The Effect of Tensile Stress on the Erosion of Polyimide in an Atomic Oxygen Environment

摘要

Polyimide (PI) films, used as thermal blankets for satellites, are exposed to AO irradiation and subjected to hypervelocity debris impacts. Ground based experiments showed that due to these impacts, residual tensile stresses are formed in the PI causing accelerated erosion in an AO environment. However, fundamental research in regard to stress related AO erosion effect is missing.The objective of this work is to study the erosion mechanism of Kapton (commercial PI) films which are subjected to tensile stresses in an environment simulating AO exposure. The combined effect of the tensile stresses' magnitude and direction on Kapton films erosion while exposed to AO environment are studied in terms of changes in surface morphology.The results reveal that the Kapton's surface morphology is affected by the stress intensity and by its applied direction relative to the polymer chains direction. At low AO fluencies, without applied stress, a classical carpet-like morphology was attained. Under combined effect of stress and AO irradiation, an ordered surface was formed almost orthogonal to the direction of the applied stress.