The enhancement of gas and vapor transport rates induced by the addition of fumed silica nano-particles to fluorinated glassy polymers and PTMSP is experimentally studied and the behaviours is interpreted and quantitatively modeled considering the additional free volume created by incorporation of filler. That effect can be evaluated accurately from gas solubility data, using the NELF model. The solubility of CH4 and CO2 in matrices of Teflon AF1600, AF2400 and PTMSP, filled with variable amounts of fumed silica nano-particles, was measured at 35°C; the solubility of n-C4 and n-C5 vapors, as well as their diffusivity and the dilation induced in the same polymer matrices were also measured at 25°C. The fractional free volume (FFV) values, estimated on the basis of CH4 solubility data, were used to predict the solubility of the other penetrants inspected, with excellent agreement with experimental data. In addition, a single empirical correlation can be drawn, for both AF1600 and AF2400-based mixed matrices, between the infinite dilution diffusivity of vapors and the FFV value calculated from solubility data. Similarly, a simple correlation valid for both matrices is obtained as well for the dependence of diffusivity on penetrant concentration. In parallel the transport in hybrid membranes formed by PTMSP and SiO2 obtained from tetraethoxysilane (TEOS) via sol-gel reaction, with silica content ranging from 10 to 30% was examined following the same approach. In that case the effect of the filler is to decrease the FFV of the polymer matrix thus reducing both solubility and diffusivity. In all cases, use of the NELF model allows also to give an estimate of the swelling induced by the sorption process on the basis of virtually one simple data point of gas solubility.

Experimental and theoretical analysis of the solubility and diffusivity of gases and vapors in mixed matrix and hybrid membranes

GALIZIA, MICHELE;DE ANGELIS, MARIA GRAZIA;SARTI, GIULIO CESARE
2010

Abstract

The enhancement of gas and vapor transport rates induced by the addition of fumed silica nano-particles to fluorinated glassy polymers and PTMSP is experimentally studied and the behaviours is interpreted and quantitatively modeled considering the additional free volume created by incorporation of filler. That effect can be evaluated accurately from gas solubility data, using the NELF model. The solubility of CH4 and CO2 in matrices of Teflon AF1600, AF2400 and PTMSP, filled with variable amounts of fumed silica nano-particles, was measured at 35°C; the solubility of n-C4 and n-C5 vapors, as well as their diffusivity and the dilation induced in the same polymer matrices were also measured at 25°C. The fractional free volume (FFV) values, estimated on the basis of CH4 solubility data, were used to predict the solubility of the other penetrants inspected, with excellent agreement with experimental data. In addition, a single empirical correlation can be drawn, for both AF1600 and AF2400-based mixed matrices, between the infinite dilution diffusivity of vapors and the FFV value calculated from solubility data. Similarly, a simple correlation valid for both matrices is obtained as well for the dependence of diffusivity on penetrant concentration. In parallel the transport in hybrid membranes formed by PTMSP and SiO2 obtained from tetraethoxysilane (TEOS) via sol-gel reaction, with silica content ranging from 10 to 30% was examined following the same approach. In that case the effect of the filler is to decrease the FFV of the polymer matrix thus reducing both solubility and diffusivity. In all cases, use of the NELF model allows also to give an estimate of the swelling induced by the sorption process on the basis of virtually one simple data point of gas solubility.
Proceedings IMSTEC10/AMS6
M.C. Ferrari; M. Galizia; M.G. De Angelis; G.C. Sarti
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/98734
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