Residual solvent effect on the permeation properties of fluorinated polyimide films

The main aim of this study was to determine how the residual solvent remain ing after fabrication affected the gas permeation properties of 6FDA-mPDA p olyimide films. For this purpose, films were made by spreading solutions of polyimide from different solvents on glass plates, then treated at 200 deg rees C for different periods of time. The films obtained were characterized by differential scanning calorimetry, thermogravimetry and permeametry. Pe rmeation parameters (D, P, S) of the films towards N-2, and CO, were determ ined at 35 degrees C. They were found to be dependent on the residual solve nt in the films. Whatever the solvent, the difference in behaviour was foun d to decrease as the amount of solvent became smaller and to increase with the molar volume of the solvent. Solvents with high molar volumes left an i mprint in the material during thermal treatment. (C) 1999 Elsevier Science B.V. All rights reserved.