Measurement of Mass Gain Behavior due to Hydration and Reduction of Uncertainty Induced by Time Lag of Weighing on Pristine Kapton Film after Heating in Vacuum

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To simulate material degradations in space environments, materials are exposed to various space environment factors in vacuum. In vacuum, low-molecular-weight component, moisture, and etc. desorb from the materials, and it follows the mass loss. The vacuum-desorbed materials, however, adsorb the moisture due to retrieval from vacuum chamber into the atmosphere condition. The mass gain due to hydration disturb the accuracy of an atomic oxygen fluence measurement and an outgassing test. In this study, we have evaluated the mass gain behaviour of vacuum-desorbed material due to hydration. To desorb the moisture, the test specimens were heated in vacuum. After dehydration in vacuum, the mass of test specimen was measured by using an ultra-micro balance inside the low-humidity controlled globe box to evaluate the mass equivalent to that in vacuum condition and then the mass was measured under controlled condition of 50% relative humidity to evaluate the mass gain in atmosphere. From the experimental results, we have evaluated the uncertainties due to hydration occurring during the time lag between sample retrieval from a vacuum chamber to sample weighing, quantitatively. The back extrapolation using the regression curve based on the solution of diffusion equation is effective on the reduction of uncertainties.