A novel macromolecular flame retardant based on sulfonyl diphenol monomer for simultaneous fire safety, transparency and high performance of thin-walled polycarbonate

Abstract

In order to further advance the development of transparency, fire safety, and high-performance thin-walled polycarbonate (PC), it is essential to avoid the negative impact of traditional flame retardants on the overall performance of PC. In this work, a new copolymer polycarbonate (ASPC) containing sulfonyl diphenol monomer was synthesized by interfacial polycondensation, and it was used as a flame retardant for PC. Due to the fact that the compounds containing sulfonic acid groups produced by the decomposition of ASPC in a high temperature environment promote the crosslinking and rearrangement of PC, the PC can generate a denser char layer during combustion, thus effectively preventing the exchange of heat and gas inside and outside the matrix. To addition of 20 wt% ASPC can make PC with a thickness of 1.5 mm to pass the UL 94 V-0 rating and LOI increased to 33.5 %. The peak of heat release rate (PHRR) and smoke produce rate (PSPR) of PC/ASPC-20 was decreased by 32.4 % and 38.4 %, respectively. More importantly, the addition of ASPC can delay the speed of flame spread, provide people with more escape time and reduce the fire hazard. Furthermore, the ASPC is good compatibility with PC due to the structural similarity between ASPC and PC. Therefore, PC/ASPC maintains the comparable transparency and tensile properties of PC. The transmittance of PC/ASPC-20 is 87.7 %, and the elongation at break is 32.5 % higher than that of PC. This work provides a new solution for the preparation of flame-retardant modification of transparent and thin-walled PC, and expands the application scope of PC composites.