Abstract: There is described a family of copolyester compositions for producing heat nd flame resistant fibers, said compositions being prepared by polycondensating (A) an aromatic diacid, (B) a diol, (C) a tetrabrominated diol, (D) a derivative of a polyvalent metal, all said components being hereinbelow defined, the polycondensation process being carried out in several successive stages of copolycondensation of components (A), (B) and (C) until reaching a stable viscosity, then adding component (D), and stopping the reaction before the intrinsic viscosity of the composition decreases below a value proper for subsequent spinning.

Abstract: The present invention relates to polycondensates of the formula 10, their use for absorbing metal ions of the transition elements of the periodic system and their use for the preparation of polymers containing metals of formula 11 which have e.g. improved resistance to heat and to chemicals compared to the corresponding polycondensates of formula 10.

Abstract: A process for preparing certain halogenated aromatic polyesters having a predetermined molecular weight is provided. Such polyesters are prepared by solution polymerization of an appropriate bisphenol and diacid halide wherein the diacid halide is added to a solution containing the bisphenol until the viscosity of the resulting polymer containing solution reaches a predetermined solution viscosity limit at which time the further addition of diacid halide is terminated. The solution viscosity limit is indicative of the attainment of said predetermined molecular weight. The identification of said solution viscosity limit is achieved by a feedback mechanism wherein the viscosity of the polymer containing solution is monitored or sensed during or after the addition of the diacid halide to the bisphenol containing solution.

Abstract: A thermostable flameproofing agent for copolyesters is prepared by reacting ne mol of a diester of an alkali dicarboxyaryl sulphonate with 1-2 mols of at least one tetrabrominated diol in the presence of a transesterification catalyst chosen in the group consisting of compounds of Zn, Co, Ca, Sn, Ti and Mn. Copolyester compositions adapted for the preparation of formed bodies are prepared by the polycondensation of a dicarboxylic arylic acid or its diesters and a saturated aliphatic diol with said flameproofing agent and up to 1% by weight of a derivative of phosphorus in the presence of a catalyst consisting of Sb.sub.2 O.sub.3 or GeO.sub.2. Said compositions preferably have an intrinsic viscosity not less than 0.40 dl/g before their transformation into formed bodies and not less than 0.35 dl/g after said transformation.

Abstract: Aromatic polyester compositions having improved hydrolytic stability comprise, in admixture, (1) a linear aromatic polyester prepared from an aromatic dicarboxylic acid and a bisphenol, and (2) a polymer comprising the reaction product of a styrene/maleic anhydride copolymer and a diene rubber.

Abstract: Linear thermoplastic polyesters obtained from aromatic dicarboxylic acids and diols are modified with dimeric acids. As a result of the lowering in the melt viscosity, processing at lower temperatures is made possible by this means, while the mechanical properties are only slightly changed.

Abstract: This invention relates to a class of synthetic polyesters and copolyesters which display optical anisotrophy in the molten state and to the fibers, films, and other shaped articles obtained from the optically anisotropic melts.

Abstract: Para-ordered aromatic heterocyclic polymers containing pendant phenyl groups along the polymer chain backbones. The polymers possess a high degree of thermal stability that renders them particularly useful in high temperature applications such as in the fabrication of plastics, composites and fibrous materials.