Browsing by Keyword "Surface tension"
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Item Effect of the unsaturation degree and concentration of fatty acids on the properties of WPI-based edible films(2007-02) Fernández, Laura; De Apodaca, Elena Díaz; Cebrián, Marta; Villarán, M. Carmen; Maté, Juan I.; Alimentación SostenibleThe incorporation of lipids into hydrophilic protein films allows the modification of their barrier properties, improving its commercial application as preservation medium on different foods. The main objective of this study was to develop films from Whey Protein Isolate (WPI) together with saturated and unsaturated fatty acids and to determine the effect of concentration and unsaturation degree on surface tension of the coating solution and on water vapor permeability (WVP), mechanical properties (tensile strength and elongation at break), and opacity, of the films. The results obtained showed that surface tension was significantly decreased by adding unsaturated fatty acids (oleic and linoleic acid), whereas the greatest effect on WVP reduction was achieved with stearic acid. The addition of stearic acid resulted in a decrease of elongation and an increase of tension strength; however unsaturated fatty acid content did not modify the elongation and slightly reduce a tensile strength.Item Hydrogen permeation and stability in ultra-thin Pd-Ru supported membranes(2020-03-04) Liu, Jinxia; Bellini, Stefano; de Nooijer, Niek C.A.; Sun, Yu; Pacheco Tanaka, David Alfredo; Tang, Chunhua; Li, Hui; Gallucci, Fausto; Caravella, Alessio; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSIn this paper, we report the performance of supported PdRu membranes for possible applications to hydrogen purification and/or production. For this purpose, we fabricated three ultra-thin α-alumina-supported membranes by combined plating techniques: a PdAg membrane (3 μm-thick ca.) and two PdRu (1.8 μm-thick ca.). The former is set as a benchmark for comparison. The membranes were characterised using different methodologies: permeation tests, thermal treatment and SEM analysis. Preliminary leakage tests performed with nitrogen has revealed that the two PdRu membranes, namely PdRu#1 and PdRu#2, show a non-ideal (non-infinite) selectivity, which is relatively low for the former (around 830 at 400 °C) and sufficiently high for the latter (2645 at 400 °C). This indicates a relevant presence of defects in the PdRu#2 membrane, differently from what observed for the PdAg and PdRu#1 ones. The permeation tests show that the hydrogen permeating flux is stable up to around 550 °C, with an apparently unusual behaviour at higher temperatures (600 °C), where we observe a slightly decrease of hydrogen flux with an increase of the nitrogen one. Moreover, a peculiar bubble-shaped structure is observed in the metal layer of all membranes after usage by means of SEM image analysis. This is explained by considering the effect of the Pd-alloy grain surface energy, which tends to minimise the exposed surface area of the grain interface by creating sphere-like bubble in the lattice, similar to what occurs for soap bubbles in water. The above-mentioned decrease in hydrogen flux at 600 °C is explained to be caused by the bubble formation, which pushes the alloy deeper in the support pores.