聚丙烯疏水微孔共混膜成膜机理及形态结构调控研究

The polypropylene based co-blending hydrophobic microporous membrane will be prepared via thermally induced phase separation(TIPS). From the phase separation thermodynamic point of view, the influence of co-blending polymers concentration, polymer molecular weight, dilution agents and relative factors on the thermodynamic mechanism of phase separation for blending-dilution ternary system will be developed. The glass transition temperature will be determined, and the mechanism of co-blending polymers α crystallization and β crystallization formation during liquid-liquid phase separation and solid-liquid phase separation will be realized and controlled in this work. From the phase separation dynamics point of view, the influence of quench temperature rate, crystalization rate, extraction rate and the relative factors on the dynamics mechanism of phase separation for blending-dilution ternary system will be studied. The formation mechanisms of co-blending rich phase and diluents rich phase and both competitive growth rule will be investigated.The co-blending α crystallization and β crystallization nucleation and growth will be studied at the same time. The complete theory for the co-blending hydrophobic microporous membranes preparation will be developed, the method of controlling the co-blending membrane pore size, pore size distribution, porosity parameters and pore morphology, the characteristics of mechanical strength and hydrophobility will be established. Finally, the numerical simulation and experimental validation studies will be carried out to clarify the relationships among the "Membrane materials - preparation process controlling - microscopic structure regulation - macroscopic structure characterization - separation performance evaluation - simulation theory ".

本课题采用热致相分离方法（TIPS）制备聚丙烯疏水微孔共混膜。从相分离热力学角度，研究共混物浓度、聚合物分子量、稀释剂种类等因素对共混物-稀释剂三元体系平衡热力学及TIPS非平衡热力学相分离机理的影响。确定共混物玻璃化转变温度，分析液-液相分离和固-液相分离热力学机理对聚合物α结晶与β结晶形成的影响机制。从相分离动力学角度，研究TIPS过程淬冷速率、结晶速率和萃取速率等因素对共混物-稀释剂三元体系相分离机理的影响。探讨共混物贫相生成、富相的结晶固化及两者共存时的竞争生长规律，研究共混物α结晶与β结晶成核及生长规律。形成完善的TIPS方法制备聚丙烯疏水微孔共混膜成膜理论，建立对孔径、孔径分布及孔隙率等孔特性参数、膜机械强度及疏水性的调控方法。开展数值模拟和实验验证研究，阐明聚丙烯疏水微孔共混膜"膜材料－制备过程控制－微观结构调控－宏观结构表征－分离性能评价-模拟理论反馈"之间的关系。

本课题采用热致相分离方法（TIPS）制备了聚丙烯疏水微孔共混膜，包括聚丙烯/聚对苯二甲酸乙二醇酯(PP/PET)膜；聚丙烯/聚氯乙烯(PP/PVC)膜，聚丙烯/乙烯-醋酸乙烯共聚物(PP/EVA)膜，聚丙烯/纳米二氧化钛(PP/TiO2)膜，高密度聚乙烯/乙烯-醋酸乙烯(HDPE/EVA)膜，聚丙烯/乙烯辛烯共聚物(PP/POE)膜。分别从相分离热力学角度和相分离动力学角度开展成膜机理研究，形成完善的TIPS方法制备聚丙烯疏水微孔共混膜成膜理论，建立对孔径、孔径分布及孔隙率等孔特性参数、膜机械强度及疏水性的调控方法。首次在分离膜中引入增容剂，用于改善相容性差的共混体系，扩展了热致相分离法制备共混膜的材料选择范围。开展真空膜蒸馏过程数值模拟用于过程强化研究，并进行实验验证。优化制膜工艺，获得了可用于淡化浓海水真空膜蒸馏过程的低润湿性能、高分离性能的膜材料，膜渗透通量高达27.6kg/(m2•h) 、截留率高达99.9%，产水电导率小于10µS•cm-1。研究成果应用于“海水淡化浓海水制盐及制溴产业化关键技术”项目，并于2017年获天津市科学技术进步一等奖。