Abstract:

Polyethylene vinyl acetate/low-density polyethylene/aluminum hydroxide compounds were prepared using whisker as an impact modifier. Their microstructure， flame retardant properties， mechanical properties and electrical properties were characterized using scanning electron microscope， thermogravimetric analyzer， oxygen index meter， cone calorimeter， universal tensile machine and high resistance meter. The results indicated that aluminum hydroxide particles were well dispersed in the matrix without obvious agglomeration， and the whiskers were staggered in the compounds with tightly bonding onto the matrix interface. The flame retardancy of the compounds was improved due to the enhancement of carbon layer resulting from the network skeleton of the pyrolysis products of whiskers. When the addition amount of magnesium hydroxide sulfate hydrates whisker（MHSH）， aluminum borate whisker， and calcium sulfate whisker（CSW） was set to be 13.5 phr， 6.75 phr， and 6.75 phr， respectively， the compound sample exhibits optimal flame retardant performance with a mass retention rate of 32.7 wt% at 800 °C. With this formulation， the compound achieved a limiting oxygen index of 26.8 vol%， a peak heat release rate（pHRR） of 364.4 kW/m²， a total heat release of 20.8 MJ/m²， and a total smoke release（TSR） of 187.2 m²/m². MHSH can reduce the pHRR and TSR and enhance the tensile strength of the compounds. CSW can delay the time to ignition， reduce the flashover trend， increase the TSR， and increase the elongation at break of the compounds. However， whiskers generated a limited influence on the tensile strength， shore hardness， and electrical insulation properties of the compounds.

Key words: polyethylene vinyl acetate, low density polyethylene, composite, whisker, flame retardancy, toughening