Degradation in soil behavior of artificially aged polyethylene films with pro-oxidants

Bio-based, biodegradable in soil, as well as degradable polyethylene mulching films with pro-oxidants, have been introduced in the market in an effort to deal with the serious problem of managing plastic waste streams generated from conventional mulching films. In a previous experimental investigation, a series of naturally degraded under water melon cultivation conditions linear low density polyethylene (LLDPE) mulching films with pro-oxidants, buried in the field for 8.5 years, were recovered intact even though undergoing a continuous slow abiotic degradation in soil. The aim of the present article was to simulate the behavior of the LLDPE mulching films with pro-oxidants under a much longer time-scale (e.g. some decades). Toward this purpose, samples of LLDPE with pro-oxidants film were artificially degraded to simulate severe degradation/fragmentation of these films while been buried in the soil for many years, following the end of the cultivation season. Further degradation of these severely degraded samples was investigated by burying them in the soil over a period of seven years. During this burial period, all degradation parameters and their evolution with time were measured. The artificially degraded LLDPE film samples with pro-oxidants, in contrast to the naturally degraded film that remained intact for 8.5 years, were gradually transformed into tiny micro-fragments in the soil. These fragments, through a continuing abiotic degradation process under natural soil conditions are eventually transformed into invisible micro-fragments. The fate of these micro-fragments and their long-term impact to the environment and human health is unpredictable. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42289.