Abstract: Unsaturated polyester resins to which thermotropic polymers have been added may be cured with a smaller quantity of copolymerizable monomer for a given viscosity of the unsaturated polyester and are useful for the production of moulded parts and grouting and filling compositions which have wide applications in the building industry, the electrical industry, boat building, medical technology and the motor vehicle industry.

Abstract: The new bisesters of unsaturated carboxylic acids corresponding to the following formula ##STR1## may be used in curable polyester resin mixtures which may in turn be used for the production of moldings. The curable mixtures obtainable from the new bisesters of unsaturated carboxylic acids show a higher glass transition temperature than normal polyester resins and, despite a higher crosslink density, show broader-mesh crosslinking.

Abstract: Thermotropic, fully aromatic polyesters and polyester carbonates are produced by esterification of optionally substituted p-hydroxybenzoic acids and aromatic dicarboxylic acids with diaryl carbonate at temperatures in the range from 100.degree. to 220.degree. C. and subsequent transesterification of the aryl ester obtained with diphenols and, optinally, more diaryl carbonate, accompanied by polycondensation, at temperatures in the range from 250.degree. to 330.degree. C., the esterification, the transesterification and the polycondensation being carried out in the presence of heterocyclic compounds containing 1 to 3 nitrogen atoms.

Abstract: Thermotropic fully aromatic polyester carbonates containing condensed residues of optionally substituted 3-hydroxybenzoic acid have great rigidity, impact strength and elongation at break and yet can be processed under the usual conditions owing to their advantageous fusion viscosity.