The enhancement of gas diffusivity observed after addition of fumed silica nano-particles to glassy polymers can be described and modeled by considering the additional fractional free volume (FFV) created by filler insertion, which can be evaluated from gas solubility data in the composite matrix by means of the NELF model. In this work, a detailed characterization of the solubility of n-C4 and n-C5 vapors, as well as of their diffusivity in matrices of AF 2400 filled with variable amounts of fumed silica has been performed at 25°C. On the bases of n-C4 solubility in the mixed matrix the FFV variation due to filler loading can be estimated and then used to predict the solubility of n-C5 that is found in good agreement with experimental data. Finally, an empirical correlation can be drawn between the FFV value obtained from solubility data and the infinite dilution diffusivity of the penetrants, as well as with the concentration dependence of the penetrant diffusivity.
VAPOR SORPTION AND DIFFUSION IN MIXED MATRICES BASED ON TEFLON® AF 2400
DE ANGELIS, MARIA GRAZIA;SARTI, GIULIO CESARE
2010
Abstract
The enhancement of gas diffusivity observed after addition of fumed silica nano-particles to glassy polymers can be described and modeled by considering the additional fractional free volume (FFV) created by filler insertion, which can be evaluated from gas solubility data in the composite matrix by means of the NELF model. In this work, a detailed characterization of the solubility of n-C4 and n-C5 vapors, as well as of their diffusivity in matrices of AF 2400 filled with variable amounts of fumed silica has been performed at 25°C. On the bases of n-C4 solubility in the mixed matrix the FFV variation due to filler loading can be estimated and then used to predict the solubility of n-C5 that is found in good agreement with experimental data. Finally, an empirical correlation can be drawn between the FFV value obtained from solubility data and the infinite dilution diffusivity of the penetrants, as well as with the concentration dependence of the penetrant diffusivity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
