Patent ID: 8039557

Claim:
A process for the preparation of vinylaromatic (co)polymers grafted on an elastomer in controlled way, comprising: a) dissolving an elastomer in a liquid phase comprising a mixture of a first amount of a vinylaromatic monomer and a polymerization solvent to form a solution, wherein a weight ratio of the vinylaromatic monomer to the polymerization solvent in the solution is between 60/40 and 100/0; b) adding to the solution a catalytic system of polymerization comprising a free radical initiator (G) with functionality F capable of withdrawing a hydrogen atom from the polymer chain of the elastomer and a stable initiator of free radicals comprising the group ═N—O(I), with a molar ratio I/G·F lower than 4; c) heating under agitation the mixture obtained in stage (b) at a temperature between 80 and 110° C., for a time sufficient to obtain the complete functionalization of the elastomer; d) feeding a second amount of the vinylaromatic monomer to the mixture, containing in solution the functionalized elastomer, and polymerizing the thus obtained mixture at a temperature equal to or greater than 120° C.; e) recovering the vinylaromatic polymer obtained at the end of the polymerization, and submitting the vinylaromatic polymer to devolatilization under vacuum, to recover the solvent and the not reacted monomer; and f) recycling the solvent/monomer mixture to stage (a).