HIGH-TEMPERATURE, POLYMERIC, STRUCTURAL FOAMS FROM HIGH INTERNAL PHASE EMULSION POLYMERIZATIONS

High temperature, polymeric, structural foams were prepared using a hi gh internal phase emulsion (HIPE) to copolymerize styrene with maleimi de based monomers. In this work, N-ethylmaleimide and a bismaleimide ( BMI) monomer, bis(3-ethyl-5-methyl-4-maleimide-phenyl) were successful ly free-radically copolymerized with styrene in a water-in-oil HIPE to produce polymeric foams with glass transition temperatures (T(g)s) ra nging from 140 to 220 degrees C depending on composition. The ethylmal eimide and BMI were uniformly Incorporated throughout the polymer, whi ch allowed the thermal performance of the foams to be tailored by cont rolling the concentration of ethylmaleimide and BMI modifiers. In addi tion, the thermal oxidative stability of the foam systems increased wi th increasing concentration of maleimide based monomers. The resulting polymeric foams contained an open cell morphology with cell sizes of approximately 10 mu m in diameter. Compression tests of the high tempe rature foam systems showed that compression strengths of approximately 700-850 kPa were obtainable at foam densities under 80 mg cm(-3) (5.0 lb ft(-3)). (C) 1997 Elsevier Science Ltd.