| dc.description.abstract | Spin finishes with various wetting properties were prepared by incorporating different wetting agents into the formulated basic spin finish master batches. They were then applied to PET high-speed melt spinning yarns. Variations of the tensile strength at 60% elongation (BE60) and the variation in mass per unit length along the yarn (yarn evenness) of the yarns were evaluated together with the corresponding dynamic contact angles of the PET film、dynamic surface tension of the spin finish emulsion and on-line spin finish distribution (Rossa SD) on the PET yarn. A decreased BE60 was found when the dynamic contact angles decreased. This indicates that spin finishes had diffused into the fiber core and, therefore, reduced the fiber strength. Comparing with the spin finish distribution, we concluded that the dynamic contact angle was the dominant factor for the plasticization of the PET yarn. The wetting behavior of the fiber surface was evaluated by measuring the on-line spin finish distribution at various distances from the spin finish applicator. It showed that the spin finish continued to spread rapidly on the yarn surface at distances smaller than 120cm. The yarn evenness was decreased, with a poor on-line spin finish distribution, and with an increased difference between the dynamic surface tensions, Δγd, for bubbling rates of 1Hz (γ1Hz) and 6Hz (γ6Hz). The on-line spin finish distribution increases with Δγd to a Δγd value of 1.7 dyne/cm. Thereafter, further increasing Δγd caused spin finish splashing from the yarn, reducing the extraction weight of the spin finish from the PET yarn. However, yarn evenness initially decreased as Δγd increased, but leveled off when Δγd exceeded 1.7 dyne/cm. Comparing with the surface friction and the surface dielectric property, we concluded that the dynamic surface tension of the spin finish emulsion played a dominant effect on the PET high-speed melt spinning.
In addition, poly (ethylene terephthalate) (PET) was blended with different amount of TiO2 nanoparticle, and then spun into fibers at different diameters. The TiO2 nanoparticles showed aggregations on the fiber surface. The aggregates became larger as the content of TiO2 nanoparticle increased and/or the diameter of spun fiber decreased, which led to an increased C1s/O1s ratio calculated from the ESCA survey scan spectra. Results also showed that the TiO2 nanoparticles showed a preference to distribute on the fiber surface, which caused unevenness of the fiber surface and led to a greatly reduced frictional force on the fiber surface. By the way, based on different amount of TiO2, a broad range of yarn friction could be made, which would provide promise to potential performance in fiber industry. | en_US |