1996 Volume 1996 Issue 10 Pages 853-860
Our previous studies have elucidated that the degradation of low density polyethylene (LDPE) in the soil proceeds synergistically by usual oxidative degradation and by enzymatic oxidative degradation. Thus it was expected that the addition of oxidizing agents which may be called as the biodegradation inducing agent, and the improvement of the accessibility of bacteria by the surface treatment of LDPE such as UV irradiation, promote the bio-degradation of LDPE. We examined the additive effect of several biodegradation inducing agents to LDPE and the degradation of the polymer in bioactive coppice soil for 12 months. Following results have been obtained: 1, The addition of vegetable oil promoted the degradation of LDPE, and the effect was more pronounced for the oxidized oil; 2, The addition of metal carboxylate such as iron stearate (II) also promoted the biodegradation; 3, UV irradiation was very effective for the bio-degradation of LDPE, and a number of hyphae which probably grew on the polymer substrate were recognized by SEM observation. The addition of a small amount of dicumyl peroxide (DCP, bis (α, α-dimethylbenzyl) peroxide) or UV irradiation was found to be very effective for the biodegradation.
The same promoting agent was compounded in ethylene-vinyl acetate copolymer (EVA). The biodegradation of EVA based sample was faster than that of LDPE based sample. We have developed the protection sheet for river dredging. The field test was carried out at Ishikari river in Hokkaido, Japan and was continued now. This is probably the first case that the bio-degradable sheet is successfully used for civil engineering.
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