Synergistic effect of zeolite on the nitrogen-containing phosphinate salt-based acrylonitrile-butadiene-styrene flame-retardant composite

The present work investigated the effects of the zeolite 4A on the flame retardancy and thermal stability of aluminum beta-(p-nitrobenzamide) ethyl methyl phosphinate (AlNP) in acrylonitrile-butadiene-styrene copolymer (ABS). The synergistic effect between AlNP and zeolite 4A was assessed with cone calorimeter test (CCT), thermogravimetric measurement (TG), Fourier transform infrared spectroscopy (FTIR) analysis of the gaseous products, and scanning electron microscopy (SEM) characterization of the residues char. Keep the total loading of the additives at 25 wt.%; ABS filled with 22 wt.% AlNP and 3 wt.% zeolite 4A (ABS-AlNP22-A(3)) reaches a UL94 V0 classification with LOI value of 29.3%. By comparison, ABS with 25 wt.% AlNP alone (ABS-AlNP25) only passes the UL 94 V 1 rating with LOI value of 26.0%. CCT results verify that the zeolite 4A can depress the heat and smoke release of combustion. The peak heat release rate, total heat release, and total smoke release of ABS-AlNP22-A(3) are reduced by 13.84%, 14.35%, and 20.4%, respectively, compared to ABS-AlNP25. The TG/FTIR analysis and morphology of the char residues from scanning electron microscopy further demonstrate that zeolite 4A could retard the volatilization of hydrocarbons and promote the char formation in the combustion process of ABS. The mechanism of synergistic effect of the zeolite 4A is proposed based on the experiment and related previous study.