Effect of hydroxides and hydroxycarbonate structure on fire retardant effectiveness and mechanical properties in ethylene-vinyl acetate copolymer

The flame retardant effect of inorganic hydroxides, like aluminum hydroxide and magnesium hydroxide in ethylene vinyl acetate copolymer, was evaluated and compared with that of other inorganic fillers such as boehmite and hydrotalcite. The thermal decomposition of the fillers and the mixtures with EVA polymer were analysed by differential scanning calorimetry (DSC), Thermogravimetry (TG) and X-ray diffraction (XRD). The most significant flame retardant effects, observed using a mass loss calorimeter, indicated that the EVA polymer filled with 50 wt.% of hydrotalcite has the slowest heat release rate and the lowest evolved gas temperature. XRD data, combined with thermal analysis results, indicated that the layered structure of hydrotalcite may play a role in the degradation mechanism. The improved fire resistance of EVA filled with hydrotalcite also results from its intumescent behaviour. (C) 2001 Elsevier Science Ltd. All rights reserved.