Graft Polyether Polyols Based on α-Methylstyrene and Acrylonitrile for Flexible Polyurethane Foams

The radical grafting copolymerisation reaction of α-Methylstyrene (α-MeSt) and Acrylonitrile (AN) as compared with the usual grafting copolymerisation reaction of Styrene (St) and AN on the polyetheric chains of polyether polyols for polyurethanes, homopolymers of propyleneoxide (PO) or copolymers PO-ethyleneoxide (EO), has been studied. The effect of St substitution by α-MeSt, another cheap and accessible 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 paid to the solid fractions isolated from the polymer polyols proving that the the synthesized products are true graft copolymers and not a physical mixture between vinyl copolymers and polyether polyols. The substitution of St by MeSt leads to graft polyether polyols having a lower degree of grafting but with excellent stability and lower viscosity as compared with the corresponding products based on St-AN. The flexible polyurethane foams based on α-MeSt-AN graft polyethers have very good properties, comparable with those derived from St-AN graft polyethers, but the compression set has an unexpected lower value, better than those of the flexible foams derived from classical St-AN graft polyethers.