Abstract: A poly(ethylene terephthalate) polyester composition which is decreased in the amount of a cyclic trimer of ethylene terephthalate formed in melting, and a method for producing the same.

Abstract: A polyamide resin composition comprising a polyamide and an alkaline earth metal compound, wherein the amount of a cyclic monomer formed by melting said composition under the conditions of a moisture content of 0.02% by weight or less, at 0.01 Torr or below, at 250.degree. C., and for 8 hours is not more than 0.7 parts by weight per 100 parts by weight of the polyamide; and fibers, films and molded articles with the use of the same.

Abstract: A high tenacity, high initial modulus polyvinyl alcohol fiber is produced by:(1) dissolving polyvinyl alcohol with a degree of polymerization of not less than 1,500 in a solvent capable of giving a 5 wt % polyvinyl alcohol solution and the solvent is further characterized in that the nuclear magnetic resonance spectrum measured at 50.degree. C. after storage of the solution at 50.degree. C. for 96 hours following preparation thereof is substantially identical with that measured at 50.degree. C. immediately after preparation thereof, with peaks for the three kinds of hydroxyl groups of polyvinyl alcohol being clearly distinguishable in each nuclear magnetic resonance spectrum,(ii) forming filaments by spinning the spinning solution under conditions which satisfy the requirementsDs.ltoreq.5.0wherein Ds is the spinning stretch ratio defined as the ratio (V.sub.2 /V.sub.1) of the take off speed (V.sub.2) to the first take off roller speed (V.sub.

Abstract: A high tenacity, high intitial modulus polyvinyl alcohol fiber showing a high level of crystalline heat of fusion, characterized in that the fiber is made of polyvinyl alcohol having a degree of polymerization of not less than 1,500, has a tenacity of not less than 17 g/d and an initial modulus of elasticity of not less than 400 g/d and shows a crystalline heat of fusion of not less than 29 cal/g, and a method of producing said polyvinyl alcohol fiber comprising:(i) dissolving polyvinyl alcohol with a degree of polymerization of not less than 1,500 in a solvent capable of giving a 5 wt % polyvinyl alcohol solution and the solvent is further characterized in that the nuclear magnetic resonance spectrum measured at 50.degree. C. after storage of the solution at 50.degree. C. for 96 hours following preparation thereof is substantially identical with that measured at 50.degree. C.