Glass fiber reinforced PET modified by few‐layer black phosphorus

Glass fiber reinforced polyethylene terephthalate (PET/GF) with enhanced flame retardancy was prepared with few‐layer black phosphorus (BPs) for the first time. The performance of red phosphorus (RP) modified PET/GF was also investigated for comparison. Results show that PET/GF with 0.9 wt% BPs (PET/GF@BP‐0.9) can eliminate the ignition of cotton by dripping. The addition of 2.7 wt% of BPs can make the PET/GF sample pass UL 94 V‐0 classification, while a much higher of 6.3 wt% RP was needed to pass the same classification. Compared with neat PET/GF, the peak heat release rate (PHRR) and total heat release (THR) rate of PET/GF@BP‐2.7 decreases ca. 52.5% and 34.8%, respectively. The studies of char residues reveal that BPs could act as a catalyst for char formation and the formed char could roughen the surface of GF and thus restrain the “wick effect.” Thermogravimetric analysis/infrared spectrometry shows that the addition of BPs significantly inhibited the release of gas‐phase products. The attractive abilities of BPs as flame retardant provide a novel and effective way of PET/GF modification.