Abstract: Polysilsesquioxane microspheres (PSQs) with six different functional groups, methyl, thiopropyl, epoxy, vinyl, aminopropyl, and methacryloxypropyl, was synthesized, which was introduced into polylactic acid (PLA) separately through melt processing, with the concentration of PSQs kept at 2 %. It was found that the PSQs could effectively improve the melt flow behavior of PLA. Poly(epoxypropoxy)silsesquioxane (PESQ) possessed the highest reactivity with PLA in the six PSQs. It rendered PLA matrix the smallest melt flow rate, 6.0 g/10min, which contrasted to 14.1 g/10 min of neat PLA. The molecular weight of PLA could be extended to 1.7 folds larger. Thermal decomposition temperature of 5 % weightlost increased by 8 ℃, and thus could inhibit PLA degradation in processing for 35 min. In addition, PESQ could also increase the toughness of PLA matrix, with impact strength increased by one fold.

Key words: poly(lactic acid), melt flow, polysilsesquioxane microsphere, functional group