Polyimide-epoxy alloys prepared via micro-modification: water sorption anddiffusion

A novel polyimide-epoxy or PI-EP alloys are prepared by the modification of polyamic acid in the concentration range of 1.54x10(-6) to 1.54x10(-2) mol /L. The methanol sorption for these alloys at 24 hrs and at equilibrium con ditions are determined and the residual solvent in fully cyclized polyimide s were calculated. The presence of the residual solvent is visualized in fu lly imidized polymer and a structure containing partly imidized amic acid m oiety is proposed and their concentration (in percentage) is calculated. Th e water sorption for these alloys at 24 hrs and at equilibrium conditions a nd the values of the water diffusion coefficient are determined from absorp tion isotherms. The PI-EP alloys have shown comparatively lower water sorpt ion and higher diffusion coefficient than the unmodified polyimide. The mec hanistic aspects of water sorption and diffusion are discussed.