CHARACTERIZATION OF THE PPO DENSE MEMBRANE PREPARED AT DIFFERENT TEMPERATURES BY ESR, ATOMIC-FORCE MICROSCOPE AND GAS PERMEATION

Dense (homogeneous) membranes were prepared from poly(2,6-dimethyl-1,4 -phenylene oxide) (PPO) by using 1,1,2-trichloroethylene as a solvent at different solvent evaporation temperatures (22, 4 and -10 degrees C ). The effect of temperature used during evaporation of solvent on the characteristics of the membrane was studied by using electron spin re sonance, atomic force microscopy and gas permeation rate. The morpholo gy of the surfaces of the membrane, the shape of spin probe in the mem brane, and the selectivity of gases depend on the temperature of evapo ration of solvent. The permeation rate of CO2 increased with the decre ase in the temperature used for the preparation of the membrane. Howev er methane permeation rate increased in the membrane prepared at -10 d egrees C. It is suggested that Langmuir sites could be favorable for t he CH4 permeation.