research 2:196\u0026ndash;202. https://doi.org/10.1016/j.aiepr.2019.09.003\u003c/li\u003e\n\u003cli\u003eSiqueira DD, Luna CBB, Ara\u0026uacute;jo EM, et al (2019) Biocomposites based on PCL and macaiba fiber. Detailed characterization of main properties. Mater Res Express 6:095335. https://doi.org/10.1088/2053-1591/ab3496\u003c/li\u003e\n\u003cli\u003eAbbas A, Park EJ, Guo J, et al (2024) Performance of bioresorbable peptide incorporated polymers produced for fused deposition modelling (FDM). Next Materials 5:100223. https://doi.org/10.1016/j.nxmate.2024.100223\u003c/li\u003e\n\u003cli\u003eToorani S, Sohrabian M, Sameezadeh M, Khalafi M (2025) Optimized Fabrication and Enhanced Flexural Properties of PCL/F-BG Nanocomposites for Hard Tissue Engineering. J Polym Environ 33:5130\u0026ndash;5148. https://doi.org/10.1007/s10924-025-03710-5\u003c/li\u003e\n\u003cli\u003eBrand M, Sharon N (2025) Analytical Modeling and Validation of Radial Stiffness in Zigzag‐Shaped Stents: Experimental and Numerical Approaches. J Biomed Mater Res B Appl Biomater 113:. https://doi.org/10.1002/jbm.b.35574\u003c/li\u003e\n\u003cli\u003eKatagiri Y, Stone G, Onuma Y, Serruys P (2017) State of the art: the inception, advent and future of fully bioresorbable scaffolds. EuroIntervention 13:734\u0026ndash;750. https://doi.org/10.4244/EIJ-D-17-00499\u003c/li\u003e\n\u003cli\u003eFarhan M, Hasan G, Sobhi A, et al (2025) Bioresorbable scaffolds advances, challenges, and future directions. Annals of Medicine \u0026amp; Surgery 87:4173\u0026ndash;4183. https://doi.org/10.1097/MS9.0000000000003424\u003c/li\u003e\n\u003cli\u003eXu D, Harvey T, Begiristain E, et al (2022) Measuring the elastic modulus of soft biomaterials using nanoindentation. J Mech Behav Biomed Mater 133:105329. https://doi.org/10.1016/j.jmbbm.2022.105329 \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Material extrusion (MEX), Polycaprolactone (PCL), Bioresorbable stents (BRS), Process–property relationships, Mechanical tunability","lastPublishedDoi":"10.21203/rs.3.rs-9089947/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9089947/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMaterial extrusion (MEX) has emerged as a promising method for fabricating bioresorbable stents (BRS); however, a systematic understanding of how process parameters regulate material-level compressive and flexural behaviour of polycaprolactone (PCL) under different loading modes remains limited. In this study, the effects of extrusion temperature (T\u003csub\u003eE\u003c/sub\u003e), material deposition speed (v\u003csub\u003eD\u003c/sub\u003e) and extrusion multiplier (M\u003csub\u003eE\u003c/sub\u003e) on the compressive and flexural responses of MEX-fabricated PCL were investigated using a response surface methodology framework. Distinct parameter sensitivities were observed between loading modes, with M\u003csub\u003eE\u003c/sub\u003e identified as the dominant factor governing both strength and modulus through its control of volumetric material delivery and consolidation quality, while T\u003csub\u003eE\u003c/sub\u003e and v\u003csub\u003eD\u003c/sub\u003e acted as secondary modulators. Regression-based statistical models were developed to capture the nonlinear process\u0026ndash;property relationships and were subsequently employed to define compression-focused, flexural-focused and multi-objective optimisation pathways, reflecting the clinically relevant trade-off between radial support and conformability in coronary stent design. Microstructural observations from cross-sectional SEM imaging provided mechanistic support for the parameter-dependent trends by revealing variations in material continuity, void distribution and defect suppression. By isolating material behaviour from geometric effects, this work establishes a tunable, geometry-independent mechanical window for MEX-fabricated PCL, offering a quantitative material baseline to support future design and optimisation of BRS architectures.\u003c/p\u003e","manuscriptTitle":"Process–Property Relationships and Mechanical Tunability of MEX-Fabricated Polycaprolactone for Bioresorbable Stent Materials","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-23 10:38:54","doi":"10.21203/rs.3.rs-9089947/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2026-03-18T13:40:20+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-18T12:37:03+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-18T03:40:09+00:00","index":"","fulltext":""},{"type":"submitted","content":"The International Journal of Advanced Manufacturing Technology","date":"2026-03-16T00:12:31+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"c04ec82f-4d83-457e-8fd3-46ccfecd17e5","owner":[],"postedDate":"March 23rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-23T10:38:58+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-23 10:38:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9089947","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9089947","identity":"rs-9089947","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}