The Preparation Of Inorganic Additives PVDF Blend Membranes And The Research Of Its Properties

This article mainly studied that the influences of the inorganic oxide for the blending five holes membrane which is maded by polyvinylidene fluoride (PVDF), polymethyl acrylic acid methyl ester (PMMA) and the thermosplastic polyurethane (TPU).The paper studied the PVDF/PMMA/TPU compatibility and the effecte of the polymer composition, the coagulation condition and the spinning technological conditions to the blending membrane structure and the performance.The hydrophilic property, microstructure, ultra filtration performance and mechanical properties of membranes were characterized by water contact angle and viscosity, scanning electron microscopy, ultra filtration experiments and tensile test. In this paper, by measuring the water flux, rejection rates, tensile strength and elongation to show the characteristics of the five-hole membrane.PVDF/PMMA/TPU are of part compatible system, When PVDF occupy large proportion in blend system, they can create a more uniform blend system. The influence of blend ratio, different additives and amount of additive on membrane properties were discussed.Through measuring the performance of membrane, it confirmed that the membrane with PVDF/(PMMA+TPU) mass ratio 6:4, PMMA:TPU= 0.8:1.2, with 0.3-0.5% content of nano oxide additives, the five-holes membrane has the best-integrated property.In addition, the spinning process will also affect the process of forming the membrane and then change the structure and performance of membrane. Through a large number of experiments, membrane performance testing and SEM scanning electron microscope used to investigate the influence of bore liquid velocity, bore liquid concentration, a high dry-spinning length and pressure for the performance of the memebrane. The results showed that it was the optimum conditions of casting solution that bore liquid velocity was 13-15ml/min, the bore liquid concentration (DMAC) was 5-7%, dry-spinning length was 13cm, spinning pressure of 0.15-0.18MPa. Under this conditions, the best performance of membrane was produced with the intention as 8.0-9.5Mpa, tensility as 30%, water flux as 170-180L/m2·h, and retention ratio as 71-83%.PVDF/PVC/PMMA five-holes membranes with 0.1% hydrochloric acid and sodium hydroxide solution post-treatment was studied and the results indicated that post-treatment with 0.1% hydrochloric acid and sodium hydroxide solution can increase water flux significantly but no distinct influence on retention.Acid and alkaline soak had little effect on mechanical property after membrane dipped in them. The results showed that PVDF/PMMA/TPU blend membranes owned good ability of resistance to acid and alkali. The membranes were used in treatment of reactive BSA solution. Fouled membranes cleaned by water, membrane added nano oxide flux recovery higher than membrane free of nano oxide. It showed that oxide can improve hydrophilicity of membranes. Membranes modified by oxide had a more resistance to acid alkali resistance, favorable antifouling performance and can be applied in wastewater treatment.