烯丙基卤在五价钼体系引发丁二烯聚合反应中的链转移作用

THE CHAIN TRANSFER ROLE OF ALLYLHALIDE IN BUTADIENE POLYMERIZATION INITIATED WITH PENTAVALENT MOLYBDENUM SYSTEM

本工作以烯丙基卤(x)为链转移剂,在非极性加氢汽油溶剂中,用MoCl_3(i-OC_5H_(11))_2—(i-Bu)_2AlO (Mo-Al)二元引发体系引发丁二烯(Bd)进行溶液聚合,探讨x对Bd聚合速度、聚合物分子量以及聚合活化能的影响,并测得了x的链转移常数。实验结果表明,烯丙基溴(Br)对聚合速度的影响甚微,烯丙基氯(Cl)和烯丙基碘(Ⅰ)却能导致聚合速度减慢;随x用量增加,分子量明显降低;在Br存在下,按Arrhenuis方程式求得的Bd聚合表现活化能为63.6千焦/摩尔,略高于不添加Br时的值。

The article examines an effct of allylhalide, as chain transfer agent, upon the rate of butadiene polymerization, polymer molecular weight and activity energy in the presence of MoCl3(i-OC5H11)2-(i-Bu)2-AlO and hydrogenated gasoline assolvent. And the chain trasfer constants of allylhalide was induced. The results show that allylbromide has little effect on the rate of butadiene polymerization, however allylchloride and allyliodide result in the drops of the polymerization rate-Molecular weight decreases rapidly as the increase of the amount of allylhalide. In the presence of allybromide, according to Arrhenius' equation, the apparent activity energy is abtained to be 63.6 kj/mole, a little more than that there is no allylbromide.