Aerobic biodegradation of calcium carbonate filled polyethylene film containing pro-oxidant additives

Two low density polyethylene films, which contained pro-oxidant additives, where investigated, one of them containing micro-milled calcium carbonate filler. Both materials were subjected to controlled thermal oxidation, the oxidation was obviously retarded in the filler-containing sample. Following this, the biodegradability of samples pre-oxidized for 40 and 80 days was investigated. The levels of carbon mineralization reached 13% and 16% for the 40 and 80 days pre-oxidized polyethylene containing filler, respectively, after approximately 16 months in a soil environment at 25 °C, and both types of sample were mineralized to about 19% in compost environment at 58 °C during the same period. The sample not containing filler was mineralized to about 7% in soil after 13 months, and about 23%, after 8 months in compost. Scanning electron microscopy revealed dense colonization of the sample surfaces in both soil and compost. The data presented here provide clear quantitative evidence that part of the polyethylene material was biodegraded.