A Comparative Study of the Fire Retardant Effect of Several Metal-Based Compounds Added to an Epoxy-Amine Thermoset

Several metal containing compounds such as layered double hydroxide of cobalt aluminum dodecanoate, cobalt (II, III) oxide, zinc acetate dihydrate, and cobalt acetate tetrahydrate have been evaluated as fire-retardant additives for a standard epoxy-amine thermoset polymer system. A cone calorimeter was used to evaluate the fire behavior properties of the composites at an external heat irradiation of 50 kW/m(2). The layered double hydroxide and the metal oxide were found to be rather ineffective fire retardant additives for the epoxy-amine thermoset. In contrast, both hydrated salts performed surprisingly well. The efficacies of metal salts of zinc acetate and cobalt acetate were correlated with the formation of a metal oxide inorganic layer that covered the surface of the underlying polymer under fire conditions. This morphology slowed the release of any flammable volatiles and reduced the heat transfer to the degrading polymer.