The impact of resorcinol bis(diphenyl phosphate) and poly(phenylene ether) on flame retardancy of PC/PBT blends

Flame retardancy of bisphenol A polycarbonate (PC)/poly(butylene terephthalate) (PBT) blends was improved by the addition of resorcinol bis(diphenyl phosphate) (RDP) and poly(phenylene ether) (PPO). A PC/PBT blend at 70/30 weight ratio obtained a V‐0 rating by the addition of 10 wt% RDP and 10 wt% PPO. The combination of 5 wt% methyl methacrylate‐butadiene‐styrene tercopolymer (MBS) with 3 wt% ethylene‐butylacrylate‐glycidyl methacrylate tercopolymer (PTW) causes a remarkable increase in toughness of the PC/PBT/RDP blend while maintaining a high rigidity. A detailed investigation of the flame‐retardant action of PC/PBT/RDP and PC/PBT/RDP/PPO blends was performed using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), TGA‐FTIR, temperature‐programmed pyrolysis/gas chromatography/mass spectrometry (TPPy/GC/MS), and scanning electron microscopy/energy dispersive spectrometer (SEM/EDS). The results demonstrate that RDP induces a higher char yield at ca. 450 °C and synchronously increases the thermal stability of the blend with PPO. The flame‐retardant role of RDP in the condensed phase was discerned from TGA, FTIR, and SEM/EDS of the residues.