Fire retardant action of resorcinol bis(diphenyl phosphate) in a PC/ABS blend. I. Combustion performance and thermal decomposition behavior

The combustion performance of polycarbonate (PC), ABS or PC/ABS blend fire retarded by resorcinol bis(diphenyl phosphate) (RDP) was studied by LOI and UL94 tests. It was shown that RDP is active in pure PC but shows weak or moderate efficiency in ABS and PC/ABS. Various co-additives which are expected to contribute to vapor or condensed phase fire retardant mechanisms were tested in PC/ABS containing RDP or PC/ABS/RDP containing novolak. Non-dripping formulations with marginal V-1/V-0 UL94 ratings and im proved LOI were identified. In accordance with the combustion study, thermogra vimetry suggests that condensed phase co-additives are preferable for improvement of RDP performance in PC/ABS.