Research Of Poly(Vinylidene Fluoride)(PVDF) Microporous Membrane Molding

In this paper, I perpare the PVDF microporous membrane via steel beltcasting,thermally induced phase separation and Immersion precipitation.These microporous membranes have different aperture, different properties.The product is characterized by SEM, water flux and porosity, IR, DSC,diameter.In immersion precipitation, I use N-dimethylacetamide(DMAC) as solvent,PVP, PEG and LiCl as porogen. I also investigate the effect of coagulationbath, the proportion of water and ethanol. In conclusion, the best is to chooseDMAC as solvent, the concentration of PVDF is21%, adding5%PVP, andthe proportion of water and ethanol is7:3. Using this method, I can preparethe PVDF microporous membrane with few microns in diameter,and goodmechanical strength. But this method repeatability is poor, process complex,and many influences.In steel belt casting method, I use N-dimethylacetamide (DMAC) andN-methyl pyrrolidone (NMP) as solvent. The configured solution evenly coatson steel belt, and combine with a certain casting temperature. Microporous membrane prepared by steel belt casting, has good crystallization, themembrane presents a translucent, and the pore size is about tens of microns.PVDF microporous membranes prepared by this method is suitable formicrofiltration membranes used in water treatment, and the process ofpreparation is simple.In thermally induced phase separation, I choose DBP and DMP as solvent. Ialso investigate the effects of concentration of solvent, cooling rate andporogen in PVDF membrane. The product is characterized by SEM, water fluxand porosity. In conclusion, the best is to choose DBP as solvent, theconcentration of PVDF is40%, air cooling. By this method,the porosity ofmicroporous membrane65%. The production process of this method issimple.The membrane has good structure and small aperture.