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A series of thioether cross-linked membranes based on sulfonated poly(arylene ether ketone)s containing propenyl groups were prepared to solve the problem of high methanol permeability for proton electrolyte membrane in direct methanol fuel cells (DMFCs). For this purpose, 4,4′-thiobisbenzenethiol was selected as cross-linker, and the cross-linked structure was formed via thiol-ene click chemical reaction between propenyl and thiol groups. Compared with pristine membrane, the thioether cross-linked membranes exhibited improved mechanical properties and dimensional stabilities. As the cross-linker increased, the swelling ratio decreased from 11.01% to 8.64% at 20°C and from 15.18% to 10.69% at 80°C. Furthermore, the modified membranes exhibited reduced methanol permeability coefficients (down to 4.03 × 10−7 cm2 s−1), which was nearly half of the pristine membrane (7.66 × 10−7 cm2 s−1). Due to the thioether units, the cross-linked membranes showed enhanced oxidative stabilities, and the longest elapsed time in Fenton’s reagent was 225 min, which was 2.5 times longer than that of pristine polymeric membrane. Although the proton conductivity decreased upon the addition of cross-linker agent, the selectivity value increased due to the lower methanol permeability. Thus, all the results implied that the thioether cross-linked membranes were promising alternative materials for DMFCs application. [ABSTRACT FROM AUTHOR]

Two kinds of glass fibers with round (RdGF) and rectangle cross-sections (RcGF) were used to reinforce polyphenylene sulfide (PPS), respectively. In this way, the effect of fiber cross-section shape on rheological and mechanical properties of the composites was studied for the first time. Results showed that the viscosity of the composites reinforced with RcGF was much lower than that of RdGF composites, owing to their higher sensitivity to flow. As a result, PPS/RcGF composites could be injection-molded at high fiber contents. Moreover, RcGF showed a better reinforcing effect on mechanical properties of PPS. So the use of RcGF could better balance the contradiction between processability and reinforcing effect for glass fiber-reinforced composites. Various characterizations were carried out to reveal the reinforcing mechanism. This work demonstrated the importance of fiber cross-section shape on design and production of fiber-reinforced composites. [ABSTRACT FROM AUTHOR]