Gas transport properties of polypropylene/clay composite membranes

© 2007 Elsevier Ltd. The authors of this study gratefully acknowledge the financial support of the Ministry of Science and Technology (MCYT, Spain) through its project No. PPQ2003-03299 and MAT 2004-00825. Dr. López Manchado also acknowledges the concession of a Ramón & Cajal contract from the MCYT.
Polypropylene membranes modified with natural and organically modified montmorillonite clays were prepared. The permeability, diffusivity and solubility of helium, oxygen and nitrogen were determined for the unfilled and filled membranes over the temperature range 25-65 degrees C. Physical properties of polypropylene membranes were investigated using X-ray diffraction, thermogravimetric analyser, tensile testing and differential scanning calorimetry. The results showed that the filled membranes exhibit lower gas permeability compared to the unfilled polypropylene membrane. For helium, a reduced diffusivity is mainly responsible for the reduction in the permeability, in contrast, for nitrogen and oxygen, both diffusivity and solubility were reduced by the presence of fillers. The X-ray diffraction spectra showed that the incorporation of the unmodified and modified clay did not affect the crystallographic nature of polypropylene.
Ministry of Science and Technology (MCYT, Spain)
Depto. de Estructura de la Materia, Física Térmica y Electrónica
Fac. de Ciencias Físicas
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