Formation of Hollow Fiber Membranes via TIPS

平板和中空纤维形式的聚合物膜是许多工业分离工艺的基础。中空纤维几何结构在膜工艺中的优势在文献中有很好的记载。传统上，相变技术已被用于从玻璃状聚合物中制备中空纤维。1981年，热诱导相分离（TIPS）法制备了平板膜。TIPS允许从更广泛的聚合物材料中生产高性能膜，由于具有更高的热稳定性和化学稳定性，在某些应用中比相转化膜具有性能优势。例如，潜在的应用包括涉及强有机溶剂和高浓度其他苛刻化学品的分离，涉及高温的分离，微电子工业中蚀刻溶液的纯化，食品工业中的乳酸回收，有毒污染物，药品和发酵产品的分离，以及膜蒸馏。在许多这些膜应用中，具有良好控制孔隙结构的各向异性膜是必不可少的。本研究的目的是为控制各向异性微孔中空纤维膜的多孔结构提供必要的基础知识。本研究项目是一项系统的、基础性的研究，旨在表征和模拟体系物理性质和工艺参数对TIPS工艺形成的中空纤维膜的可加工性、微观和宏观结构以及性能的影响。通过建模和实验的平衡，本研究正在产生控制均质溶液中的浓度和温度梯度所需的基础知识，并在实验室规模上开发各向异性中空纤维的形成过程。设计了一个完全耦合的热、质量和动量传递模型，用于预测相分离时新生膜内的温度、浓度和速度分布以及淬火后的表面孔径。

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.