1991 Volume 64 Issue 11 Pages 688-698
Continued from a previous report, the evaluation of lay-in-soil test defined treatment condition carried out for eight months for the biodegradable plastics, LDPE, L-LDPE, HDPE, added starch and other additives. As a result, a lowering of physical property and a little of weight loss were recognized on samples treated in high bioorganismic activity soil. In addition, it was recognized that the added starch and oil reduced and the oil accelerated the degradation of polymer at lay-in-soil treatment. The starch was not directly concerned to polymer degradation, but with oil it accerelated polymer degradation. As a result, increasing of carbonyl groups, lowering of oxidation initiation temperature, change of melting point and so on were observed. At the vigorous degradation parts around the void which was the result of polymer lost, element O suggesting oxidation, S, Fe, Al and S were observed concentrically by surface analysis using EPMA.
