THERMAL DEGRADATION AND THERMAL-MECHANICAL PROPERTIES OF POLY(LACTIC ACID) AND ITS BLEND WITH WHEAT STARCH

摘要

This study reports the thermalgravimetric profile, thermal endurance, and evaluates the thermal and mechanical properties of PLA, PLA/starch, and PLA/starch/MDI (methylenediphenyl diisocyanate) composites. The samples were extruded in a twin-screw extruder and hot-press molded in bone shape. For the thermal degradation study, the samples were stored for 2 days at 25°C/50% RH prior tests. Thermal-mechanical properties of the composites were determined on samples stored from 2 days at 25°C/90% RH. The presence of MDI into the PLA/starch composite did not affect the thermal decomposition profile. PLA showed the highest Arrhenius activation energy and longest thermal endurance of all samples. PLA/starch composite with MDI showed higher Arrhenius activation energy and longer thermal endurance than that without MDI. PLA/starch/MDI composite presented similar mechanical properties of PLA. The absence of MDI was noticed by weak properties of PLA/starch composites.