Abstract: Toughenable polymer compositions cross-linkable thermally or by the effect of U.V. radiation are composed of:1) A polyphenylene ether (PPE) deriving from the (co)polymerization of one or more substituted phenols by oxidative coupling;2) At least one mono-unsaturated monomer compound able to (co)polymerize in the presence of radical initiators;3) Optionally, at least one polyunsaturated monomer compound able to (co)polymerize in the presence of radical initiators;4) At least one radical polymerization initiator;5) Possibly at least one (co)polymer with elastomeric characteristics;6) Usual additives, stabilizers, accelerators and flame retardant agents.Finished articles essentially composed of an intimately copenetrated polymer blend are obtained by thermal treatment or U.V. radiation of these compositions contained in suitable moulds either along or in combination with other reinforcement materials.

Abstract: Process for the preparation of bodies of expanded cross-linked polyethylene, with closed cells, comprising the steps of:melting a polymer of ethylene selected among ethylene homopolymers, copolymers of ethylene with alpha-olefins, copolymers of ethylene with conjugated diolefins and relevant mixtures;homogenizing the polymer of ethylene in the molten state with a quantity of from 0.1 to 2.5% by weight of a cross-linking agent and with a quantity of from 2 to 25% by weight of an expanding agent, the cross-linking agent and expanding agent having a decomposition temperature higher than the melting point of the polymer of ethylene, the homogenizing step operating at temperatures of from 130.degree. to 150.degree. C., and for times of from 5 to 10 minutes;forming the homogeneous mixture in a solid parallelepiped shape by means of extrusion and subsequent cooling, or by means of moulding wherein the extrusion or moulding step is operated at temperatures within the range of from 130.degree. to 150.degree. C.