An Investigation of Poly(lactic acid) Degradation

Abstract

To elucidate the degradation mechanism of poly(lactic acid), the decrease in the intrinsic viscosity of poly(D,L-lactide) in a homogeneous water/ acetone solution was investigated. The hydrolysis of poly(D,L-lactic acid) in water/acetone solution can be catalyzed by protons. The molecular weight degradation of solid poly(D,L-lactic acid) in water was primarily affected by the degree of polymer purity. Polymerization conditions such as initiator concen tration, temperature and time did not have an obvious effect on the molecular weight degradation. In the case of polymer samples with low purity (i.e., directly polymerized or containing solvent or oligomer), degradation was ini tially very rapid. On the other hand, initial degradation of purified polymer was very slow before accelerating.