聚乳酸接枝衣康酸及其增容聚乳酸/淀粉共混物的研究

Study on graft copolymerization of polylactic acid with itaconic acid and properties of PLA/starch blends compatibilized by the grafted polymer

以过氧化苯甲酰(BPO)为引发剂,使聚乳酸(PLA)与衣康酸(ITA)进行接枝共聚反应。研究了共聚反应时间、BPO和ITA用量对接枝率的影响,并采用傅里叶变换红外光谱对接枝共聚物(PLA-g-ITA)进行结构分析。同时制备了PLA-g-ITA增容PLA/淀粉共混物,以扫描电子显微镜、万能试验机和接触角仪分别研究了接枝共聚物对PLA/淀粉共混体系相容性、力学性能和耐水性能的影响。结果表明在PLA/ITA/BPO质量比为100∶12∶4、反应时间6 h时,接枝率较高;接枝共聚物PLA-g-ITA的加入改善了聚乳酸与淀粉的相容性,提高了复合材料的力学性能,当PLA/淀粉/PLA-g-ITA(接枝率6.74%)质量比为50∶50∶15时,共混体系的拉伸强度较未添加接枝物的PLA/淀粉共混物提高了45.4%,断裂伸长率提高了69.8%,同时体系的耐水性能还得到显著提高。

The graft copolymerization of itaconic acid(ITA) onto polylactic acid(PLA) is investigated by using BPO as an initiator under various conditions.The influences of the reaction time,BPO and ITA contents on the grafting ratio are studied.The graft copolymerization is monitored by FT-IR.The graft reagent(PLA-g-ITA) is used as the reactive compatibilizer of PLA/starch blends and the influences of the compatibilizer on the compatibility,mechanical properties and water resistance of the blends are discussed by using scanning electron microscopy(SEM),universal testing machine and contact angle measurement.The results show that the graft ratio reaches the highest when the reaction time is 6 hours with the mass ratio of PLA/ITA/BPO as 100∶12∶4.The addition of PLA-g-ITA can improve the compatibility of PLA and starch and the mechanical performances of the blends.When the mass ratio of PLA/starch/PLA-g-ITA(with grafting ratio of 6.74%) is 50∶50∶15,the blend's tensile strength and elongation at break will be increased by 43.3% and 69.8%,respectively.The water resistance of the blends is improved too.