Strengthening Carbon Deposition of Polyolefin Using Combined Catalyst as a General Method for Improving Fire Retardancy

Abstract

Combination of Ni2O3 and solid acid with Brønsted acid sites and Lewis acid sites (such as HZSM‐5 and H‐beta) could dramatically improve fire retardancy of polyolefin, including polypropylene and linear low‐density polyethylene. This is mainly attributed to the formation of a large amount of residual char from degradation products of polyolefin in the intermediate stage of combustion. Thus, the amount of flammable components diffusing into the flame zone was small. The investigation on the combined effect of solid acid and Ni2O3 showed that the presence of cationic reactive intermediates, mainly originating from Brønsted acid sites on the solid acid, strongly promoted carbon deposition of the degradation products. As a general method for improving fire retardancy of polyolefin, optimizing combination of metal catalyst and solid acid will further promote efficiency of fire retardancy.magnified image

Fabrication of Ce-doped MnO2decorated graphene sheets for fire safety applications of epoxy composites: flame retardancy, smoke suppression and mechanism

“…In fact, it has been previously reported in the literature that solid acids can catalyze the degradation of polymers, which results in the formation of pyrolysis products with lower carbon numbers, and the degradation products with lower carbon numbers could easily catalyze carbonization in the presence of metal oxides. 64,65 Manganese oxides have been reported to be the most efficient solid acid for suppressing the recombination of macromolecular hydrocarbon radicals due to the presence of several acidic sites. 42,66 In this work, carbon numbers of pyrolysis products from the Ce-MnO2-GNS-EP composite also decreased compared with that of EP.…”

Improving the flame retardancy and mechanical properties of high-density polyethylene-g-maleic anhydride with a novel organic metal phosphonate

“…However, new environmental regulations have restricted the use of some halogenated flame-retardant additives that evolve toxic gas during combustion, initiating research for alternative materials for this purpose [2]. Many researchers have focused on using carbon nanotubes (CNTs), montmorillonite (MMT) and other nano-scale inorganic materials as synthetic flame-retardant materials [3][4][5][6]. Nanocomposites not only offer a significant improvement in mechanical properties over conventional formulations but also enhance the flame retardancy as well as the mechanical properties thereof [7].…”

Enhanced mechanical, thermal and flame retardant properties by combining graphene nanosheets and metal hydroxide nanorods for Acrylonitrile–Butadiene–Styrene copolymer composite

“…Very recently, the combination of transition metals Lewis acids and 2-D clay provided a promising method, which involved catalytically enhanced char formation and the formation of a surface-protective layer having a network structure [19,20]. Systematic work done by Tang's group has demonstrated that dramatically improved fire retardancy of polyolefin was realized through promoting carbonization by the combination of 2-D clay with Ni2O3 [21,22].…”