Structure-property relationships in radiation grafted poly(tetrafluoroethylene)-graft-polystyrene sulfonic acid membranes

Structure-property relationships in poly(tetrafluoroethylene)-graft-polystyrene sulfonic acid (PTFE-g-PSSA) membranes prepared by radiation-induced grafting of styrene onto poly(tetrafluoroethylene)(PTFE) films using simultaneous radiation-induced grafting followed by sulfonation reaction were established. The physico-chemical properties of the membranes such as ion exchange capacity, water uptake (swelling) and ionic conductivity were investigated in correlation with the degree of grafting (the amount sulfonated polystyrene grafted therein) and the structural changes taking place in the membrane matrix during the preparation step. The variation in the crystallinity of membranes was studied by differential scanning calorimetry (DSC). The membrane thermal stability was investigated using thermogravimetric analysis (TGA), ion exchange capacity and water uptake measurements. The membranes were found to undergo substantial structural changes in a form of ionic sites increase, hydrophicity enhancement, hydrophobicity reduction and crystallinity decrease with the increase in the degree of grafting. The all four factors were found to have a collective effect on the physico-chemical properties of the membranes but their relative contribution depends on the degree of grafting

Phase Identification of Cu-In Alloys with 45 and 41.25 at.% In Compositions

In this work, the thermal stability of Cu-In alloys with 45.0 and 41.2 at.% In nominal compositions was investigated by differential scanning calorimetry (DSC), scanning electron microscopy, wavelength dispersive spectroscopy, and in-situ synchrotron x-ray powder diffraction (S-PXRD) over a temperature range from 25 up to 400 °C. The studied samples are mainly composed of a Cu 11 In 9 phase together with minor amounts of the B phase (based on the NiAs Ni 2 In type structure) and, in one of the samples, with a minor amount of pure In. No evidence of the Cu 10 In 7 (41.2 at.% In) phase was detected, not even in the sample with 41.2 at.% In nominal overall composition. The combined use of the S-PXRD and DSC techniques allowed us to identify two phase transitions involving the Cu 11 In 9 phase, one of them corresponding to the g 0 Ð B þ Cu 11 In 9 reaction at T = 290 °C and the other to the peritectic g 0 þ L Ð Cu 11 In 9 reaction at T = 311 °C.Fil: Baque, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Technical University of Denmark; DinamarcaFil: Torrado, D.. Universidad Nacional del Comahue; ArgentinaFil: Aurelio, Gabriela. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lamas, Diego Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Aricó, Sergio Fabián. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Unidad de Actividad de Materiales (CAC); ArgentinaFil: Craievich, A. F.. Universidade de Sao Paulo; BrasilFil: Sommadossi, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue; Argentin