Observations of the effects of different chemical blowing agents on the degradation of poly(lactic acid) foams in simulated soil

Abstract

This work examined the influence of different chemical blowing agents (CBA), one endothermic and one exothermic, at the same concentration (2% by mass), on poly(acid lactic), PLA foams. The CBA was incorporated into the PLA in a single-screw extruder, and the foams were expanded by heating in an electric oven under free pressure conditions. Foam degradation in a simulated soil was performed according to the ASTM G160-03 standard. Changes in the physical-chemical, morphological and mechanical properties were used to evaluate the degradation. The results indicated that the different chemical blowing agents led to different mechanical and morphological properties for the foams, which resulted from the nature and decomposition rate of the blowing agents. Cells in the foams accelerated the degradation since they facilitated the infiltration of water toward the interior of the polymer and triggered the degradation process by hydrolysis.