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Effect of the particle size and particle agglomeration on composite membrane performance

Authors

  • M. G. García,

    1. Instituto de Física Aplicada (INFAP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Fondo para la Investigación Científica y Tecnológica (FONCYT), Universidad Nacional de San Luis (UNSL), Chacabuco 917-5700, San Luis, Argentina
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  • J. Marchese,

    1. Instituto de Física Aplicada (INFAP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Fondo para la Investigación Científica y Tecnológica (FONCYT), Universidad Nacional de San Luis (UNSL), Chacabuco 917-5700, San Luis, Argentina
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  • N. A. Ochoa

    Corresponding author
    1. Instituto de Física Aplicada (INFAP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Fondo para la Investigación Científica y Tecnológica (FONCYT), Universidad Nacional de San Luis (UNSL), Chacabuco 917-5700, San Luis, Argentina
    • Instituto de Física Aplicada (INFAP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Fondo para la Investigación Científica y Tecnológica (FONCYT), Universidad Nacional de San Luis (UNSL), Chacabuco 917-5700, San Luis, Argentina
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Abstract

One of the most used methods for studying the rigidification of polymer matrices in composite membranes is differential scanning calorimetry. Glass-transition temperatures give information about filler–polymer interaction and the rigidity of the polymer matrix. In this study, optical microscopy, mechanical property testing, and X-ray diffraction, instead of differential scanning calorimetry, were used to study both poly(ether imide) (PEI) matrix rigidification and activated carbon–PEI interfacial adhesion. Then, the permselective properties of the mixed matrix membranes were interpreted. The change in rigidity in these composite membranes was in agreement with the decrease in the flexibility of the composite materials as the filler content increased. This fact was confirmed by the tension and elongation data and X-ray diffraction (DRX) measurements. However, the Young's modulus value decreased as the carbon content increased. There was an increase in all of the gas permeability coefficients measured in the composites compared with that of PEI. As the particle size grew, a low particle surface area and a poor interfacial adhesion were observed. The carbon agglomerates acted as sites of stress concentration within the polymeric matrix. This decreased the intercatenary distances and limited the movement of polymer chains, which resulted in a more rigid matrix. The higher selectivity of the H2/CH4, H2/CO2 and O2/N2 systems observed in the composite membranes revealed that there were both a preferential sorption of certain gases in the carbon surface or carbon–polymer interface and a molecular size exclusion, which were responsible for that increment, despite the poor interfacial adhesion. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

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