The effectiveness of magnesium carbonate-based flame retardants for polyethylene-co-vinyl acetate) and poly (ethylene-co-ethyl acrylate)

In this report we outline recent work on the evaluation of magnesium carbonate-based flame retardants for polymers commonly used in halogen-free flame retardant wire and cable applications: poly(ethylene-co-vinyl acetate) (EVA) and poly(ethylene-co-ethyl acrylate) (EEA). Natural magnesium carbonate (magnesite), synthetic magnesium carbonate (hydromagnesite), and hydromagnesite/huntite blends were combined with EVA or EEA and tested for flame retardancy effectiveness with the cone calorimeter. The flammability results showed that the effectiveness of these carbonates was polymer dependent, suggesting that polymer degradation chemistry played a role in the flammability reduction mechanism. Hydromagnesites were, in general, more effective in reducing flammability, being comparable in performance to magnesium hydroxide. Finally, we report some polymer-clay (organically treated montmorillonite and magadiite) + magnesium carbonate flame retardant results which showed that the nanocomposite yielded mixed results. Specifically, the polymer-clay nanocomposite samples did not always yield the greatest reductions in peak heat release rate. Copyright (c) 2007 John Wiley & Sons, Ltd.