| Summary: | 碩士 === 國立臺北科技大學 === 化學工程所 === 94 === In recent years, fibers have developed in various types. In order to increasing the soft sense of touch and gloss, even give the new function of picking the moisture up, exclude the sweat, engineers change the die of geometry to forming micro fiber. The conjugated fiber process is the most economic and high-precision technique to manufacture synthetic fibers at present. The conjugated fiber process is the most economic and high-precision technique to manufacture synthetic fibers at present. It is known that conjugated spinning can gain Self-crimp fibers like natural wool. We are sure that two molten components with smooth interface are helpful to forming of self-crimp fibers. In addition, dog-legging phenomenon will reduce the economic benefits cause too much different property in two molten polymers. For this reason, study of controlling the material parameter and manufacturing process are important.
In this study, we utilizing the finite element approach with optimesh-3D remeshing craftsmanship is applied to investigate the interfacial encapsulation of conjugated fibers and dog-legging phenomena in the spinning process. The thesis consists of two major topics. First, we will express polymeric rheology behavior like zero-shear rate viscosity（η0）, infinite-shear rate viscosity（η∞）, nature time（λn）, relaxation time（λ）,ratio（γη）,elongation effect（ε）,shear-thinning effect（ξ）in Constant viscosity, Bird-Carreau model, Maxwell, Oldroyd-B and PTT model as the differential constitutive equation. After that, our study will examine interfacial encapsulation and performance of dog-legging phenomenon narrowly. From research result, the less viscous melt wraps around the more viscous melt, it is crucial to obtain straight interface depends on . Reducing the λ,ε,ξ,increasing γη are helpful to the formation of straight interface, and then reduce dog-legging phenomenon.
Secondarily, determination of constitutive equation and material parameters with the aid of experimental data of materials of PET and PBT, the influence of temperature, and flow rate of molten polymers in the interfacial encapsulation of side-by-side and dumbbell conjugated fibers is numerically investigated and the results were compared with experimental results of conjugated fibers by coextrusion process. It is due to not clear in elastic property of material. The viscosity of molten polymer is the controlling factor in interfacial encapsulation and dog-legging phenomenon. In order to getting the optimize manufacture condition, we utilize the Bird-Carreau model for constitutive equation with PET@290℃, PBT@255℃, the flow rate ratio is close to 50/50.
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