Preparation Of PVDF Hydrophobic Membrane By NIPS

With mixture of triethyl phosphate (TEP)-N, N-dimethylacetamide (DMAc) solvent, the flat microporous hydrophobic membranes were prepared using nonsolvent induces phase separation (NIPS) method. Many factors which could influence the performance of microporous hydrophobic membranes were studied, such as different kinds of polyvinylidene (PVDF), polytetrafluoroethylene (PTFE) particles, coagulation bath of isopropanol and non-woven fabrics as membrane support. The experimental results are as following:Firstly, the differences between PVDF and PVDF-HFP microporous membrane in membrane performance, hydrophobicity and mechanism were studied. Based on the result of experiment, the performance of PVDF membrane was better than PVDF-HFP membrane.Secondly, the introduction of PTFE particles could improve the hydrophobicity of PVDF-PTFE membrane, with the increase of dynamic contact angle (up side and down side of membrane) from 79°and 112°to 85°and 131.5°. And at the same time the morphology of membrane changed from finger-like and sponge-like structure to sponge-like structure across the whole section. Additionally, isopropanol coagulation could also improve the membrane hydrophobicity greatly from 87°to more than 130°. Base on the experiment, the ideal membrane could be prepared with 50wt.% PTFE particle loading,80wt.% isopropanol bath in 5 seconds, and then water bath with final precipitation.Finally, PVDF-PTFE microporous membrane was prepared with non-woven fabrics as membrane support. The dynamic contact angle could keep between 120°nd 130°, with improvement of about 5°fter heating in 60℃oven.