Branching And Grafting Modification On CIS 1, 4-Polybutadiene Catalyzed By Ni Compound Catalytic System

In order to synthesize branched cis 1,4-PB or grafted cis 1,4-PB with BR, Ni(naph)2-Al(i-Bu)3-(BF3-OEt2+nC8H17OH) was used to catalyse copolymerization of butadiene and structure modifier A/structure modifier D.The effect of addition amount of structure modifier (1%-8%, weight percentage) on micro-structure, molecular weight and molecular weight distribution, intrinsic viscosity, solution dynamic viscosity, degree of branch, rheology property and mechanical properties of copolymer were investigated.The results showed that branched cis 1,4-PB and grafted cis 1,4-PB also possessed high polymerization activity, high cis structure (cis 1,4%>95%) and low gel content. After branching and grafting modification, dynamic viscosity of copolymer solution decreased comparaing with linear polymer and processability also was improved. So branching and grafting could improve the problems of wall cling property in polymerization process of cis 1,4-PB catalyzed by Ni. While added 2% structure modifier A, solution dynamic viscosity of branched cis 1,4-PB was lowest, the branching index value was lowest which detected by GPC-MALLS-Viscometer Analysis.Al/B (mole ratio) had little effect on degree of branch, while Al/B was 1.0, the branching index value was lowest. While added 3% structure modifier D, solution dynamic viscosity of grafted cis 1,4-PB was lowest. Compared to cis 1,4-PB branched with structure modifier A, the solution dynamic viscosity of cis 1,4-PB grafted with structure modifier D was lowwer and the gel content was less at the same conditions. So the latter had better effects in the aspect of decreasing solution dynamic viscosity of polymer compared to the former.The rheology property and physical properties of branched and grafted cis 1,4-polybudiene were also investigated. The cold flow of modified high cis 1,4-PB were improved greatly; The short chain branched had little effect on the rheological behavior of cis 1,4-polybutadiene. The processbility and the security of processing of modified polybutadiene were improved. The change of structure of modified polybutadiene almost had no effect on physical properties of vulcanized rubber.