Processing Of Perfluorosulfonated Ion-Exchanged Membranes

Perfluorosulfonated ion-exchanged membrane (PFSIEM) is the core material for alkali-chloride industry and proton-exchanged membrane fuel cell (PEMFC). The manufacture technology of PFSIEMs is extrusion-calendering, which is mastered by Dupont and Asahi, therefore domestic need has being depending on importation. In this work, we researched extrusion processing technology of PFSIEMs, including melt-extrusion and gel-extrusion. Resin used is made in Dongyue Company, one is Perfluorosulfonyl fluoride resin(PFSR), the other is perfluorosulfonic acid resin(PFSA).DSC, TG, and capillarity rheometer were used to study the thermal stability and melt rheology of the PFSR. The results showed that PFSR has outstanding thermal stability, furthermore, the MI is 3.3g/10min at 190℃, and PFSR melt was a pseudoplastic fluid had a characteristic of shear thinning. So, PFSR is fit to melt-extrusion processing, and different thickness membranes with good appearance can be prepared by adjusting the extrusion speed and the linear speed of grazer.XRD were used to study the crystallinity of PFSIEMs, the results showed PFSIEMs have good crystallinity. Water content, water absorption, solubility, and IEC were tested, the results showed that these parameters were little affected by art of processing. Dimension change of PFSIEMs were tested, results showed that dimension change in machine direction (MD) were less than that in transverse direction (TD). The effect on mechanical property of PFSIEMs of processing art have been studied, results showed that along with the extension increasing the max. tensile strength didn't change obviously in TD (17MPa) but increased gradually in MD(reached 22MPa). Moreover, the tension strength of PFSIEMs can be improved by hot treating at 170℃.The PFSIEMs plasticized by GBL got inferior surface, but crystallinity is improved. Tension strength and dimension change are slightly changed after plasticizing. IEC and hydration property did not affected by plasticization.Prepared PFSA gel system by using GBL as the latent solvent, and the PH of gel system reached 4. Thus, it is demand that all the machines and equipments used during gel-extrusion procedure with excellent acid resistance. Gel-extruded membranes have worse surface and crystallinity than melt-extruded ones.