Effect of polyhedral oligomeric silsesquioxane on gas transport properties of polyimide

The transport properties of gases in polyimide - polyhedral oligomeric silsesquioxane (POSS) mixed matrix membrane were determined based on pure gas permeation and sorption experiments. Gas permeabilities, solubilities, diffusivities and selectivities (CO2/CH4, He/CH 4, O2/N2, He/N2) are reported over a wide pressure, temperature for polyimide-POSS mixed matrix membranes containing various loadings of POSS.; Gas transport properties of mixed matrix membrane containing inorganic molecular sieving material depends on the sieving ability of the inorganic materials, the gas sorption capacity of the sieve, the interface between the sieve and the bulk polymer matrix and the inherent properties of the polymer matrix itself. Proper selection of both the polymer matrix and the molecular sieving materials is required to obtain mixed matrix membranes with enhanced gas transport properties.; Increase in both, diffusivity of smaller penetrants and diffusivity selectivity and consequently in permeability and permselectivity will be obtained in mixed matrix membranes containing molecular sieves with precise pore openings. The properties of the bulk polymer such as excess free volume, relative flexibility/rigidity affect the gas transport properties of mixed matrix membranes. A good interface between the two phases eliminates the possibility of non-selective gas transport and maintains selectivity.; Various inorganic materials such as zeolite, carbon molecular sieves are being incorporated into polymer matrices to form mixed matrix membranes. They possess precise pore openings and are mechanically and thermally stable. Polyhedral Oligomeric Silsesquioxanes (POSS) are three dimensional rigid cage structures made up of Si-O-Si linkages. They have dimensions in the nanometer range and possess a precise pore opening of 4.5 A. They are also thermally and mechanically stable and hence are the inorganic filler of choice for this study.; The impact of POSS on the physical, mechanical and thermal properties of 6FDA-MDA polyimide is determined. The effect of functionalization of POSS on the dispersion and morphology of the polyimide-POSS composites are reported. A thorough investigation into the properties of POSS and polymer-POSS composites was done to understand the observed gas transport behavior of these membranes.; Pure gas permeation and sorption of penetrants was measured and analyzed based on understanding of pathways of gas transport in mixed matrix membranes. Specifically, pressure dependencies of gas permeabilities, solubilities and diffusivities are discussed in terms of pre-established solution diffusion and dual mode sorption theory. Temperature dependence was also determined to evaluate the performance of these mixed matrix membranes at elevated temperatures.; In this study, the versatile properties of POSS particles were harnessed for yet another application. Octa functional POSS was covalently bound onto a carbon nanofiber to increase the overall functionality/reactivity of the fiber. The strong interface thereby generated would assist in effective load transfer under applied stress when incorporated within a polymer matrix. Confirmation of covalent attachment of POSS to the carbon nanofiber was obtained using various analytical techniques. Composites were formed using these functionalized carbon nanofibers within a polyimide matrix and their tensile properties were measured.