Thermal stability and heat release effect of flame retarded PA66 prepared by end-pieces capping technology

Abstract

In order to improve the flame retardancy of PA66, bis-N-benzoguanamine-phenylphos-phamide (MCPO) was grafted to PA66 main chains by end-pieces capping technology. The thermal properties and heat release effect of flame retardant PA66 (FR PA66) composites were investigated by thermogravimetry, differential scanning calorimetry, and cone calorimetry test analyses. In the presence of 8 wt% MCPO in PA66 composites, the initial decomposition temperature (T5) and peak decomposition temperature (Tmax) of PA66 composites were 47 °C and 34 °C higher than that of pristine PA66, respectively. Compared to the traditional flame retardant PA66 composites, the heat release rate, total heat release, total smoke production, and CO release rate significantly reduced by 31.3%, 36.3%, 16.9%, and 14.7% by introducing P containing benzoguanamine derivative, respectively. Moreover, the vertical flame spread test illustrated that the melt dripping of PA66 stopped for higher precursor concentrations in the composites carbonized char, and the limiting oxygen index (LOI) value of PA66 composites reached 29% as evidenced by the LOI test.