Fabrication and mechanism research of high-efficiency water-resistant flame retardant, transparent and mechanically reinforced polycarbonate composites

In the emerging applications of optoelectronics and mobile, it has always been an urgent problem in fire safety field to ensure the excellent transparency, water resistance and mechanical properties of flame retardant polycarbonate (PC). Unfortunately, the high-efficiency flame retardants used in PC often endow it with satisfied flame retardancy at the cost of the mechanical properties, transparency of composites. Hence, in this work, the high-quality pentaerythritol phosphate flame retardant (PBPP) was successfully prepared by novel synthesis method. The results indicated that the introduction of only 2 wt% PBPP and 0.1 wt% polytetrafluoroethylene (PTFE) enabled PC to obtain a UL-94 V-0 rating and the melt dripping of PC composites was inhibited during combustion. Meanwhile, the PC/PBPP composites still maintained its original transparency. With the introduction of PBPP, the PHRR and THR of PC/PBPP were reduced by 36.0% and 11.4%, respectively. This was mainly attributed to the catalytic charring and gas-phase suppression effect of PBPP. To our surprise, the introduction of PBPP obviously increased the tensile properties and ductility of PC composites. Besides, the PC/PBPP composites still retained excellent flame retardancy and mechanical performance before and after water resistance tests due to the hydrophobicity of PBPP and its excellent compatibility with the PC matrix. This work provided a simple and effective method to prepare PC composites with excellent water resistance, flame retardancy, transparency and mechanical enhancement, which possessed great significance for the application of PC composites in emerging fields.