expandable polymer granules to basemdi vinilaromatici equipped with improved espansibilita'and process for their preparation

摘要

Expandable granulates having a composition based on vinyl-aromatic polymers, essentially consisting of: 65-99.8% by weight of a copolymer obtained by polymerizing 85-100% by weight of one or more vinyl-aromatic monomers having general formula (I) and 0.15% by weight of an alpha-alkylstyrene; 0-25% by weight, calculated with respect to the polymer (a), of carbon black; at least one of the following products: 0.01-5% by weight of graphite having an average diameter ranging from 0.5 to 50 mum; 0.01-5% by weight of oxides and/or sulfates and/or lamellar dichalcogenides of metals of groups IIA, IIIA, IIIB, IVB or VIIIB, 0.01-5% by weight of inorganic derivatives of silicon of the lamellar type; 0-5% by weight, calculated with respect to the polymer (a), of a nucleating agent; 1-6% by weight, calculated with respect to the total, of an expanding agent.