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

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.