Research Of PVDF Ultrafiltration Membrane Hydrophilization Blending Modification

Membrane material is the core of membrane separation technology. Poly (vinylidenefluoride)(PVDF) membrane get the attention of people with its good mechanical strengthand chemical stability. But its energy consumption is too large during the process of usingbecause of the strong hydrophobic, and it is easy to produce membrane pollutionproblem affecting the flux. To hydrophilization modified PVDF membrane is an effectiveway to solve the above problem.In this article, amphiphilic copolymer (SMA-g-PEG) was prepared by means ofgrafting method, with SMA and PEG as raw material, tetrahydrofuran (THF) as solvent,p-toluene sulfonic acid (PTSA) as catalyst. Reaction of esterification was happened withthe anhydride groups in SMA and the hydroxyl in PEG. This paper studied the influenceon the yield of grafting reaction with the polymer concentration, MA and PEG mole ratio,catalyst dosage and reaction time, and to determine the optimal conditions for graftingreaction by orthogonal test. The grafted products were scanned by using a Fourier infraredspectrometer, it showed that the amphiphilic copolymer were successfully preparedaccording to the appearance of vibration absorption peak at1720cm-1of ester group.The compatibility between SMA-g-PEG and PVDF was investigated, and thetheoretical basis in compatibility discriminant was introduced, and compatibility betweenSMA-g-PEG and PVDF was predicted from the perspective of thermodynamics. Using thesolubility parameter method, solvent method and the viscosity method respectively forjudgment, the results showed that the SMA-g-PEG and PVDF belonged to the partialcompatible system, and I suggested that both can blend in order to improve the hydrophilicof PVDF.The PVDF/SMA-g-PEG blend membrane was prepared by means of immersionprecipitation phase inversion membrane preparation method, with the amphiphiliccopolymer SMA-g-PEG as polymer blend, with N, N-dimethyl acetamide (DMAc) assolvent. This paper is studied on the influence of polymer concentration, polymer blendingratio, and the temperature of coagulation bath on membrane performance. Studies onmeasurement of water flux and membrane rejection have shown that the addition ofSMA-g-PEG can make water flux increased significantly, and membrane rejection fell slightly. Studies on measurement of contact angle have shown that the raising ofSMA-g-PEG ratio could reduce contact angle. FT-IR indicated that, with the amount ofSMA-g-PEG increased, the content of SMA-g-PEG increased gradually in the blendmembrane. SEM showed that the addition of SMA-g-PEG significantly altered thestructure of membrane, porosity of membrane has changed.