Fire retardant mechanism in intumescent ethylene vinyl acetate compositions

摘要

The thermal and combustion behaviour of an intumescent fire retardant system based on Polyamide 6 (PA6) and Ammonium Polyphosphate (APP), used to improve flame retardant properties of poly(ethylene-co-vinyl acetate) (EVA), loaded with Mg(OH)_2 (MH) was examined. The study of the interactions between the additives introduced in EVA was focused in particular on the MH-APP interaction. The evolution of water from MH takes place at about 400℃, with a fair overlap with ammonia and water evolution from APP degradation. Ammonia evolution from APP is facilitated by the presence of MH, in their mixture heated alone or in the polymer matrix. UL94 test shows that the interaction between MH and APP modifies the combustion behaviour of the intumescent mixture.