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Article

The Influence of Titanium Dioxide Nanosheet on Water Permeability of Silicone Rubber after Nitrogen Dioxide Aging Treatment

by
Xiangyang Peng
1,*,
Jinshuai Zhang
2,
Jiapeng Fang
2,
Zheng Wang
1,
Zhen Huang
1,
Shilong Kuang
2 and
Chunqing He
2
1
Guangdong Key Laboratory of Electric Power Equipment Reliability, Electric Power Research Institute of Guangdong Power Grid Co., Ltd., Guangzhou 510080, China
2
Key Laboratory of Nuclear Solid State Physics Hubei Province, School of Physics and Technology, Wuhan University, Wuhan 430072, China
*
Author to whom correspondence should be addressed.
Materials 2023, 16(22), 7138; https://doi.org/10.3390/ma16227138
Submission received: 8 October 2023 / Revised: 29 October 2023 / Accepted: 1 November 2023 / Published: 12 November 2023
(This article belongs to the Special Issue Recent Advances in Conductive and Electrical Insulating Polymer Composites)
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Abstract

:
In this study, the aging process of a surface-functional titanium dioxide nanosheet (f-TNS) composited room-temperature-vulcanized silicone rubber (RTV) composite coating was simulated in a NO2 generation device, and then the electrochemical impedance spectroscopy (EIS) of the aged composite coating was tested in a 3.5% NaCl solution. The water permeation process was analyzed by the changes in the impedance modulus, porosity, and breakpoint frequency of the composite coating. The experimental results show that the water permeability of aged RTV decreases first and then increases with the increase in the composite proportion of f-TNS. When the composite proportion of TNS was 0.3 wt.%, the composite sample had the minimum water permeability and the best resistance to NO2 corrosion. The effect of TNS on the NO2 aging resistance of RTV composites and its mechanism were studied by SEM, FT-IR, and XPS. The impedance modulus and porosity of the aged 0.3% f-TNS/RTV, respectively, were 1.82 × 107 Ω cm2 and 0.91 × 10−4%, which increased by 2.23 times and decreased by 0.37 times, respectively, compared with the values of aged pure RTV sample. In addition, the breakpoint frequency of the aged 0.3% f-TNS/RTV also significantly reduced to 11.3 Hz, whereas it was 35 Hz in aged pure RTV.

1. Introduction

Silicone rubber (SIR) materials [1] mainly contain high-temperature vulcanized SIR, addition-type fluid SIR, and room temperature vulcanized SIR (RTV) [2]. Because of their excellent thermal stability, mechanical strength, electrical insulation [3], and hydrophobicity characteristics, both are widely used in building decoration, medical cosmetology, daily necessities, and even aerospace and power facilities [4]. Composite insulators prepared by HTV and coated spray insulators prepared by RTV are used in the power industry on a large scale [5,6,7]. Composite insulators mainly use the Si−O and Si−CH3 chain structures of outer insulator SIR to bring about good hydrophobicity [8,9] and hydrophobic recovery [10], excellent anti-pollution flashover and electrical insulation properties, etc. At present, there are more than 10 million composite insulators in net operation [11]. However, since composite insulators always operate under the action of high-voltage electric field [12,13], in addition to the aging of common natural environmental factors such as light, thermal oxidation [14,15], popllution [16], and humidity [17,18], high-oxidizing NO2 produced by arc flashover and corona discharge caused by high voltage accelerate the decomposition of each component of SIR and increase the flaw in the body [19]. Studies have shown that the aging of NO2 can transform its basis Polydimethylsiloxane (PDMS) covered by SIR into hydrophilic and close inorganic silica. Firstly, PDMS network rupture and inorganic formation form nanopores, as well as a small number of micropores (Al(NO3)3) are generated near the surface, and then a large number of PDMS in the body layer produce a chain broken and become inorganic [20,21]. Some nano and micron holes for water diffusion are gradually formed and connected, causing the loss of hydrophobicity, anti-fouling flashover, and other characteristics, thus leading to the breakdown of internal insulation of composite insulators, broken series, and other malignant failures, posing a major threat to the operation of the power grid [22,23]. In other words, enhancement of the water permeability of SIR after NO2 aging has become an important bottleneck affecting its long-term application.
At present, various nanofillers, especially two-dimensional (2D) nanosheets, have extensive use in improving the gas barrier performance of polymer materials [24,25,26,27]. For example, Hara et al. mixed graphene oxide into a layered organosiloxane film to improve the water vapor barrier performance of the film, because the siloxane layer acts as the barrier layer for the diffusion of water molecules [28]. Zhang et al. found that when the packing content of g-C3N4 was 0.3 wt.%, the function g-C3N4/RTV had the best NO2 blocking performance [20]. Wen et al. used KH550 to modify the surface of 25 nm TiO2 nanoparticles to better disperse in a polyvinylidene fluoride (PVDF) matrix by the melt blending method. The lowest permeability coefficient of PVDF/0.5% N-TiO2 showed better mechanical and CO2-blocking properties [29]. Jia et al. mixed organic modified montmorillonite (OMMT) into SIR and found that the addition of OMMT significantly improved the N2 barrier performance of SIR [30]. Chen et al. assembled a Schottky junction-induced TiO2@Sn3O4 nano-heterojunction and found that it has a high sensitivity to NO2 gas sensing at room temperature [31]. Coincidentally, Liu et al. also found that the incorporation of TiO2 enhanced the excellent response of Ti3C2/TiO2 composites to NO2 gas [32]. Shi et al. found that the incorporation of nano TiO2/SiO2 into epoxy resin enhanced the corrosion resistance using electrochemical impedance spectroscopy (EIS) and salt spray test [33]. This suggests that TiO2 may be used as a filler to improve the NO2 aging resistance of SIR.
Therefore, in this paper, 2D titanium dioxide nanosheets (TNS)/RTV are prepared and a NO2 aging simulation is performed. The electrochemical properties of NO2-aged RTV composited samples in an aqueous solution were studied by the EIS technique. Finally, the experimenters systematically explored the influence of TNS on the water permeability of silicone rubber after the NO2 aging treatment.

2. Materials and Methods

2.1. Materials

Titanium dioxide was bought from Degussa Co., Ltd., Shainghai, China. Hydroxyl-terminated polydimethylsiloxane was provided by Guobang Chemical Co., Ltd., Jinan, China. Sodium hydroxide (NaOH) and hydrochloric acid (HCl) were provided by Sinopharm Chemical Reagent Co., Ltd., Beijing, China. Tetraethoxysilane (TEOS) and aminopropyltriethoxysilane (APTES) were purchased from Macklin Biochemical Technology Co., Ltd., Guangzhou, China. Aluminum hydroxide was provided by Aluminum Corporation of China, Zibo, China.

2.2. Preparations

Preparation of pure TNS: A total of 0.8 g Titanium dioxide was mixed into 50 mL of a 10 mol/L NaOH solution in a Teflon autoclave, and a hydrothermal process was performed at 130 °C for 3 h. Then, the hydrothermal precipitate obtained by cleaning with distilled water was poured into a 60 mL 0.1 mol/L HCl solution and stirred for 2 h. Finally, the product was cleaned with distilled water and then dried at 60 °C.
Preparation of surface functionalization TNS (f-TNS): First, the commixed silane of APTES and TEOS was prepared according to a mass percentage of 25:75; then, ethanol, water, and commixed silane were blended with a volume percentage of 70:15:15. After completion, TNS was added to the blended solution. The pH of the blended solution dispersed with TNS was adjusted to 4.5 with hydrochloric acid and left at 25 °C for 40 h. After that, the pH of the solution was adjusted to 8.5 with a sodium hydroxide solution (2.5 wt.%) and kept at 65 °C for 2 h. The underlying sediment was separated by centrifugation, cleaned and dried. f-TNS were obtained.
Preparation of nanocomposite coatings with different filler contents (0.1, 0.3, 0.5, 0.7, 1 wt.% f-TNS/RTV): Hydroxyl-terminated polydimethylsiloxane, f-TNS, and aluminum hydroxide were blended at 120 °C for 4 h. When the temperature of the mixture dropped to 40 °C, the other additional fillers were mixed, and this system was blended continuously for 1 h. Then, the mixture was poured over the glass slide and cured at 25 °C for 24 h to form the f-TNS/RTV nanocomposite coating. The resulting coating thickness was 50 ± 2 μm.
NO2 corrosion aging treatment: The f-TNS/RTV nanocomposite coating samples were put into a NO2 generation device for 24 h and the aged RTV coating samples were obtained. The NO2 generation device refers to the previous article [20].

2.3. Characterization

The f-TNS nanosheets were characterized by scanning electron microscopy (SEM, Hitachi S-4800, Hitachi, Tokyo, Japan) to obtain morphologies. The chemical environment of surface elements of the TNS was analyzed by X-ray photoelectron spectroscopy (XPS, ESCALAB 250Xi, Thermo Fisher Scientific, Shanghai, China). The EIS test workstation was the CS310 Electrochemical workstation (Coster, Wuhan, China). In addition, all samples were soaked in a 3.5 wt.% NaCl solution during the EIS test [34,35].

3. Results and Discussion

SEM was used to observe the surface morphology of TNS before and after modification. As can be seen in Figure 1a, the TNS presents a big volume agglomeration state because the two-dimensional nanosheets such as TNS have van der Waals forces between them. After modification of TEOS and APTES, particle objects appear on the surface, which may be the condensation of silane and hydroxyl on the surface of TNS to form organosilicon nanoparticles, which can improve the compatibility of inorganic TNS nanosheets in RTV.
Figure 2 shows the ATR-FTIR test results of pure TNS and f-TNS nanosheets. TNS and f-TNS nanosheets had the same peaks in FTIR spectra, including −OH at 3200 and 1650 cm−1, and Ti−O−Ti at 510 cm−1. The presence of surface hydroxyl groups in TNS provided an active site for graft condensation for silane modification. After modification by TEOS and APTES [35], the peak of Ti−O−Ti in f-TNS was offset and moved to 530 cm−1, indicating that the hydroxyl group on TNS had a condensation reaction with a silane coupling agent, thus making the peak of the Ti−O−Ti shift. The appearance of Ti−O−Ti peaks indicates that the modification of TEOS and APTES does not affect the structure of TNS, which still maintains its chemical structure. In addition, four new vibration peaks appeared at 2960, 1550, 1100, and 810 cm−1, which were, respectively, attributed to −CH2, −NH2, Ti−O−Si, and asymmetric stretching vibration Si−O−Si [36,37,38]. According to the SEM results of the above section, the surface of TNS was coated with some fluffy nano-silicone particles modified by organosilicon. Therefore, the shift of the Ti−O−Ti peak and the appearance of methylene, amino, Ti−O−Si, and Si−O−Si once again prove that silane was successfully grafted onto the surface of TNS.
To further determine the surface chemical state of modified TNS nanosheets, XPS was used to analyze the pure TNS and f-TNS. As can be seen in Table 1, Ti and O (18.58:46.91 at %) are the main element composition of TNS, and the presence of carbon is caused by the influence of the substrate during the test. For f-TNS nanosheets, the elemental composition is C, N, O, Ti, and Si (49.11:1.25:27.19:4.58:17.86 at %). The additional peak of Si and N indicates that silane was modified on the surface of the sheet. The bonding states of Ti 2p, N 1s, O 1s, and Si 2p of the f-TNS nanosheet and TNS are distinguished by a suitable combination of Lorentz and Gaussian functions. In Figure 3b, the O 1s XPS spectral peaks of the original TNS showed two peaks at 530.17 eV and 532.17 eV, corresponding to Ti−O and Ti−OH [39]. The Ti−O bond of the modified TNS appeared at 529.92 eV and was skewed towards the lower binding energy. The Ti−O movement indicated that the Ti−O−Si bond was formed on the surface of TNS. It was speculated that the hydrogen in Ti−O−H was partially replaced by silicon in Ti−O−Si, because Si is less electronegative than H, so the electron density in O is higher. As shown in Figure 4c, after modification, the characteristic peak of Ti 2p also deviated towards low binding energy, again indicating the formation of the Ti−O−Si bond. It shows that the combination of TNS and silane is not a simple physical mixing. Figure 4d shows three typical stretching vibration peaks of Si 2p at 101.9, 102.9 and 103.9 eV in Si(−O)1, Si(−O)2 and Si(−O)3 condensation systems [40]. The presence of Si−O−Si and Si−O−Ti indicated that some silane was successfully grafted onto the surface of the nanosheets according to the covalent bond.
The EIS of an unaged RTV coating with a series of f-TNS composite proportions is shown in Figure 4. After a 96 h immersion in a NaCl solution, the electrochemical impedance modulus at 0.1 Hz (|Z|) of RTV coating remained at 109 Ω cm2, indicating that the introduction of f-TNS did not destroy the water resistance of the coating, which was regarded as a pure capacitor [34], even though the coating maintained good integrity after a 96 h immersion.
Figure 5 is the EIS of pure RTV and a 0.1 wt.% f-TNS/RTV after NO2 aging for 24 h. The water permeability of aged pure RTV coating decreases, obviously. When the coating was immersed in a 3.5 wt.% NaCl solution for 96 h, the |Z| decreased obviously compared with the unaged coating. |Z| decreased from 109 Ω cm2 to about 8.2 × 106 Ω cm2, which shows that due to NO2 corrosion, the water permeability of RTV coating was destroyed. In addition, the EIS frequency at 45° is called the breakpoint frequency f b , and its magnitude could qualitatively analyze the delamination of the coating. The bigger the f b , the more severe the coating delaminate [34,35]. After NO2 aging, the f b of pure RTV was about 35 Hz, which implies that aging causes a certain degree of delamination. As shown in Figure 5b, when a 0.1 wt.% f-TNS nanosheet was filled, the |Z| of the sample increased compared with that of pure RTV, about 1.24 × 107 Ω cm2, and the f b of the sample decreased to 18.2 Hz. This shows that the incorporation of the nanosheets slows down the diffusion of NO2 gas inside the coating to a certain extent and improves water permeability. However, there is still a relatively serious delamination of the coating. The experiment continues to increase the filling amount of TNS to explore the coating formulation with the best water permeability effect.
Figure 6 is the EIS of the aging 0.3 and 0.5 wt.% f-TNS/RTV. The |Z| of a 0.3 wt.% f-TNS/RTV is about 1.82 × 107 Ω cm2, and the f b also obviously decreases, which is about 11.3 Hz. Only one time constant was observed in the Byrd diagram, and a capacitive phenomenon was observed in a wide frequency range (102–105 Hz), indicating that the increase in the functionalized nanosheet content f-TNS can largely delay and prevent the diffusion of NO2 gas inside the RTV sample. This extension of the gas diffusion path could protect internal RTV from NO2 corrosion so that the coating can maintain better integrity. As can be seen from Figure 6b, for a 0.5 wt.% f-TNs/RTV, the |Z| of the coating decreases again, about 6.28 × 106 Ω cm2, compared with that of the coating with a 0.3 wt.% filling. Accordingly, f b is also increased to 30.1 Hz. This indicates that a 0.5 wt.% f-TNs/RTV has a lesser NO2 blocking function than a 0.3 wt.% f-TNs/RTV, although the water permeability is better than that of pure RTV. It is speculated that the increase in f-TNS content may cause the aggregation of f-TNS in RTV, and the defects caused by agglomeration may become the aging breakthrough channel of NO2, and eventually become the decline of water resistance.
Figure 7 is the EIS of aged 0.7 wt.% and 1.0 wt.% f-TNS/RTV. Compared with the above coating, the |Z| of the RTV is further reduced to about 1.78 × 106 Ω cm2. In addition, the f b also become bigger once more, about 114.3 Hz. It implies that the sample is severely stratified. The |Z| of a 1.0 wt.% f-TNS/RTV shows a more serious decrease, dropping to 4.2 × 105 Ω cm2, which is smaller than that of the pure RTV coating. Meanwhile, its f b rises suddenly to 2400 Hz, which is 212.4 times the breakpoint frequency of a 0.3 wt.% f-TNS/RTV. These EIS results show that the excessive addition of the filler greatly reduces the resistance of the coating to NO2. We guess this may be due to the size of the nanometer sheet is so small that it is easy to reunite and form a large NO2 seepage channel. The filler agglomeration makes the NO2 in the coating internally spread more easily. The damage of NO2 to the coating microstructure is more serious, which affects the integrity of the coating, making its water barrier ability greatly reduced.
Figure 8 shows the variation curve of fitting RTV coating resistance (Rb) with a series of f-TNS composite proportions at different soaking times. Taking the Rb curve of pure RTV as a reference, the coating Rb increases when a 0.1 wt.% f-TNs is filled, about 1.13 × 107 Ω cm2. These results show that the composite proportion of f-TNS can play a certain role in blocking NO2 gas. For a 0.3 wt.% f-TNs/RTV, the coating Rb continues to increase to about 1.4 × 107 Ω cm2, which is the highest value for the whole set of samples. As the TNS content continues to increase, the coating Rb begins to decrease. Especially when the TNS content increases to 1 wt.%, its Rb is about five times lower than pure RTV, about 9.2 × 105 Ω cm2. The overall result is that with the increase in f-TNS content, the coating Rb first increases and then decreases; that is, the best filling ratio of f-TNS is about 0.3 wt.%.
Figure 9 shows the variation curves of the porosity and the |Z| of RTV samples with a series of f-TNS composite proportions corroded by NO2. The calculation method of porosity is referred to in the previous article [20]. It can be seen from Figure 9a that with the increase in f-TNS, the porosity of the coating decreases first and then increases. The 0.3 wt.% f-TNS/RTV has a minimum porosity of about 0.91 × 10−4%. The porosity of pure RTV coating after NO2 corrosion aging is 2.73 times that of f-TNS/RTV filled with 0.3 wt.%. When the composite proportions of f-TNS nanosheets reached 1 wt.%, the porosity of the aged RTV sample boomed by more than 100 times, reaching 1.38 × 10−2%. It can be seen from Figure 9b that with the increase in f-TNs content, the |Z| of the coating increases first and then decreases. Especially for a 0.3 wt.% f-TNS/RTV, the |Z| reaches 1.82 × 107 Ω cm2, which is 2.23 times higher than the 8.2 × 106 Ω cm2 of pure RTV. As the f-TNS continues to increase to 1 wt.%, the |Z| of the RTV sample decreases to a minimum of about 4.2 × 105 Ω cm2, which is about 50 times smaller than that of the pure RTV sample. The results of the porosity and |Z| also indicate that the optimal f-TNs composite proportion is about 0.3 wt.%.
In Figure 10, the influence of f-TNS composite proportions on the delamination of RTV can be seen more directly from the change curve of f b . With the increase in the composite proportion of f-TNS, the f b of the RTV sample first decreases and then increases. Especially when the composite proportion of f-TNs is 0.3 wt.%, the f b of the RTV sample is reduced to 11.3 Hz. And it is much smaller than that of pure RTV, which is 35 Hz. However, when the composite proportions of f-TNS in RTV increase to 1 wt.%, the f b of the RTV coating increases to 2400 Hz, which is 212.4 times that of filling 0.3 wt.%.
Since RTV coating samples with a series of f-TNS composite proportions have excellent water resistance performance before NO2 aging, it indicates that the introduction of f-TNS does not destroy the water resistance of the coating. The data of Rb, |Z|, porosity and f b of the aged RTV coatings with a series of f-TNS composite proportions show that the introduction of f-TNS can improve the NO2 corrosion aging resistance and water permeability of aged RTV. The composite coating has the best performance when the composite proportion is 0.3 wt.%, which may be because a small amount of f-TNS has a good dispersion in the coating, which can play a role of a physical barrier and increase the diffusion path, delaying the corrosion of NO2 on the coating. However, with the continuous increase in nanosheet content, f-TNS is easy to agglomerate, and the defects caused by agglomeration become a breakthrough for NO2 corrosion, and the aging is more serious than that of pure RTV, resulting in a more significant rise in the water permeability of the RTV coating.

4. Conclusions

In this paper, the composition and chemical structure of f-TNS and the influence of f-TNS on the water permeability of RTV after NO2 aging treatment were studied. SEM, FTIR, and XPS jointly confirmed that silane was successfully grafted onto TNS and the f-TNS was formed. The grafted silane enhanced the interfacial compatibility of 2D sheet TNS in RTV. After NO2 aging for 24 h and soaking in sodium chloride solution for 96 h, the |Z| and Rb of the f-TNS/RTV sample both first increased and then decreased, whereas the porosity and the f b both first decreased and then increased. All of the indexes reached the optimal value when the composite proportion of f-TNS was 0.3 wt.%, which confirms that the aged 0.3 wt.% f-TNS/RTV has the best water permeability. In short, an about 0.3 wt.% f-TNS composite proportion has good dispersion in the RTV coating, which can play the role of the physical barrier and increase the diffusion path, delaying the corrosion of NO2 on the coating. However, with the continuous increase in nanosheet content, f-TNS is easy to agglomerate, the defects caused by agglomeration become a breakthrough for NO2 corrosion, and the aging is more serious than that of pure RTV, resulting in a more significant decline in the water barrier property of the coating. This study investigated a possible method to improve the NO2 aging resistance of RTV, which has the minimum water permeability and further provides the safe operation of power grid insulators.

Author Contributions

Writing—review and editing, C.H. and J.F.; methodology, J.Z. and Z.W.; writing—original draft preparation, Z.H. and J.F.; data curation, Z.H. and J.F.; supervision, X.P. and S.K.; conceptualization, S.K., X.P. and J.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This study is supported by the National Natural Science Foundation of China (No. 12275201) and the Technology Project of China Southern Power Grid Co., Ltd. (No. GDKJXM20220997).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Raw data are available upon request.

Conflicts of Interest

The authors declare no conflict of interest.

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Materials 16 07138 g001
Figure 1. SEM images of pure TNS (a) and f-TNS (b).
Figure 1. SEM images of pure TNS (a) and f-TNS (b).
Materials 16 07138 g001
Materials 16 07138 g002
Figure 2. ATR-FTIR spectrogram of TNS and f-TNS.
Figure 2. ATR-FTIR spectrogram of TNS and f-TNS.
Materials 16 07138 g002
Materials 16 07138 g003
Figure 3. XPS full spectra analysis of pure TNS and f-TNS (a), XPS high-resolution spectra of O 1s (b), Ti 2p (c), N 1s (d), and Si 2p (e).
Figure 3. XPS full spectra analysis of pure TNS and f-TNS (a), XPS high-resolution spectra of O 1s (b), Ti 2p (c), N 1s (d), and Si 2p (e).
Materials 16 07138 g003
Materials 16 07138 g004
Figure 4. The electrochemical impedance modulus at a 0.1 Hz |Z| cave of unaged RTV with series of f-TNS composite proportions after soaking following a 96 h immersion in a NaCl solution.
Figure 4. The electrochemical impedance modulus at a 0.1 Hz |Z| cave of unaged RTV with series of f-TNS composite proportions after soaking following a 96 h immersion in a NaCl solution.
Materials 16 07138 g004
Materials 16 07138 g005
Figure 5. The EIS Bode plots of pure RTV sample after NO2 corrosion (a) and a 0.1 wt.% f-TNS/RTV sample after NO2 corrosion (b).
Figure 5. The EIS Bode plots of pure RTV sample after NO2 corrosion (a) and a 0.1 wt.% f-TNS/RTV sample after NO2 corrosion (b).
Materials 16 07138 g005
Materials 16 07138 g006
Figure 6. The EIS Bode plots of a 0.3 wt.% f-TNS/RTV sample after NO2 corrosion (a) and a 0.5 wt.% f-TNS/RTV sample after NO2 corrosion (b).
Figure 6. The EIS Bode plots of a 0.3 wt.% f-TNS/RTV sample after NO2 corrosion (a) and a 0.5 wt.% f-TNS/RTV sample after NO2 corrosion (b).
Materials 16 07138 g006
Materials 16 07138 g007
Figure 7. The EIS Bode plots of a 0.7 wt.% f-TNS/RTV sample after NO2 corrosion (a) and a 1.0 wt.% f-TNS/RTV sample after NO2 corrosion (b).
Figure 7. The EIS Bode plots of a 0.7 wt.% f-TNS/RTV sample after NO2 corrosion (a) and a 1.0 wt.% f-TNS/RTV sample after NO2 corrosion (b).
Materials 16 07138 g007
Materials 16 07138 g008
Figure 8. The resistance change cave of an aged RTV sample with a series of f-TNS composite proportions at different soaking times (a), the resistance of an aged RTV sample with a series of f-TNS composite proportions after soaking for 96 h (b).
Figure 8. The resistance change cave of an aged RTV sample with a series of f-TNS composite proportions at different soaking times (a), the resistance of an aged RTV sample with a series of f-TNS composite proportions after soaking for 96 h (b).
Materials 16 07138 g008
Materials 16 07138 g009
Figure 9. The bar graph of the porosity (a) and the |Z| (b) of the RTV coatings with a series of f-TNS composite proportions after NO2 corrosion aging.
Figure 9. The bar graph of the porosity (a) and the |Z| (b) of the RTV coatings with a series of f-TNS composite proportions after NO2 corrosion aging.
Materials 16 07138 g009
Materials 16 07138 g010
Figure 10. The bar graph of the breakpoint frequency f b of RTV coatings with a series of f-TNS composite proportions after NO2 corrosion aging.
Figure 10. The bar graph of the breakpoint frequency f b of RTV coatings with a series of f-TNS composite proportions after NO2 corrosion aging.
Materials 16 07138 g010
Table 1. The atomic proportion of each element of TNS and f-TNS.
Table 1. The atomic proportion of each element of TNS and f-TNS.
C/at %N/at %O/at %Ti/at %Si/at %
TNS34.51/46.9118.58/
f-TNS49.114.2527.191.5817.86
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MDPI and ACS Style

Peng, X.; Zhang, J.; Fang, J.; Wang, Z.; Huang, Z.; Kuang, S.; He, C. The Influence of Titanium Dioxide Nanosheet on Water Permeability of Silicone Rubber after Nitrogen Dioxide Aging Treatment. Materials 2023, 16, 7138. https://doi.org/10.3390/ma16227138

AMA Style

Peng X, Zhang J, Fang J, Wang Z, Huang Z, Kuang S, He C. The Influence of Titanium Dioxide Nanosheet on Water Permeability of Silicone Rubber after Nitrogen Dioxide Aging Treatment. Materials. 2023; 16(22):7138. https://doi.org/10.3390/ma16227138

Chicago/Turabian Style

Peng, Xiangyang, Jinshuai Zhang, Jiapeng Fang, Zheng Wang, Zhen Huang, Shilong Kuang, and Chunqing He. 2023. "The Influence of Titanium Dioxide Nanosheet on Water Permeability of Silicone Rubber after Nitrogen Dioxide Aging Treatment" Materials 16, no. 22: 7138. https://doi.org/10.3390/ma16227138

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