非等溫中空纖維膜紡絲模流分析

Numerical Simulation of Non-isothermal Melt-spinning Hollow Fiber Membrane

洪偉登(Wen-Deng Hong)

指導教授 ： 蘇淵源

國立臺北科技大學/工程學院/化學工程研究所/碩士(2011年)

摘要

非等溫拉伸法在中空纖維膜的製作過程中由於不需溶劑、稀釋劑或任何添加劑為最具環保及經濟的製程。再者由於製程中的拉伸效應會造成高分子順向配位，使得拉伸法製作的中空纖維濾膜具有高的機械強度。
所以本研究將利用三維有限元素法與Remesh/optimesh 3D和EVSS/SU的數值方法互相搭配，針對非等溫延伸法中空纖維膜之熔融紡絲部份進行有系統的模流分析，模擬時所需的材料為聚丙烯，其材料參數經由平板式流變儀和毛細管式流變儀測得知流變數據，經由polymat擬合得之。
我們使用能展現黏彈性質之材料本質方程式，依序模擬黏度、流量、彈性、出紡口冷卻條件、拉伸力及紡嘴型式對中空率之影響，瞭解材料性質與操作條件對中空纖維膜中空率的影響，並提出決定中空纖維膜中空率的關鍵因素。
模擬結果分成兩部分，觀察出紡口200 mm，黏度、流量越低、較高冷卻溫度下，配合鬆弛時間較大，則可得較高中空率，另一方面在仿真操作談及固化現象，流量為最重要之參數。然而流量、冷卻溫度在較高數值下，中空率相對而言也會較高。整體而言，拉力對中空率，會有提升速率效果。

關鍵字

中空纖維膜 ； 非等溫延伸法 ； 中空率 ； 黏彈性質

並列摘要

Non-isothermal stretching melt-spinning in the manufacturing of hollow fiber membrane, having no need of solvents, diluents and additives, is regarded as the most environmentally friendly and economical system. In addition the elongation effect coming from stretching operation makes stretched hollow fiber membrane have higher mechanical strength. This study uses three-dimensional finite element method to systematically simulate the melt-spinning process of hollow fiber membrane under non-isothermal stretching operation and investigate the influence of temperature-dependent viscosity, flow rate, relaxation time, stretching global force and stretching velocity in the hollow percentage.
Firstly, our simulation results demonstrate hollow fiber states, 200 mm below the spinneret. It shows that the lower viscosity and flow rate, the higher hollow percentage is. Higher cooling temperature and relaxation time also obtains higher hollow percentage. Secondly, the hollow fiber states at solidification point are discussed. It indicates that a imposed stretching force leads to a suddenly increase in hollow percentage and higher flow rate and cooling temperature can obtain higher hollow rate than that of hollow fibers, 200 mm below the spinneret.

並列關鍵字

non-isothermal stretching ； hollow fiber membrane ； hollow percentage

參考文獻

﹝34﹞ 申博元，中空纖維黏合機制及其模具設計之探討，台北科技大學，2005.

﹝1﹞ C. Cao, K.P. Pramoda, T.S. Chung, Y. Li, “Fabrication of dual-layer polyethersulfone(PES) hollow fiber membranes with an ultrathin dense selective layer for gas separation”, J. Membr. Sci., 245, (2004), 53.

﹝2﹞ J.J. Shieha, S.H. Leea, T. Zhoua, T.S. Chungb, Z.G. Penga, “A study on pilot-scale degassing by polypropylene (PP) hollow fiber membrane contactors”, Desalination, 234, (2008), 316.

﹝4﹞ E.J. Choi, S.Y. Kim, Y. Kwon, “One dimensional simplification in modeling som basic polymer processing operations 1.extrudate swell and fiber melt spinning”, Rheological Acta., 37, (1998), 601-613.

﹝5﹞ J.C. Slattery, S. Lee, “Analysis of melt spinning”, Journal of Non-Newtonain Fluid Mechanics., 89, (2000), 273-286.