适于微成型加工的聚乳酸／聚甲醛共混物流变行为研究

Study on Rheological Behaviors of Polylactic Acid/Polyoxymethylene Blends Suitable for Micro-Injection Molding Process

将聚甲醛(POM)与聚乳酸(PLA)熔融共混,制备了PLA/POM复合材料。POM的引入明显改善了PLA的熔融加工性能,有利于PLA微成型加工。采用熔体流动速率仪、高压毛细管流变仪和动态流变仪研究了PLA、POM及PLA/POM共混物的流变行为。结果表明:随着POM含量的增加,PLA/POM共混物的熔体流动速率亦增加;PLA、POM和PLA/POM共混物熔体具有假塑性流动特征,是非牛顿流体。随POM含量的增加,PLA/POM共混体系的剪切黏度降低,且剪切敏感指数减小,非牛顿指数升高。PLA、POM及PLA/POM共混物都具有类黏弹性,其黏弹行为均以黏性为主。此外,相对PLA,POM的加入降低了PLA/POM共混体系的复数黏度、动态储能模量和动态损耗模量,但提高了力学损耗。

Polylactic acid/polyoxymethylene composite was prepared by blending polyiactic acid （PLA） with a certain amount of polyoxymethelene （POM）. The melt processing performance of PLA was improved with the addition of POM, which was good for micro-injection process of PLA. The rheological behaviors of PLA, POM and PLAJPOM blends were systematically investigated by using melt flow index instrument, capillary rheometer and dynamic rheometer. The results show that the melt flow index of PLA/POM blends increases with the increasing of POM content. PLA, POM and PLA/POM blend melts show the characteristics of pseudoplastic fluid, which is the non-newtonian fluid. The apparent shear viscosity and shear sensitivity index of PLA! POM blends decrease, and the non-newtonian index increases with the increasing of POM content. PLA, POM and PLAJPOM blends are proved to have the viscoelasticity-like properties and the viscous behavior is mainly involved. In addition, compared with pure PLA, the complex viscosity, dynamic storage modulus and dynamic loss modulus of PLAJPOM blend reduce with the addition of POM and the dynamic mechanical loss increases at the same time.