Biodegradable behavior of polyethylene based plastics by soil burial

Abstract

Biodegradation behavior of commercial plastics including high density polyethylene based plastic (HDPE), low density polyethylene based plastic (LDPE), linear low polyethylene based plastic (LLDPE), and a mixture of HDPE and LLDPE based plastic (OXO), was studied. The degradation test was performed by soil burial for 12 months in controlled condition in the laboratory. The weight change and morphology by visual and microscopic investigation were collected every 3 months. The test was conducted at 28-30 oC and 70-90% RH. All samples showed a significant increase in brittleness and turbidity after 6 months of soil burial. Significant weight loss was observed for OXO sample after just 3 months and continued to decrease even through 12 months, while the majority weight loss for HDPE, LDPE, and LLDPE occurred after 6 months of soil burial. The morphology of the HDPE and OXO samples showed only traces of erosion and large holes after the first 6 months. However, after 12 months, significant surface damage was observed. From these findings, soil burial under controlled temperature and humidity conditions in the laboratory environment may be conducive for microorganism growth that are able to effectively degrade polyethylene based plastic products.