Dielectric proprieties and relaxation behavior of Polyimide films (PI)

Benabed, F.; Seghier, Tahar; Boudraa, S.; Seghiour, Abdellatif

doi:10.1109/cistem.2014.7076948

Cited by 5 publications

(1 citation statement)

References 2 publications

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“…For the PI, the temperature ranges for γ, β, and α relaxation are 100 K-190 K, 190 K-360 K, and 360 K-470 K, respectively. From the literature, the PI has three β relaxations [16,[18][19][20]; thus, the complete TSDC curves included five relaxations in total, denoted γ, β 1 , β 2 , β 3 , and α.…”

Section: Tsc Resultsmentioning

confidence: 99%

The effects of γ-ray on charging behaviour using polyimide

Qin¹,

Tu²,

Tan³

et al. 2018

J. Phys. D: Appl. Phys.

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Insulation material is a key component of electrical equipment in satellites; its electrical properties determine the reliability and lifetime of the whole satellite. High-energy radioactive rays in space affect the molecular structure of the polymeric insulating materials. Under the action of plasma, high energy particles, along with the magnetic fields experienced in orbits, electric charges get injected into and trapped by the insulating material creating distortions in the electric field and even electrostatic discharges. Polyimides have been widely used for insulation in spacecraft. Choosing Co-60 gamma ray with irradiation doses of 1 MGy and 5 MGy to simulate the radiation environment of space, we investigated the effect of radiation on charging behaviour. The thermal stimulated current (TSC) from a high electric field over a wide range of temperatures was measured from which the activation energy was calculated. These results for the two sources show that the percentage increase in total charge was 133.3% and 119.4%. The γ, β 3 , and α charge peaks of specimens after an irradiation dose of 1 MGy rose. In comparison, the β 2 peak of the 5 MGy-dosed specimens was enhanced. Also, there is almost no change in the γ, β 3 , and α peaks. To understand the mechanism behind the TSC changes, the resulting physicochemical characteristics of an irradiated specimen were observed employing various analyses of chemical characteristics (x-ray photoelectron spectroscopy, differential scanning calorimetry and x-ray diffraction). Compared with the non-dosed specimen, the relative content of C-N and the glass transition temperature of the 1 MGy sample decreased, and the crystallinity increased, thus increasing the γ and α peak intensities. Compared with the 1 MGy sample, only the glass transition temperature had risen, thereby enhancing the β peak intensity. With the foregoing, a theoretical base for the selection and modification of insulation materials for spacecraft is provided.

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Section: Tsc Resultsmentioning

confidence: 99%

The effects of γ-ray on charging behaviour using polyimide

Qin¹,

Tu²,

Tan³

et al. 2018

J. Phys. D: Appl. Phys.

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Electrical Conductivity Characteristic of Polyimide under Long-Term Combined Electron Irradiation and Thermal Cycle in Vacuum

Chen,

Zhang

et al. 2024

ACS Appl. Mater. Interfaces

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During long-term operation, low-earth-orbit spacecraft are exposed to a severe environment of electron irradiation and thermal cycle. This affects the electric properties of polyimide, an essential insulation material for spacecraft electrical transmission equipment, particularly the conductivity characteristic. Therefore, this paper investigates the conductivity and its evolution of polyimide after the combination of 20 keV, 8 nA/cm2 electron irradiation, and 243–343 K, 5 K/min thermal cycle in a vacuum environment for 432 h. The results show that the conductivity increases by about 2 orders of magnitude over 432 h, with the threshold field for electric-field-dependent conductivity decreasing. The conductivity growth rate varies, rising during the first 192 h, then increasing in the midelectric field, and decreasing in the high electric field regions. The thermally stimulated depolarization current method demonstrates that increases in γ, β1, and β2 trap densities, associated with enhanced motility of end groups, diamines, and dianhydrides after long-chain breaks, lead to higher conductivity and growth rate. Additionally, increases in β3 and α trap densities, related to increased CO bonds and free radicals, reduce the threshold field and the conductivity growth rate in the range of 57.0–100.0 kV/mm after 192 h. These findings provide a reference for the performance evaluation and enhancement of spacecraft polyimide materials.

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The effect of temperature cycles on conductivity mechanism using polyimide

Qin

Chen

et al. 2020

Journal of Applied Physics

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Traditionally, conductivity, a key parameter for evaluating the probability of electrostatic discharge, has been subscribed to the belief that it is a constant value. However, in actual working conditions, such as the low earth orbit environment, the conductivity value of dielectrics is not constant due to the variation in temperature. Therefore, it is of great practical significance to investigate the conductivity value of dielectrics in the time-varying field and explore the hidden mechanism of the charging phenomenon. In this paper, we investigated the dynamic conductivity value using polyimide during four temperature cycles. The result shows that there is a positive correlation between conductivity and temperature above the turning point temperature. However, when the temperature is lower than the turning point temperature, the conductivity value hardly changes with temperature. In the four cycles, the conductivity value in the same temperature decreases with the cycles. The space charge distribution test and the thermally stimulated current experiment are carried out to explain the charging phenomenon. The results show that the heterocharge accumulates continually and is captured by deep traps above 0.55 eV. It could be concluded that the thermally stimulated detrapping effect makes the charge trapping difficult, which results in the conductivity value in the same cycle changing with the temperature above the turning point temperature and the heterocharge accumulating. The trap-filling effect inhibits the charge conduction process, which makes the conductivity value in the same temperature to decrease with temperature cycles.

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Dielectric proprieties and relaxation behavior of Polyimide films (PI)

Cited by 5 publications

References 2 publications

The effects of γ-ray on charging behaviour using polyimide

The effects of γ-ray on charging behaviour using polyimide

Electrical Conductivity Characteristic of Polyimide under Long-Term Combined Electron Irradiation and Thermal Cycle in Vacuum

The effect of temperature cycles on conductivity mechanism using polyimide

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