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Biodegradation of thermally oxidized polyethylene

par Weiland, Michèle ;Daro, Arlette ;David, Christiane
Référence Polymer degradation and stability, 48, 2, page (275-289)
Publication Publié, 1995

Article révisé par les pairs

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Résumé :

The biodegradability of thermally oxidized polyethylene (PE) has been studied in various conditions: (1) on solid agar in the presence of a suspension of mixed spores of four fungi (Aspergillus niger, Penicillium funiculosum, Paecilomyces variotii and Gliocladium virens); (2) in three composting units differing in temperature, moisture content and the nature of the composted materials; and (3) in liquid medium (respirometric flasks) in the presence of three Streptomyces strains (badius, setonii, viridosporus) or of a suspension of microorganisms from compost. Qualitative evidence of bioassimilation of the oxidized PE films was obtained with fungi and in composts. Coverage of the film surface by fungi increases as the molecular weight of the PE is decreased and attains 60% when the initial Mn lies between 1500 and 600. With fungi and in compost, important surface erosion was detected by SEM for samples with initial Mn around 1000. Important changes were also observed by FTIR, DSC and GPC. This last method revealed in all cases the formation of a high molecular weight fraction that was not present before incubation with microorganisms and a shift of the whole curve toward higher molecular weight. This is evidence of chain condensation probably due to purely thermal reaction at the low partial pressure of O2 prevailing in the industrial composting units used in this work. It is probably accompanied by bioassimilation of the low molecular weight fraction. Quantitative information can be obtained by a respirometric method. For incubations performed in liquid medium in the presence of a suspension of microorganisms from compost, biodegradation was important when substrate concentration was very low (≈ 0.006%). Despite the presence of unavoidable large errors in these conditions, oxygen uptake was evident and biodegradation of the low molecular weight fraction of the sample was clearly demonstrated. © 1995.