Effect of Draw Ratio and Triggering Temperature on Properties of Hydrothermal Responsive Shape Memory Microcomposite Filaments.

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Direselgn Molla Semanie, Lei Zhang, Hanur Meku Yesuf, Biruk Fentahun Adamu, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3850397/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 11 Sep, 2024 Read the published version in Cellulose → Version 1 posted 4 You are reading this latest preprint version Abstract This paper investigates the production of hydrothermal responsive shape memory filaments with different draw ratios (0.8, 2.0, and 3.2), using microcrystalline cellulose (MCC) as a filler and shape memory polyurethane (SMPU) as a matrix. A mechanical-thermo-aqueous programming test (MTAP) was conducted to study the shape-memory properties of the microcomposite filaments. The effect of draw ratio and triggering temperature on mechanical, physical, thermal, morphological, and shape memory performances was thoroughly studied. Among the microcomposite filaments, SMPU-MCC with a draw ratio of 2.0 exhibited the highest tenacity value of 0.91 cN/dtex in its original shape, with an elongation percentage of 385.2%. The differential scanning calorimetry (DSC) results showed that the glass transition temperature (Tg) of the filaments increased as the draw ratio increased from 0.8 to 3.2, ranging from 38.35°C to 41.02°C. The crystallinity percentages obtained for pure SMPU, SMPU-MCC-0.8, SMPU-MCC-2.0, and SMPU-MCC-3.2 were 27.10%, 30.68%, 38.72%, and 36.88%, respectively. In addition, an optimum draw ratio led to a degradation temperature rise from 372.5ºC to 391.3ºC, which shows the thermal stability of the filaments was significantly influenced by the intermolecular bonding between MCC and SMPU, which intensified as the draw ratio increased from 0.8 to 2.0. Moreover, the filaments exhibited excellent mechanical and thermal properties in six cycles at the optimum draw ratio and triggering temperature, indicating their future application for repeated use without experiencing major changes in shape memory properties. Triggering temperature Draw ratio Microcrystalline cellulose Shape memory filament Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Introduction According to a recent estimate, the market for smart textiles is highly increasing and is predicted to be more than $ 130 billion by 2025 (Korkmaz Memiş & Kaplan, 2021 ). These smart textiles can be used in various areas such as medical, sports, energy harvesting, active thermoregulation, etc. Smart textiles containing active temperature-water regulation functions have great advantages for providing comfort by monitoring environmental or physiological changes and responding accordingly. This performance can be achieved by many smart materials, including shape memory polymers (SMPs), electronic textiles, shape memory alloys (SMAs), and phase change materials (Raja et al., 2013 ). Shape memory polymers (SMPs) are smart materials that have the ability to change their shape and respond according to the specific stimuli applied. SMPs have high extension rate (up to 800%) that makes them withstand significant deformation, a density of 900–1100 kg/m3, variable recovery speed and easy processing (Janis Andersons, 2020 ). Given the above advantages, they are widely used in a variety of applications, including breathable clothing for better comfort in environments with varying temperatures and moisture. There are many types of thermo-water-responsive SMPs, but shape memory polyurethane (SMPU) is best suited for the textile industry because it can be used as a coating as well as fibers used to make fabrics (Korkmaz Memiş & Kaplan, 2022 ). SMPUs are the most important type of polyurethanes (PUs) that have a two-phase structure with hard and soft segments, which makes them thermally responsive shape memory polymers. SMPU fibers can be easily made by wet and melt spinning in addition to their usage as coating and adhesive materials. Hydrothermal (moisture and temperature) sensitive shape memory polyurethane (SMPU) can be achieved by incorporating hydrophilic particles to temperature-responsive SMPUs as reinforcement. Cellulose, in particular, has gained interest due to its water absorption properties and additional advantages such as high crystallinity and strength. Despite the production of nanocellulose requires high energy consumption, which makes it expensive and contributes greatly to global warming (Janis Andersons, 2020 ), both nanocellulose and microcrystalline cellulose can provide efficient mechanical reinforcement because of their excellent mechanical properties that are small enough to be incorporated into the structure of composite fiber without adversely changing the composite fiber morphology. Using cellulose as reinforcement in composite fiber manufacturing will also increase the bio-based content of the composite products (Janis Andersons, 2020 ). Shape memory polyurethane (SMPU) filaments are not very strong to be a fabric and needs high response time and concentration for significant shape memory effect. The strength and shape memory properties of these filaments are influenced by various factors, including the solution viscosity, molecular weight, triggering temperature and draw ratio during spinning. However, draw ratio and triggering temperature are the most important factors that affects both the tensile strength and shape memory properties of the filaments (Shen et al., 2023 ). Draw ratio is defined as the degree of stretching of the spinning solution inside (primary drawing) and outside (second drawing) the coagulation bath and calculated by dividing the take-up speed after solidification by the initial extrusion speed from the spinneret (Gupta et al., 2006 ). From previous literature, it was observed that no detailed study has been conducted to specifically examine the effect of draw ratio and triggering temperature on the properties of microcrystalline cellulose-reinforced shape memory polyurethane filament. Therefore, in this study, a water and temperature responsive microcomposite filaments were produced by incorporating microcrystalline cellulose into shape memory polyurethane, and their physical, mechanical, morphological, chemical composition, and thermal properties were analyzed using DSC, TGA, XRD, SEM, FTIR, and MTAP techniques. Three different draw ratios and triggering temperatures were optimally selected, and their effect on shape memory properties of microcomposite filaments was studied, and findings of this study are discussed in detail. Experimental Materials Pellet-type temperature responsive SMPU granules (Sigma-Aldrich, USA) composed of 4,4-methylenebis(phenyl isocyanate), 1,4-butanediol, Di(propylene glycol) and Polycaprolactone was used as matrix material to produce hydrothermal responsive microcomposite filament. Microcrystalline cellulose (Sigma-Aldrich), which has a length ranging from 70 to 140µm according to the manufacturer's specifications, was incorporated as a reinforcement to enhance the strength and water responsive property of the composite filament. N, N-dimethylformamide (DMF) (Sigma-Aldrich)- is a polar solvent, which was used as a solvent. Polyoxyethylene sorbitan monooleate (commonly known as Tween 80) (Sigma-Aldrich) was used as nonionic surfactant. Preparation of Spinning Suspension The spinning solution was prepared with a suitable viscosity for spinning to produce hydrothermal (water and temperature) responsive microcomposite (SMPU-MCC) filaments using the wet spinning method. Based on literature and preliminary experiments, an optimal concentration of 25 wt% SMPU in DMF was used (Korkmaz Memiş & Kaplan, 2021 ), which resulted in efficient fiber spinning. Additionally, through an optimization process, a concentration of 15 wt% MCC was identified as the ideal concentration. SMPU polymer solution with 25 wt% and a homogeneous 15 wt% dispersion of MCC in DMF in the presence of non-ionic surfactant Tween80 at 1:2 w/w of MCC were mixed at 60°C for 6 h by a mechanic stirrer equipped with an ultrasonic homogenizer at a speed of 200 rpm. To maintain the consistency of the solution, the beakers were appropriately covered to prevent DMF evaporation and viscosity variation. Optimization and Production of Micro-composite Filament A central composite design was utilized to identify the optimal variables by establishing experimental factors and analyzing the connection between factors and responses. An optimized 15wt% concentration of MCC with 25wt% SMPU concentration was used for both pure SMPU and microcomposite filaments. MCC-SMPU spinning solution was spun with a CHEMYX wet spinning machine (CHEMYX Inc, USA), with an internal needle diameter of 1.05mm at a constant flow rate of 2ml/min, 0.81ml/min and 0.5ml/min into a coagulation bath of distilled water. The filament was then guided by a roller in the coagulation bath and transferred to the washing bath by a separately installed take-up head (Samgold MCU Digital Technology, China) at 1.9 m/min. In wet spinning, there are two drawing processes: primary drawing process in the coagulation bath and secondary drawing process after drying (Fukui et al., 2021 ). In this study, the drawing ratio refers to the primary drawing ratio, which is the ratio between the inlet speed from the spinneret and the winding or take-up speed. Draw ratio of 0.8, 2.0, and 3.2 were applied to pure SMPU and SMPU-MCC microcomposite filaments. The filaments were then immersed in distilled water for 24 hours to remove any remaining solvent (DMF) from the filament structure and dried for Ten hours at 40°C. Based on their draw ratio, the filaments were categorized and coded as SMPU-2.0 and SMPU-MCC-0.8, SMPU-MCC-2.0 and SMPU-MCC-3.2, and the schematic representation of wet spinning is shown in Fig. 1 below. Fiber Characterization Chemical and Morphological Analyses Filaments were kept under standard textile testing conditions at a temperature of 20 ± 2°C and a relative humidity of 65 ± 2%. Evaluation of the surface characteristics and dispersion of MCC within the micro-composite filaments was conducted using TM4000 Table Top Scanning Electron Microscopy (Thermo Scientific, USA) operating at 20 kV with a maximum magnification power of 3000. The crystal structure of the microcomposite filaments were analyzed using a Bruker D8 Advance diffractometer (XRD) (Bruker Corporation, USA) with a radiation wavelength of 1.542 Å. The scan range is from 5° to 60° with a scanning step size of 0.02° and a step time of 1 s. The XRD measurements were conducted at an operating voltage of 40 kV and current of 150 mA. Fourier transform infrared (FTIR) spectroscopy (PerkinElmer, USA) with a spectrum range of 4000 cm-1 to 400 cm-1, was used to analyze the functional groups and chemical structures of SMPU-MCC filaments. FTIR tests were determined in accordance with the standards outlined in the ASTM E1252 and ASTM E168 test methods. Thermo-Mechanical Analyses LLY-06E-500 Electronic Single fiber Strength Tester (Laizhou Electronic Instruments Co., Ltd, China) was used to measure the mechanical properties of the microcomposite filaments in accordance with ASTM D3822-07 at a gauge length of 20 mm and an extension rate of 200 mm/min. A minimum of ten replications were performed, and the average values were reported. The linear density of the microcomposite filaments at their original and fixed temporary shape was determined in dtex according to D2591-07 (Reapproved 2020). The thermal stability of the micro-composite filaments was assessed by thermogravimetric analysis (TGA 8000, PerkinElmer, Inc., USA) under nitrogen atmosphere between 50 and 600°C at a heating rate of 10°C/min. The decomposition temperatures (T 10 , T 50 , and T max ) of microcomposite filaments were determined from the TG data. Differential scanning calorimetry (DSC 8500, PerkinElmer Instruments, USA) was utilized to study the thermal characteristics of the microcomposite filaments. The analysis was performed according to ISO 11,357:1–7 standards, with microcomposite filaments weighing 5–10 mg being heated at a rate of 10°C/min from − 10 to 200°C and then cooled at a rate of 20°C/min to 20°C to clear the thermal history. In the second heating, the samples were heated from 20 to 200°C at a rate of 10°C/min and then cooled to room temperature. The glass transition temperature (Tg) of the microcomposite filaments was determined from the first heating. Shape Memory Properties of the Fiber The mechanical-thermo-aqueous programming test was followed to determine the shape memory properties of micro-composite filaments with initial length (Li) taken as 5 cm. There were four phases in this programming test. First, the sample was 100% stretched into a temporary length (Lt) by immersing it in hot water with a triggering temperature of Tg + 5°C, Tg + 10°C and Tg + 20°C for ten minutes. The filaments were then cooled down below the glass transition temperature around 23°C, and dried for 12 hours to fix the temporary length. At this point, the load was removed and fixed temporary length (Lf) was measured. Finally, the shape memory effect (SME) was initiated by again immersing the filaments at a recovery temperature varying according to their Tg for 10 minutes in order to release the thermal and water switches, and samples were restored to their original recovered length (Lr). The procedure was replicated for six cycles and the glass transition temperature Tg + 5°C, Tg + 10°C, Tg + 20°C of each sample was used as the triggering temperature (Santiago et al., 2016 ). The shape-memory properties of a material can be evaluated using two important parameters: the shape-recovery ratio (Rr) and the shape-fixity ratio (Rf) (Gordon & Gordon, 2016 ). Shape-recovery ratio (Rr) measures the ability of the microcomposite filament to return to its original shape after deformation (Eq. 1 ). It is calculated by dividing the deformation recovered by the maximum deformation during the programming test. Whereas shape-fixity ratio (Rf) measures the ability of the filaments to maintain its temporary shape (Eq. 2 ) and is calculated by dividing the deformation after the loads is removed by the maximum deformation (Tang et al., 2020 ). $${R}_{r}=\left(\frac{{L}_{t}-{L}_{r}}{{L}_{t}-{L}_{i}}\right)\times 100\%$$ 1 $${R}_{f}=\left(\frac{{L}_{f}-{L}_{i}}{{L}_{t}-{L}_{i}}\right)\times 100\%$$ 2 Where Li represents the initial length of the samples, Lt is the temporary length before the load is removed, Lf represents the fixed temporary length after cooling and removal of the load, Lr is the recovered length, and Rr and Rf represent the shape recovery and shape fixity ratios, respectively. The schematic representation of mechanical-thermo-aqueous programming test is illustrated in Fig. 2 . RESULTS AND DISCUSSIONS Physical and Mechanical properties of Filaments Figure 3 presents linear densities of pure SMPU and SMPU-MCC microcomposite filaments at their original and fixed temporary shapes ranging between 155.3–193.7dtex. The incorporation of MCC into the SMPU matrix appears to have a notable impact on the linear density of the microcomposite filaments. The linear density of pure SMPU filaments at their original length was 176.6dtex with a draw ratio of 2.0 that increases to 181.4dtex in SMPU-MCC filaments with the same draw ratio. The linear density of SMPU-MCC filaments with a 0.8 draw ratio is higher (193.7dtex) than that of pure SMPU. This increment suggests that MCC contributes to the mass of the composite filament due to its inherent density and rigidity. This is also supported by previous findings (González et al., 2023 ) (Korkmaz Memiş & Kaplan, 2021 )(Gherissi et al., 2012 ). Furthermore, SMPU-MCC microcomposite filaments with draw ratio of 3.2 exhibit the lowest linear density (170.2dtex at original shape and 168.6dtex at fixed temporary shape), suggesting that higher draw ratios decrease mass per unit length of the filaments. Shape memory polyurethane (SMPU) exhibits high elongation but relatively low strength compared to other synthetic fibers. To improve its strength as a textile filament fiber, reinforcement materials such as cellulose can be incorporated. Figure 4 (a) illustrates the stress-strain curves of microcomposite filaments in their original shape, while Fig. 4 (b) shows the curves in their fixed temporary shape at different draw ratios. The microcomposite filaments in their original shape exhibit higher tenacity and elongation compared to those in their fixed temporary shape. Among microcomposite filaments, SMPU-MCC-2.0 demonstrates the highest tenacity value of 0.91cN/dtex at its original shape, with an elongation percentage of 385.2%. However, this value decreases to a tenacity of 0.74cN/dtex and an elongation of 331.8% at fixed temporary shape. The improved tenacity can be attributed to enhanced load transfer resulting from improved chain alignment between the matrix and cellulose particles. The presence of microcrystalline cellulose (MCC) also establishes a percolation network within the filament structure, stabilized by hydrogen bonding (Korkmaz Memiş & Kaplan, 2021 ). This network enables more effective load transfer between the SMPU matrix and cellulose particles. In contrast, the MCC-SMPU microcomposite filament with 0.8 draw ratio exhibits the lowest tenacity value, measuring 0.6cN/dtex in its original shape, which decreases to 0.39cN/dtex in its fixed temporary shape. This indicates insufficient drawing, resulting in relatively disordered polymer chains (González et al., 2023 ). Chemical and Morphological Analyses Figure 5 shows a cross-sectional view of pure shape memory polyurethane (SMPU) and SMPU-MCC microcomposite filaments at a magnification of 400x. The figure clearly illustrates that increase in draw ratio enhances the integrity of polymer chains with microcrystalline cellulose (MCC). Pure SMPU with a draw ratio of 2.0 has slightly irregular cross-section with visible foldings (Richardson, 2009 ). On the other hand, SMPU-MCC microcomposite filaments exhibit relatively circular and regular cross-sections with more uniform distribution of MCC within the filament structure as the draw ratio increases. However, excessive stretching of the soft segments in SMPU-MCC filaments with a draw ratio of 3.2 decreases its shape memory properties (Zhang et al., 2019 )(Shojaeiarani et al., 2021 ). The longitudinal SEM images of the microcomposite filaments at magnifications of 200x are presented in Fig. 6 (a)-(d). Pure shape memory polyurethane filament fiber with drawing ratio of 2.0 (SMPU-2.0) shows a separate fiber edge and microcracks. Korkmaz et al 2021, expalined this situation as the absence of reinforcement (microcrystalline cellulose), which affects viscosity and results in a low mass transfer rate difference between the coagulating solvent diffusion into the spinning solution and solvent extraction into the coagulation bath (Korkmaz Memiş & Kaplan, 2021 ). Whereas microcrystalline cellulose-reinforced SMPU filament with a drawing ratio of 0.8 exhibits clear polymer chain folding which decreases as the drawing ratio increases, ultimately resulting in good fiber alignment. Despite, the molecular arrangement and chain conformation significantly improved in SMPU-MCC-3.2 as show in Fig. 6 (d), there is excessive stretching of polymer chains that affects the shape memory property and stretchability of the fiber (Gupta et al., 2006 ). Figure 7 shows the FT-IR spectra of pure SMPU and SMPU-MCC microcomposite filaments. Pure SMPU with a draw ratio of 2.0 exhibits a characteristic IR absorption peak at 3271 cm-1, which corresponds to the stretching bands of (-NH-) and (-OH-) groups in polyurethane (PU) polymers. The peaks at 2852 cm-1 and 1630 cm-1 correspond to the symmetric stretching vibrations of (-CH-) groups and the stretching bending vibrations of (-C = O-) groups in the (COO-) units of shape memory polyurethane. For SMPU-MCC microcomposite filaments, the characteristic peaks related to the stretching vibrations of (-OH-) and (-NH-) groups shift from 3271 cm-1 to 3380 cm-1, 3351 cm-1, and 3329 cm-1which indicates the presence of additional hydroxyl (-OH) functional groups found in microcrystalline cellulose (Raja et al., 2013 )(Liem et al., 2007 )(Zhang et al., 2019 ). The characteristic peaks at 2852cm-1, 2980cm-1, 2953cm-1 and 2939cm-1 for SMPU-2.0, SMPU-MCC-0.8, SMPU-MCC-2.0, and SMPU-MCC-3.2 indicates (-CH 2 -) and (-C-H-) stretching vibration of hydrocarbon chains found in filaments. Peak absorption at 1753 cm-1, 1726cm-1 and 1718cm-1 indicates (-C = O-) stretching vibrations while the peak at 1630 cm-1 corresponds to the (-C = C-) bending bond from the functional group of alkenes present in cellulose and aromatic compounds in Polycaprolactone of SMPU (Richardson, 2009 ). The slight shift in wavenumber and intensity observed in microcomposite filaments can be attributed to the incorporation of microcrystalline cellulose (MCC) into the SMPU matrix and the improved polymer chain alignment and molecular orientation because of increased drawing, which disrupts the hydrogen bonds between (-NH-) and (-C = O-) due to the strong interaction between MCC and SMPU (Raja et al., 2013 )(Korkmaz Memiş & Kaplan, 2020 )(Zhong & Nsengiyumva, 2022 )(Shojaeiarani et al., 2021 ). Figure 8 shows the X-ray diffraction (XRD) patterns of pure SMPU and MCC-SMPU microcomposite filaments. It can be observed that the pure SMPU filament exhibits a peak at 2θ = 20.42°, indicating its poorly crystalline or amorphous structure. This peak suggests the presence of small crystallites scattered within the short-range ordered hard segments or relatively amorphous region within the filament's structure (Korkmaz Memiş & Kaplan, 2021 ). On the other hand, the SMPU-MCC microcomposite filaments shows XRD peaks at 2θ = 22.39°, 22.12°, and 22.24°, which indicate the presence of cellulose particles in the filament structure (Urba et al., 2022 ). The intensity of the XRD peaks increases with an increased draw ratio of the microcomposite filaments. The crystalline nature and the degree of crystallinity can be characterized by the sharpness and peak intensity value, respectively. The crystallinity percentages obtained for pure SMPU, SMPU-MCC-0.8, SMPU-MCC-2.0, and SMPU-MCC-3.2 are 27.10%, 30.68%, 38.72%, and 36.88%, respectively. This demonstrates that an increased draw ratio enhances the crystallinity of the filaments (Barkoula et al., 2008 ). Thermal Analyses The glass transition temperature (Tg) of microcomposite filaments with different draw ratios was evaluated using differential scanning calorimetry (DSC). The DSC results from the first heating scan (Fig. 9 ) indicated that the Tg of the pure shape memory polyurethane (SMPU-2.0) filament was 41.65°C whereas the Tg of SMPU-MCC-0.8, SMPU-MCC-2.0, SMPU-MCC-3.2 was 38.35°C, 41.02°C and 40.35°C respectively. As the draw ratio increased to 2.0, the Tg of MCC-SMPU microcomposite filaments increased from 38.35°C to 41.02°C. The observed increase in Tg with increasing draw ratio can be attributed to the alignment and orientation of the polymer chains (Tomisawa et al., 2017 ). However, for a draw ratio of 3.2, the decrease in Tg can be related to excessive stretching of the filaments, resulting structural defects and disruptions in chain alignment. These defects facilitate easier initiation of chain mobility at a lower temperature, leading to a decrease in Tg (Gupta,.et al, 2006). The incorporation of MCC into the filament structure of SMPU-2.0 results in a higher glass transition temperature (Tg) compared to SMPU-MCC microcomposite filaments with the same draw ratio. This observation aligns with the findings of Korkmaz et al. 2021, where they reported a decrease in Tg of composite filaments with the addition of cellulose nanowhiskers (CNW). According to Korkmaz et al., the reduction in Tg with CNW addition can be attributed to the plasticizing effect and micro-Brownian thermal motions of molecular chain segments generated by CNW particles. These particles disrupt the dominant original interactions among the polymer chains in SMPU, facilitating chain mobility at lower temperatures (Korkmaz Memiş & Kaplan, 2021 ). It was similarly reported by Gan et al. in 2020, that the addition of nanocellulose fibrils to a PVOH (polyvinyl alcohol) composite resulted in a decrease in the glass transition temperature (Tg). This decrease was attributed to the increased mobility of the soft domains within the polymer matrix. Furthermore, the incorporation of microcrystalline cellulose disrupted the original interactions between the rigid and soft segments of the polymer, leading to a higher degree of microphase separation within the matrix (Gan et al., 2020 ). Figure 10 illustrates the Thermogravimetric Analysis (TGA) results obtained to determine the effect of draw ratio and incorporation of MCC on the thermal stability of SMPU filaments. As shown in Table 1 , the significant increase from 309.9ºC to 328.39ºC for T 10% indicates an enhancement in the thermal stability of the microcomposite filaments due to improved interaction between MCC and the SMPU matrix through hydrogen bonding. The maximum weight loss temperature (Tmax) of the microcomposite filaments is considered the most important temperature for evaluating thermal stability (Simão et al., 2015 ). An increase in draw ratio leads to a temperature rise from 372.5ºC to 391.3ºC, indicating that the thermal stability of the composites is strongly influenced by intermolecular bonding between MCC and SMPU, which intensifies as the draw ratio increases from 0.8 to 2.0. According to Gan et al. 2020 , strong intermolecular bonding enhances the energy required for chain cleavage of macromolecules, thereby improving the thermal stability (Gan et al., 2020 ). However, a decrease in degradation temperature is observed for a draw ratio of 3.2, which could be attributed to the critical volume fraction and the percolation threshold, as well as the instability of crystallites caused by the high draw ratio leading to chain fracture (Ahmed et al., 2015 )(González et al., 2023 )(Liu et al., 2014 ). Table 1 Peak temperatures and char residue of microcomposite filaments Sample Code T 10% (°C) T 50% (°C) T max (°C) Char residue (wt%) SMPU-2.0 309.9 336.9 370.3 4.96 SMPU-MCC-0.8 328.39 379.24 372.5 11.48 SMPU-MCC-2.0 325.6 380.96 391.3 10.97 SMPU-MCC-3.2 323.5 380.4 372.58 10.82 Shape Memory Properties Shape memory properties of hydrothermal responsive MCC-SMPU microcomposite filaments mainly depends on the presence of microcrystalline cellulose in SMPU that introduces hydrophilic properties and the temperature sensitive behavior of shape memory polyurethanes. When the microcomposite filaments were placed in hot water above their glass transition temperature (Tg) with applied force, the hydroxyl groups present in MCC formed hydrogen bonds with water molecules. Consequently, the storage modulus of the filaments decreased, indicating a softening of the material (Korkmaz Memiş & Kaplan, 2021 ). Shape recovery and shape fixity ratios were used to calculate shape memory properties of microcomposite filaments at six consecutive cycles and three triggering temperatures (i.e., Tg + 5ºC, Tg + 10ºC and Tg + 20ºC). Soft segment of microcomposite filaments makes the material to maintain its temporary shape and expressed as shape fixity (Korkmaz Memiş & Kaplan, 2021 ) (Richardson, 2009 ). Whereas the hard segment of microcomposite filaments makes the fiber to return to its original shape. In Fig. 11 (a), the shape fixity and shape recovery ratios of pure SMPU and microcomposite filaments are shown at the triggering temperature of Tg + 5ºC. It can be observed that the shape fixity initially decreases for the first three cycles, but starts to increase from the fourth and fifth cycles onwards, eventually becoming constant after the fifth cycle. On the other hand, the shape recovery of the filaments shows a decreasing trend over five consecutive cycles, and then stabilizes from the sixth cycle onwards, with the exception of a slight fluctuation observed for SMPU-MCC-0.8 at the third cycle. Moving on to Fig. 11 (b), the shape fixity of the filaments increases for the first and second cycles, but decreases for the third and fourth cycles. In contrast, the shape recovery behavior varies among the different filaments. SMPU-MCC filaments with a draw ratio of 2 and 0.8 exhibit a relatively consistent decrease in shape recovery, while the other filaments display some instability, with both increasing and decreasing shape recovery ratios. When the triggering temperature is increased to Tg + 20ºC (Fig. 11 (c)), all filaments demonstrate relatively stable shape fixity, with a slight increasing pattern. Moreover, the shape fixity values at this triggering temperature are higher compared to the other triggering temperatures. Additionally, the shape recovery performance is significantly enhanced at the beginning of the test, followed by a steady decrease thereafter. Notably, SMPU-MCC filaments with a draw ratio of 3.2 exhibit the lowest shape recovery ratio at lower triggering temperatures, consistently demonstrating a loss in their memorizing performance. According to Korkmaz et al. (2021), the shape fixity of composite filaments is enhanced during wet-dry transitions. This is attributed to the increased cleavage and re-formation of hydrogen bonds facilitated by cellulose. The presence of water molecules promotes stronger hydrogen bonding between cellulose particles and the shape memory polyurethane (SMPU) matrix, resulting in improved shape fixation upon drying (Korkmaz Memiş & Kaplan, 2021 ). The shape fixity ratio of microcomposite filaments increases with draw ratio and triggering temperature. A higher draw ratio leads to alignment of molecular chains resulting in increased crystallinity within the filament. The increased crystallinity provides more structural rigidity to the filament and leads to enhanced resistance against instantaneous elastic recovery. As a result, the filament exhibits a higher shape fixity ratio, indicating improved ability to retain its fixed temporary shape after the load is removed (Richardson, 2009 ). The shape recovery ratio decreases as the draw ratio increases, which is related to the reduced chain mobility of the soft segments (Richardson, 2009 ).In the case of MCC-SMPU with a draw ratio of 2.0, the shape recovery ratio was determined to be 93.6% (Fig. 11 (d)). This value is consistent with findings from previous studies. For instance, Korkmaz et al. (2021) reported a shape recovery ratio ranging from 91–100% for SMPU reinforced cellulose nanowhiskers given that shape memory polymers with a shape recovery ratio exceeding 80% can be considered excellent (Korkmaz Memiş & Kaplan, 2021 ). Figure 12 (a-d) shows shape fixity and shape recovery ratios of each filament separately at different triggering temperature. As shown below in Fig. 12 a, the shape recovery ratio for pure SMPU with draw ratio of 2 increased with triggering temperature increases from Tg + 5 to Tg + 10 but started decreasing when temperature becomes Tg + 20ºC. this triggering temperature effect decreased for SMPU-MCC-0.8 and SMPU-MCC2.0 as shown in (b) and (c). The shape recovery ratio observed in the second cycle of mechanical-thermo-aqueous programming tests was found to be lower than that of the first cycle, attributed to the deformation and rearrangement of molecular chains within the filament fiber. However, the shape fixity ratio of the microcomposite filaments in the second round increased as the draw ratio increased. This indicates that additional soft segments were created due to the breakage of weak interactions between polymer chains, such as dipole-dipole interactions, hydrogen bonding, or physical crosslinking. These segments enabled the absorption of external stress by unfolding and extending their molecular chains (Hui, 2020 ). In both sets of graphs, it is observed that the shape recovery ratio decreases with an increasing number of cycles, while the shape fixity increases either a constant or fluctuating pattern for both pure SMPU and microcomposite filaments. The decrease in shape recovery can be attributed to the repeated stretching undergone during multiple cycles, which leads to an increase in molecular orientation in the stretch direction and the formation of frozen crystals (Santiago et al., 2016 ) (Liu et al., 2014 ). This effect is significant for filaments with higher draw ratios, as the increased crystallinity associated with higher draw ratios results in a greater reduction in shape recovery compared to filaments with lower draw ratios. This finding is consistent with previous research conducted by Richardson in 2009 (Richardson, 2009 ). However, there is a slight increment in the shape recovery ratio for pure SMPU and SMPU-MCC microcomposite filaments at lower triggering temperatures but there is no shape recovery increment clear pattern that shows relationship between draw ratio, temperature, and the number of cycles. As the number of cycles increases, shape fixity also increases attributed to a decrease in instantaneous elastic recovery (Ei) (shown in Fig. 2 ) (Barkoula et al., 2008 ). Conclusion In this study, hydrothermal responsive shape memory microcomposite filaments with draw ratio of 0.8, 2.0 and 3.2 were successfully produced through wet spinning process from 25%SMPU matrix and 15wt% MCC filler concentration. The incorporation of microcrystalline cellulose and an increase in draw ratio improved the mechanical properties and crystallinity of the microcomposite filaments, resulting in higher tenacity compared to pure SMPU filaments. DSC results indicated that Tg for triggering the shape memory effect of SMPU-MCC microcomposite filaments were between 38.35°C to 41.02°C whereas for pure SMPU filaments was 41.65°C. According to the TGA results, microcomposite filaments showed stable thermal properties from 370.3°C to 391.3°C with increase in draw ratio and addition of microcrystalline cellulose which are suitable for textile applications. The shape memory properties of microcomposite filaments were determined by mechanical- thermo-aqueous programming tests under hot water above glass transition temperature. In addition to shape memory properties, chemical, morphological, physical, mechanical, and thermal characteristics were studied. From the results, all microcomposite filaments produced showed excellent shape memory properties at 100% deformation at different draw ratios and triggering temperatures. MCC-SMPU-3.2 showed the lowest shape recovery ratio in all six cycles of all pure SMPU and SMPU-MCC microcomposite filaments in different draw ratios. As draw ratio increased, shape fixity ratios enhanced significantly including SMPU-MCC-3.2. In addition, SMPU-MCC microcomposite filaments maintained their original thermal responsiveness and gained a water-responsive shape memory property through the percolation network of MCC, which formed reversible hydrogen bonds with water molecules. Furthermore, the consecutive test cycle for shape memory properties demonstrated that microcomposite filaments can be used repeatedly without significant decrease in their shape memory properties. Generally, all microcomposite filaments, especially SMPU-MCC-2.0, exhibited excellent mechanical properties and hydrothermal responsive shape memory performance, highlighting their high potential for applications in smart textiles like waterproof and breathable garments, sportswear, and socks. Further research will be required on lowering the triggering temperature while maintaining the shape memory and mechanical performance, as well as transforming the manufactured filaments into finished products. Declarations Ethical Approval: Not applicable . Competing interests: The authors declare that they have no competing interests. Author Contributions Direselgn Molla Semanie conducted the lab work, testing, and manuscript writing. Lei Zhang, Hanur Meku Yesuf, Biruk Fentahun Adamu, Dr. Buguang Zhou did material preparation, data collection and draft review. Prof. Guo Jiansheng provided guidance and follow-up throughout the entire research process. Funding: The authors have not disclosed any funding. Availability of data and materials The datasets used in this study are available from the corresponding author upon reasonable request. References Ahmed, N., Kausar, A., & Muhammad, B. (2015). Advances in Shape Memory Polyurethanes and Composites : A Review Advances in Shape Memory Polyurethanes and Composites : Polymer-Plastics Technology and Engineering , 54 (13), 1410–1423. https://doi.org/10.1080/03602559.2015.1021490 Barkoula, N. M., Alcock, B., Cabrera, N. O., & Peijs, T. (2008). Flame-Retardancy Properties of Intumescent Ammonium Poly(Phosphate) and Mineral Filler Magnesium Hydroxide in Combination with Graphene. Polymers and Polymer Composites , 16 (2), 101–113. https://doi.org/10.1002/pc Fukui, Y., Teramua, T., & Yoshimi, T. (2021). Analysis of Fiber Drawing in Wet Spinning for Surface Roughness. MATEC Web of Conferences , 333 , 11006. https://doi.org/10.1051/matecconf/202133311006 Gan, P. G., Sam, S. T., Abdullah, M. F. bin, & Omar, M. F. (2020). Thermal properties of nanocellulose-reinforced composites: A review. Journal of Applied Polymer Science , 137 (11). https://doi.org/10.1002/app.48544 Gherissi, A., Cheikh, R. Ben, Dévaux, E., & Abbassi, F. (2012). Cellulose whiskers micro-fibers effect in the mechanical proprieties of PP and PLA composites fibers obtained by spinning process. Applied Mechanics and Materials , 146 (August), 12–26. https://doi.org/10.4028/www.scientific.net/AMM.146.12 González, J., Ardanuy, M., González, M., Rodriguez, R., & Jovančić, P. (2023). Polyurethane shape memory filament yarns: Melt spinning, carbon-based reinforcement, and characterization. Textile Research Journal , 93 (3–4), 957–970. https://doi.org/10.1177/00405175221114165 Gordon, R. F., & Gordon, R. F. (2016). The Properties and Applications of Shape Memory Polyurethanes. Advanced Performance Materials , 7857 , 254–258. https://doi.org/10.1080/10667857.1993.11784997 Gupta, B., Revagade, N., Anjum, N., Atthoff, B., & Hilborn, J. (2006). Preparation of poly(lactic acid) fiber by dry-jet-wet-spinning. I. Influence of draw ratio on fiber properties. Journal of Applied Polymer Science , 100 (2), 1239–1246. https://doi.org/10.1002/app.23497 Hui, J. (2020). Synthesis and characterization of two-way shape memory polymers (Issue September). Janis Andersons, M. K. and U. C. (2020). Reinforcement Efficiency of Cellulose Microfibers for the Tensile Stiffness and Strength of Rigid Low-Density Polyurethane Foams. Materials , 13 (2725), 1–15. Korkmaz Memiş, N., & Kaplan, S. (2020). Dual responsive wool fabric by cellulose nanowhisker reinforced shape memory polyurethane. Journal of Applied Polymer Science , 137 (19), 28–38. https://doi.org/10.1002/app.48674 Korkmaz Memiş, N., & Kaplan, S. (2021). Production of thermal and water responsive shape memory polyurethane nanocomposite filaments with cellulose nanowhisker incorporation. Cellulose , 28 (11), 7075–7096. https://doi.org/10.1007/s10570-021-03966-9 Korkmaz Memiş, N., & Kaplan, S. (2022). Smart polyester fabric with comfort regulation by temperature and moisture responsive shape memory nanocomposite treatment. Journal of Industrial Textiles , 51 (5_suppl), 7920S-7941S. https://doi.org/10.1177/1528083720975652 Liem, H., Yeung, L. Y., & Hu, J. L. (2007). A prerequisite for the effective transfer of the shape-memory effect to cotton fibers. SMART MATERIALS AND STRUCTURES , 16 , 748–733. https://doi.org/10.1088/0964-1726/16/3/023 Liu, Y., Li, Y., Chen, H., Yang, G., Zheng, X., & Zhou, S. (2014). Water-induced shape-memory poly(d,l-lactide)/microcrystalline cellulose composites. 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Composites Part C: Open Access , 5 (May), 100164. https://doi.org/10.1016/j.jcomc.2021.100164 Simão, C. D., Reparaz, J. S., Wagner, M. R., & Graczykowski, B. (2015). Optical and mechanical properties of nanofibrillated cellulose. Carbohydrated Polymers , 14 , 1–24. https://doi.org/10.1016/j.carbpol.2015.03.032 Tang, L., Wang, Y., Zhou, T., Li, Y., & Li, Q. (2020). Enhanced Toughness and Mechanical Property of Epoxy Resins with Good Shape Memory Behaviors . 21 (6), 1187–1194. https://doi.org/10.1007/s12221-020-9684-3 Tomisawa, R., Ikaga, T., Kim, K. H., Ohkoshi, Y., Okada, K., Masunaga, H., Kanaya, T., Masuda, M., & Maeda, Y. (2017). Effect of draw ratio on fiber structure development of polyethylene terephthalate. Polymer , 116 , 357–366. https://doi.org/10.1016/j.polymer.2016.12.071 Urba, L., Takeda, K., Staszczak, M., Kalat, M. N., Marek, K., & Pieczyska, A. (2022). Characterization of Polyurethane Shape Memory Polymer and Determination of Shape Fixity and Shape Recovery in Subsequent Thermomechanical Cycles. Polymers , 14 , 1–20. Zhang, Y., Hu, J., Zhao, X., Xie, R., Qin, T., & Ji, F. (2019). Mechanically Robust Shape Memory Polyurethane Nanocomposites for Minimally Invasive Bone Repair. ACS Applied Bio Materials , 2 (3), 1056–1065. https://doi.org/10.1021/acsabm.8b00655 Zhong, S., & Nsengiyumva, W. (2022). Nondestructive Testing and Evaluation of Fiber-Reinforced Composite Structures. In Nondestructive Testing and Evaluation of Fiber-Reinforced Composite Structures . https://doi.org/10.1007/978-981-19-0848-4 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 11 Sep, 2024 Read the published version in Cellulose → Version 1 posted Editorial decision: Revision requested 29 Feb, 2024 Submission checks completed at journal 11 Jan, 2024 Editor assigned by journal 11 Jan, 2024 First submitted to journal 10 Jan, 2024 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-3850397","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":266520264,"identity":"c0c4754f-47b5-4621-a957-60061bee710a","order_by":0,"name":"Direselgn Molla Semanie","email":"","orcid":"","institution":"Ministry of Education, Donghua University","correspondingAuthor":false,"prefix":"","firstName":"Direselgn","middleName":"Molla","lastName":"Semanie","suffix":""},{"id":266520265,"identity":"b6c0476f-07cd-42dd-a4fd-77c2f07fe2e2","order_by":1,"name":"Lei Zhang","email":"","orcid":"","institution":"Ministry of Education, Donghua University","correspondingAuthor":false,"prefix":"","firstName":"Lei","middleName":"","lastName":"Zhang","suffix":""},{"id":266520266,"identity":"c5943f6a-b7e6-44d9-93c3-c8eed3e91e9d","order_by":2,"name":"Hanur Meku Yesuf","email":"","orcid":"","institution":"Ministry of Education, Donghua University","correspondingAuthor":false,"prefix":"","firstName":"Hanur","middleName":"Meku","lastName":"Yesuf","suffix":""},{"id":266520267,"identity":"4406926f-73e9-46f3-8fc6-814603f39962","order_by":3,"name":"Biruk Fentahun Adamu","email":"","orcid":"","institution":"Ministry of Education, Donghua University","correspondingAuthor":false,"prefix":"","firstName":"Biruk","middleName":"Fentahun","lastName":"Adamu","suffix":""},{"id":266520268,"identity":"1814868f-24d3-4b1e-973a-ee5acaa93590","order_by":4,"name":"Dr. Buguang Zhou","email":"","orcid":"","institution":"Ministry of Education, Donghua University","correspondingAuthor":false,"prefix":"Dr.","firstName":"Buguang","middleName":"","lastName":"Zhou","suffix":""},{"id":266520269,"identity":"3c0022e5-da17-439c-b6b4-8a17812007e9","order_by":5,"name":"Prof. Guo Jiansheng","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAu0lEQVRIiWNgGAWjYBACxgYQWcGcAKIkSNByhhQtEH1tpGhh7j9+TeLjPOs8gwPMB2/zMNjlEbZgRk6Z5Mxt6cUGB9iSrXkYkouJ0MKTJs277XDihgM8ZtI8DAcSGwhq6T8D1DIHpIX/G5FaGtKPSfM2gG1hI1LLjBxmyxnH0hNnHmYztpxjkExYi2H/8Yc3PtRYJ/Ydb354402FHRFaGngMICxmEGFASD0QyDOwPyBC2SgYBaNgFIxoAAAwyTwxXeTecAAAAABJRU5ErkJggg==","orcid":"","institution":"Ministry of Education, Donghua University","correspondingAuthor":true,"prefix":"","firstName":"Prof.","middleName":"Guo","lastName":"Jiansheng","suffix":""}],"badges":[],"createdAt":"2024-01-10 13:29:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3850397/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3850397/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10570-024-06146-7","type":"published","date":"2024-09-11T15:57:52+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":49523054,"identity":"612da3f0-50b6-401c-b1a8-61caee4cfb7b","added_by":"auto","created_at":"2024-01-12 10:36:23","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":784870,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic representation of wet spinning process\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/b6f13ca6f0d06f39dc47d176.png"},{"id":49522654,"identity":"c9b68542-03d6-482d-90ee-ab1f6eaf30b8","added_by":"auto","created_at":"2024-01-12 10:28:23","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":40579,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic representation of mechanical-thermo-aqueous programming test\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/a4e9054eb1abe0e97b727718.png"},{"id":49522656,"identity":"401d8701-86f3-4c2c-aeef-0a523e31e361","added_by":"auto","created_at":"2024-01-12 10:28:23","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":701743,"visible":true,"origin":"","legend":"\u003cp\u003eLinear density of filaments at their a) original shape b) Fixed temporary shape\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/c034abc4a9cf11d27a162f9a.png"},{"id":49522657,"identity":"190923f6-8bba-41e3-8db1-20ba86acde18","added_by":"auto","created_at":"2024-01-12 10:28:23","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":180558,"visible":true,"origin":"","legend":"\u003cp\u003eTensile properties of Microcomposite filaments at their a) original shape b) fixed temporary shape\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/1deee23b22aca6b0464d18d8.png"},{"id":49523606,"identity":"c0adfeb5-f06b-47c1-97bf-a18dc06d7acd","added_by":"auto","created_at":"2024-01-12 10:44:23","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1555310,"visible":true,"origin":"","legend":"\u003cp\u003eCross-sectional SEM images of (a), SMPU-2.0 (b), SMPU-MCC-0.8 (c), SMPU-MCC-2.0 (d), SMPU-MCC-3.2\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/012b7752a448d74f875756a2.png"},{"id":49523053,"identity":"55791151-55db-4e44-ac60-aee13fa5a39c","added_by":"auto","created_at":"2024-01-12 10:36:23","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":901077,"visible":true,"origin":"","legend":"\u003cp\u003eLongitudinal SEM images of (a), SMPU-2.0 (b), SMPU-MCC-0.8 (c), SMPU-MCC-2.0 (d), SMPU-MCC-3.2\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/3ddd7fb8f208f95c31d04217.png"},{"id":49522660,"identity":"4505be37-cfaa-49db-9020-40fee416c41e","added_by":"auto","created_at":"2024-01-12 10:28:23","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":33971,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra values of microcomposite filaments\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/137e7fe5cd4001b8a6f3ebb3.png"},{"id":49522659,"identity":"f416df1f-06da-496d-92f9-c5d2423d8b6c","added_by":"auto","created_at":"2024-01-12 10:28:23","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":17838,"visible":true,"origin":"","legend":"\u003cp\u003eXRD patterns of microcomposite filaments at different draw ratio\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/4a8badff6e5cdac0e490a855.png"},{"id":49522662,"identity":"98bed999-4bed-4b44-bfa7-a8e281470752","added_by":"auto","created_at":"2024-01-12 10:28:23","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":13857,"visible":true,"origin":"","legend":"\u003cp\u003eFirst heating DSC scans for pure SMPU and SMPU-MCC microcomposite filaments\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/0b5f5ad3631314425d8fb551.png"},{"id":49522664,"identity":"7837805a-f2a1-42fa-8857-4b191d470850","added_by":"auto","created_at":"2024-01-12 10:28:23","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":259634,"visible":true,"origin":"","legend":"\u003cp\u003eTGA and DTG curves of (a) SMPU-2.0 (b) MCC-SMPU-0.8 (c) MCC-SMPU-2.0 (d) MCC-SMPU-3.2 microcomposite filaments\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/84322b091ea3dcb7878d5560.png"},{"id":49523055,"identity":"60b33785-bda0-4053-b03b-232dc19f1df6","added_by":"auto","created_at":"2024-01-12 10:36:23","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":739565,"visible":true,"origin":"","legend":"\u003cp\u003eShape memory properties of Microcomposite filaments with different draw ratio at (a), Tg + 5ºC (b), Tg + 10ºC (c), Tg + 20ºC (d), 1\u003csup\u003est\u003c/sup\u003e cycle\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/ce2bab2fddd32c6ddd014aa5.png"},{"id":49523057,"identity":"acc4ad6e-5258-41fc-836a-ac6c955de85e","added_by":"auto","created_at":"2024-01-12 10:36:23","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":458058,"visible":true,"origin":"","legend":"\u003cp\u003eShape memory properties of Microcomposite filaments in different triggering temperature and cycles (a), SMPU-2.0 (b), SMPU-MCC-0.8 (c), SMPU-MCC-2.0 (d), SMPU-MCC-3.2\u003c/p\u003e","description":"","filename":"floatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/87235e47ae8bf2911d3f2c2f.png"},{"id":64619482,"identity":"b68ba960-96a7-4377-a7fb-9a0c3aedd740","added_by":"auto","created_at":"2024-09-16 16:15:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":7040642,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3850397/v1/c8dee7ba-3d59-47ec-927b-40551145489b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effect of Draw Ratio and Triggering Temperature on Properties of Hydrothermal Responsive Shape Memory Microcomposite Filaments.","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAccording to a recent estimate, the market for smart textiles is highly increasing and is predicted to be more than \u003cspan\u003e$\u003c/span\u003e130\u0026nbsp;billion by 2025 (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). These smart textiles can be used in various areas such as medical, sports, energy harvesting, active thermoregulation, etc. Smart textiles containing active temperature-water regulation functions have great advantages for providing comfort by monitoring environmental or physiological changes and responding accordingly. This performance can be achieved by many smart materials, including shape memory polymers (SMPs), electronic textiles, shape memory alloys (SMAs), and phase change materials (Raja et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eShape memory polymers (SMPs) are smart materials that have the ability to change their shape and respond according to the specific stimuli applied. SMPs have high extension rate (up to 800%) that makes them withstand significant deformation, a density of 900\u0026ndash;1100 kg/m3, variable recovery speed and easy processing (Janis Andersons, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Given the above advantages, they are widely used in a variety of applications, including breathable clothing for better comfort in environments with varying temperatures and moisture. There are many types of thermo-water-responsive SMPs, but shape memory polyurethane (SMPU) is best suited for the textile industry because it can be used as a coating as well as fibers used to make fabrics (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSMPUs are the most important type of polyurethanes (PUs) that have a two-phase structure with hard and soft segments, which makes them thermally responsive shape memory polymers. SMPU fibers can be easily made by wet and melt spinning in addition to their usage as coating and adhesive materials. Hydrothermal (moisture and temperature) sensitive shape memory polyurethane (SMPU) can be achieved by incorporating hydrophilic particles to temperature-responsive SMPUs as reinforcement. Cellulose, in particular, has gained interest due to its water absorption properties and additional advantages such as high crystallinity and strength.\u003c/p\u003e \u003cp\u003eDespite the production of nanocellulose requires high energy consumption, which makes it expensive and contributes greatly to global warming (Janis Andersons, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), both nanocellulose and microcrystalline cellulose can provide efficient mechanical reinforcement because of their excellent mechanical properties that are small enough to be incorporated into the structure of composite fiber without adversely changing the composite fiber morphology. Using cellulose as reinforcement in composite fiber manufacturing will also increase the bio-based content of the composite products (Janis Andersons, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eShape memory polyurethane (SMPU) filaments are not very strong to be a fabric and needs high response time and concentration for significant shape memory effect. The strength and shape memory properties of these filaments are influenced by various factors, including the solution viscosity, molecular weight, triggering temperature and draw ratio during spinning. However, draw ratio and triggering temperature are the most important factors that affects both the tensile strength and shape memory properties of the filaments (Shen et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Draw ratio is defined as the degree of stretching of the spinning solution inside (primary drawing) and outside (second drawing) the coagulation bath and calculated by dividing the take-up speed after solidification by the initial extrusion speed from the spinneret (Gupta et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFrom previous literature, it was observed that no detailed study has been conducted to specifically examine the effect of draw ratio and triggering temperature on the properties of microcrystalline cellulose-reinforced shape memory polyurethane filament. Therefore, in this study, a water and temperature responsive microcomposite filaments were produced by incorporating microcrystalline cellulose into shape memory polyurethane, and their physical, mechanical, morphological, chemical composition, and thermal properties were analyzed using DSC, TGA, XRD, SEM, FTIR, and MTAP techniques. Three different draw ratios and triggering temperatures were optimally selected, and their effect on shape memory properties of microcomposite filaments was studied, and findings of this study are discussed in detail.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eMaterials\u003c/h2\u003e \u003cp\u003ePellet-type temperature responsive SMPU granules (Sigma-Aldrich, USA) composed of 4,4-methylenebis(phenyl isocyanate), 1,4-butanediol, Di(propylene glycol) and Polycaprolactone was used as matrix material to produce hydrothermal responsive microcomposite filament. Microcrystalline cellulose (Sigma-Aldrich), which has a length ranging from 70 to 140\u0026micro;m according to the manufacturer's specifications, was incorporated as a reinforcement to enhance the strength and water responsive property of the composite filament. N, N-dimethylformamide (DMF) (Sigma-Aldrich)- is a polar solvent, which was used as a solvent. Polyoxyethylene sorbitan monooleate (commonly known as Tween 80) (Sigma-Aldrich) was used as nonionic surfactant.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of Spinning Suspension\u003c/h2\u003e \u003cp\u003eThe spinning solution was prepared with a suitable viscosity for spinning to produce hydrothermal (water and temperature) responsive microcomposite (SMPU-MCC) filaments using the wet spinning method. Based on literature and preliminary experiments, an optimal concentration of 25 wt% SMPU in DMF was used (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), which resulted in efficient fiber spinning. Additionally, through an optimization process, a concentration of 15 wt% MCC was identified as the ideal concentration. SMPU polymer solution with 25 wt% and a homogeneous 15 wt% dispersion of MCC in DMF in the presence of non-ionic surfactant Tween80 at 1:2 w/w of MCC were mixed at 60\u0026deg;C for 6 h by a mechanic stirrer equipped with an ultrasonic homogenizer at a speed of 200 rpm. To maintain the consistency of the solution, the beakers were appropriately covered to prevent DMF evaporation and viscosity variation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eOptimization and Production of Micro-composite Filament\u003c/h2\u003e \u003cp\u003eA central composite design was utilized to identify the optimal variables by establishing experimental factors and analyzing the connection between factors and responses. An optimized 15wt% concentration of MCC with 25wt% SMPU concentration was used for both pure SMPU and microcomposite filaments. MCC-SMPU spinning solution was spun with a CHEMYX wet spinning machine (CHEMYX Inc, USA), with an internal needle diameter of 1.05mm at a constant flow rate of 2ml/min, 0.81ml/min and 0.5ml/min into a coagulation bath of distilled water. The filament was then guided by a roller in the coagulation bath and transferred to the washing bath by a separately installed take-up head (Samgold MCU Digital Technology, China) at 1.9 m/min. In wet spinning, there are two drawing processes: primary drawing process in the coagulation bath and secondary drawing process after drying (Fukui et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). In this study, the drawing ratio refers to the primary drawing ratio, which is the ratio between the inlet speed from the spinneret and the winding or take-up speed. Draw ratio of 0.8, 2.0, and 3.2 were applied to pure SMPU and SMPU-MCC microcomposite filaments. The filaments were then immersed in distilled water for 24 hours to remove any remaining solvent (DMF) from the filament structure and dried for Ten hours at 40\u0026deg;C. Based on their draw ratio, the filaments were categorized and coded as SMPU-2.0 and SMPU-MCC-0.8, SMPU-MCC-2.0 and SMPU-MCC-3.2, and the schematic representation of wet spinning is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e below.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eFiber Characterization\u003c/h2\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003eChemical and Morphological Analyses\u003c/h2\u003e \u003cp\u003eFilaments were kept under standard textile testing conditions at a temperature of 20\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C and a relative humidity of 65\u0026thinsp;\u0026plusmn;\u0026thinsp;2%. Evaluation of the surface characteristics and dispersion of MCC within the micro-composite filaments was conducted using TM4000 Table Top Scanning Electron Microscopy (Thermo Scientific, USA) operating at 20 kV with a maximum magnification power of 3000.\u003c/p\u003e \u003cp\u003eThe crystal structure of the microcomposite filaments were analyzed using a Bruker D8 Advance diffractometer (XRD) (Bruker Corporation, USA) with a radiation wavelength of 1.542 \u0026Aring;. The scan range is from 5\u0026deg; to 60\u0026deg; with a scanning step size of 0.02\u0026deg; and a step time of 1 s. The XRD measurements were conducted at an operating voltage of 40 kV and current of 150 mA.\u003c/p\u003e \u003cp\u003eFourier transform infrared (FTIR) spectroscopy (PerkinElmer, USA) with a spectrum range of 4000 cm-1 to 400 cm-1, was used to analyze the functional groups and chemical structures of SMPU-MCC filaments. FTIR tests were determined in accordance with the standards outlined in the ASTM E1252 and ASTM E168 test methods.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eThermo-Mechanical Analyses\u003c/h2\u003e \u003cp\u003eLLY-06E-500 Electronic Single fiber Strength Tester (Laizhou Electronic Instruments Co., Ltd, China) was used to measure the mechanical properties of the microcomposite filaments in accordance with ASTM D3822-07 at a gauge length of 20 mm and an extension rate of 200 mm/min. A minimum of ten replications were performed, and the average values were reported. The linear density of the microcomposite filaments at their original and fixed temporary shape was determined in dtex according to D2591-07 (Reapproved 2020).\u003c/p\u003e \u003cp\u003eThe thermal stability of the micro-composite filaments was assessed by thermogravimetric analysis (TGA 8000, PerkinElmer, Inc., USA) under nitrogen atmosphere between 50 and 600\u0026deg;C at a heating rate of 10\u0026deg;C/min. The decomposition temperatures (T\u003csub\u003e10\u003c/sub\u003e, T\u003csub\u003e50\u003c/sub\u003e, and T\u003csub\u003emax\u003c/sub\u003e) of microcomposite filaments were determined from the TG data. Differential scanning calorimetry (DSC 8500, PerkinElmer Instruments, USA) was utilized to study the thermal characteristics of the microcomposite filaments. The analysis was performed according to ISO 11,357:1\u0026ndash;7 standards, with microcomposite filaments weighing 5\u0026ndash;10 mg being heated at a rate of 10\u0026deg;C/min from \u0026minus;\u0026thinsp;10 to 200\u0026deg;C and then cooled at a rate of 20\u0026deg;C/min to 20\u0026deg;C to clear the thermal history. In the second heating, the samples were heated from 20 to 200\u0026deg;C at a rate of 10\u0026deg;C/min and then cooled to room temperature. The glass transition temperature (Tg) of the microcomposite filaments was determined from the first heating.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eShape Memory Properties of the Fiber\u003c/h2\u003e \u003cp\u003eThe mechanical-thermo-aqueous programming test was followed to determine the shape memory properties of micro-composite filaments with initial length (Li) taken as 5 cm. There were four phases in this programming test. First, the sample was 100% stretched into a temporary length (Lt) by immersing it in hot water with a triggering temperature of Tg\u0026thinsp;+\u0026thinsp;5\u0026deg;C, Tg\u0026thinsp;+\u0026thinsp;10\u0026deg;C and Tg\u0026thinsp;+\u0026thinsp;20\u0026deg;C for ten minutes. The filaments were then cooled down below the glass transition temperature around 23\u0026deg;C, and dried for 12 hours to fix the temporary length. At this point, the load was removed and fixed temporary length (Lf) was measured. Finally, the shape memory effect (SME) was initiated by again immersing the filaments at a recovery temperature varying according to their Tg for 10 minutes in order to release the thermal and water switches, and samples were restored to their original recovered length (Lr). The procedure was replicated for six cycles and the glass transition temperature Tg\u0026thinsp;+\u0026thinsp;5\u0026deg;C, Tg\u0026thinsp;+\u0026thinsp;10\u0026deg;C, Tg\u0026thinsp;+\u0026thinsp;20\u0026deg;C of each sample was used as the triggering temperature (Santiago et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe shape-memory properties of a material can be evaluated using two important parameters: the shape-recovery ratio (Rr) and the shape-fixity ratio (Rf) (Gordon \u0026amp; Gordon, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Shape-recovery ratio (Rr) measures the ability of the microcomposite filament to return to its original shape after deformation (Eq.\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). It is calculated by dividing the deformation recovered by the maximum deformation during the programming test. Whereas shape-fixity ratio (Rf) measures the ability of the filaments to maintain its temporary shape (Eq.\u0026nbsp;\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) and is calculated by dividing the deformation after the loads is removed by the maximum deformation (Tang et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$${R}_{r}=\\left(\\frac{{L}_{t}-{L}_{r}}{{L}_{t}-{L}_{i}}\\right)\\times 100\\%$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$${R}_{f}=\\left(\\frac{{L}_{f}-{L}_{i}}{{L}_{t}-{L}_{i}}\\right)\\times 100\\%$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere Li represents the initial length of the samples, Lt is the temporary length before the load is removed, Lf represents the fixed temporary length after cooling and removal of the load, Lr is the recovered length, and Rr and Rf represent the shape recovery and shape fixity ratios, respectively. The schematic representation of mechanical-thermo-aqueous programming test is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS AND DISCUSSIONS","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003ePhysical and Mechanical properties of Filaments\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e presents linear densities of pure SMPU and SMPU-MCC microcomposite filaments at their original and fixed temporary shapes ranging between 155.3\u0026ndash;193.7dtex. The incorporation of MCC into the SMPU matrix appears to have a notable impact on the linear density of the microcomposite filaments. The linear density of pure SMPU filaments at their original length was 176.6dtex with a draw ratio of 2.0 that increases to 181.4dtex in SMPU-MCC filaments with the same draw ratio. The linear density of SMPU-MCC filaments with a 0.8 draw ratio is higher (193.7dtex) than that of pure SMPU. This increment suggests that MCC contributes to the mass of the composite filament due to its inherent density and rigidity. This is also supported by previous findings (Gonz\u0026aacute;lez et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)(Gherissi et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Furthermore, SMPU-MCC microcomposite filaments with draw ratio of 3.2 exhibit the lowest linear density (170.2dtex at original shape and 168.6dtex at fixed temporary shape), suggesting that higher draw ratios decrease mass per unit length of the filaments.\u003c/p\u003e \u003cp\u003eShape memory polyurethane (SMPU) exhibits high elongation but relatively low strength compared to other synthetic fibers. To improve its strength as a textile filament fiber, reinforcement materials such as cellulose can be incorporated. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(a) illustrates the stress-strain curves of microcomposite filaments in their original shape, while Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(b) shows the curves in their fixed temporary shape at different draw ratios. The microcomposite filaments in their original shape exhibit higher tenacity and elongation compared to those in their fixed temporary shape. Among microcomposite filaments, SMPU-MCC-2.0 demonstrates the highest tenacity value of 0.91cN/dtex at its original shape, with an elongation percentage of 385.2%. However, this value decreases to a tenacity of 0.74cN/dtex and an elongation of 331.8% at fixed temporary shape. The improved tenacity can be attributed to enhanced load transfer resulting from improved chain alignment between the matrix and cellulose particles. The presence of microcrystalline cellulose (MCC) also establishes a percolation network within the filament structure, stabilized by hydrogen bonding (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). This network enables more effective load transfer between the SMPU matrix and cellulose particles. In contrast, the MCC-SMPU microcomposite filament with 0.8 draw ratio exhibits the lowest tenacity value, measuring 0.6cN/dtex in its original shape, which decreases to 0.39cN/dtex in its fixed temporary shape. This indicates insufficient drawing, resulting in relatively disordered polymer chains (Gonz\u0026aacute;lez et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eChemical and Morphological Analyses\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows a cross-sectional view of pure shape memory polyurethane (SMPU) and SMPU-MCC microcomposite filaments at a magnification of 400x. The figure clearly illustrates that increase in draw ratio enhances the integrity of polymer chains with microcrystalline cellulose (MCC). Pure SMPU with a draw ratio of 2.0 has slightly irregular cross-section with visible foldings (Richardson, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). On the other hand, SMPU-MCC microcomposite filaments exhibit relatively circular and regular cross-sections with more uniform distribution of MCC within the filament structure as the draw ratio increases. However, excessive stretching of the soft segments in SMPU-MCC filaments with a draw ratio of 3.2 decreases its shape memory properties (Zhang et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2019\u003c/span\u003e)(Shojaeiarani et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe longitudinal SEM images of the microcomposite filaments at magnifications of 200x are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(a)-(d). Pure shape memory polyurethane filament fiber with drawing ratio of 2.0 (SMPU-2.0) shows a separate fiber edge and microcracks. Korkmaz et al 2021, expalined this situation as the absence of reinforcement (microcrystalline cellulose), which affects viscosity and results in a low mass transfer rate difference between the coagulating solvent diffusion into the spinning solution and solvent extraction into the coagulation bath (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Whereas microcrystalline cellulose-reinforced SMPU filament with a drawing ratio of 0.8 exhibits clear polymer chain folding which decreases as the drawing ratio increases, ultimately resulting in good fiber alignment. Despite, the molecular arrangement and chain conformation significantly improved in SMPU-MCC-3.2 as show in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(d), there is excessive stretching of polymer chains that affects the shape memory property and stretchability of the fiber (Gupta et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e shows the FT-IR spectra of pure SMPU and SMPU-MCC microcomposite filaments. Pure SMPU with a draw ratio of 2.0 exhibits a characteristic IR absorption peak at 3271 cm-1, which corresponds to the stretching bands of (-NH-) and (-OH-) groups in polyurethane (PU) polymers. The peaks at 2852 cm-1 and 1630 cm-1 correspond to the symmetric stretching vibrations of (-CH-) groups and the stretching bending vibrations of (-C\u0026thinsp;=\u0026thinsp;O-) groups in the (COO-) units of shape memory polyurethane. For SMPU-MCC microcomposite filaments, the characteristic peaks related to the stretching vibrations of (-OH-) and (-NH-) groups shift from 3271 cm-1 to 3380 cm-1, 3351 cm-1, and 3329 cm-1which indicates the presence of additional hydroxyl (-OH) functional groups found in microcrystalline cellulose (Raja et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2013\u003c/span\u003e)(Liem et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2007\u003c/span\u003e)(Zhang et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The characteristic peaks at 2852cm-1, 2980cm-1, 2953cm-1 and 2939cm-1 for SMPU-2.0, SMPU-MCC-0.8, SMPU-MCC-2.0, and SMPU-MCC-3.2 indicates (-CH\u003csub\u003e2\u003c/sub\u003e-) and (-C-H-) stretching vibration of hydrocarbon chains found in filaments. Peak absorption at 1753 cm-1, 1726cm-1 and 1718cm-1 indicates (-C\u0026thinsp;=\u0026thinsp;O-) stretching vibrations while the peak at 1630 cm-1 corresponds to the (-C\u0026thinsp;=\u0026thinsp;C-) bending bond from the functional group of alkenes present in cellulose and aromatic compounds in Polycaprolactone of SMPU (Richardson, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). The slight shift in wavenumber and intensity observed in microcomposite filaments can be attributed to the incorporation of microcrystalline cellulose (MCC) into the SMPU matrix and the improved polymer chain alignment and molecular orientation because of increased drawing, which disrupts the hydrogen bonds between (-NH-) and (-C\u0026thinsp;=\u0026thinsp;O-) due to the strong interaction between MCC and SMPU (Raja et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2013\u003c/span\u003e)(Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e)(Zhong \u0026amp; Nsengiyumva, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)(Shojaeiarani et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e shows the X-ray diffraction (XRD) patterns of pure SMPU and MCC-SMPU microcomposite filaments. It can be observed that the pure SMPU filament exhibits a peak at 2θ\u0026thinsp;=\u0026thinsp;20.42\u0026deg;, indicating its poorly crystalline or amorphous structure. This peak suggests the presence of small crystallites scattered within the short-range ordered hard segments or relatively amorphous region within the filament's structure (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). On the other hand, the SMPU-MCC microcomposite filaments shows XRD peaks at 2θ\u0026thinsp;=\u0026thinsp;22.39\u0026deg;, 22.12\u0026deg;, and 22.24\u0026deg;, which indicate the presence of cellulose particles in the filament structure (Urba et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The intensity of the XRD peaks increases with an increased draw ratio of the microcomposite filaments. The crystalline nature and the degree of crystallinity can be characterized by the sharpness and peak intensity value, respectively. The crystallinity percentages obtained for pure SMPU, SMPU-MCC-0.8, SMPU-MCC-2.0, and SMPU-MCC-3.2 are 27.10%, 30.68%, 38.72%, and 36.88%, respectively. This demonstrates that an increased draw ratio enhances the crystallinity of the filaments (Barkoula et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eThermal Analyses\u003c/h2\u003e \u003cp\u003eThe glass transition temperature (Tg) of microcomposite filaments with different draw ratios was evaluated using differential scanning calorimetry (DSC). The DSC results from the first heating scan (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e) indicated that the Tg of the pure shape memory polyurethane (SMPU-2.0) filament was 41.65\u0026deg;C whereas the Tg of SMPU-MCC-0.8, SMPU-MCC-2.0, SMPU-MCC-3.2 was 38.35\u0026deg;C, 41.02\u0026deg;C and 40.35\u0026deg;C respectively. As the draw ratio increased to 2.0, the Tg of MCC-SMPU microcomposite filaments increased from 38.35\u0026deg;C to 41.02\u0026deg;C. The observed increase in Tg with increasing draw ratio can be attributed to the alignment and orientation of the polymer chains (Tomisawa et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). However, for a draw ratio of 3.2, the decrease in Tg can be related to excessive stretching of the filaments, resulting structural defects and disruptions in chain alignment. These defects facilitate easier initiation of chain mobility at a lower temperature, leading to a decrease in Tg (Gupta,.et al, 2006). The incorporation of MCC into the filament structure of SMPU-2.0 results in a higher glass transition temperature (Tg) compared to SMPU-MCC microcomposite filaments with the same draw ratio. This observation aligns with the findings of Korkmaz et al. 2021, where they reported a decrease in Tg of composite filaments with the addition of cellulose nanowhiskers (CNW). According to Korkmaz et al., the reduction in Tg with CNW addition can be attributed to the plasticizing effect and micro-Brownian thermal motions of molecular chain segments generated by CNW particles. These particles disrupt the dominant original interactions among the polymer chains in SMPU, facilitating chain mobility at lower temperatures (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). It was similarly reported by Gan et al. in 2020, that the addition of nanocellulose fibrils to a PVOH (polyvinyl alcohol) composite resulted in a decrease in the glass transition temperature (Tg). This decrease was attributed to the increased mobility of the soft domains within the polymer matrix. Furthermore, the incorporation of microcrystalline cellulose disrupted the original interactions between the rigid and soft segments of the polymer, leading to a higher degree of microphase separation within the matrix (Gan et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e illustrates the Thermogravimetric Analysis (TGA) results obtained to determine the effect of draw ratio and incorporation of MCC on the thermal stability of SMPU filaments. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the significant increase from 309.9\u0026ordm;C to 328.39\u0026ordm;C for T\u003csub\u003e10%\u003c/sub\u003e indicates an enhancement in the thermal stability of the microcomposite filaments due to improved interaction between MCC and the SMPU matrix through hydrogen bonding. The maximum weight loss temperature (Tmax) of the microcomposite filaments is considered the most important temperature for evaluating thermal stability (Sim\u0026atilde;o et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). An increase in draw ratio leads to a temperature rise from 372.5\u0026ordm;C to 391.3\u0026ordm;C, indicating that the thermal stability of the composites is strongly influenced by intermolecular bonding between MCC and SMPU, which intensifies as the draw ratio increases from 0.8 to 2.0. According to Gan et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, strong intermolecular bonding enhances the energy required for chain cleavage of macromolecules, thereby improving the thermal stability (Gan et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). However, a decrease in degradation temperature is observed for a draw ratio of 3.2, which could be attributed to the critical volume fraction and the percolation threshold, as well as the instability of crystallites caused by the high draw ratio leading to chain fracture (Ahmed et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2015\u003c/span\u003e)(Gonz\u0026aacute;lez et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2023\u003c/span\u003e)(Liu et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\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\u003ePeak temperatures and char residue of microcomposite filaments\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" 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=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample Code\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eT\u003csub\u003e10%\u003c/sub\u003e (\u0026deg;C)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eT\u003csub\u003e50%\u003c/sub\u003e (\u0026deg;C)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eT\u003csub\u003emax\u003c/sub\u003e (\u0026deg;C)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eChar residue (wt%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSMPU-2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e309.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e336.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e370.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4.96\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSMPU-MCC-0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e328.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e379.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e372.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11.48\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSMPU-MCC-2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e325.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e380.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e391.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSMPU-MCC-3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e323.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e380.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e372.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.82\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=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eShape Memory Properties\u003c/h2\u003e \u003cp\u003eShape memory properties of hydrothermal responsive MCC-SMPU microcomposite filaments mainly depends on the presence of microcrystalline cellulose in SMPU that introduces hydrophilic properties and the temperature sensitive behavior of shape memory polyurethanes. When the microcomposite filaments were placed in hot water above their glass transition temperature (Tg) with applied force, the hydroxyl groups present in MCC formed hydrogen bonds with water molecules. Consequently, the storage modulus of the filaments decreased, indicating a softening of the material (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eShape recovery and shape fixity ratios were used to calculate shape memory properties of microcomposite filaments at six consecutive cycles and three triggering temperatures (i.e., Tg\u0026thinsp;+\u0026thinsp;5\u0026ordm;C, Tg\u0026thinsp;+\u0026thinsp;10\u0026ordm;C and Tg\u0026thinsp;+\u0026thinsp;20\u0026ordm;C). Soft segment of microcomposite filaments makes the material to maintain its temporary shape and expressed as shape fixity (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) (Richardson, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Whereas the hard segment of microcomposite filaments makes the fiber to return to its original shape. In Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e(a), the shape fixity and shape recovery ratios of pure SMPU and microcomposite filaments are shown at the triggering temperature of Tg\u0026thinsp;+\u0026thinsp;5\u0026ordm;C. It can be observed that the shape fixity initially decreases for the first three cycles, but starts to increase from the fourth and fifth cycles onwards, eventually becoming constant after the fifth cycle. On the other hand, the shape recovery of the filaments shows a decreasing trend over five consecutive cycles, and then stabilizes from the sixth cycle onwards, with the exception of a slight fluctuation observed for SMPU-MCC-0.8 at the third cycle. Moving on to Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e(b), the shape fixity of the filaments increases for the first and second cycles, but decreases for the third and fourth cycles. In contrast, the shape recovery behavior varies among the different filaments. SMPU-MCC filaments with a draw ratio of 2 and 0.8 exhibit a relatively consistent decrease in shape recovery, while the other filaments display some instability, with both increasing and decreasing shape recovery ratios. When the triggering temperature is increased to Tg\u0026thinsp;+\u0026thinsp;20\u0026ordm;C (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e(c)), all filaments demonstrate relatively stable shape fixity, with a slight increasing pattern. Moreover, the shape fixity values at this triggering temperature are higher compared to the other triggering temperatures. Additionally, the shape recovery performance is significantly enhanced at the beginning of the test, followed by a steady decrease thereafter. Notably, SMPU-MCC filaments with a draw ratio of 3.2 exhibit the lowest shape recovery ratio at lower triggering temperatures, consistently demonstrating a loss in their memorizing performance.\u003c/p\u003e \u003cp\u003eAccording to Korkmaz et al. (2021), the shape fixity of composite filaments is enhanced during wet-dry transitions. This is attributed to the increased cleavage and re-formation of hydrogen bonds facilitated by cellulose. The presence of water molecules promotes stronger hydrogen bonding between cellulose particles and the shape memory polyurethane (SMPU) matrix, resulting in improved shape fixation upon drying (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The shape fixity ratio of microcomposite filaments increases with draw ratio and triggering temperature. A higher draw ratio leads to alignment of molecular chains resulting in increased crystallinity within the filament. The increased crystallinity provides more structural rigidity to the filament and leads to enhanced resistance against instantaneous elastic recovery. As a result, the filament exhibits a higher shape fixity ratio, indicating improved ability to retain its fixed temporary shape after the load is removed (Richardson, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe shape recovery ratio decreases as the draw ratio increases, which is related to the reduced chain mobility of the soft segments (Richardson, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).In the case of MCC-SMPU with a draw ratio of 2.0, the shape recovery ratio was determined to be 93.6% (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e(d)). This value is consistent with findings from previous studies. For instance, Korkmaz et al. (2021) reported a shape recovery ratio ranging from 91\u0026ndash;100% for SMPU reinforced cellulose nanowhiskers given that shape memory polymers with a shape recovery ratio exceeding 80% can be considered excellent (Korkmaz Memiş \u0026amp; Kaplan, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e (a-d) shows shape fixity and shape recovery ratios of each filament separately at different triggering temperature. As shown below in Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003ea, the shape recovery ratio for pure SMPU with draw ratio of 2 increased with triggering temperature increases from Tg\u0026thinsp;+\u0026thinsp;5 to Tg\u0026thinsp;+\u0026thinsp;10 but started decreasing when temperature becomes Tg\u0026thinsp;+\u0026thinsp;20\u0026ordm;C. this triggering temperature effect decreased for SMPU-MCC-0.8 and SMPU-MCC2.0 as shown in (b) and (c). The shape recovery ratio observed in the second cycle of mechanical-thermo-aqueous programming tests was found to be lower than that of the first cycle, attributed to the deformation and rearrangement of molecular chains within the filament fiber. However, the shape fixity ratio of the microcomposite filaments in the second round increased as the draw ratio increased. This indicates that additional soft segments were created due to the breakage of weak interactions between polymer chains, such as dipole-dipole interactions, hydrogen bonding, or physical crosslinking. These segments enabled the absorption of external stress by unfolding and extending their molecular chains (Hui, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn both sets of graphs, it is observed that the shape recovery ratio decreases with an increasing number of cycles, while the shape fixity increases either a constant or fluctuating pattern for both pure SMPU and microcomposite filaments. The decrease in shape recovery can be attributed to the repeated stretching undergone during multiple cycles, which leads to an increase in molecular orientation in the stretch direction and the formation of frozen crystals (Santiago et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) (Liu et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). This effect is significant for filaments with higher draw ratios, as the increased crystallinity associated with higher draw ratios results in a greater reduction in shape recovery compared to filaments with lower draw ratios. This finding is consistent with previous research conducted by Richardson in 2009 (Richardson, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHowever, there is a slight increment in the shape recovery ratio for pure SMPU and SMPU-MCC microcomposite filaments at lower triggering temperatures but there is no shape recovery increment clear pattern that shows relationship between draw ratio, temperature, and the number of cycles. As the number of cycles increases, shape fixity also increases attributed to a decrease in instantaneous elastic recovery (Ei) (shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) (Barkoula et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn this study, hydrothermal responsive shape memory microcomposite filaments with draw ratio of 0.8, 2.0 and 3.2 were successfully produced through wet spinning process from 25%SMPU matrix and 15wt% MCC filler concentration. The incorporation of microcrystalline cellulose and an increase in draw ratio improved the mechanical properties and crystallinity of the microcomposite filaments, resulting in higher tenacity compared to pure SMPU filaments. DSC results indicated that Tg for triggering the shape memory effect of SMPU-MCC microcomposite filaments were between 38.35\u0026deg;C to 41.02\u0026deg;C whereas for pure SMPU filaments was 41.65\u0026deg;C. According to the TGA results, microcomposite filaments showed stable thermal properties from 370.3\u0026deg;C to 391.3\u0026deg;C with increase in draw ratio and addition of microcrystalline cellulose which are suitable for textile applications. The shape memory properties of microcomposite filaments were determined by mechanical- thermo-aqueous programming tests under hot water above glass transition temperature. In addition to shape memory properties, chemical, morphological, physical, mechanical, and thermal characteristics were studied. From the results, all microcomposite filaments produced showed excellent shape memory properties at 100% deformation at different draw ratios and triggering temperatures. MCC-SMPU-3.2 showed the lowest shape recovery ratio in all six cycles of all pure SMPU and SMPU-MCC microcomposite filaments in different draw ratios. As draw ratio increased, shape fixity ratios enhanced significantly including SMPU-MCC-3.2. In addition, SMPU-MCC microcomposite filaments maintained their original thermal responsiveness and gained a water-responsive shape memory property through the percolation network of MCC, which formed reversible hydrogen bonds with water molecules. Furthermore, the consecutive test cycle for shape memory properties demonstrated that microcomposite filaments can be used repeatedly without significant decrease in their shape memory properties. Generally, all microcomposite filaments, especially SMPU-MCC-2.0, exhibited excellent mechanical properties and hydrothermal responsive shape memory performance, highlighting their high potential for applications in smart textiles like waterproof and breathable garments, sportswear, and socks. Further research will be required on lowering the triggering temperature while maintaining the shape memory and mechanical performance, as well as transforming the manufactured filaments into finished products.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical Approval:\u0026nbsp;\u003c/strong\u003eNot applicable\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u0026nbsp;\u003c/strong\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003eAuthor Contributions\u003c/p\u003e\n\u003cp\u003eDireselgn Molla Semanie conducted the lab work, testing, and manuscript writing.\u0026nbsp;Lei Zhang, Hanur Meku Yesuf, Biruk Fentahun Adamu, Dr. Buguang Zhou\u0026nbsp;did material preparation, data collection and draft review. \u0026nbsp;Prof. Guo Jiansheng provided guidance and follow-up throughout the entire research process.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e The authors have not disclosed any funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used in this study are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAhmed, N., Kausar, A., \u0026amp; Muhammad, B. 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In \u003cem\u003eNondestructive Testing and Evaluation of Fiber-Reinforced Composite Structures\u003c/em\u003e. https://doi.org/10.1007/978-981-19-0848-4\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"cellulose","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cels","sideBox":"Learn more about [Cellulose](https://www.springer.com/journal/10570)","snPcode":"10570","submissionUrl":"https://submission.nature.com/new-submission/10570/3","title":"Cellulose","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Triggering temperature, Draw ratio, Microcrystalline cellulose, Shape memory filament","lastPublishedDoi":"10.21203/rs.3.rs-3850397/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3850397/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis paper investigates the production of hydrothermal responsive shape memory filaments with different draw ratios (0.8, 2.0, and 3.2), using microcrystalline cellulose (MCC) as a filler and shape memory polyurethane (SMPU) as a matrix. A mechanical-thermo-aqueous programming test (MTAP) was conducted to study the shape-memory properties of the microcomposite filaments. The effect of draw ratio and triggering temperature on mechanical, physical, thermal, morphological, and shape memory performances was thoroughly studied. Among the microcomposite filaments, SMPU-MCC with a draw ratio of 2.0 exhibited the highest tenacity value of 0.91 cN/dtex in its original shape, with an elongation percentage of 385.2%. The differential scanning calorimetry (DSC) results showed that the glass transition temperature (Tg) of the filaments increased as the draw ratio increased from 0.8 to 3.2, ranging from 38.35\u0026deg;C to 41.02\u0026deg;C. The crystallinity percentages obtained for pure SMPU, SMPU-MCC-0.8, SMPU-MCC-2.0, and SMPU-MCC-3.2 were 27.10%, 30.68%, 38.72%, and 36.88%, respectively. In addition, an optimum draw ratio led to a degradation temperature rise from 372.5\u0026ordm;C to 391.3\u0026ordm;C, which shows the thermal stability of the filaments was significantly influenced by the intermolecular bonding between MCC and SMPU, which intensified as the draw ratio increased from 0.8 to 2.0. Moreover, the filaments exhibited excellent mechanical and thermal properties in six cycles at the optimum draw ratio and triggering temperature, indicating their future application for repeated use without experiencing major changes in shape memory properties.\u003c/p\u003e","manuscriptTitle":"Effect of Draw Ratio and Triggering Temperature on Properties of Hydrothermal Responsive Shape Memory Microcomposite Filaments.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-12 10:28:18","doi":"10.21203/rs.3.rs-3850397/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-03-01T03:04:51+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-01-11T07:45:54+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-01-11T07:45:54+00:00","index":"","fulltext":""},{"type":"submitted","content":"Cellulose","date":"2024-01-10T13:19:05+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"cellulose","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cels","sideBox":"Learn more about [Cellulose](https://www.springer.com/journal/10570)","snPcode":"10570","submissionUrl":"https://submission.nature.com/new-submission/10570/3","title":"Cellulose","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"19dd175b-ebf1-4da8-99f0-38d74edd1086","owner":[],"postedDate":"January 12th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-09-16T16:08:43+00:00","versionOfRecord":{"articleIdentity":"rs-3850397","link":"https://doi.org/10.1007/s10570-024-06146-7","journal":{"identity":"cellulose","isVorOnly":false,"title":"Cellulose"},"publishedOn":"2024-09-11 15:57:52","publishedOnDateReadable":"September 11th, 2024"},"versionCreatedAt":"2024-01-12 10:28:18","video":"","vorDoi":"10.1007/s10570-024-06146-7","vorDoiUrl":"https://doi.org/10.1007/s10570-024-06146-7","workflowStages":[]},"version":"v1","identity":"rs-3850397","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3850397","identity":"rs-3850397","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}