Formation of Hollow Fiber Membranes via TIPS

CTS-0004534德克萨斯州道格拉斯·R·劳埃德大学简介扁平和中空纤维形式的聚合物膜是许多工业分离过程的基础。中空纤维几何结构在膜过程中的优势在文献中得到了很好的证明。传统上，相转化技术一直被用来从玻璃聚合物中制备中空纤维。1981年，人们引入了热诱导相分离(TIPS)方法来制备平板薄膜。TIPS允许从更广泛的聚合物材料中生产高性能膜，这些材料由于更好的热稳定性和化学稳定性而在某些应用中提供比相转化膜更好的性能优势。例如，潜在的应用包括强有机溶剂和高浓度其他苛刻化学品的分离，高温分离，微电子工业中蚀刻溶液的净化，食品工业中的乳酸回收，有毒污染物、药物和发酵产品的分离，以及膜蒸馏。在许多这样的膜应用中，具有良好控制的孔结构的各向异性膜是必不可少的。这项研究的目的是提供控制各向异性、微孔、中空纤维膜中孔结构所需的基本知识。本研究项目是一项系统的基础性研究，旨在表征和模拟系统物理性质和工艺参数对通过TIPS工艺形成的中空纤维膜的加工性、微观和宏观结构以及性能的影响。通过模型和实验的平衡，这项研究正在产生控制均匀溶液中的浓度和温度梯度所需的基本知识，并开发实验室规模的各向异性中空纤维的形成过程。建立了一个完全耦合的热、质、动量传递模型，用于预测初生膜在相分离时的温度、浓度和速度分布，以及淬火后膜的表面孔径。

CTS-0004534Douglas R. LloydUniversity of TexasABSTRACTPolymeric membranes in flat sheet and hollow fiber form are the basis of many industrial separation processes. The advantages of the hollow fiber geometry in membrane processes are well documented in the literature. Traditionally, phase inversion techniques have been used to make the hollow fibers from glassy polymers. In 1981, the thermally induced phase separation (TIPS) method for making flat sheet membranes was introduced. TIPS allows the production of high performance membranes from a broader range of polymeric materials that offer performance advantages over phase inversion membranes for certain applications because of greater thermal and chemical stability. For example, potential applications include separations involving of strong organic solvents and high concentrations other harsh chemicals, separations involving elevated temperatures, purification of etching solutions in the micro-electronics industry, lactic acid recovery in the food industry, and separation of toxic pollutants, pharmaceutics, and fermentation products, as well as membrane distillation. In many of these membrane applications, it is essential to have an anisotropic membrane with well controlled pore structure. The objective of the proposed research is to provide the requisite fundamental knowledge necessary to control porous structure in anisotropic, microporous, hollow fiber membranes produced via TIPS.This research project constitutes a systematic and fundamental study to characterize and model the impact of system physical properties and processing parameters on the processability, microscopic and macroscopic structure, and performance of hollow fiber membranes formed via the TIPS process. Through a balance of modeling and experiments, this research is generating the fundamental knowledge needed to control the concentration and temperature gradients in the homogeneous solution and to develop the process for the formation of anisotropic hollow fibers on a laboratory scale. A fully coupled heat-, mass-, and momentum-transfer model for predicting the temperature, concentration and velocity profiles within the nascent membrane at the time of phase separation and surface pore size after quenching is being devised.