Are novel aryl phosphates competitors for bisphenol A bis(diphenyl phosphate) in halogen-free flame-retarded polycarbonate/acrylonitrile-butadiene- styrene blends?

摘要

The reactivity of the flame retardant and its decomposition temperature control the condensed-phase action in bisphenol A polycarbonate/acrylonitrile- butadiene-styrene/polytetrafluoroethylene (PC/ABS _(PTFE)) blends. Thus, to increase charring in the condensed phase of PC/ABS _(PTFE) + aryl phosphate, two halogen-free flame retardants were synthesized: 3,3,5-trimethylcyclohexylbisphenol bis(diphenyl phosphate) (TMC-BDP) and bisphenol A bis(diethyl phosphate) (BEP). Their performance is compared to bisphenol A bis(diphenyl phosphate) (BDP) in PC/ABS PTFE blend. The comprehensive study was carried out using thermogravimetry (TG); TG coupled with Fourier transform infrared spectrometer (TG-FTIR); the Underwriters Laboratory burning chamber (UL 94); limiting oxygen index (LOI); cone calorimeter at different irradiations; tensile, bending and heat distortion temperature tests; as well as rheological studies and differential scanning calorimeter (DSC). With respect to pyrolysis, TMC-BDP works as well as BDP in the PC/ABS PTFE blend by enhancing the cross-linking of PC, whereas BEP shows worse performance because it prefers cross-linking with itself rather than with PC. As to its fire behavior, PC/ABS _(PTFE) + TMC-BDP presents results very similar to PC/ABS _(PTFE) + BDP; the blend PC/ABS _(PTFE) + BEP shows lower flame inhibition and higher total heat evolved (THE). The UL 94 for the materials with TMC-BDP and BDP improved from HB to V0 for specimens of 3.2 mm thickness compared to PC/ABS PTFE and PC/ABS _(PTFE) + BEP; the LOI increased from around 24% up to around 28%, respectively. BEP works as the strongest plasticizer in PC/ABS PTFE, whereas the blends with TMC-BDP and BDP present the same rheological properties. PC/ABS _(PTFE) + TMC-BDP exhibits the best mechanical properties among all flame-retarded blends.