Polymer alloy of poly (arilentioeter) and a process for producing it.

A composition polyarylene thioether obtainable by radical polymerization of 0.1 to 100 parts by weight of at least one monomer polymerisable REDICALMENTE IN THE PRESENCE OF 100 parts by weight of particulate polyarylene thioether having a repeating UNIT FORMULA (I). AS THE MAIN CONSTITUENT, wherein at least part of the monomer is polymerized WITHIN THE PARTICLE PORORS.