Effects of tin additives on the flammability and smoke emission characteristics of halogen-free ethylene-vinyl acetate copolymer

Zinc hydroxystannate (ZHS) is found to be an effective partial replacement for the conventional hydrated fire-retardant fillers alumina trihydrate (ATH) and magnesium hydroxide (MH) when incorporated into a halogen-free EVA cable compound. In contrast to earlier findings for halogen-containing polymers, ZHS-coated versions of the fillers are somewhat less effective than equivalent composition mixtures of ZHS+filler. Incorporation of ZHS also greatly enhances the performance of an ATH/nano-clay synergistic fire-retardant system in the EVA formulation and allows marked reductions to be made in overall filler level with no or little compromise in terms of flame-retardant and smoke-suppressant properties.