Abstract: A process is described for oxidative polymerization of a monomeric 2,6-disubstituted phenol in the presence of a catalyst comprising a manganese compound, an N-alkylalkanolamine and a basic compound. The process produces a polyphenyleneether which does not exhibit deterioration in molecular weight and undesirable coloration when subject to heat, such as the heat ordinarily applied in molding. The polyethyleneether have excellent tensile strength and elongation.

Abstract: A graft copolymer having enhanced moldability with high mechanical strength capable of forming a molded article having excellent gloss, transparency and color is prepared by grafting styrene polymer segments formed under specific conditions selected onto the backbone polymer of polyphenylene ether. Said styrene polymer segments are formed by melting and kneading continuously a mixture of (a) polyphenylene ether expressed by the general formula of: ##STR1## WHEREIN R.sub.1 and R.sub.2 represent an alkyl group having 1-4 carbon atoms or a halogen atom, respectively, and n represents the degree of polymerization and is 90-250, (b) a styrene polymer containing at least 80 weight % of styrene units and (c) styrene-containing monomers in the presence of a radical initiator at a temperature in the range from 160.degree. to 300.degree. C thereby to complete graft polymerization within a time ranging from 0.