Effect of polyimide with different amount on flame retardant property of silicone foam

In this work, silicone foams (SF) modified by polyimide (PI) with a relatively low density (0.195–0.278 g/cm³) were obtained from a mixture of hydroxyl-terminated polymethylsiloxane (PDMS-OH), ethylene-terminated polydimethysiloxane (PDMS-Vi), polymethylhydrosiloxane (PDMS-H), polyimide precursor (PEAS) powders, and catalysts. These compositions were crosslinked at high temperature with branched PDMS-H in the presence of dibutyltin dilaurate (T12) and 25% tetramethyl ammonium hydroxide solution as the catalysts. The SF were prepared by a dehydrocondensation reaction and had a good homogeneity of pores, with a kind of blowing agent (PDMS-H). SF without the addition of PEAS powders showed a limited oxygen index (LOI) of 19.5%, whereas polyimide modified silicone foam (PMSF) formed with the addition of PEAS powders had much higher LOI values achieving 26.5%, with 7.5 wt.% of PEAS powder that was synthesised by 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride and diaminodiphenylmethane. The T_5% of PMSF with the addition of PEAS powders, under the condition of N₂ increased from 340°C to 520°C.