| Summary: | 碩士 === 國立臺灣科技大學 === 纖維及高分子工程系 === 89 === The concentrations and temperatures of ultrahigh-molecular-weight polyethylene (UHMWPE) gel solutions exhibited a significant influence on their rheological and spinning properties. The shear viscosities of UHMWPE solutions increased consistently with increasing concentrations at a constant temperature above 80℃. Tremendous high shear viscosities of UHMWPE gel solutions were found as the temperatures reached 120-140℃, at which their shear viscosity values approached the maximum. The spinnable solutions are those gel solutions with optimum shear viscosities and relatively good homogeneity in nature. Moreover, the gel solution concentrations and spinning temperatures exhibited a significant influence on the drawability and microstructure of the as-spun fibers. At each spinning temperature, the achievable draw ratios obtained for as-spun fibers prepared near the optimum concentration are significantly higher than those of as-spun fibers prepared at other concentrations. The critical draw ratio of the as-spun fiber prepared at the optimum concentration approached a maximum value, as the spinning temperature reached the optimum value of 150℃. Further investigations indicated that the best orientation of Shish-Kebab morphology, birefringence, crystallinity, thermal and tensile properties were always accompanied with the as-spun fiber prepared at the optimum concentration and temperature. Similar to those found for the as-spun fibers, the birefringence and tensile properties of the drawn fibers prepared at the optimum condition were always higher than those of drawn fibers prepared at other conditions but stretched to the same draw ratio. Possible mechanisms accounting for these interesting phenomena are proposed.
|
|---|
