Degradability of radiation crosslinked PCL in the supercooled state under various environments

Biodegradability in soil and in activated sludge as well as chemical degrad ation by methylamine solution of gamma-irradiated poly(epsilon-caprolactone ) in the supercooled state (PCL) has been investigated. Biodegradation in s oil burial resulted in almost equivalent rate for unirradiated PCL and irra diated PCL at 160 kGy (containing 80% of gel). After 6 months, about 60% we ight losses were achieved. Aerobic biodegradation using activated sludge fo r PCL irradiated at 160 kGy shows higher degradation rate compared to unirr adiated one. Chemical degradation of PCL was car-led out using aqueous meth ylamine 40% at 35 degrees C. The results reveal that crosslinked PCL (80% o f gel) has higher degradation rate compared to uncrosslinked one. These are due to crosslinked PCL having smaller crystallites size, which were formed during cooling after molding process and shorter molecular chain formed du ring irradiation. For soil burial test, since controlling of microbiall pop ulations and environment changes by season are difficult, effect of morphol ogy on degradation did not appear clearly. From these findings, it is concl uded that biodegradation easily occurs even for PCL introduced crosslinking structure by irradiation. (C) 1999 Elsevier Science Ltd. All rights reserv ed.