Enhanced flame retardance in polyethylene/magnesium hydroxide/polycarbosilane blends

This work aims to enhance the flame retardant efficiency of magnesium hydroxide (MH) in polyethylene (PE) with incorporation of polycarbosilane (PCS) as ceramic precursor to form a cohesive barrier during combustion. A novel synergistic effect between MH and PCS was evidenced by oxygen index/nitrous oxide index (OI/NOI) and cone calorimeter (CONE) to endow PE with high flame retardant properties and the fire safety performances. The ceramic reaction between PCS and MgO was found by X-ray diffraction (XRD) to form a silicate ceramic phase, which bonded MgO particles and promoted the formation of self-supporting ceramic-like char. According to the results of thermogravimetric analysis coupled with infrared spectroscopy (TG-FTIR), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and X-ray photoelectron spectroscopy (XPS), the thermal stability of MH/PCS and PE/MH/PCS was improved and the multi-layered char structure formed due to the migration and redistribution of PCS. As a result, the enhanced flame retardant mechanism of PE/MH/PCS was mainly in the condensed phase and closely related with the barrier effects of the char, which restrained the heat and mass transfer during combustion.