Dielectric water sorption analysis

Abstract

The sorption of water vapor in Kapton (polyimide) films has been investigated with a new method, dielectric sorption analysis (DSA). The technique is based on high-resolution time-resolved capacitance measurements performed during exposure of an organic coating to humidified nitrogen. The basis of the method is described together with experimental details related to the capacitance measurement, long-term stability, reproducibility, and other characteristics of the setup. The technique allows the determination of the sorption/desorption and diffusion characteristics of a coating on a time scale varying from seconds to days. Mass transport properties derived from complementary weight measurements are in good agreement with the DSA results. Real-time monitoring of the moisture sorption in organic coatings demonstrates the potential of the technique in the field of nondestructive coating inspection and testing. © 2006 American Institute of Physics.