淀粉-醋酸乙酯-甲基丙烯酸甲酯接枝共聚物的合成及生物降解研究

用硝酸铈铵为引发剂，合成了淀粉 醋酸乙烯酯 甲基丙烯酸甲酯接枝共聚物，用质子核磁共振谱研究了接枝支链的化学组成，用Ｘ 射线粉末衍射研究了接枝共聚物的结晶结构变化，分别用实验室酶分解法和室外土壤掩埋法测定了接枝共聚物的生物降解性能，结果说明，仅接枝共聚物中的淀粉部分能被微生物降解，接枝支链部分不能被降解．

STUDY ON THE SYNTHESIS AND BIODEGRADATION OF STARCH\|GRAFT\|(VAc\| co \|MMA) COPOLYMER

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 outdoor soil burial.In the laboratory,at 37℃,in the presence of bacillus subtilis,the grafted starch demonstrated a rapid 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 chain nearly unaffected by the bacillus subtitilis.After 20 days outdoor soil burial in summer,the weight loss was 42%,demonstrated a nearly equal degradation rate compared with enzyme degradation in the laboratory at room temperature (that is 44% after 20 days).