Enhanced flame retardance in polyethylene/magnesium hydroxide/polycarbosilane blends
Abstract 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.