%0 Journal Article
%T THE RADIATION-INDUCED RACEMIZATIOIN AND CHAINSCISSION IN CRYSTALLINE ISOTACTIC POLY (METHYL METHACRYLATE)<br>结晶对等规立构聚甲基丙烯酸甲酯辐射消旋和辐射裂解的影响
%A LUO Yun-xia
%A GUAN Jian-qiu
%A YANG Hong
%A Li Shu-hua
%A YU Bin
%A DING Meng-xian
%A JIANG Bing-zheng
%A <br>罗云霞
%A 关剑秋
%A 杨弘
%A 李淑华
%A 虞斌
%A 丁孟贤
%A 姜炳政
%J 高分子学报
%D 1992
%I 
%X The radiation-induced racemization and chain-scission of crystalline isotactic poly (methyl methacrylate) (i-PMMA) were studied with proton NMR, DSC and molecular weight(MW) determination. It is shown from MW results that the chain-scission reduces in crystalline phase. Its G-value is only half of that in amorphous region. NMR study on the radiation-induced change of stereospecific structure indicates that iso-PMMA transforms gradually into syndiotactic and atactic ones, similar to what happens in amorphous phase.However,radiation-induced racemi-zation in crystalline state is more remarkable than chain-scission reaction.Such an effect could be well explained with the effect of "cage"and steric hindrance on above-mentioned two reac-tion mechanisms,as we proposed before.Because of both reactions taking place within cystal-line region,the reduction of melting point of iso-PMMA with radiation dose is more remarkable.The G-value of the damage in crystalline phase estimated is 8.8,which is much higher than that in polyethylene.
%K 辐射裂解
%K 辐射消旋
%K PMMA
%K 结晶
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=6E709DC38FA1D09A4B578DD0906875B5B44D4D294832BB8E&cid=6579068328FE643F&jid=15971983683C7643EE80F1CE621DEB60&aid=74630696D73EB0793647B2EF088DD1CF&yid=F53A2717BDB04D52&iid=E158A972A605785F&sid=44FDB9366EDDFA2B&eid=A22854835F81B3F8&journal_id=1000-3304&journal_name=高分子学报&referenced_num=1&reference_num=2