Abstract: A method of making billets, whereby a composite billet is produced by continuous casting or rolling, which billet is star-shaped in cross section and has at least two ray members disposed symmetrically relative to the central longitudinal axis of the composite billet; the base of each star ray member of the composite billet at the place of its juncture with the central portion thereof is selected to be 0.72 to 2.3 of the ray member height, the other base being 0.5 to 1.

Abstract: A process for producing high-impact polystyrene which comprises polymerization of styrene in the presence of a reinforcing agent, i.e. a conjugated diolefin polymer, random copolymer, graft-copolymer or block-copolymer of a conjugated diolefin with styrene or a mixture of said copolymers and an anionic catalyst based on organic derivatives of alkali metals or adducts thereof in a medium of inert hydrocarbon solvents such as aliphatic, cycloaliphatic and aromatic solvents or mixtures thereof. On completion of polymerization the resulting polymer is subjected to cross-linking by means of peroxide compounds or redox systems, followed by isolation of the desired product.The process for producing high-impact polystyrene according to the present invention makes it possible to shorten the technological cycle due to increased polymerization rate, to facilitate production technology, and to manufacture polystyrene with improved properties.