Fully Biodegradable Poly (lactic acid)/Poly (butylene adipate-co-terephthalate) Blends with highly toughness Based on in situ Interfacial Compatibilization by functional epoxy compound

Fully Biodegradable Poly (lactic acid)/Poly (butylene adipate-co-terephthalate) Blends with highly toughness Based on in situ Interfacial Compatibilization by functional epoxy compound | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Fully Biodegradable Poly (lactic acid)/Poly (butylene adipate-co-terephthalate) Blends with highly toughness Based on in situ Interfacial Compatibilization by functional epoxy compound Yunda Shen, Bingrui Jin, Liang Ren, Hongnian Gan, Jiankun Li, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6564026/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 11 Sep, 2025 Read the published version in Journal of Polymer Research → Version 1 posted 5 You are reading this latest preprint version Abstract Synergistically integrating poly(butylene adipate-co-terephthalate (PBAT) with polylactic acid (PLA) presents an economical strategy to develop biodegradable materials by leveraging their complementary characteristics. However, the inherent phase incompatibility between PBAT and induces severe interfacial defects, fundamentally limiting the development of high-strength biodegradable composites. In this study, glycidyl methacrylate (GMA) is grafted onto PBAT through reactive blending during the melting process, whereupon PLA/PBAT-g-GMA blends are prepared by means of an in-situ compatibilization approach, in an attempt to achieve PLA/PBAT blends with satisfactory comprehensive properties. The effects of PBAT content and GMA grafting rate on the interfacial compatibility, microstructure, mechanical properties, thermal performance, crystalline behavior and rheological processability of PLA/PBT blends are investigated in detail. Systematic research has shown that the compatibility of PLA/PBAT blends has been significantly improved by implementing reactive compatibilization methods, and when the PBAT-g-GMA (2.84) content is 40%, the impact strength of the blend can reach 961 J/m without affecting rigidity, which indicates that our work proposes an effective approach to fabricate high-performance PLA/PBAT blends through simple, environmentally friendly, and low-cost processing methods. Furthermore, the crystallization performance of the PLA/PBAT blend has been enhanced, while its thermal performance remains unaffected. The rheological analysis shows that the storage modulus, loss modulus, and complex viscosity significantly increase with the increase of PBAT content and GMA grafting rate, which improves processing performance of blends. SEM shows that as the grafting rate of GMA increases, the particle size distribution of PBAT becomes smaller and more uniform. polylactic acid (PLA) poly (butylene adipate-co-terephthalate) (PBAT) glycidyl methacrylate (GMA) grafting rate 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 1 Introduction Plastics, prized for their cost efficiency, multifunctionality, processability, and balanced performance, are extensively employed in diverse sectors including automotive manufacturing, construction materials, and biomedical engineering, profoundly reshaping modern lifestyles and industrial methodologies [ 1 – 3 ] . However, due to its recalcitrance to degradation, it has resulted in the emergence of numerous significant environmental concerns [ 4 , 5 ] . The transition to bio-based biodegradable plastics is pivotal for carbon neutrality, effectively curbing fossil resource consumption, offsetting greenhouse gas emissions, and eradicating white pollution through sustainable end-of-life material management. [ 6 , 7 ] . Polylactic acid (PLA) is an aliphatic polyester derived from starch, which has become one of the most popular and intensively researched biopolymers due to its high transparency, high strength, exceptional biodegradability, and biocompatibility [ 8 – 11 ] . However, its high brittleness limits the further application of polylactide in industrial production and daily life [ 12 ] . To accomplish superior performance biodegradable plastics, the blending of PLA with another flexible biodegradable polymer material has been confirmed as an effective approach, such as poly (butylene adipate-co-terephthalate) (PBAT), poly propylene carbonate (PPC) [ 13 – 16 ] . PBAT, a random aliphatic-aromatic copolymer synthesized from adipic acid, terephthalic acid, and butylene glycol, is a low-stiffness, flexible biopolymer that is primarily considered an alternative to polyolefins [ 17 , 18 ] . The introduction of PBAT as a toughening modifier into PLA effectively mitigates the inherent brittleness of PLA through phase-separated morphology optimization and interfacial stress transfer enhancement, thereby achieving a state of complementary advantages without compromising its biodegradability [ 19 ] . Nevertheless, PLA has an aliphatic structure, whereas PBAT has an aromatic structure, which results in a relatively high enthalpy of mixing and poor compatibility between the two [ 20 – 22 ] . Additionally, there is a notable disparity in solubility parameters between the two, with PLA exhibiting a solubility parameter of 10.1 (cal/cm³)¹/², and PBAT displaying a solubility parameter of 23.0 (cal/cm³)¹/², under chloroform as the solvent, making it difficult to mix [ 23 ] . Consequently, PLA/PBAT blends typically exhibit diminished mechanical performance compared to their individual polymer constituents, highlighting the critical need for interfacial compatibility optimization [ 20 ] . At the present, the principal methods for enhancing the compatibility between PLA and PBAT interfaces are non-reactive compatibilization and reactive compatibilization [ 24 ] . Non-reactive compatibilization, otherwise referred to as physical compatibilization, is the utilization of interactions between compatibilizers and polymer components, encompassing intermolecular forces, ionic forces and hydrogen bonds, to enhance the compatibility between phases that are otherwise incompatible [ 25 – 27 ] . The process primarily employs homopolymers, block copolymers, and graft copolymers that have good compatibility with both phases to entangle with polymer physics, thereby inducing "emulsification" or "coupling" at the interface to improve compatibility [ 3 ] . Ding et al. [ 28 ] synthesized PLA-PBAT-PLA triblock copolymers containing PLA blocks of varying chain lengths (LPB and HPB) as compatibilizers for PLA/PBAT blends. Compared to low molecular weight PLA blocks (LPB) in copolymers, HPB demonstrated superior compatibilizing efficiency, leading to a sevenfold enhancement in elongation at break for PLA/PBAT blends with 5% HPB compared to unmodified blends. The incorporation of compatibilizers significantly decreased the dispersed phase particle size from 1.5 µm to 0.5 µm while improving interfacial compatibility between PLA and PBAT. However, the interaction force between components subsequent to this method of compatibilization remains inadequate. When subjected to significant external forces, the phase interface tends to debone easily, leading to suboptimal overall mechanical properties of the blend system. Consequently, the compatibilization and modification effects are mediocre [ 29 ] . Reactive compatibilization induces in-situ formation of architecturally complex copolymers (block/graft/comb) at phase boundaries via interfacial chemical reactions, achieving interfacial tension reduction and enhanced phase adhesion [ 30 ] . This methodology has significantly growth in polymer blend research in recent years, emerging as the predominant strategy for engineering high-performance incompatible polymer systems [ 31 – 33 ] . Han et al. [ 31 ] used high epoxy value epoxidized soybean oil (ESO) as a reactive compatibilizer to enhance the compatibility of PLA/PBAT blends through chemical reactions between the epoxy groups of ESO and the terminal hydroxyl and carboxyl groups of PLA and PBAT. This investigation fabricated PLA/PBAT blends with controlled compositional variations via an in-situ compatibilization strategy. Comprehensive characterization integrating Fourier-transform infrared spectroscopy (FTIR), Mechanical properties, Thermal performance (TGA, DSC), rheological profiling, and scanning electron microscopy (SEM), aiming to provide a more superior all-round performance material. 2 Material and methods 2.1 Materials PLA (LX175, MFR of 3 g/10min) was sourced from Heilongjiang Xinda Enterprise Group Co., Ltd (China). PBAT (MFR from 2.5 to 4.5 g/10 min) was sourced from Xinjiang Lanshan Tunhe Chemical Co., Ltd, (China). Dicumyl peroxide (DCP, analytical pure) and Glycidyl methacrylate (GMA, analytical pure) were obtained from Aladdin Chemicals Co. (USA). 2.2 Preparation and purification of PBAT-g-GMA Prior to blending, all polymers were vacuum dried to eliminate moisture at 60°C for 24 h. This process was carried out in an HAAKE torque rheometer (TYP557-9301, Thermo Scientific, Germany) at a temperature of 140 ℃ for 8 min, with 60 rpm. The mass ratios of PBAT/GMA/DCP were 100:8:0.3 and 100:15:0.5, respectively. Figure 1 showed the reaction mechanism of PBAT-g-GMA. During the grafting process, GMA, initiator DCP, and certain by-products would remain on the surface of the grafted material, affecting the next step of testing and analysis. Therefore, it was imperative to purify the grafted PBAT-g-GMA. After the PBAT-g-GMA graft was completely dissolved in a certain amount of chloroform solution, it was slowly poured into an excess of ethanol for precipitation (V chloroform :V ethanol =1:20) and stirred appropriately, and the precipitate obtains by filtration also needed to be washed sufficiently with ethanol to ensure that residual debris on the surface of the precipitate was removed, and finally, the precipitate was placed in an oven at 80 ℃ under a vacuum for drying to a constant weight [ 34 ] . 2.3 Preparation of PLA/PBAT blends The experimental formulations are detailed in Table 1 . Prior to processing, PLA, PBAT, and PBAT-g-GMA were vacuum-dried at 60°C for 12 h. The pre-treated polymers were then melt blended in a Haake torque rheometer under controlled conditions (145°C, 60 rpm) for 8 minutes. The preparation process of PLA/PBAT blend is shown in Fig. 2 . Table 1 Formulations for PLA/PBAT blends Sample PLA/g PBAT/g PBAT-g-GMA(1.64)/g PBAT-g-GMA(2.83)/g PPT10 90 10 — — PPT20 80 20 — — PPT30 70 30 — — PPT40 60 40 — — PPT50 50 50 — — PPG10(1.64) 90 — 10 — PPG20(1.64) 80 — 20 — PPG30(1.64) 70 — 30 — PPG40(1.64) 60 — 40 — PPG50(1.64) 50 — 50 — PPG10(2.83) 90 — — 10 PPG20(2.83) 80 — — 20 PPG30(2.83) 70 — — 30 PPG40(2.83) 60 — — 40 PPG50(2.83) 50 — — 50 Note: 1.64 and 2.83 represent the grafting rates of PBAT-g-GMA, respectively, %. 2.4 Characterization 2.4.1 FTIR test The PLA, PPG40(2.83), PBAT and PBAT-g-GMA(2.83) were formed into membranes on a plate vulcanizing machine (XLB, Qingdao Yadong Rubber Machine Co., Ltd.), and the GMA was pressed using potassium bromide and then analyzed by FTIR. The spectral analysis was conducted from 4000 − 400 cm⁻¹ using 64 scans at a resolution of 4 cm⁻¹. 2.4.2 Determination of PBAT-g-GMA grafting rate The epoxy group in the GMA structure was capable of undergoing a ring-opening reaction with trichloroacetic acid (CCl 3 COOH) at high temperatures (Fig. 3 ), which enabled the calculation of the grafting rate of PBAT-g-GMA [ 35 ] . The specific steps were as follows: Dissolve 1 g of purified sample in 70 mL of xylene, then add 10 mL of CCl 3 COOH/xylene (0.5 mol/L) to the mixture, keep the solution at 135 ℃ and reflux for about 2 h. Following a cooling process to ambient temperature, the solution was titrated to the end point using a KOH-ethanol standard solution (0.5 mol/L) with phenolphthalein (C 0 = 10 g/L) as indicator. The titration was halted when the color development persisted for 30 seconds, and no precipitate was observed during the process. The grafting rate (G) can be calculated using the following formula: $$\:\text{G}\text{=}\frac{{\text{(C}}_{\text{1}}{\text{V}}_{\text{1}}\text{-}{\text{C}}_{\text{2}}{\text{V}}_{\text{2}}\text{)×142.5}}{\text{1000}\text{M}}\text{×100%}$$ 1 Here, C 1 , C 2 represent the concentrations of CCl 3 COOH/xylene solution and KOH ethanol solution, respectively, mol/L; V 1 , V 2 respectively represent the added volume of CCl 3 COOH/xylene solution and the consumed volume of potassium hydroxide ethanol solution, mL; M represents the mass of the graft sample, g. 2.4.3 Mechanical properties test Impact strength test was conducted in accordance with GB/T1843-2008 standard using the cantilever beam impact tester (XJU-22, China). Separately, tensile tests were performed following GB/T1040-2018 specifications with an Instron-1121 universal testing machine (Instron, USA), maintaining a displacement rate (30 mm/min). 2.4.4 Thermogravimetric test Perform test on approximately 5-10mg of the sample using the PYRIS-1 instrument (PerkinElmer, USA). The thermal program involved heating from 30℃ to 600℃ at a constant rate of 20℃/min under nitrogen atmosphere. 2.4.5 Rheological test Circular specimens (1 mm thick × 1 mm diameter) were fabricated per standardized protocols for rotational rheometric analysis using an AR2000 rheometer (TA Instruments, USA). The dynamic mechanical testing regimen maintained isothermal control at 170°C with angular frequency scanning from 0.1 to 100 rad/s. 2.4.6 Differential Scanning Calorimetry (DSC) The thermal behavior of the samples (5 ~ 10 mg) was characterized by differential scanning calorimetry (ZF-DSC-D2, Shanghai Zufa Industrial Co., China) with the following protocol: (1) Heating from − 50°C to 150°C at 10°C/min under N₂ flow, (2) 3 min isothermal stabilization at 150°C to remove thermal history, (3) Cooling to -50°C at 10°C/min with 3 min equilibration, (4) Final reheating to 150°C for phase transition analysis. The crystallinity ( Xc ) of PLA components in blend could be calculated using the following formula: $$\:\text{X}\text{c=}\frac{\varDelta\:{H}_{m}-\varDelta\:{H}_{CC}}{{W}_{f}\text{×∆}{H}_{m}^{0}}\text{×}\text{100%}$$ 2 Among them, \(\:\varDelta\:{H}_{m}\) and \(\:\varDelta\:{H}_{CC}\) were the melting enthalpy and cold crystallization enthalpy during secondary heating, respectively; \(\:\text{∆}{H}_{m}^{0}\) was the melting enthalpy of PLA when fully crystallized, which was 93.7 J/g; \(\:{W}_{f}\) was the weight fraction of PLA in the blend. 2.4.7 X-ray diffractometer testing (XRD) Test was performed via X-ray diffraction (MiniFlex-C, Rigaku, Japan) with angular scanning from 45° to 5° at 5°/min scanning rate. 2.4.8 Scanning electron microscopy (SEM) Samples were gold-sputtered and examined with a Carl Zeiss Sigma 500 scanning electron microscope (Germany). 3. Results and discussion 3.1 FTIR analysis As depicted in Fig. 4 , the range of 2910 ~ 2945 cm − 1 represents the antisymmetric stretching vibration of saturated alkyl group (-CH), the absorption peak at 1720 cm⁻¹ corresponds to characteristic peak of C = O stretching vibration of ester or ketone compounds, and the absorption peak at 1257 cm − 1 is induced by the C-O-C asymmetric stretching vibration of aliphatic compounds, which are common to the three substances of GMA, PBAT and PBAT-g-GMA [ 36 ] . Furthermore, an absorption peak resulting from the C = C stretching vibration is detected at 1639 cm − 1 in the spectrum of GMA, which is not present in the spectrum of PBAT-g-GMA. This indicates that neither GMA monomer nor GMA self-polymerization product remain in the grafts. The absorption peak appears near 910 cm − 1 is caused by the stretching vibration peak of the epoxide functional group in the structure of GMA, and there is no corresponding functional group in PBAT, while a new absorption peak appears near 910 cm − 1 in PBAT-g-GMA [ 37 ] . Therefore, based on the aforementioned analysis, the conclusion can be drawn that GMA has been accomplishedly grafted onto PBAT. 3.2 Analysis of compatibilization mechanism in blending systems In an effort to investigate the chemical reactions and structural changes that occur during the melt blending process of the polymers, FTIR spectroscopy is performed on PLA, PPG40 (2.83), and PBAT-g-GMA (2.83). As depicted in Fig. 5 , the characteristic absorption peak of PPG40 (2.83) undergoes a decrease and narrowing at 910 cm − 1 . This is a consequence of the epoxy functional group of PBAT-g-GMA (2.83) undergoing chemical interaction with the end groups (-OH or -COOH) of PLA during the melt process. Figure 6 shows the chemical reaction between PLA and PBAT-g-GMA during the melt reaction blending process. During the blending process, PBAT-g-GMA undergoes in-situ reaction with the -OH and -COOH functional groups at the end of the PLA chain, resulting in the formation of PLA-g-PBAT branched copolymers at the interface of the blend. Under the influence of thermodynamic forces, these copolymers can migrate to the interphase between PLA and PBAT phases, which reduces the interfacial tension between the two phases, thereby making the particles of PBAT phase more finely and uniformly dispersed in the PLA matrix [ 3 ] . In addition, the hydroxyl groups of PLA-g-PBAT can further react with PBAT-g-GMA, continuously forming cross-linked network structures, which act as bridges between PLA and PBAT phases by increasing the molecular density at the interphase between the two phases. Owing to the enhanced interfacial adhesion of the PBAT dispersed phase within the PLA matrix due to increased entanglement of molecular chains at the interphase, achieving the goal of efficient toughening of PLA [ 38 ] . 3.2 Mechanical properties analysis The combined mechanical properties of material are one of the main factors that determine its practical application scenarios [ 39 ] . It can be observed in Table 2 that the PBAT content influences the mechanical properties of PLA/PBAT blends, enhancing toughness through the incorporation of epoxy compounds while suppressing the reduction in tensile modulus. As depicted in Fig. 7 (a), from the PPT series blends that although the incorporation of PBAT elastomer into PLA does indeed reduce brittleness, the impact strength is still unsatisfactory. Even if the PBAT content is 50 wt%, the impact strength of the PPT50 blend is only 89 J/m. Owing to the extremely weak interfacial interaction between the two phases due to the coarse size and uneven distribution of dispersed phase particles of PBAT in PLA matrix, PBAT dispersed phase particles readily detach from the matrix when PPT series blends are subjected to external impact [ 40 ] . This phenomenon renders it impossible for mechanical stress to be uniformly transferred from the PLA matrix to the PBAT phase, causing the elastomer to form stress concentration points, which in turn causes shear yielding and plastic deformation to dissipate a large amount of energy [ 41 ] . Table 2 Mechanical properties of PLA/PBAT blends Sample Impact strength (J/m) Yield strength (MPa) Tensile modulus (MPa) PLA 27.2 ± 0.8 50.5 ± 1.5 2497 ± 75 PPT10 43.0 ± 1.3 48.3 ± 1.4 2092 ± 63 PPT20 58.8 ± 1.8 44.2 ± 1.3 1936 ± 58 PPT30 61.8 ± 1.9 40.3 ± 1.2 1620 ± 49 PPT40 63.6 ± 1.9 31.5 ± 0.9 1116 ± 33 PPT50 89.0 ± 2.7 21.4 ± 0.6 682 ± 20 PPG10(1.64) 47.2 ± 1.4 45.7 ± 1.4 1892 ± 57 PPG20(1.64) 69.0 ± 2.1 41.0 ± 1.2 1767 ± 53 PPG30(1.64) 465 ± 19 35.8 ± 1.1 1521 ± 46 PPG40(1.64) 547 ± 22 28.3 ± 0.8 1162 ± 35 PPG50(1.64) 757 ± 30 22.7 ± 0.7 810 ± 24 PPG10(2.83) 101 ± 3 40.0 ± 1.2 1810 ± 54 PPG20(2.83) 224 ± 7 39.0 ± 1.2 1732 ± 52 PPG30(2.83) 611 ± 24 35.3 ± 1.1 1457 ± 44 PPG40(2.83) 961 ± 38 32.5 ± 1.0 1256 ± 38 PPG50(2.83) 887 ± 35 26.0 ± 0.8 1029 ± 31 In the PPG (1.64) blend system, the epoxy groups of PBAT-g-GMA undergo chemical interactions with hydroxyl/carboxyl groups on PLA chains, resulting in the formation of PLA-g-GMA-g-PBAT graft copolymers. This process effectively reduces interfacial tension between PBAT and PLA phases, strengthens interfacial adhesion, and ultimately leads to a significant improvement in the impact resistance of the blends. It is important to note, however, that at low content levels (below 20 wt%), the toughening effect of PBAT-g-GMA (1.64) is almost identical to that of PBAT. This may be attributed to the lack of effective in-situ compatibilization reaction at the interface of the blend at low GMA content, resulting in the absence of PLA-g-PBAT copolymer formation and the weak interfacial adhesion of the mixture [ 38 ] . Upon further increasing the grafting rate of PBAT-g-GMA, it can be seen from the PPG (2.83) series blends that the impact strength of the blend reaches 101 J/m, almost four times that of PLA, with only 10 wt% of PBAT-g-GMA (2.8) added. In particular, the impact strength of the PLA/PBAT blends is 961 J/m at a PBAT-g-GMA (2.83) content of 40 wt%, which is approximately 35 times that of PLA (27.2 J/m). These findings suggest that the grafting rate of GMA plays a significant role in the toughening effect. Figure 7 (b) and 7(c) show the trend of changes in the tensile properties of the blend. It can be seen from this that the improvement of toughness in blends is based on sacrificing their strength and rigidity, as the presence of elastomers makes it easier for the molecular chains of the blend to slide. The three blends exhibit a progressive reduction in yield strength and tensile modulus as the increase of PBAT content, but the degree of decrease is not the same, which is still related to the interface effect between them. Due to the poor interfacial compatibility of PPT series blends, when the PBAT content is too low, the external force on the PLA matrix is unable to effectively propagate to the PBAT dispersion, and the PLA masks the presence of the flexible PBAT, resulting in a diminished decrease in yield strength and tensile modulus when compared to PPG (1.64) and PPG (2.83). However, when the PBAT content reaches a critical value (approximately 30wt%), numerous non-uniformly dispersed elastomeric PBAT phase particles will significantly disrupt the internal stress-bearing structure of the PLA matrix, leading to a higher decrease in yield strength and elastic modulus compared to both others. In contrast, due to the excellent compatibility of PPG (2.83) series blends, even at low PBAT content, the external forces exerted on PLA can effectively propagate to PBAT. In high PBAT content, the internal structure of PLA in the blend still maintains a certain degree of integrity, which effectively resists the downward trend of yield strength and elastic modulus. Furthermore, the PPG (1.64) series of blends exhibit a similar regularity and is situated between the first two. The radar plot (Fig. 7 (d)) holistically evaluates the mechanical performance of PLA and its blends. Although the modulus of elasticity of PPG (2.83) is reduced compared to PLA, it remains essentially unchanged in comparison to PPT and PPG (1.64), and the impact strength is significantly enhanced, which further underscores the role of the epoxy compounds in enhancing the compatibility and the mechanical properties of the materials. 3.4 DSC analysis It can be discerned from the non-isothermal cooling curve of PLA that there is no discernible crystallization peak feature, indicating that the crystallizability of PLA is poor and that insufficient time is available to enable the growth of a complete spherical crystal structure at the current cooling rate [ 42 ] . The crystallization curve of the PLA/PBAT blend system shows a clear PBAT crystallization peak in the range of 50–80 ℃. With the increase in PBAT-g-GMA addition and GMA grafting rate, the crystallization peak transforms into an indistinct crystallization peak similar to that of the PLA, indicating that the compatibility of the blend system has been improved [ 43 ] . Figure 8 (b) presents the second-heating DSC curves of PLA and its blends, while Table 3 provides complementary numerical data on thermal transitions. In PPT40, the Tg of PLA components is observed to increase, which is related to the uneven distribution and immiscibility of the two components in the blend system. Following the addition of PBAT-GMA, a reduction in T g of PLA is evident, predominantly as a consequence of the reaction between the epoxy groups in PBAT-g-GMA and the hydroxyl groups in PLA reduces the hydrogen bonding in the blends and then weakens the interaction between molecular chains [ 44 ] . It is worth noting that, although the Tg of PPG40(2.83) (58.83 ℃) is lower than the PLA (60.5 ℃), its Tg is higher than that of PPG40(1.64) (58.32 ℃). This may be connected with the sufficient crosslinking within the blend [ 38 ] . Furthermore, as the amount of PBAT or PBAT-g-GMA increases, the T cc shifts towards elevated temperatures, rising from 111.4 ℃ to 125.8 ℃, manifesting that the incorporation of PBAT and PBAT-g-GMA impedes the cold crystallization of PLA. This phenomenon may be attributed to the formation of extended chain ends or branches between PLA and PBAT, which act as additional nucleation sites, impeding the cold crystallization process and decelerating the rate of cold crystallization of PLA, but which provide a good breeding ground for PLA crystallization [ 45 ] . With regard to the melting peaks, the blend systems exhibit a tendency towards lower temperatures following the incorporation of PBAT or PBAT-g-GMA. Moreover, as shown in Table 4, the Xc of the PPG40 (2.83) demonstrates a notable increase to 6.33%, suggesting that the grafted components serve as nucleating agents, effectively improving the crystallization capability of the blend system [ 43 ] . Table 3 DSC analysis characteristic data of PLA and PLA/PBAT blends Sample T g (℃) T cc (℃) T m (℃) \(\:\varDelta\:{H}_{CC}\) (J/g) \(\:\varDelta\:{H}_{m}\) (J/g) X c \(\:\text{(}\text{\%}\text{)}\) PLA 60.5 111.4 159.5 9.86 12.32 2.63 PPG20(2.83) 60 125.2 153.2 20.57 23.12 3.40 PPT40 61.4 129.2 154.2 13.05 15.66 4.64 PPG40(1.64) 58.32 132.5 153.2 5.81 9.32 6.24 PPG40(2.83) 58.83 125.8 152.5 12.25 15.81 6.33 Note: T g is the glass transition temperature; T cc is the cold crystallization temperature; T m is the melting temperature; ∆H cc is the enthalpy of cold crystallization; ∆H m is the enthalpy of melting; X c represents crystallinity. 3.4 Thermogravimetric analysis The Thermogravimetric test results are shown in Fig. 9 , and the main characteristic temperatures of the TGA for blends are summarized in Table 3 . As depicted in Fig. 9 a, PLA undergoes a one-step thermal degradation process, with PLA reaching its initial decomposition temperature ( T onset ) at 333.2°C and almost no residue at 392.3°C. PBAT has a longer chain segment and aromatic structure, and its thermal stability is better than that of PLA. However, with the addition of PBAT, both PLA/PBAT and PLA/PBAT-g-GMA blends showed a decrease in the T onset values. This may be due to the presence of PBAT, which enhances the ester exchange reaction within PLA, catalyzing to some extent the thermal degradation reaction of the blend [ 46 ] . In addition, GMA also has a certain negative impact on the T onset of PLA/PBAT, which may be due to the chemical interaction between the chain end of PLA and the PBAT-g-GMA molecular chain, forming the copolymer PLA-g-PBAT, which decomposes first due to its poor thermal stability [ 47 ] . In Fig. 9 (b), it can be observed that all PLA/PBAT blends exhibit two thermal degradation steps. The more PBAT content is added, the higher T max of the first step of the PLA/PBAT blend, and the degradation trend at this temperature gradually decreases. This indicates that for PLA/PBAT blend systems, under the same conditions, increasing the number of PBATs with good thermal properties is indeed beneficial for improving the thermal stability of the material. In the second step of thermal degradation, it may be mainly the thermal degradation reaction of PBAT itself, so the content of PBAT and GMA has less impact on the thermal stability of the blend at this stage. Table 3 Thermogravimetric data of PLA/PBAT blends Sample T onset (℃) T 50% (℃) T final (℃) T max (℃) Step1 Step2 PLA 333.2 361.3 392.3 364.7 — PPG20(2.83) 319.6 353.5 488.8 351.7 401.6 PPT40 315.7 364.9 494.7 355.8 401.8 PPG40(1.64) 306.9 370.5 507.4 362.4 401.6 PPG40(2.83) 306.2 365.4 509.7 359.3 400.3 Note: T onset is the temperature at which the sample loses 5% of its mass, T 50% is the temperature at which the sample loses 50% of its mass, and T final is the temperature at which the sample loses 95% of its mass, T max is the temperature at which the sample has the maximum weight loss rate. 3.5 Rheological properties analysis From Fig. 10 (a), the shear thinning behavior of PLA and PLA/PBAT blends can be clearly observed. Compared with PLA, the complex viscosity (η*) of PLA blends decreases significantly with increasing shear rate. Meanwhile, the η* of PLA blends gradually increases with higher PBAT content. After adding 20 wt% PBAT, the complex viscosity of PPT20 at 1 rad/s increases from 2364.68 Pa·s to 14196 Pa·s, a nearly 500% enhancement. Furthermore, mechanical properties analysis has indicated that when the content of PBAT reaches a critical value (approximately 30 wt%), the morphology of the PLA/PBAT blend system may undergo a transformation, resulting in a reversal of complex viscosity trend. This is consistent with the fact that PPT40 in this study has lower complex viscosity than PPT20. The complex viscosity evolution critically relates to on PBAT dispersion in PLA: uniform distribution enhances viscosity through strong interfacial interactions and entanglement networks, while exceeding PBAT induces phase separation and viscosity reduction due to weakened interfacial effects. The incorporation of GMA into the PLA/PBAT blend system facilitates the formation of branched or micro-crosslinked structures at the polymer interfaces, which enhances the dispersion of the PBAT phase, increases intermolecular chain entanglement, and consequently elevates the viscosity of blends [ 48 ] . As shown in Fig. 10 (b), the storage modulus (G') of all samples increases with angular frequency. This behavior arises because the crosslinking between PLA and PBAT (or PBAT-g-GMA) causes a reversal in the relaxation and deformation rates of molecular chains within the blend system. At higher angular frequency, the disentanglement rate of molecular chains cannot keep pace with the entanglement rate, leading to a continuous increase in G' [ 49 ] . Notably, while the flexible chains of PBAT can enhance the entanglement density of the blend system to some extent, the maximum entanglement density is achieved at an optimal PBAT content. Without GMA compatibilization, further increases in PBAT content actually reduce the system's entanglement density. This explains why PPT20 exhibits a higher G' than PPT40. For the PPG blend series, ring-opening reactions between GMA and PLA terminal groups strengthen PLA/PBAT interactions, resulting in higher G'. Figure 10 (c) demonstrates that the loss modulus (G'') of PLA and PLA blends increases progressively with testing frequency. In the low-frequency region, the G'' of the blends exhibits a trend similar to that of G', which can be explained by the following mechanism: Higher crosslinking density within the blends reduces the free volume between molecular chains, thereby increasing the resistance to chain motion. The sliding of polymer chains results in greater energy dissipation, which is manifested as enhanced G'' values [ 50 ] . 3.7 XRD analysis In order to gain further insight into the crystal structure and changes in the blend system, X-ray diffraction tests were conducted on PLA/PBAT blends. Figure 11 illustrates the relationship between crystal diffraction intensity and the scanning range of the PLA/PBAT blend. It can be observed that PLA did not exhibit diffraction peak patterns that were particularly pronounced within the testing range of XRD. This is due to the fact that PLA belongs to amorphous crystals with a relatively low degree of crystallization, resulting in a relatively flat diffraction peak pattern within the range of 15–25°. The incorporation of PBAT as a toughening agent to PLA resulted in no significant shifts in diffraction peak positions or pattern variations, confirming that the crystalline architecture of PLA remained unaltered during blending. 3.7 Microscopic morphology analysis As depicted in Fig. 12 (a), the impact fracture plane of PLA is smooth and devoid of discernible features, indicative of a low toughness brittle failure mode. The coarsened structure of PLA matrix deformation can be clearly found in Fig. 12 (b) and Fig. 12 (d), which indicates that the blended system, due to the presence of the elastomer PBAT, is subjected to stress, a small amount of shear yielding and plastic deformation has already occurred within the material, and the brittle fracture of PLA gradually evolves to ductile fracture. In addition, larger-sized and non-uniformly distributed PBAT particles can be seen on the surface of the PLA body, where a clear gap also appears around the PBAT particles, which is an interfacial debonding of the two-phase separation presented by the PLA/PBAT incompatible system [ 51 ] . However, when PBAT was grafted with compatibilizer GMA, a compatibilization reaction occurred between PBAT-g-GMA and PLA. This resulted in a decrease in the dispersed particle size of PBAT, an increase in the distribution uniformity, and a reduction in the phase gap between PLA and PBAT. Consequently, the boundary between the two phases became increasingly blurred, as illustrated in Fig. 12 (c), Fig. 12 (e), and Fig. 12 (f), PBAT phase is difficult to distinguish from PLA matrix. Compared with PPG20 (2.83), the phase interface of PPG40 (1.64) and PPG40 (2.83) can form more stress concentration points, which is equivalent to more "nuclei" producing crazing. Upon impact, a significant amount of micro-mechanical deformation of the matrix results in the loss of greater fracture energy, which is consistent with the rough structure observed in the SEM images Fig. 12 (e) and Fig. 12 (f). PPG40(2.83) has better toughness than PPG40(1.64) because the higher the content of GMA, the smaller and more uniform the particle size distribution of PBAT. In Fig. 12 (e), larger plastic deformation bodies can still be observed, and their sizes are also uneven, while in Fig. 12 (f), the deformation bodies are smaller and relatively uniform in size. 4 Conclusion In this study, a series of PLA/PBAT blends are prepared by melt blending using an in-situ compatibilization strategy, and the effects of PBAT content and GMA grafting rate on the compatibility, microstructure, crystalline behavior, thermal stability, rheological properties and mechanical properties of the system were investigated. The conclusion is as follows: FTIR analysis shows that GMA compatibilizer has been successfully grafted onto the PBAT molecular chain. In addition, during the blending process of PLA and PBAT-g-GMA, the epoxy groups on GMA react with the end groups of PLA. Mechanical properties analysis indicates that the increase of PBAT content and GMA grafting rate, the impact strength of blends is significantly improved. In particular, the addition of 40 weight% PBAT-g-GMA (2.83) results in the impact strength of 961 J/m for the PLA/PBAT blend, which is approximately 35 times that of PLA. Crystallization performance implies that the presence of PBAT-g-GMA reduces the cold crystallization rate of PLA, changes the crystallization environment of PLA, increases crystallinity, but does not alter the crystalline structure. Rheological tests demonstrated that the storage modulus, loss modulus and complex viscosity exhibited a substantial increase with rising PBAT content and GMA grafting rate, which improves the processability of the blends. From the SEM images, the improvement in toughness of PLA/PBAT blends can be attributed to the plastic deformation of PBAT in the matrix and the enhancement of interfacial bonding between polymers. Declarations Notes The authors declare no competing financial interest. Funding Declaration This work is financially supported by the Project of Jilin Provincial Department of Science and Technology (20240301030GX) and Changchun Universities and Institutes Pilot Selection Project (24GXYSZZ41). Data Availability Statement The data that support the findings of this study were available from the corresponding author upon reasonable request. Credit Author Statement Yunda Shen: Conceptualization, Methodology, Validation, Formal analysis, Data Curation, Writing-Original Draft, Investigation, Writing-Review & Editing Bingrui Jin: Data Curation, Investigation Hongnian Gan: Validation, Formal analysis Jiankun Li: Investigation, Validation Dan Zhao: Data Curation, Formal analysis Huizhong Shen: Conceptualization, Methodology, Investigation Liang Ren: Methodology, Validation, Data Curation, Funding acquisition, Project administration, Writing-Original Draft, Writing-Review & Editing, Resources, Supervision Mingyao Zhang: Conceptualization, Methodology, Formal analysis, Writing-Review & Editing, Resources, Supervision, Project administration, Funding acquisition References Zhang JP, Zhong W, Chen N, et al. Multiobjective Optimization of the Economic Efficiency of Biodegradable Plastic Products: Carbon Emissions and Analysis of Geographical Advantages for Production Capacity. Sustainability, 2025, 17(7): 2874. 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Journal of Applied Polymer Science, 2025, DOI: 10.1002/app.56857. Xu J, Zhang PB, Fan MM, et al. Silane-modified MOF-5 as a compatibilizer for PBAT/PLA blends: Enhancement of mechanical properties, antimicrobial properties, and water barrier properties. Polymer, 2024, DOI: 10.1016/j.polymer.2024.127875. Cite Share Download PDF Status: Published Journal Publication published 11 Sep, 2025 Read the published version in Journal of Polymer Research → Version 1 posted Reviewers agreed at journal 15 May, 2025 Reviewers invited by journal 15 May, 2025 Editor invited by journal 05 May, 2025 Editor assigned by journal 05 May, 2025 First submitted to journal 01 May, 2025 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. 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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-6564026","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":456934091,"identity":"2565878d-2a51-4632-bb43-e55e8366272f","order_by":0,"name":"Yunda Shen","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Yunda","middleName":"","lastName":"Shen","suffix":""},{"id":456934092,"identity":"0cdea306-9364-45ae-96c1-9cb7c1c735b1","order_by":1,"name":"Bingrui 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curve\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-6564026/v1/b8a7e96d09e6ecda1f02a1a8.png"},{"id":83052163,"identity":"f399139b-6649-409d-ac35-3db27e8638d3","added_by":"auto","created_at":"2025-05-19 12:55:57","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":169557,"visible":true,"origin":"","legend":"\u003cp\u003eThermogravimetric analysis curves of PLA PLA/PBAT blends:\u003c/p\u003e\n\u003cp\u003e(a) TGA curve, (b) DTG curve\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-6564026/v1/6135bf25dbec58d1b5c82531.png"},{"id":83053573,"identity":"c4c83db0-fdd1-451a-82c8-538e72d68f46","added_by":"auto","created_at":"2025-05-19 13:11:56","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":311584,"visible":true,"origin":"","legend":"\u003cp\u003eRheological properties of PLA/PBAT blends: (a)complex viscosity,\u003c/p\u003e\n\u003cp\u003e(b)storage modulus, (c) loss modulus\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-6564026/v1/c382fa3c5cc56e027558d14d.png"},{"id":83052169,"identity":"b0072414-ec52-4fed-bdac-b9709da68f42","added_by":"auto","created_at":"2025-05-19 12:55:57","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":1243049,"visible":true,"origin":"","legend":"\u003cp\u003eXRD curves of PLA/PBAT blends\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-6564026/v1/e411a06e6b8a1f28cbb157b4.png"},{"id":83052171,"identity":"8f50ed13-23e5-45df-b732-ea85b9fe4d04","added_by":"auto","created_at":"2025-05-19 12:55:57","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":1385883,"visible":true,"origin":"","legend":"\u003cp\u003eSEM image of impact fracture of PLA/PBAT blends (1000x): (a)PLA; (b)PPT20; (c) PPG20(2.83); (d)PPT40; (e)PPG40(1.64); (f)PPG40(2.83)\u003c/p\u003e","description":"","filename":"floatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-6564026/v1/cdfc7d12bafb8ebd2a4ab4eb.png"},{"id":91359110,"identity":"80be5b42-09dc-46eb-8dfb-3079385ee563","added_by":"auto","created_at":"2025-09-15 16:05:16","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":14114899,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6564026/v1/32b9e682-bf56-4c55-9148-114b2b9e1e00.pdf"}],"financialInterests":"","formattedTitle":"Fully Biodegradable Poly (lactic acid)/Poly (butylene adipate-co-terephthalate) Blends with highly toughness Based on in situ Interfacial Compatibilization by functional epoxy compound","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003ePlastics, prized for their cost efficiency, multifunctionality, processability, and balanced performance, are extensively employed in diverse sectors including automotive manufacturing, construction materials, and biomedical engineering, profoundly reshaping modern lifestyles and industrial methodologies \u003csup\u003e[\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. However, due to its recalcitrance to degradation, it has resulted in the emergence of numerous significant environmental concerns \u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. The transition to bio-based biodegradable plastics is pivotal for carbon neutrality, effectively curbing fossil resource consumption, offsetting greenhouse gas emissions, and eradicating white pollution through sustainable end-of-life material management. \u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. Polylactic acid (PLA) is an aliphatic polyester derived from starch, which has become one of the most popular and intensively researched biopolymers due to its high transparency, high strength, exceptional biodegradability, and biocompatibility \u003csup\u003e[\u003cspan additionalcitationids=\"CR9 CR10\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. However, its high brittleness limits the further application of polylactide in industrial production and daily life \u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. To accomplish superior performance biodegradable plastics, the blending of PLA with another flexible biodegradable polymer material has been confirmed as an effective approach, such as poly (butylene adipate-co-terephthalate) (PBAT), poly propylene carbonate (PPC) \u003csup\u003e[\u003cspan additionalcitationids=\"CR14 CR15\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003ePBAT, a random aliphatic-aromatic copolymer synthesized from adipic acid, terephthalic acid, and butylene glycol, is a low-stiffness, flexible biopolymer that is primarily considered an alternative to polyolefins \u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. The introduction of PBAT as a toughening modifier into PLA effectively mitigates the inherent brittleness of PLA through phase-separated morphology optimization and interfacial stress transfer enhancement, thereby achieving a state of complementary advantages without compromising its biodegradability \u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e. Nevertheless, PLA has an aliphatic structure, whereas PBAT has an aromatic structure, which results in a relatively high enthalpy of mixing and poor compatibility between the two \u003csup\u003e[\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. Additionally, there is a notable disparity in solubility parameters between the two, with PLA exhibiting a solubility parameter of 10.1 (cal/cm\u0026sup3;)\u0026sup1;/\u0026sup2;, and PBAT displaying a solubility parameter of 23.0 (cal/cm\u0026sup3;)\u0026sup1;/\u0026sup2;, under chloroform as the solvent, making it difficult to mix \u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e. Consequently, PLA/PBAT blends typically exhibit diminished mechanical performance compared to their individual polymer constituents, highlighting the critical need for interfacial compatibility optimization \u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAt the present, the principal methods for enhancing the compatibility between PLA and PBAT interfaces are non-reactive compatibilization and reactive compatibilization \u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e. Non-reactive compatibilization, otherwise referred to as physical compatibilization, is the utilization of interactions between compatibilizers and polymer components, encompassing intermolecular forces, ionic forces and hydrogen bonds, to enhance the compatibility between phases that are otherwise incompatible \u003csup\u003e[\u003cspan additionalcitationids=\"CR26\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e. The process primarily employs homopolymers, block copolymers, and graft copolymers that have good compatibility with both phases to entangle with polymer physics, thereby inducing \"emulsification\" or \"coupling\" at the interface to improve compatibility \u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. Ding et al. \u003csup\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e synthesized PLA-PBAT-PLA triblock copolymers containing PLA blocks of varying chain lengths (LPB and HPB) as compatibilizers for PLA/PBAT blends. Compared to low molecular weight PLA blocks (LPB) in copolymers, HPB demonstrated superior compatibilizing efficiency, leading to a sevenfold enhancement in elongation at break for PLA/PBAT blends with 5% HPB compared to unmodified blends. The incorporation of compatibilizers significantly decreased the dispersed phase particle size from 1.5 \u0026micro;m to 0.5 \u0026micro;m while improving interfacial compatibility between PLA and PBAT. However, the interaction force between components subsequent to this method of compatibilization remains inadequate. When subjected to significant external forces, the phase interface tends to debone easily, leading to suboptimal overall mechanical properties of the blend system. Consequently, the compatibilization and modification effects are mediocre \u003csup\u003e[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eReactive compatibilization induces in-situ formation of architecturally complex copolymers (block/graft/comb) at phase boundaries via interfacial chemical reactions, achieving interfacial tension reduction and enhanced phase adhesion \u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e. This methodology has significantly growth in polymer blend research in recent years, emerging as the predominant strategy for engineering high-performance incompatible polymer systems \u003csup\u003e[\u003cspan additionalcitationids=\"CR32\" citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/sup\u003e. Han et al. \u003csup\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/sup\u003e used high epoxy value epoxidized soybean oil (ESO) as a reactive compatibilizer to enhance the compatibility of PLA/PBAT blends through chemical reactions between the epoxy groups of ESO and the terminal hydroxyl and carboxyl groups of PLA and PBAT.\u003c/p\u003e \u003cp\u003eThis investigation fabricated PLA/PBAT blends with controlled compositional variations via an in-situ compatibilization strategy. Comprehensive characterization integrating Fourier-transform infrared spectroscopy (FTIR), Mechanical properties, Thermal performance (TGA, DSC), rheological profiling, and scanning electron microscopy (SEM), aiming to provide a more superior all-round performance material.\u003c/p\u003e"},{"header":"2 Material and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003e2.1 Materials\u003c/h2\u003e\n \u003cp\u003ePLA (LX175, MFR of 3 g/10min) was sourced from Heilongjiang Xinda Enterprise Group Co., Ltd (China). PBAT (MFR from 2.5 to 4.5 g/10 min) was sourced from Xinjiang Lanshan Tunhe Chemical Co., Ltd, (China). Dicumyl peroxide (DCP, analytical pure) and Glycidyl methacrylate (GMA, analytical pure) were obtained from Aladdin Chemicals Co. (USA).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003e2.2 Preparation and purification of PBAT-g-GMA\u003c/h2\u003e\n \u003cp\u003ePrior to blending, all polymers were vacuum dried to eliminate moisture at 60\u0026deg;C for 24 h. This process was carried out in an HAAKE torque rheometer (TYP557-9301, Thermo Scientific, Germany) at a temperature of 140 ℃ for 8 min, with 60 rpm. The mass ratios of PBAT/GMA/DCP were 100:8:0.3 and 100:15:0.5, respectively. Figure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e showed the reaction mechanism of PBAT-g-GMA.\u003c/p\u003e\n \u003cp\u003eDuring the grafting process, GMA, initiator DCP, and certain by-products would remain on the surface of the grafted material, affecting the next step of testing and analysis. Therefore, it was imperative to purify the grafted PBAT-g-GMA. After the PBAT-g-GMA graft was completely dissolved in a certain amount of chloroform solution, it was slowly poured into an excess of ethanol for precipitation (V\u003csub\u003echloroform\u003c/sub\u003e:V\u003csub\u003eethanol\u003c/sub\u003e =1:20) and stirred appropriately, and the precipitate obtains by filtration also needed to be washed sufficiently with ethanol to ensure that residual debris on the surface of the precipitate was removed, and finally, the precipitate was placed in an oven at 80 ℃ under a vacuum for drying to a constant weight \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003e2.3 Preparation of PLA/PBAT blends\u003c/h2\u003e\n \u003cp\u003eThe experimental formulations are detailed in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. Prior to processing, PLA, PBAT, and PBAT-g-GMA were vacuum-dried at 60\u0026deg;C for 12 h. The pre-treated polymers were then melt blended in a Haake torque rheometer under controlled conditions (145\u0026deg;C, 60 rpm) for 8 minutes. The preparation process of PLA/PBAT blend is shown in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eFormulations for PLA/PBAT blends\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePLA/g\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePBAT/g\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePBAT-g-GMA(1.64)/g\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePBAT-g-GMA(2.83)/g\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG10(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG20(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG30(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG40(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG50(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG10(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG20(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG30(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG40(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG50(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\"\u003eNote: 1.64 and 2.83 represent the grafting rates of PBAT-g-GMA, respectively, %.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n \u003ch2\u003e2.4 Characterization\u003c/h2\u003e\n \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\n \u003ch2\u003e2.4.1 FTIR test\u003c/h2\u003e\n \u003cp\u003eThe PLA, PPG40(2.83), PBAT and PBAT-g-GMA(2.83) were formed into membranes on a plate vulcanizing machine (XLB, Qingdao Yadong Rubber Machine Co., Ltd.), and the GMA was pressed using potassium bromide and then analyzed by FTIR. The spectral analysis was conducted from 4000\u0026thinsp;\u0026minus;\u0026thinsp;400 cm⁻\u0026sup1; using 64 scans at a resolution of 4 cm⁻\u0026sup1;.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e\n \u003ch2\u003e2.4.2 Determination of PBAT-g-GMA grafting rate\u003c/h2\u003e\n \u003cp\u003eThe epoxy group in the GMA structure was capable of undergoing a ring-opening reaction with trichloroacetic acid (CCl\u003csub\u003e3\u003c/sub\u003eCOOH) at high temperatures (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e), which enabled the calculation of the grafting rate of PBAT-g-GMA \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e. The specific steps were as follows:\u003c/p\u003e\n \u003cp\u003eDissolve 1 g of purified sample in 70 mL of xylene, then add 10 mL of CCl\u003csub\u003e3\u003c/sub\u003eCOOH/xylene (0.5 mol/L) to the mixture, keep the solution at 135 ℃ and reflux for about 2 h. Following a cooling process to ambient temperature, the solution was titrated to the end point using a KOH-ethanol standard solution (0.5 mol/L) with phenolphthalein (C\u003csub\u003e0\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;10 g/L) as indicator. The titration was halted when the color development persisted for 30 seconds, and no precipitate was observed during the process. The grafting rate (G) can be calculated using the following formula:\u003c/p\u003e\n \u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e$$\\:\\text{G}\\text{=}\\frac{{\\text{(C}}_{\\text{1}}{\\text{V}}_{\\text{1}}\\text{-}{\\text{C}}_{\\text{2}}{\\text{V}}_{\\text{2}}\\text{)\u0026times;142.5}}{\\text{1000}\\text{M}}\\text{\u0026times;100%}$$\u003c/div\u003e\n \u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003eHere, \u003cstrong\u003eC\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e, \u003cstrong\u003eC\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e represent the concentrations of CCl\u003csub\u003e3\u003c/sub\u003eCOOH/xylene solution and KOH ethanol solution, respectively, mol/L; \u003cstrong\u003eV\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e, \u003cstrong\u003eV\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e respectively represent the added volume of CCl\u003csub\u003e3\u003c/sub\u003eCOOH/xylene solution and the consumed volume of potassium hydroxide ethanol solution, mL; \u003cstrong\u003eM\u003c/strong\u003e represents the mass of the graft sample, g.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e\n \u003ch2\u003e2.4.3 Mechanical properties test\u003c/h2\u003e\n \u003cp\u003eImpact strength test was conducted in accordance with GB/T1843-2008 standard using the cantilever beam impact tester (XJU-22, China). Separately, tensile tests were performed following GB/T1040-2018 specifications with an Instron-1121 universal testing machine (Instron, USA), maintaining a displacement rate (30 mm/min).\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e\n \u003ch2\u003e2.4.4 Thermogravimetric test\u003c/h2\u003e\n \u003cp\u003ePerform test on approximately 5-10mg of the sample using the PYRIS-1 instrument (PerkinElmer, USA). The thermal program involved heating from 30℃ to 600℃ at a constant rate of 20℃/min under nitrogen atmosphere.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e\n \u003ch2\u003e2.4.5 Rheological test\u003c/h2\u003e\n \u003cp\u003eCircular specimens (1 mm thick \u0026times; 1 mm diameter) were fabricated per standardized protocols for rotational rheometric analysis using an AR2000 rheometer (TA Instruments, USA). The dynamic mechanical testing regimen maintained isothermal control at 170\u0026deg;C with angular frequency scanning from 0.1 to 100 rad/s.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e\n \u003ch2\u003e2.4.6 Differential Scanning Calorimetry (DSC)\u003c/h2\u003e\n \u003cp\u003eThe thermal behavior of the samples (5\u0026thinsp;~\u0026thinsp;10 mg) was characterized by differential scanning calorimetry (ZF-DSC-D2, Shanghai Zufa Industrial Co., China) with the following protocol: (1) Heating from \u0026minus;\u0026thinsp;50\u0026deg;C to 150\u0026deg;C at 10\u0026deg;C/min under N₂ flow, (2) 3 min isothermal stabilization at 150\u0026deg;C to remove thermal history, (3) Cooling to -50\u0026deg;C at 10\u0026deg;C/min with 3 min equilibration, (4) Final reheating to 150\u0026deg;C for phase transition analysis. The crystallinity (\u003cem\u003eXc\u003c/em\u003e) of PLA components in blend could be calculated using the following formula:\u003c/p\u003e\n \u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e$$\\:\\text{X}\\text{c=}\\frac{\\varDelta\\:{H}_{m}-\\varDelta\\:{H}_{CC}}{{W}_{f}\\text{\u0026times;∆}{H}_{m}^{0}}\\text{\u0026times;}\\text{100%}$$\u003c/div\u003e\n \u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003eAmong them, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varDelta\\:{H}_{m}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varDelta\\:{H}_{CC}\\)\u003c/span\u003e\u003c/span\u003e were the melting enthalpy and cold crystallization enthalpy during secondary heating, respectively; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{∆}{H}_{m}^{0}\\)\u003c/span\u003e\u003c/span\u003e was the melting enthalpy of PLA when fully crystallized, which was 93.7 J/g; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{W}_{f}\\)\u003c/span\u003e\u003c/span\u003e was the weight fraction of PLA in the blend.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e\n \u003ch2\u003e2.4.7 X-ray diffractometer testing (XRD)\u003c/h2\u003e\n \u003cp\u003eTest was performed via X-ray diffraction (MiniFlex-C, Rigaku, Japan) with angular scanning from 45\u0026deg; to 5\u0026deg; at 5\u0026deg;/min scanning rate.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e\n \u003ch2\u003e2.4.8 Scanning electron microscopy (SEM)\u003c/h2\u003e\n \u003cp\u003eSamples were gold-sputtered and examined with a Carl Zeiss Sigma 500 scanning electron microscope (Germany).\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1 FTIR analysis\u003c/h2\u003e\n \u003cp\u003eAs depicted in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e, the range of 2910\u0026thinsp;~\u0026thinsp;2945 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e represents the antisymmetric stretching vibration of saturated alkyl group (-CH), the absorption peak at 1720 cm⁻\u0026sup1; corresponds to characteristic peak of C\u0026thinsp;=\u0026thinsp;O stretching vibration of ester or ketone compounds, and the absorption peak at 1257 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is induced by the C-O-C asymmetric stretching vibration of aliphatic compounds, which are common to the three substances of GMA, PBAT and PBAT-g-GMA \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eFurthermore, an absorption peak resulting from the C\u0026thinsp;=\u0026thinsp;C stretching vibration is detected at 1639 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in the spectrum of GMA, which is not present in the spectrum of PBAT-g-GMA. This indicates that neither GMA monomer nor GMA self-polymerization product remain in the grafts. The absorption peak appears near 910 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is caused by the stretching vibration peak of the epoxide functional group in the structure of GMA, and there is no corresponding functional group in PBAT, while a new absorption peak appears near 910 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in PBAT-g-GMA \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e]\u003c/sup\u003e. Therefore, based on the aforementioned analysis, the conclusion can be drawn that GMA has been accomplishedly grafted onto PBAT.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2 Analysis of compatibilization mechanism in blending systems\u003c/h2\u003e\n \u003cp\u003eIn an effort to investigate the chemical reactions and structural changes that occur during the melt blending process of the polymers, FTIR spectroscopy is performed on PLA, PPG40 (2.83), and PBAT-g-GMA (2.83). As depicted in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e, the characteristic absorption peak of PPG40 (2.83) undergoes a decrease and narrowing at 910 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. This is a consequence of the epoxy functional group of PBAT-g-GMA (2.83) undergoing chemical interaction with the end groups (-OH or -COOH) of PLA during the melt process.\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e shows the chemical reaction between PLA and PBAT-g-GMA during the melt reaction blending process. During the blending process, PBAT-g-GMA undergoes in-situ reaction with the -OH and -COOH functional groups at the end of the PLA chain, resulting in the formation of PLA-g-PBAT branched copolymers at the interface of the blend. Under the influence of thermodynamic forces, these copolymers can migrate to the interphase between PLA and PBAT phases, which reduces the interfacial tension between the two phases, thereby making the particles of PBAT phase more finely and uniformly dispersed in the PLA matrix \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. In addition, the hydroxyl groups of PLA-g-PBAT can further react with PBAT-g-GMA, continuously forming cross-linked network structures, which act as bridges between PLA and PBAT phases by increasing the molecular density at the interphase between the two phases. Owing to the enhanced interfacial adhesion of the PBAT dispersed phase within the PLA matrix due to increased entanglement of molecular chains at the interphase, achieving the goal of efficient toughening of PLA \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2 Mechanical properties analysis\u003c/h2\u003e\n \u003cp\u003eThe combined mechanical properties of material are one of the main factors that determine its practical application scenarios \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e]\u003c/sup\u003e. It can be observed in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e that the PBAT content influences the mechanical properties of PLA/PBAT blends, enhancing toughness through the incorporation of epoxy compounds while suppressing the reduction in tensile modulus.\u003c/p\u003e\n \u003cp\u003eAs depicted in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e(a), from the PPT series blends that although the incorporation of PBAT elastomer into PLA does indeed reduce brittleness, the impact strength is still unsatisfactory. Even if the PBAT content is 50 wt%, the impact strength of the PPT50 blend is only 89 J/m. Owing to the extremely weak interfacial interaction between the two phases due to the coarse size and uneven distribution of dispersed phase particles of PBAT in PLA matrix, PBAT dispersed phase particles readily detach from the matrix when PPT series blends are subjected to external impact \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e]\u003c/sup\u003e. This phenomenon renders it impossible for mechanical stress to be uniformly transferred from the PLA matrix to the PBAT phase, causing the elastomer to form stress concentration points, which in turn causes shear yielding and plastic deformation to dissipate a large amount of energy \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\u0026nbsp;\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eMechanical properties of PLA/PBAT blends\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eImpact strength\u003c/p\u003e\n \u003cp\u003e(J/m)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eYield strength (MPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTensile modulus (MPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePLA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2497\u0026thinsp;\u0026plusmn;\u0026thinsp;75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e43.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e48.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2092\u0026thinsp;\u0026plusmn;\u0026thinsp;63\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e58.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e44.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1936\u0026thinsp;\u0026plusmn;\u0026thinsp;58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e61.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e40.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1620\u0026thinsp;\u0026plusmn;\u0026thinsp;49\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e63.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e31.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1116\u0026thinsp;\u0026plusmn;\u0026thinsp;33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e89.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e21.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e682\u0026thinsp;\u0026plusmn;\u0026thinsp;20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG10(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e47.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e45.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1892\u0026thinsp;\u0026plusmn;\u0026thinsp;57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG20(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e69.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e41.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1767\u0026thinsp;\u0026plusmn;\u0026thinsp;53\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG30(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e465\u0026thinsp;\u0026plusmn;\u0026thinsp;19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e35.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1521\u0026thinsp;\u0026plusmn;\u0026thinsp;46\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG40(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e547\u0026thinsp;\u0026plusmn;\u0026thinsp;22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e28.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1162\u0026thinsp;\u0026plusmn;\u0026thinsp;35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG50(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e757\u0026thinsp;\u0026plusmn;\u0026thinsp;30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e22.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e810\u0026thinsp;\u0026plusmn;\u0026thinsp;24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG10(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e101\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e40.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1810\u0026thinsp;\u0026plusmn;\u0026thinsp;54\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG20(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e224\u0026thinsp;\u0026plusmn;\u0026thinsp;7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e39.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1732\u0026thinsp;\u0026plusmn;\u0026thinsp;52\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG30(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e611\u0026thinsp;\u0026plusmn;\u0026thinsp;24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e35.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1457\u0026thinsp;\u0026plusmn;\u0026thinsp;44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG40(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e961\u0026thinsp;\u0026plusmn;\u0026thinsp;38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e32.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1256\u0026thinsp;\u0026plusmn;\u0026thinsp;38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG50(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e887\u0026thinsp;\u0026plusmn;\u0026thinsp;35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e26.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1029\u0026thinsp;\u0026plusmn;\u0026thinsp;31\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003eIn the PPG (1.64) blend system, the epoxy groups of PBAT-g-GMA undergo chemical interactions with hydroxyl/carboxyl groups on PLA chains, resulting in the formation of PLA-g-GMA-g-PBAT graft copolymers. This process effectively reduces interfacial tension between PBAT and PLA phases, strengthens interfacial adhesion, and ultimately leads to a significant improvement in the impact resistance of the blends. It is important to note, however, that at low content levels (below 20 wt%), the toughening effect of PBAT-g-GMA (1.64) is almost identical to that of PBAT. This may be attributed to the lack of effective in-situ compatibilization reaction at the interface of the blend at low GMA content, resulting in the absence of PLA-g-PBAT copolymer formation and the weak interfacial adhesion of the mixture \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eUpon further increasing the grafting rate of PBAT-g-GMA, it can be seen from the PPG (2.83) series blends that the impact strength of the blend reaches 101 J/m, almost four times that of PLA, with only 10 wt% of PBAT-g-GMA (2.8) added. In particular, the impact strength of the PLA/PBAT blends is 961 J/m at a PBAT-g-GMA (2.83) content of 40 wt%, which is approximately 35 times that of PLA (27.2 J/m). These findings suggest that the grafting rate of GMA plays a significant role in the toughening effect.\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e(b) and 7(c) show the trend of changes in the tensile properties of the blend. It can be seen from this that the improvement of toughness in blends is based on sacrificing their strength and rigidity, as the presence of elastomers makes it easier for the molecular chains of the blend to slide. The three blends exhibit a progressive reduction in yield strength and tensile modulus as the increase of PBAT content, but the degree of decrease is not the same, which is still related to the interface effect between them. Due to the poor interfacial compatibility of PPT series blends, when the PBAT content is too low, the external force on the PLA matrix is unable to effectively propagate to the PBAT dispersion, and the PLA masks the presence of the flexible PBAT, resulting in a diminished decrease in yield strength and tensile modulus when compared to PPG (1.64) and PPG (2.83). However, when the PBAT content reaches a critical value (approximately 30wt%), numerous non-uniformly dispersed elastomeric PBAT phase particles will significantly disrupt the internal stress-bearing structure of the PLA matrix, leading to a higher decrease in yield strength and elastic modulus compared to both others. In contrast, due to the excellent compatibility of PPG (2.83) series blends, even at low PBAT content, the external forces exerted on PLA can effectively propagate to PBAT. In high PBAT content, the internal structure of PLA in the blend still maintains a certain degree of integrity, which effectively resists the downward trend of yield strength and elastic modulus. Furthermore, the PPG (1.64) series of blends exhibit a similar regularity and is situated between the first two.\u003c/p\u003e\n \u003cp\u003eThe radar plot (Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e(d)) holistically evaluates the mechanical performance of PLA and its blends. Although the modulus of elasticity of PPG (2.83) is reduced compared to PLA, it remains essentially unchanged in comparison to PPT and PPG (1.64), and the impact strength is significantly enhanced, which further underscores the role of the epoxy compounds in enhancing the compatibility and the mechanical properties of the materials.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\n \u003ch2\u003e3.4 DSC analysis\u003c/h2\u003e\n \u003cp\u003eIt can be discerned from the non-isothermal cooling curve of PLA that there is no discernible crystallization peak feature, indicating that the crystallizability of PLA is poor and that insufficient time is available to enable the growth of a complete spherical crystal structure at the current cooling rate \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e]\u003c/sup\u003e. The crystallization curve of the PLA/PBAT blend system shows a clear PBAT crystallization peak in the range of 50\u0026ndash;80 ℃. With the increase in PBAT-g-GMA addition and GMA grafting rate, the crystallization peak transforms into an indistinct crystallization peak similar to that of the PLA, indicating that the compatibility of the blend system has been improved \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e]\u003c/sup\u003e. Figure \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e(b) presents the second-heating DSC curves of PLA and its blends, while Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e provides complementary numerical data on thermal transitions. In PPT40, the \u003cem\u003eTg\u003c/em\u003e of PLA components is observed to increase, which is related to the uneven distribution and immiscibility of the two components in the blend system. Following the addition of PBAT-GMA, a reduction in \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eg\u003c/em\u003e\u003c/sub\u003e of PLA is evident, predominantly as a consequence of the reaction between the epoxy groups in PBAT-g-GMA and the hydroxyl groups in PLA reduces the hydrogen bonding in the blends and then weakens the interaction between molecular chains \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e]\u003c/sup\u003e. It is worth noting that, although the Tg of PPG40(2.83) (58.83 ℃) is lower than the PLA (60.5 ℃), its Tg is higher than that of PPG40(1.64) (58.32 ℃). This may be connected with the sufficient crosslinking within the blend \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/sup\u003e. Furthermore, as the amount of PBAT or PBAT-g-GMA increases, the \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ecc\u003c/em\u003e\u003c/sub\u003e shifts towards elevated temperatures, rising from 111.4 ℃ to 125.8 ℃, manifesting that the incorporation of PBAT and PBAT-g-GMA impedes the cold crystallization of PLA. This phenomenon may be attributed to the formation of extended chain ends or branches between PLA and PBAT, which act as additional nucleation sites, impeding the cold crystallization process and decelerating the rate of cold crystallization of PLA, but which provide a good breeding ground for PLA crystallization \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e]\u003c/sup\u003e. With regard to the melting peaks, the blend systems exhibit a tendency towards lower temperatures following the incorporation of PBAT or PBAT-g-GMA. Moreover, as shown in Table 4, the Xc of the PPG40 (2.83) demonstrates a notable increase to 6.33%, suggesting that the grafted components serve as nucleating agents, effectively improving the crystallization capability of the blend system \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\u0026nbsp;\u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eDSC analysis characteristic data of PLA and PLA/PBAT blends\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003e(℃)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003ecc\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003e(℃)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003e(℃)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varDelta\\:{H}_{CC}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003e(J/g)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varDelta\\:{H}_{m}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003e(J/g)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eX\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\text{(}\\text{\\%}\\text{)}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePLA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e111.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e159.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e9.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e12.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.63\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG20(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e125.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e153.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e23.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.40\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e61.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e129.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e154.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e15.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.64\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG40(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e58.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e132.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e153.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e9.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e6.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG40(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e58.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e125.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e152.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e12.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e15.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e6.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003eNote: \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eg\u003c/em\u003e\u003c/sub\u003e is the glass transition temperature; \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ecc\u003c/em\u003e\u003c/sub\u003e is the cold crystallization temperature; \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e is the melting temperature; \u003cem\u003e∆H\u003c/em\u003e\u003csub\u003e\u003cem\u003ecc\u003c/em\u003e\u003c/sub\u003e is the enthalpy of cold crystallization; \u003cem\u003e∆H\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e is the enthalpy of melting; \u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e represents crystallinity.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e\n \u003ch2\u003e3.4 Thermogravimetric analysis\u003c/h2\u003e\n \u003cp\u003eThe Thermogravimetric test results are shown in Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e, and the main characteristic temperatures of the TGA for blends are summarized in Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e. As depicted in Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003ea, PLA undergoes a one-step thermal degradation process, with PLA reaching its initial decomposition temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003eonset\u003c/sub\u003e) at 333.2\u0026deg;C and almost no residue at 392.3\u0026deg;C. PBAT has a longer chain segment and aromatic structure, and its thermal stability is better than that of PLA. However, with the addition of PBAT, both PLA/PBAT and PLA/PBAT-g-GMA blends showed a decrease in the \u003cem\u003eT\u003c/em\u003e\u003csub\u003eonset\u003c/sub\u003e values. This may be due to the presence of PBAT, which enhances the ester exchange reaction within PLA, catalyzing to some extent the thermal degradation reaction of the blend \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e]\u003c/sup\u003e. In addition, GMA also has a certain negative impact on the \u003cem\u003eT\u003c/em\u003e\u003csub\u003eonset\u003c/sub\u003e of PLA/PBAT, which may be due to the chemical interaction between the chain end of PLA and the PBAT-g-GMA molecular chain, forming the copolymer PLA-g-PBAT, which decomposes first due to its poor thermal stability \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e]\u003c/sup\u003e. In Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e(b), it can be observed that all PLA/PBAT blends exhibit two thermal degradation steps. The more PBAT content is added, the higher \u003cem\u003eT\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e of the first step of the PLA/PBAT blend, and the degradation trend at this temperature gradually decreases. This indicates that for PLA/PBAT blend systems, under the same conditions, increasing the number of PBATs with good thermal properties is indeed beneficial for improving the thermal stability of the material. In the second step of thermal degradation, it may be mainly the thermal degradation reaction of PBAT itself, so the content of PBAT and GMA has less impact on the thermal stability of the blend at this stage.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\u0026nbsp;\u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eThermogravimetric data of PLA/PBAT blends\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003eonset\u003c/sub\u003e (℃)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003e50%\u003c/sub\u003e (℃)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003efinal\u003c/sub\u003e (℃)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e (℃)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eStep1\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eStep2\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePLA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e333.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e361.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e392.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e364.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG20(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e319.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e353.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e488.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e351.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e401.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPT40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e315.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e364.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e494.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e355.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e401.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG40(1.64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e306.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e370.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e507.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e362.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e401.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePPG40(2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e306.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e365.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e509.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e359.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e400.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\"\u003eNote: \u003cem\u003eT\u003c/em\u003e\u003csub\u003eonset\u003c/sub\u003e is the temperature at which the sample loses 5% of its mass, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e50%\u003c/sub\u003e is the temperature at which the sample loses 50% of its mass, and \u003cem\u003eT\u003c/em\u003e\u003csub\u003efinal\u003c/sub\u003e is the temperature at which the sample loses 95% of its mass, \u003cem\u003eT\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e is the temperature at which the sample has the maximum weight loss rate.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec21\" class=\"Section2\"\u003e\n \u003ch2\u003e3.5 Rheological properties analysis\u003c/h2\u003e\n \u003cp\u003eFrom Fig. \u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e(a), the shear thinning behavior of PLA and PLA/PBAT blends can be clearly observed. Compared with PLA, the complex viscosity (\u0026eta;*) of PLA blends decreases significantly with increasing shear rate. Meanwhile, the \u0026eta;* of PLA blends gradually increases with higher PBAT content. After adding 20 wt% PBAT, the complex viscosity of PPT20 at 1 rad/s increases from 2364.68 Pa\u0026middot;s to 14196 Pa\u0026middot;s, a nearly 500% enhancement. Furthermore, mechanical properties analysis has indicated that when the content of PBAT reaches a critical value (approximately 30 wt%), the morphology of the PLA/PBAT blend system may undergo a transformation, resulting in a reversal of complex viscosity trend. This is consistent with the fact that PPT40 in this study has lower complex viscosity than PPT20. The complex viscosity evolution critically relates to on PBAT dispersion in PLA: uniform distribution enhances viscosity through strong interfacial interactions and entanglement networks, while exceeding PBAT induces phase separation and viscosity reduction due to weakened interfacial effects. The incorporation of GMA into the PLA/PBAT blend system facilitates the formation of branched or micro-crosslinked structures at the polymer interfaces, which enhances the dispersion of the PBAT phase, increases intermolecular chain entanglement, and consequently elevates the viscosity of blends \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e48\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eAs shown in Fig. \u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e(b), the storage modulus (G\u0026apos;) of all samples increases with angular frequency. This behavior arises because the crosslinking between PLA and PBAT (or PBAT-g-GMA) causes a reversal in the relaxation and deformation rates of molecular chains within the blend system. At higher angular frequency, the disentanglement rate of molecular chains cannot keep pace with the entanglement rate, leading to a continuous increase in G\u0026apos; \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e49\u003c/span\u003e]\u003c/sup\u003e. Notably, while the flexible chains of PBAT can enhance the entanglement density of the blend system to some extent, the maximum entanglement density is achieved at an optimal PBAT content. Without GMA compatibilization, further increases in PBAT content actually reduce the system\u0026apos;s entanglement density. This explains why PPT20 exhibits a higher G\u0026apos; than PPT40. For the PPG blend series, ring-opening reactions between GMA and PLA terminal groups strengthen PLA/PBAT interactions, resulting in higher G\u0026apos;. Figure \u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e(c) demonstrates that the loss modulus (G\u0026apos;\u0026apos;) of PLA and PLA blends increases progressively with testing frequency. In the low-frequency region, the G\u0026apos;\u0026apos; of the blends exhibits a trend similar to that of G\u0026apos;, which can be explained by the following mechanism: Higher crosslinking density within the blends reduces the free volume between molecular chains, thereby increasing the resistance to chain motion. The sliding of polymer chains results in greater energy dissipation, which is manifested as enhanced G\u0026apos;\u0026apos; values \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e50\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec22\" class=\"Section2\"\u003e\n \u003ch2\u003e3.7 XRD analysis\u003c/h2\u003e\n \u003cp\u003eIn order to gain further insight into the crystal structure and changes in the blend system, X-ray diffraction tests were conducted on PLA/PBAT blends. Figure \u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003e illustrates the relationship between crystal diffraction intensity and the scanning range of the PLA/PBAT blend. It can be observed that PLA did not exhibit diffraction peak patterns that were particularly pronounced within the testing range of XRD. This is due to the fact that PLA belongs to amorphous crystals with a relatively low degree of crystallization, resulting in a relatively flat diffraction peak pattern within the range of 15\u0026ndash;25\u0026deg;. The incorporation of PBAT as a toughening agent to PLA resulted in no significant shifts in diffraction peak positions or pattern variations, confirming that the crystalline architecture of PLA remained unaltered during blending.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec23\" class=\"Section2\"\u003e\n \u003ch2\u003e3.7 Microscopic morphology analysis\u003c/h2\u003e\n \u003cp\u003eAs depicted in Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e(a), the impact fracture plane of PLA is smooth and devoid of discernible features, indicative of a low toughness brittle failure mode. The coarsened structure of PLA matrix deformation can be clearly found in Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e(b) and Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e(d), which indicates that the blended system, due to the presence of the elastomer PBAT, is subjected to stress, a small amount of shear yielding and plastic deformation has already occurred within the material, and the brittle fracture of PLA gradually evolves to ductile fracture. In addition, larger-sized and non-uniformly distributed PBAT particles can be seen on the surface of the PLA body, where a clear gap also appears around the PBAT particles, which is an interfacial debonding of the two-phase separation presented by the PLA/PBAT incompatible system \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e51\u003c/span\u003e]\u003c/sup\u003e. However, when PBAT was grafted with compatibilizer GMA, a compatibilization reaction occurred between PBAT-g-GMA and PLA. This resulted in a decrease in the dispersed particle size of PBAT, an increase in the distribution uniformity, and a reduction in the phase gap between PLA and PBAT. Consequently, the boundary between the two phases became increasingly blurred, as illustrated in Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e(c), Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e(e), and Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e(f), PBAT phase is difficult to distinguish from PLA matrix. Compared with PPG20 (2.83), the phase interface of PPG40 (1.64) and PPG40 (2.83) can form more stress concentration points, which is equivalent to more \u0026quot;nuclei\u0026quot; producing crazing. Upon impact, a significant amount of micro-mechanical deformation of the matrix results in the loss of greater fracture energy, which is consistent with the rough structure observed in the SEM images Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e(e) and Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e(f). PPG40(2.83) has better toughness than PPG40(1.64) because the higher the content of GMA, the smaller and more uniform the particle size distribution of PBAT. In Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e(e), larger plastic deformation bodies can still be observed, and their sizes are also uneven, while in Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e(f), the deformation bodies are smaller and relatively uniform in size.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4 Conclusion","content":"\u003cp\u003eIn this study, a series of PLA/PBAT blends are prepared by melt blending using an in-situ compatibilization strategy, and the effects of PBAT content and GMA grafting rate on the compatibility, microstructure, crystalline behavior, thermal stability, rheological properties and mechanical properties of the system were investigated. The conclusion is as follows:\u003c/p\u003e \u003cp\u003eFTIR analysis shows that GMA compatibilizer has been successfully grafted onto the PBAT molecular chain. In addition, during the blending process of PLA and PBAT-g-GMA, the epoxy groups on GMA react with the end groups of PLA.\u003c/p\u003e \u003cp\u003eMechanical properties analysis indicates that the increase of PBAT content and GMA grafting rate, the impact strength of blends is significantly improved. In particular, the addition of 40 weight% PBAT-g-GMA (2.83) results in the impact strength of 961 J/m for the PLA/PBAT blend, which is approximately 35 times that of PLA.\u003c/p\u003e \u003cp\u003eCrystallization performance implies that the presence of PBAT-g-GMA reduces the cold crystallization rate of PLA, changes the crystallization environment of PLA, increases crystallinity, but does not alter the crystalline structure.\u003c/p\u003e \u003cp\u003eRheological tests demonstrated that the storage modulus, loss modulus and complex viscosity exhibited a substantial increase with rising PBAT content and GMA grafting rate, which improves the processability of the blends.\u003c/p\u003e \u003cp\u003eFrom the SEM images, the improvement in toughness of PLA/PBAT blends can be attributed to the plastic deformation of PBAT in the matrix and the enhancement of interfacial bonding between polymers.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eNotes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing financial interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Declaration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work is financially supported by the Project of Jilin Provincial Department of Science and Technology (20240301030GX) and Changchun Universities and Institutes Pilot Selection Project (24GXYSZZ41).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study were available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCredit Author Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eYunda Shen: Conceptualization, Methodology, Validation, Formal analysis, Data Curation, Writing-Original Draft, Investigation, Writing-Review \u0026amp; Editing\u003c/p\u003e\n\u003cp\u003eBingrui Jin: Data Curation, Investigation\u003c/p\u003e\n\u003cp\u003eHongnian Gan: Validation, Formal analysis\u003c/p\u003e\n\u003cp\u003eJiankun Li: Investigation, Validation\u003c/p\u003e\n\u003cp\u003eDan Zhao: Data Curation, Formal analysis\u003c/p\u003e\n\u003cp\u003eHuizhong Shen: Conceptualization, Methodology, Investigation\u003c/p\u003e\n\u003cp\u003eLiang Ren: Methodology, Validation, Data Curation, Funding acquisition, Project administration, Writing-Original Draft, Writing-Review \u0026amp; Editing, Resources, Supervision\u003c/p\u003e\n\u003cp\u003eMingyao Zhang: Conceptualization, Methodology, Formal analysis, Writing-Review \u0026amp; Editing, Resources, Supervision, Project administration, Funding acquisition\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eZhang JP, Zhong W, Chen N, et al. 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Preparation and Properties of Toughened PLA/PBAT Blends Based on EVA and Multi-Functional Epoxy Chain Extender. Journal of Applied Polymer Science, 2025, DOI: 10.1002/app.56857.\u003c/li\u003e\n\u003cli\u003eXu J, Zhang PB, Fan MM, et al. Silane-modified MOF-5 as a compatibilizer for PBAT/PLA blends: Enhancement of mechanical properties, antimicrobial properties, and water barrier properties. Polymer, 2024, DOI: 10.1016/j.polymer.2024.127875.\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":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"polylactic acid (PLA), poly (butylene adipate-co-terephthalate) (PBAT), glycidyl methacrylate (GMA), grafting rate","lastPublishedDoi":"10.21203/rs.3.rs-6564026/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6564026/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eSynergistically integrating poly(butylene adipate-co-terephthalate (PBAT) with polylactic acid (PLA) presents an economical strategy to develop biodegradable materials by leveraging their complementary characteristics. However, the inherent phase incompatibility between PBAT and induces severe interfacial defects, fundamentally limiting the development of high-strength biodegradable composites. In this study, glycidyl methacrylate (GMA) is grafted onto PBAT through reactive blending during the melting process, whereupon PLA/PBAT-g-GMA blends are prepared by means of an in-situ compatibilization approach, in an attempt to achieve PLA/PBAT blends with satisfactory comprehensive properties. The effects of PBAT content and GMA grafting rate on the interfacial compatibility, microstructure, mechanical properties, thermal performance, crystalline behavior and rheological processability of PLA/PBT blends are investigated in detail. Systematic research has shown that the compatibility of PLA/PBAT blends has been significantly improved by implementing reactive compatibilization methods, and when the PBAT-g-GMA (2.84) content is 40%, the impact strength of the blend can reach 961 J/m without affecting rigidity, which indicates that our work proposes an effective approach to fabricate high-performance PLA/PBAT blends through simple, environmentally friendly, and low-cost processing methods. Furthermore, the crystallization performance of the PLA/PBAT blend has been enhanced, while its thermal performance remains unaffected. The rheological analysis shows that the storage modulus, loss modulus, and complex viscosity significantly increase with the increase of PBAT content and GMA grafting rate, which improves processing performance of blends. SEM shows that as the grafting rate of GMA increases, the particle size distribution of PBAT becomes smaller and more uniform.\u003c/p\u003e","manuscriptTitle":"Fully Biodegradable Poly (lactic acid)/Poly (butylene adipate-co-terephthalate) Blends with highly toughness Based on in situ Interfacial Compatibilization by functional epoxy compound","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-19 12:55:52","doi":"10.21203/rs.3.rs-6564026/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-05-15T08:03:27+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-05-15T07:58:01+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Journal of Polymer Research","date":"2025-05-05T20:04:59+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-05T09:16:08+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Polymer Research","date":"2025-05-02T00:27:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"3394b2af-c0c2-4402-bc70-3b250aef0ce6","owner":[],"postedDate":"May 19th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-09-15T16:02:29+00:00","versionOfRecord":{"articleIdentity":"rs-6564026","link":"https://doi.org/10.1007/s10965-025-04571-1","journal":{"identity":"journal-of-polymer-research","isVorOnly":false,"title":"Journal of Polymer Research"},"publishedOn":"2025-09-11 15:56:54","publishedOnDateReadable":"September 11th, 2025"},"versionCreatedAt":"2025-05-19 12:55:52","video":"","vorDoi":"10.1007/s10965-025-04571-1","vorDoiUrl":"https://doi.org/10.1007/s10965-025-04571-1","workflowStages":[]},"version":"v1","identity":"rs-6564026","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6564026","identity":"rs-6564026","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}