SYNTHESIS AND FORMULATION OF NOVEL PHOSPHORYLATED DAME RETARDANT CURATIVES FOR THERMOSET RESINS

More than 20 novel phosphorylated monomers have been prepared. General synthetic targets were of the form: Di/tri amino cyclotriphosphazenes , Di/tri hydroxy cyclotriphosphazenes, Phosphine oxide derivatives. Th ese dual-function materials act both as flame retardants and as curati ves. Ease and cost of synthesis were taken into account in choosing pr omising candidates for further study. Limited formulation was then per formed in epoxy resin systems to determine flammability and thermomech anical properties, and also the efficiency of these flame retardant ma terials as curatives. Two curatives, based upon phosphine oxide and ph osphazene chemistries, were scaled up to more than 10 kg, and were eva luated in a range of thermoset resin systems. Flammability characteris ation was carried out using OSU (Ohio State University) and cone calor imeters to measure ignitability, heat release rate, smoke and toxic ga s production. Screening of thermal and mechanical properties was also performed. Three formulations showed promising overall properties: tou ghened phosphine oxide based epoxy, untoughened phosphine oxide based bismaleimide resin, toughened phosphazene based epoxy, and these were selected for further work with composite materials. (C) 1996 Published by Elsevier Science Limited