Effect of Different Drying Methods on PPESK Carbon Membrane

The carbon membranes derived from the PPESK precursor in CHCl3 solvent for gas separation were prepared with freezing and refrigeration drying methods. The influences of drying methods on the structure and gas separation performance of PPESK carbon membranes were investigated. FTIR, TG, XRD and gas permeation tests were used to characterize the change of chemical and carbon structure and gas separation properties of carbon membranes prepared with different drying methods. The result indicated that the effects of drying methods on the structure and performance of PPESK carbon membranes are to promote the precursor to form a polymeric membrane with the different chemical structure during the drying and make the chemical structure of derived polymeric membranes change in different ways during the later preoxidation and carbonization. Compared with refrigeration drying, the freezing drying weakened decomposition reaction and promoted condensation reaction during-preoxidation and carbonization. As a result, the frozen membrane exhibited a better gas separation performance with a good flexility due to its dense microstructure. The freezing drying was the optimum way to prepare PPESK carbon membranes using CHCl3 as solvent.