Flammability and mechanical properties of EVA/LDPE blended with MHSH whiskers and ATH

Abstract

Poly(ethylene vinyl acetate) (EVA) and low density polyethylene (LDPE) composites blended with aluminum hydroxide (ATH) and magnesium hydroxide sulfate hydrate (MHSH) whiskers have been prepared by melt mixing, and the flammability as well as mechanical and electrical properties were studied by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 test, cone calorimetry, tensile and electrical test. The results indicate that with the increasing addition of the MHSH whisker and ATH, there are more MHSH whiskers and ATH particles in the cryo fracture of the composites, meanwhile, the thermal stability of composites is improved, and the thermal degradation rate of the second stage in the temperature ranges of 410 °C ∼ 510 °C decreases greatly. The increasing content of MHSH whiskers and ATH leads to significant improvements in the flame retardant efficiency, but the elongation at break and the electric properties are deteriorated, because of the labyrinth effect of the dispersed ATH particles presented between the frameworks of MHSH whiskers in the EVA/LDPE composites. The B2 formulation has a good comprehensive properties, its tensile strength and elongation at break are 10.43 MPa and 183.27% respectively, and reach V-0 in UL-94 test, in line with market application standards.