Study On Novel Initiating System For Prepartion Of Linear Butyl Rubber And Synthesis Of Star-Shaped Butyl Rubber

Polyisobutylene and its copolymers have good air tightness, energy absorption properties and anti-aging property, and can not be substituted in manufacturing the tire tube because of their special structure. Now, according to the different topological structure, commercial butyl rubber can be divided into two types:linear butyl rubber and star-branched butyl rubber.The study comprised two parts. Firstly, the effects of initiating systems on conversion, molecular weight and molecular weight distribution, average unsaturated degree of linear butyl rubber were studied. Secondly, star-shaped multifunctional macromolecule branching agent using for synthesis of star-branched butyl rubber was successfully synthesized via living anionic polymerization, and the effects of the composition, addition methods, addition amount of branching agent on molecular weight and molecular weight distribution of star-branched butyl rubber were studied. The results showed that,(1) Compared with the conventional initiating system AICl3/H2O for cationic copolymerization of isobutylene and isoprene, TiCl4/H2O leads to relatively high monomer conversion and low polymerization rate. The molecular weight and molecular weight distribution of butyl rubber obtained could meet the commercial qualification (Japan).(2) The copolymerization of isobutylene and isoprene were initiated by the new initiating systems based on AlEt3-mClm (m=2or3) and SnBu4.nCln. The resultant butyl rubber with high molecular weight (number average molecular weight1.5times of industrial product) and various molecular weight distribution could be obtained under different molar ratio of Al compound to Sn conpound.(3) Macromolecular branching agent of star-shaped block copolymer could be synthesized via living anionic polymerization with designed molecular weight, and the average arm number was in the range of4.7to6.8.(4)During the polymerization for preparing the star-branched butyl rubber, it was beneficial to obtain the product with high molecular weight by adding coinitiator before the introduction of branching agent.