Influence of BN doped 2‐hydroxyethyl methacrylate phosphate coated expandable graphite on flame retardancy and thermal conductivity of styrene‐butadiene rubber composites

Abstract

AbstractAs one of the three general rubbers, styrene‐butadiene rubber (SBR) is widely used in the manufacturing of tires and cables. However, due to its unsatisfactory performance of flame retardancy and thermal conductivity, its rang of application is limited. In order to improve SBR's flame retardancy and thermal conductivity, flame retardant and thermal conductive additive EG microcapsules (BN‐PPEG) were prepared by doping boron nitride (BN) with 2‐hydroxyethyl methacrylate phosphate (HEMAP) as shell. The results of Fourier transform infrared spectroscopy, x‐ray diffraction, scanning electron microscope energy and TG showed that BN‐PPEG was successfully prepared. The thermal conductivity of the SBR composite added with 15 phr BN‐PPEG was 58.0% higher than that of pure SBR, and its limiting oxygen index (LOI) value reached 26.6%, which was 38.5% higher than that of pure SBR. The peak heat release rate (pHRR) of the composites was 53.9% lower than that of pure SBR. The main reasons were that the physical barrier of BN and EG, the phosphorous free radicals captured active free radicals generated by the decomposition of HEMAP when heated, and the carbonization of SBR was promoted by generated phosphoric acid, metaphosphoric acid and other substances.