Patent ID: 7304114

Claim:
A process for preparing a liquid rubber composition for a cured thermoset resin, wherein the liquid rubber composition is characterized as being miscible in the uncured state of the thermoset resin and immiscible in the cured state of the thermoset resins, the liquid rubber composition comprising polymer chains having at least one non-functional aromatic terminal end-group and at least one unsaturated end group, a weight average molecular weight of at least 500 g/mol, a glass transition temperature less than 0° C., the process comprising initiating polymerization of a reaction mixture comprising a nonaromatic peroxide initiator, an aromatic solvent, and a free radical-initiated polymerizable low Tg monomer; conducting the polymerization in a batch process; and maintaining the polymerization at a temperature of 25° to less than 300° C. for a time effective to form a reaction product containing the polymer chains.