添加剂PEG对共混超滤膜结构和性能的影响

以不同分子量聚乙二醇 (PEG)作为PSf/A共混超滤膜的添加剂 ,测定所制备膜的水通量、截留率 .结果表明 ,膜的水通量随PEG分子量的变化呈现非线性关系 .当PEG分子量为4000时 ,水通量达到最大值115.2mL·(cm²·h)^-1,是不加PEG时的6倍 .通过超滤实验结果以及膜结构的电镜照片的观察 ,研究了PSf/A共混超滤膜体系中PEG作用的规律 .PEG分子量的增加改变了PSf/A铸膜液体系的相平衡关系 ,使铸膜液成为热力学不稳定体系 ,加速了相分离的发生 ;另外 ,PEG分子量的增加提高了铸膜液的粘度 ,引起相分离的延迟,这2种作用影响了膜的最终结构和性能.

Effects of PEG Additives on Structure and Performance of Blend Membranes

Polysulfone(PSf)/polymer A blend membranes are fabricated by phase inversion process from casting solution of PSf, polymer A, DMAc, and polyethylene glycol (PEG). The resulting membranes prepared by changing the molecular weight of PEG additives are characterized by scanning electron microscope observation, measurement of water flux and trypsin retention. Experiments of water flux show that water fluxes have non-liner relationship with PEG molecular weight. The water flux of the membrane prepared from the PSf/A/PEG-4000/DMAc casting solution was 115.2mL·(cm²·h)^-1, six time as much as membrane without PEG-0. The PEG as a non-solvent changed thermodynamic properties in polymer solution, promoting phase demixing of casting solution; otherwise, it increased solution viscosity, delaying phase demixing. The two different effects work simultaneously, influencing structure and performance of the membranes.