DEVELOPMENT OF NEW POLYETHYLENE HOLLOW FIBER MEMBRANE WITH ASYMMETRIC STRUCTURE USED FOR WATER RECYCLE SYSTEM

1.萃取干燥对微孔聚乙烯膜结构的影响用10种不同的萃取剂脱除聚乙烯膜中的矿物油，用两种不同的蒸发条件脱除萃取剂，制得微孔膜。考察了萃取剂的选择和干燥条件对膜形态的影响，并用膜的尺寸、微观结构和渗透率进行了表征。萃取剂的溶解度参数、沸点和表面张力与膜的形态有关。热诱导相分离法制备聚(乙烯-乙烯醇)(EVOH)膜的热力学和动力学研究随着EVOH中乙烯含量的增加，液-液界面(双节线)向高温方向移动。对于乙烯含量为32-44摩尔%的EVOHs，形成了泡孔，而对于乙烯含量为27摩尔%的EVOHs，则只发生了聚合物结晶。热诱导相分离法制备聚乙烯/EVOH中空纤维膜及其性能研究采用TIPS法制备了微孔PE/EVOH膜。详细考察了聚合物相对分子质量、气隙间距、冷却浴组成、乙烯含量等实验条件对膜性能的影响。通过热诱导相分离模拟不对称结构的形成用具有聚合物浓度梯度的聚丙烯-二苯醚溶液制备了一侧小孔、另一侧大孔的非对称膜。基于Cahn-Hilliard模型，对变节分解相分离过程进行了模拟。模拟结果与实验结果吻合较好。

1. Effect of extraction and drying on microporous polyethylene membrane structureTen different extractant and were used to remove mineral oil from polyethylene films and two different evaporation conditions were used to remove the extractant and produce microporous membranes. The dimension, microstructure and permeability of the membranes were used to measure the impact of extractant choice and drying conditions on the membrane morphology. The solubility parameters, boiling points and surface tensions of the extractants were related to the membrane morphology.2. Thermodynamic and kinetic studies on the poly (ethylene-co-vinyl alcohol) (EVOH) membrane formation by thermally induced phase separationThe liquid-liquid phase boundaries (binodal line) was shifted to higher temperature when ethylene content in EVOH increased. For EVOHs with ethylene content of 32-44 mol%, cellular pores were formed, while only polymer crystallization occurred for EVOH with 27 mol% ethylene content.3. preparation and Characteristics of polyethylene and EVOH hollow fiber membranes via thermally induced phase separationMicroporous PE and EVOH membranes were prepared by TIPS process. The effects of the experimental condition such as polymer molecular weight, air gap distance, cooling bath composition and ethylene content of EVOH on the membrane performance were investigated in detail.4. Simulation of asymmetric structure formation via thermally induced phase separationAsymmetric membranes having smaller pores at one side and larger pores at the other side were prepares by TIPS of polypropylene-diphenyl ether solution with polymer concentration gradient. The simulation of phase separation process by the spinodal decomposition was carried out based on Cahn-Hilliard model. The simulation results of pore size and the thickness of skin layer were approximately in agreement with the experimental results.