Abstract: Process for the production of aromatic polyester resins starting from resins with an IV from 0.1 to 0.4 dl/g comprising the steps of blending the resin with a dianhydride of a tetracarboxylic acid, extruding the resin under the form of a strand, cooling the strand or the chips obtainable by cutting the strand, at a temperature between 150° C. and 210° C. and maintaining the same temperature for sufficient time to obtain a crystalline product wherein the DSC curves of the same do not show presence of premelt peaks or only so in a negligible amount.

Abstract: Process for the crystallization of aromatic polyester resins having IV between 0,5 and 0.7 dl/g wherein the resin is extruded in the form of a strand at extruder exit or the chips obtained by cutting the strand are crystallized maintaining them at temperature between 160° C. and 220° C. for sufficient time to obtain a crystallized product wherein the DSC curves do not show the presence of practically any premelt peaks.

Abstract: Aromatic polyester resins, having improved mechanical and hydrolysis resistant properties, by mixing said aromatic polyester resin with a phenoxy resin, a dianhydride of a tetracarboxylic acid and liquid crystals.

Abstract: Polyester resins containing up to 5% by weight of a polymeric liquid crystal and an upgrading agent capable of increasing the I.V. of the resin by polyaddition reaction in the solid state with the end groups of the resin. Fibers, films and biaxially oriented articles obtained from the resins.

Abstract: Process for the production of aromatic polyester resins starting from resins with an IV from 0.1 to 0.4 dl/g comprising the steps of blending the resin with a dianhydride of a tetracarboxylic acid, extruding the resin under the form of a strand, cooling the strand or the chips obtainable by cutting the strand, at a temperature between 150.degree. C. and 210.degree. C. and maintaining the same temperature for sufficient time to obtain a crystalline product wherein the DSC curves of the same do not show presence of premelt peaks or only in a negligible amount.

Abstract: Articles from a polyester resin reinforced with glass fiber obtained by melt-shaping of the resin mixed with the glass fiber and a polyfunctional compound capable of increasing the intrinsic viscosity of the resin by addition reactions with the end groups of the rein using melt residence times during the shaping phase lower than 120 sec. and temperatures lower than 300.degree. C.

Abstract: Process for the solid state polycondensation of polyamide resins by the use in the polycondensation reactor of a quantity of an inert gas such that the ratio by weight between the solid capacity/h at the reactor outlet and that one of gas fed into the reactor is lower than 0.5.

Abstract: A process for the preparation of polymeric alloys from polyester resins and polymers containing groups capable of giving addition reaction with functional compounds containing at least two reactive groups comprising the melt state mixture stage of polyester resin, reactive polymer and functional compound of mixture pelletizing and following polyaddition reaction in the solid state at temperatures between 150.degree. and 220.degree. C. to obtain an increase of the polymer intrinsic viscosity of 0.1 dl/g in comparison with the starting polyester resin.

Abstract: Cooling process for polyester and/or polyamide resins downstream of solid-state polycondensation plants in which the cooling is carried out by passing the solid material through two types of equipment in series, of which one is a fluid-bed, the other is a solid/wall cooling equipment. The fluid bed equipment is fed with a stream of inert-gas coming from the solid-state polycondensation reactor, previously subjected to by-products purification, drying and cooling.

Abstract: Concentrates of dianhydrides of tetracarboxylic acids in polycarbonate resins containing up to about 50% by weight of dianhydride. The concentrates can be added to aromatic polyester resins in the melt in quantities equivalent to contents of dianhydride from 0.05 to 2% by weight of the resin.

Abstract: Aromatic polyester resins are continuously crystallized in a fluid bed crystallizer, where the fluidizing gas (nitrogen) enters at a temperature not lower than 195.degree. C. and the average residence time is higher than 5 minutes.

Abstract: Process for the solid state polycondensation of polyester resins, where an inert gas is circulating in a moving bed of polymer at a temperature between 180.degree. and 230.degree. C., characterized by the fact that the ratio by weight between the gas rate of flow per hour and that one of the discharged polymer is lower than 0.6.

Abstract: Polyamide resins characterized in melt state by high sensitivity to shear forces and high visco-elasticity, obtained by polycondensation/polyaddition in the solid state in presence of polyfunctional compounds capable of reacting with resin terminal groups and/or in presence of polyester resins employed in quantity up to about 40% by weight of the resin mixtures.

Abstract: Filaments from a polyester resin having an elastic modulus higher than 30 GPa and stress at break greater than 300 MPa. The filaments are obtained by upgrading under stretch filaments prepared from polyester resin mixed in the melt with a polyfunctional compound able to increase the polymer intrinsic viscosity by addition reaction in the solid state with the terminal groups of the resin.

Abstract: Polyester resins containing up to 5% by weight of a polymeric liquid crystal and an upgrading agent capable of increasing the I. V. of the resin by polyaddition reaction in the solid state with the end groups of the resin. Fibres, films and biaxially oriented articles obtained from the resins.

Abstract: A new process has been developed for separating the water and acetic acid present in the aqueous phase contained in cellulose acetate flakes precipitated from esterification solutions of cellulose. The process includes the step of simultaneously extracting water and acetic acid from the aqueous phase with supercritical carbon dioxide until the content of water and acetic acid in the flakes is substantially reduced.

Abstract: Aromatic polyester resins having improved color characteristics obtained incorporating in the resins in the preparation phase of the resin by polycondensation of a diol with an aromatic bicarboxylic acid a violet toner formed of 9,10 anthraquinone -2-hydroxy-4-p-toluidine or having an absorption spectrum comparable to that of the above anthraquinone compound.

Abstract: Process for the purification of an inert gas recycled from a solid state polycondensation (SSP) reactor of aromatic polyester resins, comprising the step of adding the gas with oxygen or gas containing oxygen in stoichiometric quantity or in such an excess that the gas at the outlet of the catalytic bed contains no more than 250 ppm of oxygen, circulating the gas on a catalytic bed comprising Pt or Pt and Pd heated at temperatures from 250.degree. to 600.degree. C. and recycling the gas to SSP reactor with previous drying to eliminate the water formed in the oxidation stage.

Abstract: Process for the production of polyester resins suitable for the manufacture of fibers including a phase of esterification of an aromatic dicarboxylic acid with an alkylenic glycol or of transesterification of a diester of the dicarboxylic acid with the alkylenic glycol, of polycondensation of diester obtained to form a prepolymer with intrinsic viscosity between 0.2 and 0.5 dl/g and, lastly, of polycondensation of the melt polymeric mass added with a dianhydride of a tetracarboxylic acid kept in agitation and on which an inert gas current is circulated.

Abstract: Process for the purification of inert gases containing impurities of organic nature particularly of gas (nitrogen) coming from solid state polycondensation reactors or polyester resins including the gas treatment with the stoichiometric quantity (or slightly higher) of oxygen as regards the present impurities at a temperature between 250.degree. and 600.degree. C. by using Pt or Pt/Pd catalysts supported on a porous solid and the gas recycling directly to the polycondensation reactor before drying to eliminate the water produced during the reaction of impurities oxidation.