Abstract: Thermoplastic molding compositions modified with carboxyl groups and comprising:A) at least one polyarylene ether andB) if desired, at least one filler or reinforcing material, wherein the molding composition also includesC) at least one modified polyarylene ether which contains carboxyl groups and has recurring structural elements of the formulae I and II ##STR1## where Ar, Ar.sup.1, Ar.sup.2, Ar.sup.3, T, Z, Y, t, q, x and n are as variously defined, andR.sup.1 is H, C.sub.1 -C.sub.6 -alkyl or --(CH.sub.2).sub.n --COOH; and where the molar ratio of units of the formula I to units of the formula II is in the range from 0.05:99.95 to 99.95:0.05;the use of these molding compositions for producing films, fibers and shaped articles, and the objects produced using the molding compositions, are described.

Abstract: Molding materials containingA) from at least 60% by weight of polyarylene ethers are mixed withB) from 0.001 to 0.2% by weight of a carbonate or bicarbonate of an alkali metal or a mixture thereofand furthermoreC) from 0 to 40% by weight of additives or processing assistants or mixtures thereof based on the components A to Cand a process for producing such molding materials.

Abstract: Polyimides are obtainable by reacting a dianhydride component with a diamine component, at least one diamine containing cycloaliphatic units, with the proviso that the dianhydride component is a mixture of different dianhydrides if the diamine component consists only of one diamine containing cycloaliphatic units and the diamine component is a mixture of different diamines if the dianhydride component consists of only one dianhydride.

Abstract: Polyimides can be obtained by reacting a dianhydride component comprising 3,4,3',4'-bisphenyltetracarboxylic dianhydride, oxydiphthalic dianhydride and in addition further aromatic dianhydrides, and a diamine component comprising diamines of the formula ##STR1## and in addition further aromatic diamines.