Structure/Permeability Relationships of Silicon-Containing Polyimides.
PLANNING RESEARCH CORP HAMPTON VA
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A study has been in progress for several years at Syracuse University on the relationships between the chemical structure of polymers and their permeability and selectivity to different gases. A better understanding of these relationships is of great importance for the development of new processes for the separation of gases by selective permeation through polymer membranes. Two classes of polymers have been investigated up to now for this purpose, namely silicone polymers polyorganosiloxanes and polyimides 1-5. Therefore, it was of interest also to study the structurepermeability relationships of silicon-containing polyimides. Accordingly, the following types of polymers were used in this study 1 silicone-polyimide copolymers, and 2 silicon- modified polyimides., i.e., polyimides containing silicon atoms in the backbone chains. These polymers were employed in the form of thin, nonporous membranes, and their permeability to H2, 02, N2, CO2, and CH4 was determined at 35.OC and at pressures up to about 120 psig - 8.2 atm.. The results of the study are discussed below.