Poly(aryloxyphosphazene) Foams.

Abstract : A new family of polymers based on the phosphorus-nitrogen backbone, the poly(aryloxyphosphazenes), was investigated as fire-retardant materials to replace existing materials. The poly(aryloxyphosphazenes) have a high degree of flame retardancy and excellent dielectric properties. Efforts were devoted to synthesis of ((C6H5O)2PN-(4-C2H5C6H4O)2PN)n and evaluation of methods for formation of expanded closed cell foams of low density. Vulcanizates of this polymer (unexpanded) were found to possess adequate tensile strength (2410 psi) and elongation (380%). Studies of these foams for use as thermal insulation showed times to vision obscuration at least seven times as long as currently used fire-retardant marine thermal insulation. Little generation of toxic or corrosive products upon burning of the poly(aryloxyphosphazene) was found. Foams of approximately 6 lbs/cu ft density were produced by the use of chemical blowing agents and molding and curing under controlled pressure at temperature. Flame spread indices were obtained. Their physical and mechanical properties met the standards defined by MIL P-0015280F.