柠檬酸基聚酯/聚乳酸共混物的力学性能

通过缩聚反应制备一种可生物降解的柠檬酸基聚酯（PEGCA），采用转矩流变仪将不同反应程度的PEGCA与聚乳酸（PLA）共混，制备出一种可完全生物降解的柠檬酸基聚酯/聚乳酸共混物，考察了共混物的拉伸、冲击和弯曲性能，并采用扫描电子显微镜观察其形貌.结果表明：PEGCA对PLA的增韧效果明显，使得共混物的断裂伸长率可达316%，冲击强度提高了近7倍；在不同的应变速率下，PEGCA/PLA共混物的力学性能不同，增大应变速率，将使共混物的拉伸强度提高，断裂伸长率降低；不同反应程度的PEGCA在PLA基体中的分散性不同，低反应程度的PEGCA的分散性较差，其共混物在较高变形速率下表现出更优异的韧性和延展性.

Mechanical Properties of Biodegradable Citric Acid-Based Polyester/Polylactide Blends

A biodegradable citric acid-based polyester (PEGCA) was synthesized by direct copolycondensation. The full biodegradable blends of PLA and PEGCA with different reaction degrees were made by using a torque rheometer. The tensile, impact and flexural properties were investigated and the morphologies of blends were assessed by scanning electron microscopy. The result shows that the PEGCA effectively improves the toughness of the blends. The elongation at break of the blends reaches 316% and the impact strength is also increased by 7 times. The tensile properties of PEGCA/PLA blends differ under different strain rate. The higher the strain rate is, the higher the tensile strength and the lower the elongation at break becomes. The dispersion of PEGCA with different reaction degrees in PLA affects the mechanical properties of the blends. The reaction degree of PEGCA affects the dispersion of PEGCA in PLA matrix. The PEGCA with low reaction degree shows relatively small dispersed phases in PLA matrix and its blend shows a better toughness and drawability under high strain rate.