Hydrolytic Degradation of Kapton Film

Abstract

An investigation of the hydrolytic degradation of Kapton polyimide film has been conducted. Tensile properties were measured on (a) unaged material, (b) material which had been immersed in water at temperatures from 50-100°C for up to 5,000 hours, (c) material which had been stressed to 5,000 psi while being exposed to 95-100% relative humidity at 75° and 85°C, and (d) material which had been repetitively cycled through a combination of ultraviolet radiation and condensing humidity at 50-60 °C. The property degradation as a function of time was found to be best represented by an exponential decay curve for all exposure conditions. The immersion time required for the film to lose a prescribed percentage of its initial ten sile properties was determined for each aging temperature, and these "lifetimes" were correlated with temperature using the Arrhenius relationship. Over the temperature range examined, excellent linearity was obtained. Following the same criteria as with the immersion specimen, "lifetimes" were determined for the stressed humidity ex posures and ultraviolet-humidity cyclic exposures. Both of these exposure environ ments significantly accelerated the rate of degradation over that observed in the unstressed water immersions at equivalent temperatures.