Enhanced flame retardancy of polyethylene/magnesium hydroxide with polycarbosilane

Abstract

Polycarbosilane (PCS) was used for surface modification of magnesium hydroxide (MNH) to enhance the flame retardant effectiveness by forming cohesive binding between MgO particles with ceramic adhesive. Chemical interaction and ceramic reaction were revealed between PCS and MNH, which made for a compact, thermal stable and ceramic-like barrier during the combustion of polyethylene (PE). The flame retardancy of PE/MNH/PCS composites was greatly enhanced and a limiting oxygen index (LOI) of 35.0 was achieved at the PCS/MNH ratio of 4/26 in the composite with 30 wt.% PCS modified MNH. Such results were superior in terms of high LOI value at low global content of MNH. Thanks to the better shielding effect of the integrated and self-supporting ceramic char, the peak heat release rate (p-HRR) and the total heat release (THR) of PE/MNH/PCS composites with 50 wt.% PCS modified MNH were remarkably decreased by 36% and 25% in comparison with PE/MNH with 50 wt.% MNH, respectively. The ceramic reaction between PCS and MNH, the superior thermal stability due to crosslinked PCS and the good barrier function of cohesive ceramic layer play important roles in the effective flame retardant mechanism.

Enhanced Flame Retardancy in Ethylene–Vinyl Acetate Copolymer/Magnesium Hydroxide/Polycarbosilane Blends

“…The TTI and THR of EVA and EVA/PCS were similar to one another. The pHRR and the residual mass of EVA/PCS were a little higher than those of EVA, which was induced by the high heat release and high degradation products left by PCS in condensed phase [ 26 , 27 ]. Moreover, the TSP of EVA/PCS was a little lower than that of EVA.…”

“…PCS-modified MH was prepared as described in [ 26 ]. The flame-retardant composites were prepared via the melt-blending method with a HAPRO rheometer (Harbin Hapro Electric Technology Co., LTD., Harbin, China.).…”

“…As widely accepted, the combustion behaviors are highly related to the char formed during combustion [ 18 , 22 , 23 ]. Meanwhile, the limiting oxygen index (LOI) at a moderate content of the synergists can be related to the char [ 26 , 27 ].…”

“…Polycarbosilane (PCS) was widely reported as a polymer ceramic precursor with a polymeric backbone composed of silicon atoms and difunctional organic groups that connect the silicon atoms [ 28 ]. According to our previous investigation [ 26 , 27 ], the positive effects of PCS were reported to enhance the flame retardancy of polyethylene (PE) with MH as an inorganic flame retardant. The ceramic char was revealed to function as a barrier to heat and mass transfer during the combustion.…”

Expanded Polystyrene Beads Coated with Intumescent Flame Retardant Material to Achieve Fire Safety Standards

“…Among the available alternatives, mineral flame retardants, such as aluminum hydroxide (Al(OH) 3 herein ATH) and magnesium hydroxide (Mg(OH) 2 herein MH), are widely used due to its unique properties, such as low toxicity, minimum corrosion, and low cost [26][27][28][29]. To achieve a satisfactory flame retardant performance, mineral fillers, such as ATH loadings, are relatively high (often between 40% and 70%).…”