| Budget Amount *help |
¥10,800,000 (Direct Cost: ¥10,800,000)
Fiscal Year 2002: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2001: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2000: ¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1999: ¥4,100,000 (Direct Cost: ¥4,100,000)
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| Research Abstract |
Biodegradation properties of six kinds of biodegradable plastics (thickness, 3mm ) for a dumb-bell shape of injection molding were investigated in soil, river water, seawater, and activated sludge, or exposed to the air. The changes in weight, tensile strength and the surface of materials with a scanning electron microscopie before/after biodegradation were measured and observed. The number of microbial synthesized polyester-degrading microorganisms in different environments was estimated by a film-MPN method, and FT-IR spectra were also measured for degradation mechanism. Results showed microbial or chemical synthesized polyester and the polymeric alloy containing starch, modified polyvinyl alcohol (PVA) and polycaprolactone (PCL) possessed high biodegradability in farm soil, in river water or in seawater. Furthermore, results showed that microbial or chemical synthesized polyester and polyestercarbonate (PEC) possessed high biodegradability in the activated sludge. However, the weight losing of poly(lactic acid) (PLA) was not found in any environments. Biodegradability of biodegradable polymer related to numbers of degrading microorganisms in soils in different region, but in different kinds of environments, such as in soil, in river water or in activated sludge, the biodegradability of biodegradable polymer did not relate to numbers of degrading microorganisms. From the FT-IR spectra of microbial sybthesized polyester before/after biodegradation, it was presumed that the ester bonds were cleaved with the progress of decomposition. As for the polymeric alloy of starch, PVA, PCL, it was presumed that starch was decomposed at an early stage.
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