Development of Polyetherimide (PEI) - Polyvinyl acetate (PVAc), Glassy-rubbery Polymeric Blend Membrane for CO2/CH4 Separation

In membrane technology, polymeric membrane has been widely used for natural gas purification but the tradeoff limitation between permeability and selectivity has restricted the overall gas separation performances. This project aimed to develop and synthesis a novel glassy-rubbery polymeric blend polymeric membrane which composed of polyetherimide (PEI) and polyvinyl acetate (PVAc) polymers in N-Methyl-2-pyrrolidone (NMP) solvent. Solution casting and evaporation technique was selected in synthesizing the proposed blend polymeric membranes. In addition, morphology, interaction of chemicals, thermal stability as well as the miscibility of polymer blending were characterized by FESEM, FTIR, TGA and DSC respectively. The overall gas separation performances of the membrane were evaluated in terms of permeability and selectivity.
In this study, all membranes were casted successfully. FESEM results showed that all pure and blend membranes were homogeneous in structure and no void were observed at molecular level. This observation has confirmed the miscibility of polymers blending. Moreover, FTIR analysis was conducted and it reviewed that the functional groups of individual polymers such as aldehyde, ketone and ether were remained in the structure of blend membranes which indicated no alternation and changes of chemical structure in blend membranes. On top of that, TGA result presented that a slightly lower degradation temperature in blend membranes. This reflected that thermal stability of blend membrane has been reduced compared to pure PEI membrane. Furthermore, a single and lower glass transition temperature were found in DSC analysis which confirmed the compatibility and good interaction between PEI and PVAc. However, the present of PVAc in PEI polymer has reduced the glass transition temperature of pure PEI membrane.