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 m oderate efficiency in ABS and PC/ABS. Various co-additives which are expect ed to contribute to vapor or condensed phase fire retardant mechanisms were tested in PC/ABS containing RDP or PC/ABS/RDP containing novolak. Non-drip ping formulations with marginal V-1/V-0 UL94 rating; and improved LOI were identified. In accordance with the combustion study, thermogravimetry sugge sts that condensed phase co-additives are preferable for improvement of RDP performance in PC/ABS.