Startch-graft-(VAc-co-MMA) copolymer was synthesized by graft copolymeri-zation of starch with VAc and MMA using Ce(Ⅳ) salt as initiator and water as reaction medium. 1H NMR technique was employed to study the composition of the graft chain

poly(VAc-co-MMA).The results show that the composition of the two monomer units in the graft chain varies slightly with the variation of the mole ratio of MMA to VAc in the feed.The mole ratio of the two monomer units in the copolymer is nearly 1.X-ray diffraction measurement indicates that the crystal structure of starch was greatly destroyed after graft copolymerization. The biodegradation behavior of the starch graft copolymer and the graft chain were investigated through enzyme attack in the laboratory and outaoor soil burial. In the laboratory

at 37℃

in the presence of bacillus subtilis

the grafted starch demonstrated arapid biodegradation rate.The weight loss was 15% after one day and reached a maximum of 66% after 25 days.This value is very close to the starch content(67%) in the specimen.The biodegradation at room temperature was also studied. The results show that at room temperature

the biodegradation rate is a little lower than that at 37℃.Further study indicates that the biodegradation originated from starch

the graft hain nearly unaffected by the bacillus subtitilis.After20 days outdoor soil burial in summer

the weight loss was 42%

demonstrated a nedrlly equal degradation rate compared with enzyme degradation in the laboratory at room temperature (that is 44% after 20days).