Researcher Zhang Xuetong, Suzhou Institute of Nanotechnology, Chinese Academy of Sciences: Polyimide aerogel fiber has excellent flame retardancy and strength

Abstract: Aerogel fibers with ultra-high porosity, large specific surface area and ultra-low density have received more and more attention because they are considered to be the next generation of thermal insulation fibers
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However, due to the obvious conflict between the static sol-gel transition of aerosol and the dynamic wet spinning process in the traditional wet spinning method, the traditional wet spinning method is still used to produce arbitrary aerogel fibers.
It is a huge challenge
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Recently, the team of researcher Zhang Xuetong from the Suzhou Institute of Nanotechnology and Nanobionics, Chinese Academy of Sciences developed a sol-gel containment transition (SGCT) strategy for the manufacture of various mesoporous aerogel fibers, in which the aerogel is first coagulated by surface tension The colloidal precursor solution is driven into the capillary, and then the gel fiber is easily formed in the narrow space.
After the static sol-gel process, the mesoporous aerogel fiber is obtained through the supercritical CO2 drying process
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?? Related papers are published on "ACS Nano" with the title Polyimide Aerogel Fibers with Superior Flame Resistance, Strength, Hydrophobicity, and Flexibility Made via a Universal Sol–Gel Confined Transition Strategy
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Under normal circumstances, polyimide (PI) aerogel fibers prepared by the SGCT method have a large specific surface area (up to 364 m2/g), excellent mechanical properties (elastic modulus of 123 MPa), and excellent hydrophobicity Sex (when in contact)
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The angle is 153°) and excellent flexibility (the radius of curvature is 200μm)
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Therefore, even in harsh environments, aerogel woven fabrics made of PI aerogel fibers have excellent thermal insulation properties in a wide temperature range
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In addition, any kinds of aerogel fibers have been successfully manufactured, including organic aerogel fibers, inorganic aerogel fibers and organic-inorganic hybrid aerogel fibers, which shows the universality of the SGCT strategy, which is not only for development Different kinds of aerogel fibers provide a way
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Components, but also play an irreplaceable role in promoting the upgrading of the fiber field
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? [Main image see analysis] Diagram 1.
(a) Schematic diagram of SGCT strategy for preparing polyimide aerogel fiber, (b) contact angle of PAA solution in glass capillary, (c) diagram of PAA solution in vertical capillary, And (d) the inclined capillary, and (e) the process of removing the gel fiber from the capillary
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Figure 1.
(a) Digital photo of PI aerogel fiber
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(B) Optical micrograph of a single PI aerogel fiber knotted
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(C, d) Digital photos of polyimide aerogel fibers woven into the fabric at different magnifications
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(E-h) Surface and cross-sectional morphology of PI-300 aerogel fibers
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Figure 2.
(a) The hydrophobicity of a single PI aerogel fiber
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(B) Super flexibility of a single PI aerogel fiber
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(C) PI aerogel fabric suspended with 500 grams of water, and (d) tensile stress-strain curves of aerogel fibers of different diameters
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The illustration shows a single PI-300 aerogel fiber with a weight of 100 g and strong mechanical strength
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(E) The ignition test comparison between commercial cotton fiber and PI aerogel fiber shows that the flame retardancy of PI aerogel fiber is better than that of commercial cotton fiber
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Figure 3.
(a) Infrared image of a single aerogel fiber on a hot stage at 100 and 250°C
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The surface temperature of the aerogel fiber is obtained from the infrared image
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(B) The temperature difference (|ΔT|) between the fiber surface and the hot stage corresponds to the temperature of the stage
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(C) Digital photos and infrared photos of PI aerogel textiles and cotton textiles at room temperature and thermal insulation test
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(D) A schematic diagram of an experimental device used to test the thermal insulation properties of PI aerogel fabrics and cotton textiles at high temperatures
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(E) Temperature-time curve of PI aerogel fabric and cotton fabric at a stable temperature of 150°C
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(F) Temperature-time curves of PI aerogel fabric and cotton fabric at unstable temperatures (150 and 205°C)
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(G) A schematic diagram of an experimental device used to test the thermal insulation properties of PI aerogel fabrics and cotton textiles at low temperatures
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(H,i) When liquid nitrogen is injected, the temperature-time curve (h) of PI aerogel fabric and cotton fabric in the cold stage is at -165°C and (i) -100°C
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Figure 4.
Various aerogel fibers constructed by the SGCT strategy: (a) agarose, (b) aramid nanofibers, (c) resorcinol formaldehyde, (d) graphene, (e) Resorcinol formaldehyde-derived carbon, (f) SiO2, (g) PI/SiO2, (h) graphene/CNT and (i) aramid nanofiber/carboxymethyl cellulose
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? [Summary] The author has successfully manufactured PI aerogel fibers with a typical mesoporous structure through the SGCT method
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The obtained PI aerogel fiber showed high mechanical properties (strength 11 MPa; elongation at break 25%), super hydrophobic (water CA = 153°), and excellent flexibility (radius of curvature = 200μm) And excellent flame retardancy
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In addition, the PI fabric woven from aerogel fibers has a lower thermal conductivity (0.
025-0.
032 W m-1 K-1) and excellent insulation in a lower temperature range (?165-250°C).
Thermal
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The results show that PI aerogel fiber may be an excellent thermal insulation material in harsh environments, and can be used in fields such as cold protection, fire resistance, and daily heat insulation
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In addition, more different aerogel fibers (including organic, inorganic and organic/inorganic hybrid substances) have been successfully prepared through this strategy, and the performance of aerogel fibers can remain the same as that of bulk aerogels, which shows that Aerogel has unparalleled versatility
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SGCT's strategy for manufacturing various aerogel fibers
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In short, with such excellent usability and controllability, this general SGCT strategy can establish a method for the production of organic and inorganic aerogel fibers.
This method will be used in many application fields and will be a scientific belt for aerogels.
Great progress
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? References: doi.
org/10.
1021/acsnano.
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