聚乳酸/聚己二酸二甘醇酯/甲基丙烯酸甲酯-丁二烯-苯乙烯共聚物生物降解薄膜的制备及性能

采用甲基丙烯酸甲酯-丁二烯-苯乙烯共聚物(MBS)对聚乳酸(PLA)进行增韧改性,增韧后的PLA再与增塑剂聚己二酸二甘醇酯(PDEGA)熔融共混挤出并吹膜。将PDEGA的质量分数固定为8%,改变PLA和MBS的比例,探讨了不同含量的MBS对PLA/PDEGA/MBS薄膜力学性能、光学性能、流变性能以及结晶性能的影响,用扫描电镜观察薄膜撕裂断面形态,用偏光显微镜观察PLA的结晶形貌。结果表明,加入PDEGA后,薄膜的Tg下降了近8℃,Tcc下降了约17℃;随着MBS的不断加入,拉伸强度、撕裂强度分别在25MPa和120kN/m以上,PLA薄膜的断裂伸长率由PLA的3.5%提高到薄膜的40%以上,薄膜的模量、黏度都有所增加;随着MBS含量的增加,PLA球晶的边界逐渐变得模糊,球晶数量增加,球晶尺寸明显变小,但PLA的结晶类型没有改变;薄膜保持了良好的透明性和降解性。

Preparation and Properties of Biodegradable Polylactide/Polydiethylene Glycol Adipate/Methyl Methacrylate-Butadiene-Styrene Blown Films

Polylactide(PLA)was first toughened with methyl methacrylate-butadiene-styrene(MBS)copolymer,then the toughened PLA was further blended with polydiethylene glycol adipate(PDEGA)using a twin-screw extruder.Finally,the extruded samples were blown by blown film technique.The mass fraction of PDEGA was fixed to 8%,and the ratio of PLA and MBS was changed.Mechanical properties,optical properties and rheological properties were studied,the fracture morphology of the film was observed by SEM,and the crystalline morphology of PLA was observed by POM.The results show that Tgof PLA is decreased by nearly 8℃,and Tccof PLA is decreased about 17℃.With the continuous addition of MBS,the tensile strength is above 25MPa,tear strength is above 120kN/m,the elongation at break of PLA film is increased from 3.5%(pure PLA)to 40%,the modulus and viscosity also increase.With the increase of MBS content,the boundary of PLA spherulites gradually becomes blurred,the number of spherulites are increased,the spherulite size decreases obviously.The addition of PDEGA and MBS does not change crystallization types of the PLA matrix.The PLA/PDEGA/MBS films maintain good transparency and degradability.