The improvement of gel spinning fibers as clothing materials

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In accordance with the recent dramatic development of polymer science, a number of researches have been carried out to produce synthethic fibers with different performance characteristics. The present studies deal with primarily with the investigation of the influence of molecular weight on drawability in order to prepare high strength and high modulus fibers of poly- -olefins, polyamide, polyester, and cellulose. Special attention has been paid to morphological properties because they have a significant effect on mechanical and thermal properties.Throughout this study, the morphology and the mechanical properties of semicrystalline polymers were clarified. More precisely, (1) The crystal lattice moduli in the chain direction for polyethylene (PE) and polypropylene (PP) are independent of temperature close to their melting Points, but their Young's moduli decreases with temperature. This is due to a decrease in their crystallinity with temperature. (2) The crystal lattice modulus and the linear thermal expansion coefficient measured by X-ray diffraction are different from the intrinsic crystal lattice modulus and the coefficient in a general polymeric system, in which the oriented crystalline layers are surrounded by an oriented amorphous phase. (3) The origin of the crystal dispersion of PE and PP are dependent upon their own morphology. Namely, the activation energies of the crystal dispersion become lower with increasing draw ratio. (4) The cross-linking of PE is performed with a chemical reaction using dicuml peroxide under drawing process of the dried gel film. The drastic improvement in high temperature resistance is realized for the specimens with Young's modulus of 100 GPa at 20ﾟC.