Thermally degradable low-density polyethylene samples containing TDPA(TM) pro-oxidant additives from EPI Inc. were submitted to an investigation aimed at evaluating their ultimate biodegradation (e.g. mineralization) in soil and mature compost incubation media. Respirometric tests aimed at simulating soil burial and composting (mature compost) conditions, were used for testing the potential biodegradability of polyolefins in the environment. An LDPE-TDPA film sample provided by EPI Inc. was also submitted to a thermal oxidative degradation treatment in order to mimic the thermophilic phase of a full scale composting process. Retrieved degradation specimens, their solvent extracts and residues were also tested in soil burial respirometric tests in order to evaluate their potential biodegradability. Original and test samples submitted to biotic environments were characterized by means of spectroscopic analysis. LDPE-TDPA sample replicates undergo biodegradation as mediated by soil microorganisms in respirometric experiments. High mineralization levels were observed, above 60%, comparable to those occurring in the case of several natural polymers in natural environments; the time for biodegradation, though, is relatively longer. However, it is clear from the positive biodegradation profile that biodegradation continues. The degradation process is accompanied by a dramatic change in the structural characteristics of the test samples. To the best of our knowledge, this is the first study clearly indicating the biodegradation and assimilation of a synthetic polyolefin at a substantial level, even though reached at fairly long incubation time. (C) 2003 Elsevier Science Ltd. All rights reserved.
