Study On The Modification Of Melt-spun Polyurethane Fibre

To improve the properties of melt-spun polyurethane fibre and enlarge it's application, the effects of several additives on the spinnability, microstructures, rheological property and other physico-mechanical properties of thermoplastic polyurethane were studied with Hakke torque and capillary rheometers, infrared spectra,X-ray diffraction and other measurement devices. The correlation between crystallinity, elasticity and heat resistance of the melt-spun and dry-spun polyurethane fibres were discussed and compared based on the degree and the size of crystallization and tensile properties. The effect of the heat set treatment under different temperatures on the microstructure and properties of polyurethane fibre were analysed. Here are the important findings: 1. The plasticization, the physical and chemical interactions of coupling agents with polyurethane and the reinforcement of coupling agent pretreated nanoparticles all increased the polymer melt viscosities.While in the loading and melting processes of the polymer with additives, the polymer molar mass was reduced rapidly. 2. Nanoparticles formed by coupling agents and funcationalized silicone oils via self-condensation with good dispersions made the spinning process smooth, while plasticizer showed excellent spinnability. Plasticizer increased the degree of crystallization, and thus improved the mechanical properties and thermal stability of polyurethane.The combination of plasticizer S and coupling agent A remarkably improved the mechanical properties and elasticity of the melt-spun fiber.With the increase of the plasticizer, extension work and mechanical loss became large.Functionalized silicone oils did form a rubbery island phase deduced from the calculation of mechanical loss. 3. The heat set treatment and heat resistance crosslinking agent can both improve the heat-resistance of melt-spun polyurethane, so did the ratio of dry-heat recovery.The ratio of dry-heat recovery of the modified fibers CR-ESC (crosslinking) and CR-ESH (heat) were 58.8% and 60.2%, while the unmodified CR-ES was 56.2%. 4. The temperature of heat set treatment was suggested to be 100-120℃when the plasticization of plasticiser, the self-condensation of the functionalized silicone oils and coupling agents, the diffusion and thermal degradation of the macromolecular chain were considered. Finally, the ratio of dry-heat recovery of melt-spun fibre, dyeing temperature and the heat set treatment temperture for the fabrics from the fibers made from industrial production line were 66%, 110℃and 140℃respectively, instead of 56.2%, 90-100℃and 125℃respectively. Major properties had come close to those of the imported counterpart from Japan.