Development of flame retardant phosphorus- and silicon-containing polybenzoxazines

The copolymerisation of benzoxazine of bisphenol A and diglycidyl ether of (2,5-dihydroxyphenyl)diphenyl phosphine oxide or diglycidyloxymethylphenylsilane has been studied. In all samples the molar ratio of the benzoxazine-epoxy system was varied to achieve different phosphorus or silicon contents. Their thermal, dynamic-mechanical and flame retardant properties were evaluated. The high limiting oxygen index values confirmed that the phosphorus-containing benzoxazine-epoxy resins are effective flame retardants, but no efficiency of silicon on flame retardation was observed.