Fabrication and properties of anisotropic polyimide aerogels with aligned tube‐like pore structure

Chen, Shaokang; Wu, Pingbo; Yu, Zhi; Zou, Huawei; Liu, Pengbo

doi:10.1002/app.48769

Cited by 8 publications

(3 citation statements)

References 26 publications

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“…Since the mesoporous structure of aerogels limits heat conduction efficiency, aerogels have great promise as thermal insulation materials 38–40 . Low‐temperature and humid circumstances were employed to demonstrate the thermal insulation capabilities of the hydrophobized aerogels, as illustrated in Figure 8.…”

Section: Resultsmentioning

confidence: 99%

“…Since the mesoporous structure of aerogels limits heat conduction efficiency, aerogels have great promise as thermal insulation materials. [38][39][40] Low-temperature and humid circumstances were employed to demonstrate the thermal insulation capabilities of the hydrophobized aerogels, as illustrated in Figure 8. First, a piece of stainless-steel metal block with high thermal conductivity was frozen to below minus 40 C, and then the modified aerogels (using the T-2 treatment procedure, as indicated in Table 2) were deposited on the frozen metal block.…”

Section: Thermal Insulation Performancementioning

confidence: 99%

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Robust hydrophobic modification of para‐aramid nanofibers/polyvinyl alcohol composite aerogels with 1H,1H,2H,2H‐perfluorooctyltriethoxysilane

Ren

Hasuo

Tabata

et al. 2022

J of Applied Polymer Sci

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Aerogels are frequently exposed to moisture or come into direct contact with water in real-world applications, posing a threat to their stable performance. Herein, based on the characteristic that the liquid phase can efficiently diffuse in the solid cross-linked network of gels, a robust hydrophobic modification approach for paraaramid nanofibers/polyvinyl alcohol (ANFs/PVA) composite aerogels with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) is demonstrated. The type of solvent, the concentration of hydrochloric acid (HCl) required promoting PFOTES hydrolysis, and the treatment time for hydrophobic modification are discussed individually. The ANFs/PVA/PFOTES aerogels with a water contact angle of 131.0 were obtained through supercritical fluid drying employing acetone as the solvent, with a concentration of 0.1 mol/L HCl of 0.35 vol%, and a treatment duration of 2 h. The hydrogen bond between ANFs and PVA, and the grafting of PFOTES on PVA have both been verified by Fourier-transform infrared spectroscopy. The porous structure of the modified aerogels was improved simultaneously, according to scanning electron microscope and Brunauer-Emmett-Teller characterizations.With the help of a thermal imaging camera, ANFs/PVA/PFOTES aerogels exhibit stable thermal insulation capability in low temperature and humid environments, which holds great promise for a wide range of applications.

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Section: Resultsmentioning

confidence: 99%

Section: Thermal Insulation Performancementioning

confidence: 99%

Robust hydrophobic modification of para‐aramid nanofibers/polyvinyl alcohol composite aerogels with 1H,1H,2H,2H‐perfluorooctyltriethoxysilane

Ren

Hasuo

Tabata

et al. 2022

J of Applied Polymer Sci

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“…By repeating this operation, a five-layer sample was obtained. After freeze drying and thermal imidization, [44,45] the gradient PI aerogel was thus obtained. The final thickness of every layer of five-layer PI aerogel was about 4 to 5 mm.…”

Section: Preparation Of Pi Aerogels Via Layer-by-layer Assembly Methodsmentioning

confidence: 99%

Properties of gradient polyimide aerogels prepared through layer‐by‐layer assembly

Yuan

et al. 2020

Polymer Engineering & Sci

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A series of density gradient polyimide (PI) aerogels were prepared using layer‐by‐layer assembly and radial freezing method. Briefly, a layer of poly(amic acid) (PAA) ammonium salt aqueous solution was first radially frozen. Then, the second layer of PAA ammonium salt (PAS) aqueous solution of different concentration was added on the top of the first PAS layer and radially frozen. A multilayer gradient PAS solid sample could therefore be fabricated by repeating this similar procedure. The density gradient PI aerogels were obtained after freezing drying and final thermal imidization treatment. Each layer of gradient PI aerogels had anisotropic pore structure, which consisted of tube‐like pores along the radial direction and toward the center axis of the cylindrical samples. The compressive strength of five‐layer gradient PI aerogel was higher than that of three‐layer gradient and single‐layer PI aerogels with the same density. The gradient PI aerogels exhibited anisotropic heat transfer behavior in the direction of density gradient, and heat transfer from the higher density side to the lower density side was faster.

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Short‐cut polyisophthaloyl metaphenylene diamine fiber reinforced polyimide aerogel composites for improving thermal insulation and mechanical performance

Liu,

Wang,

Zhang

et al. 2024

J of Applied Polymer Sci

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Polyimide aerogels are often constrained by the poor mechanical performance when used as thermal insulation. In addition, there is requirement for flame retardant performance in the practical use. In this paper, a fiber‐reinforced polyimide aerogel material was prepared by compounding polyisophthaloyl metaphenylene diamine fibers with the aerogel, which present good thermal insulation and excellent mechanical properties, flame retardancy, thermal stability, and certain hydrophobicity, as well as being very lightweight. The compressive strength of the polyimide aerogel was increased from 0.34 to 0.58 MPa by using the fibers as the reinforcing phase; meanwhile, the flame‐retardant property was improved, and the limit oxygen index was increased from 33.8 to 36.5. The composite aerogel material has good potential for application in the fields of thermal insulation, building insulation, aerospace, etc.

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Fabrication and properties of anisotropic polyimide aerogels with aligned tube‐like pore structure

Cited by 8 publications

References 26 publications

Robust hydrophobic modification of para‐aramid nanofibers/polyvinyl alcohol composite aerogels with 1H,1H,2H,2H‐perfluorooctyltriethoxysilane

Robust hydrophobic modification of para‐aramid nanofibers/polyvinyl alcohol composite aerogels with 1H,1H,2H,2H‐perfluorooctyltriethoxysilane

Properties of gradient polyimide aerogels prepared through layer‐by‐layer assembly

Short‐cut polyisophthaloyl metaphenylene diamine fiber reinforced polyimide aerogel composites for improving thermal insulation and mechanical performance

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