Morphology and Properties of Polylactide and Polycarbonate Green Blends

摘要

The renewability of polylactide (PLA) is highly valued in terms of energy and carbon savings. The biodegradability of PLA, however, has limited its use toward the disposable applications, such as agriculture and food packaging. To apply PLA in other fields with long term purposes, one needs to overcome not only the biodegradable nature, but also its brittleness and softening problem at temperature higher than 60 °C. One way to resolve these problems is to generate PLA composites with another non-biodegradable ingredient. In this work, PLA was melt-blended with polycarbonate (PC) modified with high molecular weight bisphenol A type modifier. Both the mechanical properties and the thermal properties were investigated. The blends showed two distinct glass transition behaviors. Glass transition temperatures of the PLA phase were literally not changed. On the other hand, the glass transition temperature of the PC phase moved toward T_g of PLA with the addition of the modifiers, suggesting some degree of interactions. Microscopic observations revealed non-uniformly dispersed PC inclusions in the PLA matrix, confirming that phase separation has occurred.