Process for the preparation of crystalline vinylaromatic polymers with a predominantly syndiotactic structure

摘要

Process for the preparation of crystalline vinylaromatic polymers with a predominantly syndiotactic structure which comprises polymerizing the vinylaromatic monomers, alone or mixed with at least another copolymerizable ethylenically unsaturated monomer, in the presence of a catalytic system essentially consisting of: a) an adduct between a derivative of titanium having the formula R1R2R3R4Ti and a calix-ÄnÜ-arene, or an oxa-calix-ÄnÜ-arene; b) a co-catalyst selected from an alkylalumoxane and a compound of boron having the formula (II): BX1X2X3 or its salt.