Map of gas and vapor permeability in polymer blends

A novel method for measuring local permeabilities of gas or vapor in polymers was proposed and developed. The method utilizes a thin reactive layer of potassium prepared on one side of the examined polymer film. Molecules of an appropriate gas (oxygen, water vapor) diffusing through the film corrode the reactive layer to various extent at various places, proportionally to the amount of the gas passed. A “permeation map” is created which can be visualized with optical microscopy. Compatibilized polystyrene/polypropylene blend was examined with this method. The permeability map pattern obtained was in accord with the morphology of that system. The lateral resolution attained was approximately 2 µm.

Fig. 4. Time dependence of optical density of the image of the reactive layer above and between the stripes. A novel method for measuring local permeabilities of gases or vapors in polymers was proposed and developed. The method was successfully tested on a polyimide membrane with Fig. 5. Permeation map of compatibilized polystyrene/polyproylene membrane. Potassium reactive layer intact after 25 min of water vapor permeation (a). Reactive layer corroded after 325 min of water vapor permeation (b).