Study On Improved Preparation And Properties Of Heterogeneous Cation Exchange Membranes

The sulfonic amphiphilic ion exchange polymer (S-SEBS) was obtained through the hydrogenated polystyrene-ethylene/butylenes random copolymer-styrene triblock copolymer(SEBS) by the acetyl sulphate and the sulfonation process was researched. Three series of heterogeneous cation exchange membranes were prepared in the addition of the different content of the S-SEBS which had different ion exchange capacity between ion exchange resin and polymer binder, and the properties of the heterogeneous cation exchange membranes were investigated, such as ion exchange capacity water uptake, area resistance, transport number, salt diffusion coefficient, water permeability coefficient, diffusion coefficient of water pressure and bursting strength, to research the influence of the membranes properties with the addition of S-SEBS. The performance changes after the membranes were used a period of time were explored, Results as follows.The results of FT-IR spectra showed that sulfonated products of the42%-SEBS and67%-S-SEBS appeared peaks at the wavelength of1040cm-1,1100cm-1,1230cm-1and1310cm-1, what’s more, the absorption peak was pointed obviously with the increase of ion exchange capacity. For the42%-SEBS and the67%-SEBS, the best sulphonated temperature was40℃and50℃respectively. And the sulfonating reaction kinetics indicated that sulphonated rate of the SEBS enhanced abidingly in the first5hours, then kept stable. Membrane performance measurement demonstrated that the addition of S-SEBS in the heterogeneous cation exchange membranes led to the decrease of area resistance which lowered by2Ω·cm2when the amount of S-SEBS was20%. When the amount and the IEC of S-SEBS increased, the water uptake aggrandized, salt diffusion coefficient and water permeability coefficient were ascending, however, transport number and diffusion coefficient of water pressure were descending, and bursting strength stayed unchanged. For the membranes with hot water treated, the shedding degree alleviated obviously with S-SEBS which offered a novel preparation of heterogeneous cation exchange membranes by add S-SEBS between ion exchange resin and polymer binder, because S-SEBS which was amphiphilic ion exchange polymer can combine the ion exchange resin and polymer binder more firmly, the shedding degree and hole defects of membrane will wipe off, moreover, the area resistance lower.