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Abstract

Curable composition comprising: (a) one or more particular polyisocyanates or a polyurethane prepolymer obtained by the polycondensation of a polyisocyanate in excess, chosen from said polyisocyanates, with one or more polyols comprising at least two free alcohol functional groups, chosen from polypropoxylated or polyethoxylated bisphenol A compounds and polyfunctional polycaprolactone-alcohols; (b) one or more polyols comprising at least two free alcohol functional groups, chosen from polypropoxylated or polyethoxylated bisphenol A compounds and polyfunctional polycaprolactone-alcohols, and polyurethane prepolymers obtained by the polycondensation of one or more polyols in excess, chosen from the above polyols, with one or more particular polyisocyanates, the ratio of the number of isocyanate functional groups of the polyisocyanate component (a) to the number of alcohol functional groups of the polyol component (b) being between 1.00 and 1.20; and (c) 5% to 80% by weight, relative to the total weight of (a), (b) and (c), of one or more polystyrene-block-polybutadiene-block-poly(methyl methacrylate) block copolymers;method of preparing such a composition and transparent optical material obtained by heating said composition.

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