Preparation, Characterization and Gas Permeation of Polyimide Mixed Matrix Membranes

Abstract

Some mixed matrix membranes (MMMs) were fabricated using polyimides in order to improve performance of CO2/CH4 separation. Polyimides of Matrimid 5218 and P84 were used as the polymer backbones and different inorganic particles including aerosil silica 200, zeolites of 4A and ZSM-5, homemade carbon nanotube (CNT), and carbon molecular sieve (CMS) were used as fillers. Effects of polymers type, type and content of different fillers up to 15%, and fabrication procedure on MMMs separation performance were investigated. Scanning electron microscopy (SEM) images showed acceptable connections between the two phases of polymers and fillers and the MMMs showed better separation performance compared with the pristine polymeric membranes. Although glassy polyimides are hard to connect with the fillers, thermal treatment at temperatures around glass transition temperatures (Tg) of the employed polyimides, repaired probable defects and there were no voids around the fillers as SEM images and gas permeation tests revealed. Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) also confirmed good contact between the two phases as MMMs exhibited higher thermal stabilities.