Poly(lactide), PLA, suffers from brittleness and low heat deflection temperature (HDT), which limits its application as an engineering plastic. In this work, poly(L-lactide)/poly(D-lactide)/ethylene-vinyl acetate-glycidyl methacrylate random copolymer (PLLA/PDLA/EVM-GMA = 1/1/x) composites were prepared by melt blending, and the in situ formed EVM-g-PLA copolymers improved the compatibility between PLA and EVM-GMA. Subsequently, the blends were subjected to a two-step annealing process during compression molding, i.e. first annealing at 120 °C to rapidly form a certain amount of stereocomplex (sc) crystallites as nucleation sites, and then annealing at 200 °C to guide the formation of new sc crystallites. Both differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) measurements confirmed the formation of highly stereocomplexed PLA products. Mechanical results showed that the PLLA/PDLA blend with 20 wt% of EVM-GMA had a notched impact strength up to 65 kJ/m² and an elongation at break of 48%, while maintaining a tensile strength of 40 MPa. Meanwhile, dynamic mechanical analysis (DMA) and heat deflection tests showed that the PLA composite had an HDT up to 142 °C which is 90 °C higher than that of normal PLA products. Scanning electron microscopy (SEM) confirmed the fine dispersion of EVM-GMA particles, which facilitated to understand the toughening mechanism. Furthermore, the highly stereocomplexed PLA composites simultaneously exhibited excellent chemical and hydrolysis resistance. Therefore, these fascinating properties may extend the application range of sc-PLA material as an engineering bioplastic.

聚乳酸（PLA）具有脆性和低热变形温度（HDT），这限制了其作为工程塑料的应用。在这项工作中，通过熔融共混制备了聚（L-丙交酯）/聚（D-丙交酯）/乙烯-乙酸乙烯酯-甲基丙烯酸缩水甘油酯无规共聚物（PLLA / PDLA / EVM-GMA = 1/1 / x），并且在原位形成的EVM-g-PLA共聚物改善了PLA与EVM-GMA之间的相容性。随后，共混物在压缩成型过程中经历两步退火过程，即首先在120°C退火以快速形成一定数量的立体络合物（sc）微晶作为成核位点，然后在200°C退火以引导形成新的sc微晶。差示扫描量热法（DSC）和广角X射线衍射（WAXD）测量均证实了高度立体复合的PLA产品的形成。力学结果表明，PLLA / PDLA共混物与20 wt％EVM-GMA的缺口冲击强度高达65 kJ / m ²断裂伸长率为48％，同时保持40MPa的拉伸强度。同时，动态力学分析（DMA）和热变形测试表明，PLA复合材料的HDT高达142°C，比普通PLA产品高90°C。扫描电子显微镜（SEM）证实了EVM-GMA颗粒具有良好的分散性，有助于理解增韧机理。此外，高度立体复杂的PLA复合材料同时具有出色的耐化学性和耐水解性。因此，这些引人入胜的特性可以扩展sc-PLA材料作为工程生物塑料的应用范围。