Compositions of polyolefins having combustion retarding properties and hardened by irradiation

The invention concerns improved compositions of polyolefins that may be hardened by irradiation and give non porous compositions of use as insulation for metal wires and cables having improved combustion retarding properties, as well as improved physical and electric properties. It also relates to a process for preparing these compositions. Specifically, the invention concerns, combustion retarding compositions having polymers as basis, comprising an ethylene copolymer/vinyl acetate, halogenated combustion retarder, an antimony compound, a charge of smoked silica, an acid acceptor, an antioxidant and a reticulation agent and that may be mixed with a strong shearing action, shaped and hardened by irradiation to obtain porosity free products