Robust preparation and multiple pore structure design of poly (tetrafluoroethylene-co-hexafluoropropylene) hollow fiber membrane by melt spinning and post-treatment

摘要

In this work, poly (tetrafluoroethylene-co-hexafluoropropylene) (FEP) hollow fiber membranes were fabricated by melt-spinning method with solvent-free condition, while no coagulation bath was involved. The robust and solvent-free method for preparation of FEP hollow fiber greatly reduced environmental pollution for no solvent recovery problem. Calcium carbonate (CaCO3) as pore-forming agent, and dioctyl phthalate (DOP) as plasticizer as well as dispersant were used in this study. Meanwhile, the formation mechanism of multi-microporous structure with stretching pores, interface microvoids and dissolved micropores was studied, that the addition of CaCO3 brought about interfacial microvoids during the hot stretching-setting treatment and a dissolved pore structure after soaking and washing with hydrochloric acid bath. Furthermore, the effects of hot stretching-setting and hydrochloric acid solution treatment on the membranes' structure and performance were characterized. The morphology exhibited that the prepared FEP hollow fiber membrane presented a kind of homogeneous membrane and the pore size distribution range remained relatively stable and narrow. Moreover, FEP membrane revealed excellent stability and solvent resistance with the mechanical strength retention rate up to 90%. These findings suggest that the FEP hollow fiber membrane prepared by this method will be great potential in the field of separation and purification in harsh conditions. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.