Abstract
We investigated primary biodegradability of Poly Lactic Acid (PLA) using PLA hydrolysis tests under various composting temperatures and pHs.
Under the pH range used in this study, higher test temperatures accelerated primary biodegradation by hydrolysis, and there was a marked reduction in molecular weight. However, in the range of pH 6.0-8.0 there was little effect of pH on both molecular weight reduction and weight reduction. Under more alkaline conditions, i.e., at pH 9.0, a marked reduction in molecular weight and weight loss were observed. Examination of test sample cross sections showed that PLA hydrolysis started from their outer surface.
From these findings, we conclude that dynamic temperatures and pH changes in the composting process promote primary biodegradation of PLA, enabling complete biodegradation. This demonstrates the concept that composting is a useful method for degradation.
