GRAFT POLYETHER POLYOLS BASED ON ALPHA-METHYLSTYRENE AND ACRYLONITRILE FOR FLEXIBLE POLYURETHANE FOAMS

The radical grafting copolymerisation reaction of alpha-Methylstyrene (alpha-MeSt) and Acrylonitrile (AN) as compared with the usual graftin g copolymerisation reaction of Styrene (St) and AN on the polyetheric chains of polyether polyols for polyurethanes, homopolymers of propyle neoxide (PO) or copolymers PO-ethyleneoxide (EO), has been studied. Th e effect of St substitution by alpha-MeSt, another cheap and accessibl e vinylic monomer, has been investigated, concerning the properties of the resultant graft polyethers and the physico-mechanical properties of the resultant flexible polyurethane foams. Special attention was pa id to the solid fractions isolated from the polymer polyols proving th at the the synthesized products are true graft copolymers and not a ph ysical mixture between vinyl copolymers and polyether polyols. The sub stitution of St by MeSt leads to graft polyether polyols having a lowe r degree of grafting but with excellent stability and lower viscosity as compared with the corresponding products based on St-AN. The flexib le polyurethane foams based on alpha-MeSt AN graft polyethers have ver y good properties, comparable with those derived from St-AN graft poly ethers, but the compression set has an unexpected lower value, better than those of the flexible foams derived from classical St-AN graft po lyethers.