Process for modification of polyphenylene ether or related polymers with a cyclic acid anhydride and the use thereof in modified, high temperature rigid polymer of vinyl substituted aromatics

Process for incorporating a modified polyphenylene ether into a poly(vinyl substituted aromatic) polymer, comprising polymerizing a vinyl substituted aromatic monomer in the presence of the modified polyphenylene ether obtained by a previous reaction of a polymer of the formula:

• ##STR4## wherein R.sub.1 and R.sub.4 each represent hydrogen, halogen, a phenyl group, alkenyl group, alkadienyl group, an aryloxy group, or wherein R.sub.1 and R.sub.4 each represent an alkyl group or an alkoxy group, each of the latter containing 12 or less carbon atoms and each optionally substituted by halogen, cyano, hydroxy, phenyl or amino, whereas alkyl or alkoxy groups attached to the terminal phenol nucleus of the chain optionally are substituted by an amino, dialkylamino or a di(alkanoyl) amide group, wherein the alkyl groups each contain 4 or less carbon atoms, wherein R.sub.2 and R.sub.3 each represent hydrogen, halogen, a phenyl group, alkenyl group, alkadienyl group, aryloxy group, or wherein R.sub.2 and R.sub.3 each represent a primary or secondary alkyl group or alkoxy group as defined for R.sub.1 and R.sub.4, optionally substituted by halogen, cyano, hydroxy, phenyl, and wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 represent different or the same groups in one repeating unit, and n represents an integer having a value of at least 50, with a cyclic acid anhydride of the formula:
• ##STR5## wherein Y represents a bivalent radical of the formulae ##STR6## wherein m represents an integer in the range of from 2 to 8 and wherein R.sub.5 and R.sub.6 each independently represent an alkyl group of 1 to 4 carbon atoms, a phenyl group or an aralkyl group or wherein R.sub.5 and R.sub.6 together with the carbon atoms of the double carbon-carbon bond form a cycloalkenyl, cycloalkadienyl or aryl group, in the presence of a non nucleophilic base and in an inert polar organic solvent.