A silicone diphenylsulfonate for improving the flame retardancy of polycarbonate

Abstract

Silicone diphenylsulfonate (SDPSF) was synthesized via nucleophilic substitution reaction between dihydroxyalkyl‐terminated silicone oil and benzene sulfonyl chloride, and its chemical structure was confirmed by Fourier transform infrared (FTIR) and 1H NMR. The effect of SDPSF on the flame retardancy, thermal stability, combustion behavior, and mechanical properties of PC/SDPSF blends were investigated. The PC/2 wt% SDPSF blend achieved the UL‐94 (3 mm) V‐0 rating and limiting oxygen index value of 30.3% together with the lowest values of the total heat release (32.2 MJ/M2), peak heat release rate (239.5 kW/M2), CO production (0.48 kg/kg), and fire growth index (1.09 kW/s·m2). It demonstrated that the SDPSF improved evidently the flame retardancy and fire safety of the polycarbonate (PC) matrix. The blend also gave a slightly reduced tensile strength (60.0 MPa) and notched impact strength (57.0 kJ/m2). The TG‐FTIR spectra of the pyrolysis gases demonstrated that the SDPSF promoted the decomposition of PC matrix on advance to release much more nonflammable gases in the early combustion process, meanwhile, the analysis of the char residues confirmed that the SDPSF facilitated the formation of compact and continuous layers with higher graphitization degree to isolate the transfer of heat and combustible volatiles.