Morteza sadeghi - Department of Chemical engineering, Isfahan University of Technology, Isfahan, ۸۴۱۵۶-۸۳۱۱, Iran
Mohammad Ali Semsarzadeh - Polymer Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran
Mehdi Barikani - Department of polyurethane, faculty of science, Iran Polymer and Petrochemical Institute, Tehran, Iran

The effect of silica nano particles on the permeability of CO2, CH4, O2 and N2 gases in polyester based polyurethane membranes has been investigated. Silica particles were prepared via the sol-gel method through the hydrolysis of tetraethoxy silane (TEOS). PU and PU-silica hybrid membranes were prepared by thermal phase inversion method. Five PU/silica hybrid membranes contain silica particles up to 28.8 wt% silica in polymer prepared. The obtained SEM micrographs and FT-IR spectras confirmed the nano-scale distribution of silica particles in the polymer matrix. The WAXD studies show no changes in crystal peak of hard segments by increasing the silica particles in polymer. It is concluded from characterization results that the silica particles are mostly dispersed in soft segment domains. Gas permeation experiments represented reduction in permeability of the gases through the membranes and increase in gas selectivity by increasing the silica content in the polymer matrix. Reduction in gas permeability is due to decrease in segmental chain mobility at soft segment regions. Permeability of CO2 was decreased from 96 barrer in pure polyurethane to 45 barrer in the nano-composite containing 28.8 wt% of the silica particles. Furthermore, the selectivity of CO2/N2 in the corresponding membranes demonstrated an increase from 42.87 in pure PU to 55 in the composite membranes.

polyurethane, membrane, silica, gas permeation, nanocomposite