Synthesis of a magnesium/aluminum/iron layered double hydroxide and its flammability characteristics in halogen‐free, flame‐retardant ethylene/vinyl acetate copolymer composites

Abstract Mg–Al–Fe ternary hydrotalcites were synthesized by a coprecipitation method and characterized with powder X‐ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The flame‐retardant effects of Mg/Al–CO 3 layered double hydroxides (LDHs) and Mg/Al/Fe–CO 3 LDHs in an ethylene/vinyl acetate copolymer (EVA) were studied with the limited oxygen index (LOI), the UL‐94 test, and the cone calorimeter test (CCT), and the thermal degradation behavior of the composites was examined by thermogravimetric analysis. The results showed that the LOI values of the EVA/(Mg/Al/Fe–CO 3 LDH) composites were basically higher than those of the EVA/(Mg/Al–CO 3 LDH) composites at the same additive level. In the UL‐94 test, there was no rating for the EVA/(Mg/Al–CO 3 LDH) composite at the 50% additive level, and a dripping phenomenon occurred. However, the EVA/(Mg/Al/Fe–CO 3 LDH) composites at the same loading level of LDHs containing a suitable amount of Fe 3+ ion reached the V‐0 rating, the dripping phenomenon disappearing. The CCTs indicated that the heat release rate (HRR) of the EVA composites with Mg/Al/Fe–CO 3 LDHs containing a suitable amount of Fe 3+ decreased greatly in comparison with that of the composites with Mg/Al–CO 3 LDHs. The introduction of a given amount of Fe 3+ ion into Mg/Al–CO 3 LDHs resulted in an increase in the LOI, a decrease in the HRR, and the achievement of the UL‐94 V‐0 rating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008