Evaluation of biodegradability of several biodegradable plastics in natural environments

Abstract

Biodegradation behavior of six kinds of biodegradable plastics injection-molded and having a dumbbell shape was investigated in soil, river water, seawater, and activated sludge, or on soil. The changes in weight, strength and the surface of materials after biodegradation were measured or observed. The number of microbially synthesized polyester-degrading microorganisms in different environments was estimated by a Film-MPN method. The obtained results showed microbially or chemically synthesized polyesters and the polymeric alloy containing starch, modified poly(vinyl alcohol) (PVA) and polycaprolactone (PCL) possessed high biodegradability in farm soil, in river water or in seawater. Furthermore, results showed that microbially or chemically synthesized polyester and poly(ester-carbonate) (PEC) possessed high biodegradability in the activated sludge. However, the weight loss of poly(lactic acid) (PLA) was not found in any environments. Biodegradability of biodegradable polymers related to numbers of degrading microorganisms in the soil environments.