Abstract: Anisotropic melts are disclosed which can be shaped, based on aromatic polyesters containing linkages of the arylaliphatic ether type.These melts consist of homopolyesters having units of the formulae: ##STR1## in which n equals 4 or 6 and X=H, Cl or CH.sub.3, with the proviso that when n equals 4, X only represents Cl or CH.sub.3, the flow points of these polymers being between 200.degree. and 340.degree. C. These anisotropic melts make it possible to obtain filaments, films and molded articles possessing good mechanical properties.

Abstract: High molecular weight thermotropic copolyesters are disclosed which can be shaped. These copolyesters consist or consist essentially of units of the formulae:(--O--X.sub.1 --O--).sub.a, (--O--X.sub.2 --O--).sub.b, (--O--X.sub.3 --O--).sub.c, --CO--Y--CO-- or --CO--Z--CO--,in which: X.sub.1 represents a monosubstituted para-phenylene radical; X.sub.2 represents an unsubstituted 1,4-phenylene radical; and X.sub.3 represents a disubstituted para-phenylene radical, a 4,4'-diphenylene radical or a p,p'-diphenylene ether radical, where 0.4.ltoreq.a.ltoreq.1, O.ltoreq.b.ltoreq.0.6, O.ltoreq.c.ltoreq.0.1 and a+b+c=1; Y represents a 1,4-cyclohexylene radical, a radical having two phenylene groups joined to one another by a single bond or an acyclic chain, or a divalent aromatic radical having at least two fused phenyl nuclei; and Z represents a radical --(CH.sub.2).sub.n --, in which 3.ltoreq.n.ltoreq.10, the molar ratio Z/Y+Z being between 0.2 and 0.5.

Abstract: A thermotropic carbonate polyester of high molecular weight which can be shaped is disclosed, characterized in that it possesses an inherent viscosity of more than 0.3 dlg.sup.-1 (measured on a solution containing 0.5 g of polymer in 100 cm.sup.3 of a 50/5 by volume mixture of para-chlorophenol and 1,2-dichloroethane) and a flow point which is above or equal to 150.degree. C. and below 330.degree. C., and in that it consists essentially of units of the formulae:--O--R--O--.sub.a, --O--R.sub.1 --O--.sub.b (I) ##STR1## and ti --CO--R.sub.2 --CO-- (III)in which the radicals R, which are identical, each represent a para-phenylene radical which is monosubstituted by a methyl or ethyl group or a chlorine or bromine atom;the radicals R.sub.1 each represent an unsubstituted paraphenylene radical, with 0.3.ltoreq.a.ltoreq.1, 0.ltoreq.b.ltoreq.0.7 and a+b=1; andthe radicals R.sub.

Abstract: A process is disclosed for the production of alkylaromatic copolyesters, characterized in that there are reacted, successively, at a temperature below 250.degree. C., a diester of a dihydroxyaromatic compound and an aliphatid diacid of the general formula HOOC(CH.sub.2).sub.n COOH, in which 3.ltoreq.n.ltoreq.10, with a molar ratio of the diester to the diacid of between 1.5 and 4, until the degree of completion of the reaction is greater than or equal to 85%, and them, at a temperature above 250.degree. C., an aromatic and/or cycloaliphatic dicarboxylic acid, and in that the product obtained is subjected to a polycondensation reaction under reduced pressure for a duration which is less than or equal to 1 hour 30 minutes. This process makes it possible to produce copolyesters which may be readily converted in the molten state to threads, films and molded articles.

Abstract: Disclosed are block-type aryl copolyesters, the process for obtaining these as well as the filaments produced therefrom, and the process for obtaining such filaments.The aryl copolyesters contain from 10 to 90% of recurring flexible units of the formula ##STR1## WHERE R is an aliphatic, alicyclic or araliphatic radical, x is an integer from 2 to 6, and y = 0 or 1, andFrom 90 to 10% of recurring rigid units of the formula ##STR2## and have an inherent viscosity of at least 0.25. The raw spun filaments produced therefrom possess a modulus of elasticity of at least 1,000 g/tex, and preferably at least 1,500 g/tex, and are obtained by melt-spinning at a temperature such that the copolyester is optically anisotropic at rest and in the relaxed state, followed by winding up the filament in a per se known manner. Such filaments can be used advantageously as reinforcing filaments.