HIGH-IMPACT CAST SHEETS OF POLY(METHYL METHACRYLATE) WITH LOW-LEVELS OF POLYURETHANE

High impact strength, high transparency cast sheets of polyurethane (P U)-reinforced poly(methyl methacrylate) (PMMA) were obtained by means of IPN techniques. The PU content was kept low (less than 10%). The im pact strength is maximum at a critical PU concentration, and for a giv en morphology. The study of various synthesis parameters led to the co nclusion that the size of interstitial PMMA nodules - and therefore th e optical and mechanical properties of the final material - are determ ined by the crosslink density of the swollen PU network at the onset o f the methyl methacrylate polymerization.