Lulu Zhang

Changes in chemical structure and optical properties of polyimide films induced by ion bombardment

The effect of ion bombardment on the chemical structure and optical properties of polyimide films was investigated. Oxygen and nitrogen ion beams with energies in the range of 0.5–1.0 keV and doses between 1.7×1015 and 8.2×1016 ions/cm2 were irradiated on the films, and in situ x-ray photoelectron spectroscopy (XPS) and spectral transmittance analyses were carried out. The in situ XPS analyses showed that the addition reaction of oxygen and nitrogen atoms and desorption of components caused chemical structural changes in ion-bombarded polyimides. The in situ spectral analyses showed that the spectral transmittances of films were decreased by ion bombardment.

Exposure of spacecraft polymers to energetic ions, electrons and ultraviolet light

Abstract The influence of high-energy charged-particle bombardment and UV light irradiation on chemical structure of polyimide films was investigated to clarify the mechanism of material degradation in space. The films were exposed to oxygen or nitrogen ion beams with 0.5 keV, to electron beams with 20–30 keV and to UV and visible light of 250–600 nm. X-ray photoelectron spectroscopic analysis showed structural changes of the exposed polymers. The optical properties of transmittance and reflectance were also found to be degraded.

X-ray Photoelectron Spectroscopy Study of the Interactions of O+ and N+ Ions with Polyimide Films

With an increase in the use of polyimides in aerospace applications, the degradation of polyimides caused in the space environment is receiving more attention. In this paper, a ground experiment in which polyimides were exposed to high-energy ions in the space plasma environment was carried out. The effects of oxygen or nitrogen ion bombardment on the chemical structure of polyimide films were investigated by X-ray photoelectron spectroscopy (XPS). The polyimides were exposed to ion beams with energies in the range of 0.5–1.0 keV and in doses between 1.7 ×1015 and 8.2 ×1016 ions/cm2. An in-situ XPS analysis was also carried out, and showed that the ion bombardment changed the chemical structure of the polyimides due to the addition of oxygen and nitrogen ions and the desorption of other components.

Effects of ion bombardment on polymer films

Abstract With an increase in the use of polymers for aerospace applications, the degradation of polymers in space is receiving more attention. In this paper, we studied the influences of ionic impact on the surface polymers of spacecraft. The effects of ion bombardment on the chemical structures and optical properties of polymer films were investigated. The specimens were polyimide and teflon films. Oxygen and nitrogen ion beams with energies in the range of 0.5–1.0 keV and doses between 1.7 × 10 15 and 8.2×10 16 ions cm −2 were exposed to the polymers. In-situ X-ray photoelectron spectroscopy (XPS) and spectral transmittance analyses were carried out on the polymers before and after ion bombardment. The in-situ XPS analyses showed that the addition reactions of oxygen and nitrogen atoms and desorption of components caused changes of chemical structures in the ion-bombarded polymers. The in-situ spectral analyses showed that the spectral transmittances were decreased by the ion bombardment.

Exposure of space material insulators to energetic ions

To understand degradation of materials due to ion bombardment in a space plasma environment, polymers of polyimide, polyetheretherketone and perfluoroalkoxy, and glasses coated with MgF2 were exposed to ion beams of oxygen and nitrogen with energy levels ranging from 600 eV to 5 keV. For the polymers, x‐ray photoelectron spectroscopic analysis showed that the addition reaction of oxygen or nitrogen atoms or the disruption or separation of various structural compounds occurred depending on ion energy and dose. For the glass plate, the coating layer of MgF2 was drastically sputtered.