| Summary: | 碩士 === 國立臺北科技大學 === 化學工程研究所 === 96 === At present, fiber fabric not only has cold-proof functions for the clothes, but expect to has additional functions of picking up the moisture, arranging sweat and can be fluffy and keep glossiness on the sense of touch. In recent year, experimentalists are developing the function fibers, such as the conjugated fibers, profile fibers, and extra-thin fibers, etc. In this study we use the three-dimension finite element method to carry out the numerical simulation of conjugated fibers and profile fibers. Three types of constitutive equations, such as Newtonian fluid, Maxwell model and PTT model, were implemented to simulate the considered flow system.
In general co-extruding eccentric sheath/core conjugated fibers is made of two melting polymers from the same spinneret and contained within the same filament. Because the core layer is eccentric, an uneven cross-sectional configuration and different shrinkage of each compositions likely wrap themselves into a helical configuration upon post treatment. Not only have fluffy on the sense of touch, but also achieve additional function of picking up the moisture and arranging the sweat. Numerical simulation is utilized to investigate the effects of material viscoelasticity and operating conditions on the eccentricity of co-spun fibers. Nylon and CO-Nylon with hydrophilic function is considered as the core layer, PET and CO-PET in the sheath layer. After the determination of material parameters, the effect of viscosity, elasticity, shear thinning viscoelasticity and eccentricity of entrance on the eccentricity are investigated.
Profile fibers were made by changing geometry of spinneret. Using the surface channel formed in the fibers to absorb the sweat, diffuse, transmit, move to the surface of fabric and disperse rapidly, thus achieve the goal of leading the fabric dry. In this study, we simulated the change of the cross-sectional shape for W-typed and cross-typed fibers when they emerge from the spinneret. We first performed rheological measurements for CO-PET, CO-Nylon, PET, and PP15, and proceeded to fit the experimental data to Newtonian fluid, Maxwell, and PTT models. After the determination of material parameters the effect of viscosity, elasticity, shear thinning viscoelasticity and operation conditions on the cross section difference between the profile fiber and the spinneret was investigated respectively.
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