Modified Rubber via Grafting of Polymer on Olefinic Site

Natural rubber (NR) is a very reactive rubber because of its structure. The modification of NR with other functional groups can be achieved by incorporation of monomer carrying the desired functional group in the polymerization process using ene reaction. Grafting of a second polymer on to the natural rubber backbone leading to the chemical modification of the polyisoprene occurs at allylic double bond system. This route following grafting gave good control over the extent of reaction as the reaction limits itself on individual olefinic sites present on rubber and does not employ a catalyst that gets poisoned by non rubbers. With the help of ene reaction not only the molecular wt of the polymer that underwent grafting can be accurately determined but the no of grafting sites can also be controlled. Azo compounds have been used as effective modifiers of NR as they have long-term stability and have fewer tendencies to decompose to free radicals.