| The purpose of this work was to investigate the mechanical properties of sulfonated poly(ether ether ketone) (SPEEK) and BPO4/SPEEK membranes. It was aimed to contribute in the assessment of these materials for applications in proton exchange membrane fuel cells (PEMFC). Non-modified PEEK films were also characterized as a means to understand the properties of the said materials. PEEK and SPEEK films were studied by dynamic mechanical analysis, modulated differential scanning calorimetry, wide-angle X-ray diffraction, birefringence, and optical microscopy. It was found that sulfonation, heat treatment, and the preparation method led to remarkable changes in the microstructure, which are responsible of the hysteresis loop encountered in the thermomechanical response. The tensile properties of SPEEK and BPO4/SPEEK membranes were evaluated and the effects of immersion in water at different temperatures were explored in situ. The results evidence the impact of the degree of sulfonation and of the filler/matrix ratio on the stress-strain response. |
