Solid‐state polymerization of melt‐spun poly(ethylene terephthalate) fibers and their tensile properties

Abstract

The production of high modulus and high strength poly(ethylene terephthalate) fibers was examined by using commercially available melt-spun fibers with normal molecular weight (intrinsic viscosity ¼ 0.6 dL/g). First, molecular weight of as-spun fibers was increased up to 2.20 dL/g by a solid-state polymerization, keeping the original shape of as-spun fibers. Second, the polymerized as-spun fibers were drawn by a conventional tensile drawing. The achieved tensile modulus and strength of as-drawn fibers (without heat setting) were 20.0 and 1.1 GPa, respectively. A heat setting was carried out for the as-drawn fibers. Tensile properties of the treated fibers were greatly affected by the condition of the heat setting. This was related to the increase of sample crystallinity and molecular degradation during the treatments.

A novel and green method for polycondensation reaction of 4‐substituted phenylurazoles with different diisocyanates under solvent‐free conditions

“…Only linear chains seem to be formed,9 and usually SSP products show greater heat stability in the molten state than samples prepared in the melt; on the other hand, their monomer and oligomers content is so low because of which there is no necessity for it to be removed. Furthermore, the increase in the molecular weight during SSP is accompanied by increased crystallinity and crystal perfection,10, 11 while drying the polymer, which is important because moisture content may influence processability in the manufacture of yarns 12. In addition, there is virtually no environmental pollution, because no solvent is required, and the method can be a continuous operation 13.…”

“…Agglomeration of the reacting particles has also been reported during SSP, especially at high reaction temperatures, and is related to a low softening point of the reacting mass and to condensate retention in the system 18–20. Because of aforementioned advantages of this method of polymerization, recently a number of methods have developed in which polymers was prepared without use of solvent such as supercritical carbon dioxide,11, 21 polymerization of functional monomers on solid support,22 photoinitiated chemical vapor deposition (piCVD), which is an evolutionary CVD technique for depositing polymeric thin films in one‐step without using any solvents23 and the polymerization reaction in the water as a solvent 24…”