Preparation and Properties of Sulfonated Poly(vinyl alcohol)/Poly(aryl ether ketone)with Pendant Sulfoalkyl Groups Crosslinked Composite Proton Exchange Membrane
The sulfated poly(vinyl alcohol)(SPVA)/sulfonated poly(aryl ether ketone)with pendant sulfonic acid groups(S-SPAEK)crosslinked composite membranes(Cr-SSPxx)with different contents of SPVA were prepared by solution blend method.The Cr-SSPxx crosslinked composite membranes were obtained by heating reaction at 140℃.Fourier transform infrared spectroscopy(FT-IR)spectra show that the covalent band crosslinked structure is formed between the sulfonic acid groups on S-SPAEK and hydroxyl groups on SPVA.The scanning electron microscope(SEM)images show that the crosslinked composite membranes present better compatibility and uniformity.Through the performance research of the series of membranes,it is found that the crosslinked network structure effectively enhances the mechanical properties,thermal stability,oxidation stability and dimensional stability of the crosslinked composite membranes.The swelling rate of the crosslinked membranes shows an obvious decreasing trend with the increase of crosslinking degree.The swelling rate of Cr-SSP30 membrane is only 3.7% and 7.6% at 25℃and 80℃,respectively.The Cr-SSPxx membranes exhibit excellent methanol resistance due to the hindering effect on methanol of SPVA and the cross-linked network structure increasing the density of membrane.The methanol permeability of the crosslinked composite membranes is significantly lower than that of the S-SPAEK membrane and SPVA/S-SPAEK composite membrane.The methanol permeability of the Cr-SSP30 membrane is only 9.4×10-8 cm2/s.Although the proton conductivity of the crosslinked composite membranes is lower than that of SPVA/S-SPAEK composite membrane,this series of membranes show lower proton selectivity.The proton conductivity of Cr-SSP30 membrane is 0.034 S/cm at 25℃and 0.065 S/cm at 80℃,which can meet the requirements of direct methanol fuel cell(DMFC),and expected to be applied in DMFC.
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