Abstract: Transparent linear resinous conjugated diene/monovinyl-substituted aromatic block copolymers of improved properties are prepared by forming a monovinyl-substituted aromatic homopolymer block referred to as S.sub.1, followed by forming a conjugated diene homopolymer block, referred to as B.sub.1 and linked to segments S.sub.1, followed by the formation of a conjugated diene/monovinyl-substituted aromatic random copolymer block, referred to as B/S and linked to segment B.sub.1, followed by the formation of a monovinyl-substituted aromatic homopolymer block, referred to as S.sub.2 and linked to segment B/S thereby forming the block copolymer S.sub.1 -B.sub.1 -B/S-S.sub.2 wherein the molecular weight of the S.sub.2 block is significantly greater than the molecular weight of the S.sub.1 block.

Abstract: Vinyl aromatic-conjugated diene copolymers having polymer chains which end with an alkali metal and which are obtained by the polymerization in solution of at least one vinyl aromatic hydrocarbon and of a conjugated diene in the presence of a catalyst based on an alkali metal are decolorized by treating the copolymer with a monocarboxylic acid of general formula(Y).sub.2-n --X--(R--COOH).sub.nin which X is S, S--CH.sub.2 --S, or S--S, and Y and R are alkyl radicals having 1 to 16 carbon atoms and n is 1 or 2.