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Erscheinungsjahr
- 2021 (2) (entfernen)
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- Englisch (2)
Referierte Publikation
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Schlagworte
- DFT calculations (1)
- Elastic membrane (1)
- Electrolyte membrane (1)
- Fuell cells (1)
- Methoxytrimethlsilane (1)
- Polymer composites (1)
- Polyvinyl alcohol (1)
Organisationseinheit der BAM
The work explores the synthesis and the properties of a novel composite membrane System based on modified polystyrene (PS) grafted onto a polyvinyl chloride (PVC) membrane.
PVC membranes were prepared by solution-casting followed by exposure to an atmospheric pressure dielectric barrier discharge (DBD) with O2 to obtain an activated Surface for grafting PS to it. Moreover, the thus prepared membranes were chemically modified furthermore by amination with polyethyleneimine or sulfonation with 4 M sulfuric acid.
The membrane surface characteristics such as wettability, structure and morphology were investigated using water contact angle measurements, attenuated total reflection Fourier transform infrared spectroscopy and scanning electron microscopy experiments. The thermogravimetric stability and electrolytic responses of the membranes were studied utilizing TGA, ion exchange capacity (IEC), and solvent uptake. A significant result of plasma and chemical modification was to produce a membrane material with low permeability. Thus, the methanol permeability of the sulfonated membranes measured for 12 h was measured to 2.34$108 cm2 s1 compared to 177.00$108 cm2 s1 of Nafion 117®which is considered as a benchmark. This result indicates that the prepared sulfonated samples are an innovative and effective material for decreasing the methanol crossover in fuel cells to a great extent. This makes the PVC-g-St membranes are promising and attractive as new materials for polyelectrolyte membrane for fuel cells.
A modified composite membranes (PVA/SiOH/SiOC) were made via solution-casting process using different 1:1, 1:2, 1:3 and 1:4 volume ratios of polyvinyl alcohol (PVA):methoxytrimethylsilane (MTMS). Moreover, FT-infrared and energy-dispersive X-ray spectroscopy (EDX) were mesured to account for the network structural rearrangements involving silicon within PVA matrices. The addition of MTMS has improved the thermal and mechanical properties of the composite membranes as compared to pristine PVA. In addition, the crystallinity and the morphological changes of PVA/MTMS composites was studied using X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. Three structures were suggested based on trimethyl silanol (I) wet out condensation (II and III) with the dopped PVA followed by and H-bonding interactions (IV). The outcomes of B3LYP/6-31G(d) frequency calculations favors a three-dimensional SiOC linked network (III). Nevertheless, EDX reveals, the 3D SiOC links are not observed on the surface of composite membranes, however, is found dominant in the bulk, [(CH3)3SiOCH2CH2CH2O]n. Moreover, the solubility, density, and refractive index of the synthesized composites were measured and found depended on the ratio of PVA in the composite membranes. The current results are compared with that published earlier including dimethoxydimethylsilane at the same conditions.