Abstract: Thermoplastic cycloolefin copolymers (COCs) having high tear strength and low optical attenuation, a process for their preparation, and their use as optical waveguides (optical fibers).

Abstract: Thermoplastic cycloolefin copolymers (COCs) having low melt viscosity and low optical attenuation, a process for their preparation, and their use as optical waveguides (optical fibers).

Abstract: A thermoplastically processible aromatic polyetheramide, in which the structure comprises the repeating units of the formulae--CO--AR--CO-- (A)and--NH--Ar--O--Ar--X--Ar--O--Ar--NH-- (B)in which Ar signifies a bivalent unsubstituted or substituted aromatic radical having 6 carbon atoms, and whose linkages are in the p-position and X denotes a 2,2-propylidene linkage, the polyetheramide having an intrinsic viscosity [.eta.] in the range of 50 to 750 cm.sup.3 /g, and a glass transition temperature of above 200.degree. C., and a process for its production. The production of the polyetheramide is carried out by a low temperature solution condensation process, a solid phase condensation process, an interfacial condensation process or a melt condensation process.

Abstract: The structure of the aromatic copolyether amide which can be processed as a thermoplastic comprises recurring units of the formulae --CO--Ar.sup.1 --CO-- (A), --NH--Ar.sup.1 --O--Ar.sup.1 --X--Ar.sup.1 --O--Ar.sup.1 --NH (B) and --NH--Ar.sup.2 --NH-- (C) in which Ar.sup.1 denotes a divalent, unsubstituted or substituted aromatic radical having 6 carbon atoms which is linked in the p-position, X represents a 2,2-propylidene link and Ar.sup.2 is identical with Ar.sup.1 or is Ar.sup.1 which is linked in the m-position, or is the --Ar.sup.1 --Z--Ar.sup.1 -- group in which Z is a direct bond or is a radical --CH.sub.2 --, --C(CH.sub.3).sub.2 --, --SO.sub.2 --, --CO--, --O--, --CH.dbd.CH--, --CO--NH-- or --O--Ar.sup.1 --O-- or the radical ##STR1## in which R represents hydrogen or a branched or unbranched alkyl radical having 1-4 carbon atoms. The proportion of units (A) and of the sum of units (B) and (C) is each 100 mol-%, the proportion of units (C) being up to 50 mol-% and, if Z represents --SO.sub.

Abstract: The invention relates to a process for the preparation of aromatic polyethers by condensation of the reactants in the presence of a condensation agent consisting of a mixture of metal carbonates comprising (a) lithium and/or an alkaline earth metal carbonate and (b) sodium, potassium, rubidium and/or cesium carbonate.The combination of carbonates (a) and (b) according to the invention leads to a surprising increase in activity.