Abstract: A polymer composition comprises a polymer matrix and a siloxane-containing additive which is substantially incompatible with the polymer matrix, wherein the siloxane of the additive has a hydroxy, alkoxy or epoxy functionality, and a functionality which is capable of bonding with a silicone elastomer-forming composition which is curable by a hydrosilylation reaction. The polymer matrix preferably comprises polyphenylenesulphide, and the additive preferably comprises hydroxy-terminated methylvinyl siloxane. The composition is capable of forming plastics articles to which cured silicone elastomers can adhere.