1，3－戊二烯－苯乙烯阳离子共聚合反应竞聚率的测定

本工作以ＡｌＣｌ＿３为引发剂，正己烷为溶剂在２０℃合成了１，３戊二烯－苯乙烯共聚物，用Ｋｅｌｅｎ－Ｔｕｄｏｓ法测定的反应体系的共聚单体竞聚率为（Ｍ＿１和Ｍ＿２分别为苯乙烯和１，３－戊二烯）：ｒ＿１＝１．７８，ｒ＿２＝０．５６。对共聚物环化度的研究表明，随着共聚物中苯乙烯结构单元含量的增加，戊二烯链段的环化度较均聚物明显降低，表明聚合反应中苯乙烯单体的引入抑制了１，３－戊二烯的环化反应。

Determination of Reactivity Ratio of the Cationic Copolymerization of 1,3-Pentadiene-Styrene

The cationic copolymerization of 1,3-pentadiene (PD)-styrene(St)was carried out at 20℃,initiated by AlCl_3 in n-hexane,The reactivity ratios of St(M_1 ) and PD(M_2)determined by Kelen-Tudos method were: r_1=1.78,r_2=0.56 respectively. The molecular weights of the copolymersappeared lower than the homopolymers.The cyclization of the PD chains was also investigatr-ed. With the increase of St proportion in the copolymer chains,the cyclic fraction of the PD en-chainments in the copolymer decreases apparently.This result has been explained by the decreasein consecutive 1,2-addition PD units,which causes the cyclization reaction.