Effect of different surface modifiers on the flame retardancy of ethylene‐vinyl acetate copolymer/polyethylene/magnesium hydroxide composite systems

Abstract Halogen‐free flame‐retardant ethylene‐vinyl acetate/polyethylene/magnesium hydroxide systems are widely used in cable insulations and in sheath materials. The surface modification of magnesium hydroxide is one of the key methods to improve its dispersion and mechanical properties. The effects of different types of interfaces, formed by four surface modifications, namely KH550, KH570, stearic acid, and titanate, on the flame retardancy of composite systems have been investigated in the present study. The results showed that the four surface modifiers formed chemical bonds with the surface of magnesium hydroxide, which promoted the dispersion of particles in the matrix. However, due to the different effects of the various surface modifiers and polymer molecular chains, the interfaces exhibited different chemical structures and physical strengths, which affected the combustion of the composite materials into carbon. Thus, the composites demonstrated different flame‐retardant properties. The surface modifiers KH550, KH570 and titanate can form chemical bonds with the ethylene‐vinyl acetate (EVA) copolymer and have, thereby, a strong effect on the interfaces, which resulted in a slow ignition of the materials and the formation of a graphite carbon structure that is advantageous for heat transfer and oxygen insulation. This is conducive to the flame‐retardant performance of the composite systems.