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Polyimide film (Kapton) is an important polymer material used for the construction of spacecrafts. The performance of Kapton can be degraded for atomic oxygen erosion in space. Commonly used atomic oxygen protective layers have issues such as poor toughness and poor adhesion with the film. In this paper, Kapton/Al2O3 nanocomposite films were prepar...
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... was synthesized from a dibasic anhydride and a diamine (PMDA-ODA). The molecular formula of the Kapton is shown in Figure 1. The Kapton film was cut into small pieces with a size of 10 mm ×10 mm; it was then ultrasonically cleaned with acetone and absolute ethanol for 10 min to remove residual organic pollutants on the surface of the material. ...
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... atomic oxygen exposure, the Kapton film and Kapton/Al2O3 nanocomposite film showed mass loss, as shown in Figure 10. The figure shows the mass loss per unit area of the sample, and the dotted line is the fitted curve. ...
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... figure shows the mass loss per unit area of the sample, and the dotted line is the fitted curve. Figure 10 demonstrates that, with increasing the atomic oxygen, the mass loss per unit area of the sample gradually increases. The mass loss curve of the Kapton film is linear, with a slope of about -1.2 and has a relatively large weight loss. ...
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... oxidation weight loss process of Kapton/Al2O3 surface nanocomposite film can be divided into two stages: the pre-nonlinear stage and late linear stage. According to the change trend of the weight loss curve, the weight loss rate in the early stage is low and can be fitted as a parabola, as shown by the dotted line a in the first half of Figure 10. It is known from oxidation kinetics [39,40] that the Al2O3 layer on the surface of Kapton can separate the Kapton film matrix from the atomic oxygen molecules, preventing further diffusion of atomic oxygen to some extent and thus protecting the internal Kapton film matrix. ...
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... atomic oxygen exposure, the Kapton film and Kapton/Al 2 O 3 nanocomposite film showed mass loss, as shown in Figure 10. The figure shows the mass loss per unit area of the sample, and the dotted line is the fitted curve. ...
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... figure shows the mass loss per unit area of the sample, and the dotted line is the fitted curve. Figure 10 demonstrates that, with increasing the atomic oxygen, the mass loss per unit area of the sample gradually increases. The mass loss curve of the Kapton film is linear, with a slope of about -1.2 and has a relatively large weight loss. ...
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... oxidation weight loss process of Kapton/Al 2 O 3 surface nanocomposite film can be divided into two stages: the pre-nonlinear stage and late linear stage. According to the change trend of the weight loss curve, the weight loss rate in the early stage is low and can be fitted as a parabola, as shown by the dotted line a in the first half of Figure 10. It is known from oxidation kinetics [39,40] that the Al 2 O 3 layer on the surface of Kapton can separate the Kapton film matrix from the atomic oxygen molecules, preventing further diffusion of atomic oxygen to some extent and thus protecting the internal Kapton film matrix. ...
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... atomic oxygen reaction coefficient of the Kapton film is generally 3.0 × 10 −24 cm 3 /atom [10]. The average reaction coefficient of the Kapton/Al 2 O 3 nanocomposite film at each stage in the atomic Coatings 2019, 9, 624 9 of 16 oxygen exposure process is shown in Figure 11. It can be seen from the figure that the average atomic oxygen reaction coefficient of the Kapton/Al 2 O 3 surface nanocomposite film is ~1.0 × 10 −24 cm 3 /atom within 0-6 h, which is significantly lower than the Kapton film with a reaction coefficient of 3.0 × 10 −24 cm 3 /atom. ...
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... further analyze the changes in the surface elements of the sample before and after atomic oxygen exposure and the atomic oxygen reaction mechanism of the film, the surface molecular structure and valence bonds of the sample before and after atomic oxygen exposure of the Kapton and Kapton/Al2O3 surface nanocomposite films were analyzed via XPS [42][43][44][45]. The XPS full scan spectrum is shown in Figure 12, and the surface element composition of the sample is shown in Table 1. After exposure to atomic oxygen for 30 h, the relative carbon content on the surface of Kapton and the Kapton/Al2O3 surface nanocomposite films decreased, while the relative content of nitrogen and oxygen increased. ...
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... further analyze the changes in the surface elements of the sample before and after atomic oxygen exposure and the atomic oxygen reaction mechanism of the film, the surface molecular structure and valence bonds of the sample before and after atomic oxygen exposure of the Kapton and Kapton/Al2O3 surface nanocomposite films were analyzed via XPS [42][43][44][45]. The XPS full scan spectrum is shown in Figure 12, and the surface element composition of the sample is shown in Table 1. After exposure to atomic oxygen for 30 h, the relative carbon content on the surface of Kapton and the Kapton/Al2O3 surface nanocomposite films decreased, while the relative content of nitrogen and oxygen increased. ...
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... further analyze the changes in the surface elements of the sample before and after atomic oxygen exposure and the atomic oxygen reaction mechanism of the film, the surface molecular structure and valence bonds of the sample before and after atomic oxygen exposure of the Kapton and Kapton/Al 2 O 3 surface nanocomposite films were analyzed via XPS [42][43][44][45]. The XPS full scan spectrum is shown in Figure 12, and the surface element composition of the sample is shown in Table 1. After exposure to atomic oxygen for 30 h, the relative carbon content on the surface of Kapton and the Kapton/Al 2 O 3 surface nanocomposite films decreased, while the relative content of nitrogen and oxygen increased. ...
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... decrease of C content can be attributed to the strong oxidizability of the atomic oxygen, which will chemically react with polyimide and be oxidized to CO2 or CO, resulting in weight loss by oxidation of Kapton [9,10]. Figure 13 shows the high-resolution spectra of the C1s and O1s regions and the peak fitting curves using the XPSPEAK software (version 4.1) before and after atomic oxygen exposure of Kapton films. There are four different states of carbon atoms in the C1s spectrum, with the fitted peaks are located at binding energies of 284.37 eV (corresponding to the C-C bond in the ODA benzene ring), 285.18 eV (representing the C=C bond in the PMDA benzene ring), 285.90 eV (C-O bond), and 288.41 eV (C=O bond or C-N bond), respectively. ...
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... decrease of C content can be attributed to the strong oxidizability of the atomic oxygen, which will chemically react with polyimide and be oxidized to CO 2 or CO, resulting in weight loss by oxidation of Kapton [9,10]. Figure 13 shows the high-resolution spectra of the C1s and O1s regions and the peak fitting curves using the XPSPEAK software (version 4.1) before and after atomic oxygen exposure of Kapton films. There are four different states of carbon atoms in the C1s spectrum, with the fitted peaks are located at binding energies of 284.37 eV (corresponding to the C-C bond in the ODA benzene ring), 285.18 eV (representing the C=C bond in the PMDA benzene ring), 285.90 eV (C-O bond), and 288.41 eV (C=O bond or C-N bond), respectively. ...
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... prolonging the heat treatment time or increasing the heat treatment temperature, the clusters of particles can be stacked to form larger nanoparticles, which distribute uniformly on the modified layer and aggregating on the surface of the polyimide. The cross-section SEM observation and EDS line scanning are shown in Figure 14. An aluminumcontaining layer with thickness of about 10 microns is formed on the surface of Kapton. ...
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... prolonging the heat treatment time or increasing the heat treatment temperature, the clusters of particles can be stacked to form larger nanoparticles, which distribute uniformly on the modified layer and aggregating on the surface of the polyimide. The cross-section SEM observation and EDS line scanning are shown in Figure 14. An aluminum-containing layer with thickness of about 10 microns is formed on the surface of Kapton. ...
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... aluminum-containing layer with thickness of about 10 microns is formed on the surface of Kapton. The high-resolution XPS spectrum of the Al2p and O1s regions of the Kapton/Al2O3 composite films is shown in Figure 15. The Al2p peak is located at 74.83 eV, which is consistent with the Al2p peak in Al2O3 in the literature [46,47]. ...
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... above results indicate the successful preparation of the Kapton/Al2O3 nanocomposite film via the surface-modification-ionexchange method. The high-resolution XPS spectrum of the Al2p and O1s regions of the Kapton/Al 2 O 3 composite films is shown in Figure 15. The Al2p peak is located at 74.83 eV, which is consistent with the Al2p peak in Al 2 O 3 in the literature [46,47]. ...
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... above results indicate the successful preparation of the Kapton/Al 2 O 3 nanocomposite film via the surface-modification-ion-exchange method. The high-resolution XPS spectrum of the Al2p and O1s regions of the Kapton/Al2O3 composite films is shown in Figure 15. The Al2p peak is located at 74.83 eV, which is consistent with the Al2p peak in Al2O3 in the literature [46,47]. ...
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... above results indicate the successful preparation of the Kapton/Al2O3 nanocomposite film via the surface-modification-ionexchange method. Figure 16 shows the high-resolution spectra of the C1s and O1s regions and the peak fitting curves using XPSPEAK software before and after exposure of the Kapton/Al 2 O 3 nanocomposite films to atomic oxygen. There are also four different states of carbon atoms in the C1s spectrum, with binding energies of 284.31, 284.94, 285.82, and 288.46 eV. ...
Citations
... An effective strategy to improve polyimide film is to coat it with inorganic compounds by special methods, such as solgel [13], spray pyrolysis [14], magnetron sputtering [15], and chemical vapor deposition [16]. Jiang et al [17] prepared Al 2 O 3 -coated Kapton film through ion exchange method. Under 2.16 × 10 20 atom cm −2 flux of AO irradiation, the 10 μm Al 2 O 3 coating protects the PI substrate and reduces the E y to 1.0 × 10 −24 cm 3 /atom. ...
... Among them, the excellent chemical stability, oxidation resistance, and corrosion resistance of TiO 2 make it have great application potential in atomic oxygen protection [19][20][21]. The inorganic coatings prepared by these methods can greatly improve the resistance of polyimide to AO, reducing the erosion yield by one or two orders of magnitude [8,17,19,22]. However, due to the large deposition thickness (micron level), it has the disadvantage of being brittle and easy to crack. ...
Titanium oxide (TiO2) coated polyimide has broad application prospects under extreme conditions. In order to obtain a high-quality ultra-thin TiO2 coating on polyimide by atomic layer deposition (ALD), the polyimide was activated by in-situ oxygen plasma. It was found that a large number of polar oxygen functional groups, such as carboxyl, were generated on the surface of the activated polyimide, which can significantly promote the preparation of TiO2 coating by ALD. The nucleation and growth of TiO2 were studied by XPS monitoring and SEM observation. On the polyimide activated by oxygen plasma, the size of TiO2 nuclei decreased and the quantity of TiO2 nuclei increased, resulting in the growth of a highly uniform and dense TiO2 coating. This coating exhibited excellent resistance to atomic oxygen. When exposed to 3.5 × 1021 atom/cm2 atomic oxygen flux, the erosion yield of the polyimide coated with 100 ALD cycles of TiO2 was as low as 3.0 × 10−25 cm3/atom, which is one order less than that of the standard POLYIMIDE-ref Kapton® film.
... Another potential route is compositing the functional llers into polymer matrix, such as α-AlxTiyO/γ-NiCr, Al 2 O 3 , SiO 2 , POSS, BN, SiOx/NiC, et. al [13][14][15][16][17][18][19][20], the formation of composite materials can enhance the AO resistance of the intrinsic polymer matrix [5,21]. It is expected to solve the cracks and pinholes hidden danger from the synthesis strategy, but the limited performance gains push us to deep the understanding for its enhancing mechanism. ...
High-performance polymer/graphene composites have displayed some potentials for atomic oxygen (AO) resistance in low earth orbit spacecraft. However, such polymer composites have not yet exhibited the desired properties due to the lack of understanding of the protective mechanism. Here, the designed graphene with different kind of defects and structure were successfully synthesized to enhance the polymer, polyethylene (PE) was selected as a model polymer matrix. The theoretical and experimental results revealed that the improved AO resistance originates from synergistic effects of structure defects and exfoliation degree of graphene, where the process of defective graphene binding and stabilizing AO is thermodynamically more favorable, and the higher exfoliation of graphene results in the better dispersion in polymer matrix.Finally, Diameter-Thickness ( D/T ) was employed as an enhancing descriptor to study the structure-performance relationship of the composites, which is expected to provide the reference to tailor the high-performance polymer composites.
... Our experimentally determined elastic modulus is 1.8 GPa at room temperature and is within reasonable agreement with the published data from the manufacturer (2.5 GPa at 23 °C) [3]. Furthermore, our stress-strain results are substantiated from several previous studies on the mechanical response of Kapton films at room temperature [19][20][21]. However, the authors acknowledge that the elastic modulus reported by using [10] is outside of the measurement accuracy specified by our experimental results and is slightly lower than those of [19][20][21]. ...
... Furthermore, our stress-strain results are substantiated from several previous studies on the mechanical response of Kapton films at room temperature [19][20][21]. However, the authors acknowledge that the elastic modulus reported by using [10] is outside of the measurement accuracy specified by our experimental results and is slightly lower than those of [19][20][21]. The variation between the measured sample modulus and those reported in literature can be attributed to the use of crosshead displacement as the base for strain measurements instead of measuring the sample displacement directly (e.g., via contact or noncontact extensometry). ...
Due to the temperature dependence of stress–strain response in polymers, it is essential to characterize these materials at cryogenic temperatures for use as dielectrics in superconducting electronics. To date, limited efforts have been carried out to explore the experimental devices and procedures required for mechanical testing of polymer thin films in a cryogenic environment. In this work, we develop a novel tensile testing apparatus for thin film samples in cryogenic temperature conditions. The system’s highly cost-effective design, simple manufacturing process, and ease of integration into conventional mechanical test equipment are discussed. Finite element (FE) analyses are utilized to show the effective operating range of the apparatus in terms of environmental chamber temperature and sample stiffness. Digital image correlation (DIC) is also used to show that frame deformation is minimal during testing, validating the finite element analyses. Polyimide tape samples are tested in tension at room temperature and in a liquid nitrogen (LN2) cooled environment. Room temperature test results are compared to published data for verification. Results obtained herein demonstrate the accuracy and usability of this apparatus for mechanical characterization of thin films in cryogenic conditions. The experimental methodology presented in this work also has the potential to be extended to the characterization of thin films from other material classes for cryogenic applications.
... According to Figure 11b, the oxygen element energy spectrum of the original Kapton film can be fitted to two peaks of 532.92 and 531.97 eV, with peak areas of 36.6% and 63.4%, respectively, corresponding to the C-O bond and the C=O bond [39]. After MD + AO load spectrum test, the peak positions were 532.42 eV (C-O) and 530.91 eV (C=O), the peak areas were 33.2% and 66.8%, respectively, and the peak area of the C-O bond decreased slightly. ...
In the low earth orbit environment, many environmental factors lead to the degradation of material properties. The synergistic effect of long-term atomic oxygen (AO) irradiation and instantaneous impact of micro debris (MD) on long-term and transient space environmental factors has attracted more and more attention. In this paper, the performance evolution of Kapton films under the conditions of MD, AO single factor load spectrum and MD + AO, AO + MD asynchronous synergistic load spectrum were studied by laser driven flyer and microwave atomic oxygen technology. The macro morphology, optical properties and quality changes of Kapton films before and after each load spectrum were compared, and the mechanism of micro morphology and structure changes was explored. The results show that compared with MD + AO loading spectrum, the surface holes of Kapton films are larger under AO + MD load spectrum condition, the residual aluminum particles formed by reverse sputtering of Al particles during impact are less, the average transmittance of the film decreases slightly, and the weight loss of Kapton film is slightly more under the same atomic oxygen exposure time. Under the condition of MD + AO load spectrum, plastic tearing cracks, craters and holes are formed on the surface of Kapton film; the edge of the hole formed under the condition of AO + MD load spectrum is straight, without obvious depression and tear characteristics. Under the condition of MD + AO load spectrum, due to the adhesion of Al after the impact of micro debris, the subsequent atomic oxygen erosion of the film is reduced, so the C-C bond is not seriously damaged, and a considerable part of the residual aluminum flyer is oxidized to alumina by atomic oxygen; The AO + MD loading spectrum test makes the film first eroded by atomic oxygen, resulting in the reduction in C–O bond and C–C bond. The fracture of C–N bond is caused by the hypervelocity impact of micro debris. Hypervelocity impact leads to the thermal decomposition of the material, destroys the C–N bond in the imide ring and generates an N–H bond. This study will provide a method reference and a reference for the multi-factor ground collaborative simulation of space environment of spacecraft materials.
... Up to now, there have been two procedures for enhancing the AO resistance of the PI (PMDA-ODA) films, which are known as the passive protection and active protection. The former procedure is to incorporate the AO-resistant components, mainly inorganic or metal oxides, such as silica, alumina, zirconia, and so on, into the matrix or onto the surface of the pristine PI (PMDA-ODA) films [12][13][14][15]. These specific components could react with the AO species to afford the AO-resistant passivation layers onto the surface of PI film; thus, providing the long-term AO protection. ...
The relatively poor atomic-oxygen (AO) resistance of the standard polyimide (PI) films greatly limits the wide applications in low earth orbit (LEO) environments. The introduction of polyhedral oligomeric silsesquioxane (POSS) units into the molecular structures of the PI films has been proven to be an effective procedure for enhancing the AO resistance of the PI films. In the current work, a series of POSS-substituted poly (pyromellitic anhydride-4,4′-oxydianiline) (PMDA-ODA) films (POSS-PI) with different POSS contents were synthesized via a POSS-containing diamine, N-[(heptaisobutyl-POSS)propyl]-3,5-diaminobenzamide (DABA-POSS). Subsequently, the effects of the molecular structures on the thermal, tensile, optical, and especially the AO-erosion behaviors of the POSS-PI films were investigated. The incorporation of the latent POSS substituents decreased the thermal stability and the high-temperature dimensional stability of the pristine PI-0 (PMDA-ODA) film. For instance, the PI-30 film with the DABA-POSS content of 30 wt% in the film exhibited a 5% weight loss temperature (T5%) of 512 °C and a coefficient of linear thermal expansion (CTE) of 54.6 × 10−6/K in the temperature range of 50–250 °C, respectively, which were all inferior to those of the PI-0 film (T5% = 574 °C; CTE = 28.9 × 10−6/K). In addition, the tensile properties of the POSS-containing PI films were also deteriorated, to some extent, due to the incorporation of the DABA-POSS components. The tensile strength (TS) of the POSS-PI films decreased with the order of PI-0 > PI-10 > PI-15 > PI-20 > PI-25 > PI-30, and so did the tensile modulus (TM) and the elongations at break (Eb). PI-30 showed the TS, TM, and Eb values of 75.0 MPa, 1.55 GPa, and 16.1%, respectively, which were all lower than those of the PI-0 film (TS = 131.0 MPa, TM = 1.88 GPa, Eb = 73.2%). Nevertheless, the incorporation of POSS components obviously increased the AO resistance of the PI films. All of the POSS-PI films survived from the AO exposure with the total fluence of 2.16 × 1021 atoms/cm2, while PI-0 was totally eroded under the same circumstance. The PI-30 film showed an AO erosion yield (Es) of 1.1 × 10−25 cm3/atom, which was approximately 3.67% of the PI-0 film (Es = 3.0 × 10−24 cm3/atom). Inert silica or silicate passivation layers were detected on the surface of the POSS-PI films after AO exposure, which efficiently prevented the further erosion of the under-layer materials.
Influence of accelerated electrons, solar vacuum ultraviolet, and atomic oxygen on the electrical properties of various types of polymeric materials of spacecraft external surfaces is investigated. It is shown that upon irradiation by 95 keV electrons with fluence of 5 × 1012 cm−2 and solar quanta with a dose of 1500 equivalent sun hours, the volume electrical resistivity does not change or changes by no more than one order of magnitude for some types of the polymeric materials. Irradiation with atomic oxygen with an energy of ~ 5 eV does not lead to a change in bulk resistivity of materials, while the surface resistivity alters depending on the type of polymer. It has been established that isothermal heating in a vacuum of non-irradiated and irradiated with atomic oxygen polymeric materials for a long time leads to the appearance of maxima in the kinetic curves of changes in surface resistivity. A physical model is proposed based on the assumption that at least two processes associated with the evaporation and diffusion of sorbed water molecules or hydroxyl groups into the near-surface layers of polymers are involved in the formation of such maxima.
