Abstract: A process for preparing a white nylon-4,6 polyamide in an non-aqueous inert polar solvent at atmospheric or only slightly above atmospheric pressure at a temperature of about 150.degree. C. to about 300.degree. C. Higher molecular weight polyamides may be obtained following after-condensation.

Abstract: A process is described for the preparation of high-molecular weight white polyamides, substantially consisting of units of --NH--(CH.sub.2).sub.4 --NH--CO(CH.sub.2).sub.4 --CO--, by the after-condensation of a corresponding low-molecular prepolymer, consisting substantially of a molecular chain of units of --NH--(CH.sub.2).sub.4 --NH--CO(CH.sub.2).sub.4 --CO--, in which process the prepolymer which is employed has been prepared in the presence of an excess of 0.5 to 15 moles-% of 1,4-diaminobutane with respect to the quantity stoichiometrically equivalent to the adipic acid applied. This prepolymer is thereafter subjected to the after-condensation reaction in the solid phase in an atmosphere containing water vapor.

Abstract: A process for the preparation of white nylon 4,6 polyamide of high molecular weight from a tetramethylenediamine adipic acid prepolymer, formed under controlled conditions of temperature and water vapor pressure and wherein the plurality of cyclical end-groups in the prepolymer does not exceed 0.20 mg. equivalent per gram of prepolymer.

Abstract: A new type of poly-2-pyrrolidone suitable for melt spinning and a process for its preparation. The new poly-2-pyrrolidone is characterized in that the polymer in the virgin state has a relative viscosity (1 gram of polymer in 100 ml of 96% sulphuric acid at 20.degree. C.) of between 2.2 and 7.0, shows a weight loss of less than 5% by weight when heated from 20.degree. C. to the onset temperature of thermal degradation at a rate 4.degree. C. per minute, the ratio between the relative viscosities after and before melt spinning ranges between 0.50:1 and 0.95:1, and the relative viscosity after melt spinning is at least 1.90. The new poly-2-pyrrolidone is prepared by polymerization of 2-pyrrolidone in the presence of an anionic catalyst and an accelerator wherein N-(2-caprolactim)-caprolactam is used as the accelerator in an amount of between 0.05 and 5.0 mole percent relative to the monomer, and the polymerization is carried out at a temperature of between about 25.degree. and 70.degree. C.

Abstract: An improved, consistent quality anionic catalyst for polymerizing pyrrolidone, optionally mixed with up to 25% of another copolymerizable lactam, is disclosed in which an alkali metal pyrrolidonate, prepared by reacting an alkali metal hydroxide or alkoxide with a molar excess of pyrrolidone, is heated for at least 5 hours at 100.degree.-175.degree. C. in the absence of water and air. Reproduceable results are obtained when the catalyst so heated is used to polymerize pyrrolidone.

Abstract: Polypyrrolidone polymers and copolymers are obtained by polymerizing 2-pyrrolidone, optionally with another lactam, in the presence of a catalyst and accelerator, first in the mass until at least 10% of the monomer is converted but the reaction product is still capable of suspension, then completing the desired degree of polymerization by suspending the reaction mixture in an inert liquid dispersion agent that does not dissolve the desired polymer. Relatively high molecular weight polymers are prepared in a short amount of time using this two-stage procedure.

Abstract: A process is described for the recovery of 2-pyrrolidone monomer from polypyrrolidone waste material by heating the latter in the presence of a small amount of strong acid, and distilling off the said monomer.

Abstract: A process is described for stabilizing polypyrrolidone against thermal degradation which comprises blending into the polymer from 50 to 5000 ppm of the alkali metal salt of a nickel-biuret complex compound.