Abstract: In the preparation of impact-resistant alkenyl aromatic resinous polymers such as impact polystyrene containing halogenated monomer such as a brominated methacrylate, improved physical properties are obtained if the brominated monomer is added after phase inversion of the rubber and at a rate sufficiently slow as to maintain the identity of the rubber particles.

Abstract: An improvement in the process of forming plastic articles wherein such articles are forged from a compression formed briquette of resinous powder, such improvement comprising (1) compressing a resinous powder having lamellar crystalline nonspherulitic morphology into a substantially unoriented briquette having green strength, (2) removing the briquette from the compressing device and placing the briquette in a forging press wherein lubrication is provided between the contacting surfaces of the briquette and the forging press to permit plug flow, and (3) forging the briquette into a shaped article while maintaining the briquette at a temperature between the alpha-transition temperature and the melt temperature of the resinous powder.