Silica-Bacterial Cellulose Composite Aerogel Fibers with Excellent Mechanical Properties from Sodium Silicate Precursor

Gels ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 17
Author(s):  
Qiqi Song ◽  
Changqing Miao ◽  
Huazheng Sai ◽  
Jie Gu ◽  
Meijuan Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bacterial Cellulose ◽  
Thermal Insulation ◽  
Sol Gel ◽  
Silicate Solution ◽  
High Specific Surface Area ◽  
Composite Aerogel ◽  
Composite Gel ◽  
Novel Method ◽  
Insulation Performance

Forming fibers for fabric insulation is difficult using aerogels, which have excellent thermal insulation performance but poor mechanical properties. A previous study proposed a novel method that could effectively improve the mechanical properties of aerogels and make them into fibers for use in fabric insulation. In this study, composite aerogel fibers (CAFs) with excellent mechanical properties and thermal insulation performance were prepared using a streamlined method. The wet bacterial cellulose (BC) matrix without freeze-drying directly was immersed in an inorganic precursor (silicate) solution, followed by initiating in situ sol-gel reaction under the action of acidic catalyst after secondary shaping. Finally, after surface modification and ambient drying of the wet composite gel, CAFs were obtained. The CAFs prepared by the simplified method still had favorable mechanical properties (tensile strength of 4.5 MPa) and excellent thermal insulation properties under extreme conditions (220 °C and −60 °C). In particular, compared with previous work, the presented CAFs preparation process is simpler and more environmentally friendly. In addition, the experimental costs were reduced. Furthermore, the obtained CAFs had high specific surface area (671.3 m²/g), excellent hydrophobicity, and low density (≤0.154 g/cm3). This streamlined method was proposed to prepare aerogel fibers with excellent performance to meet the requirements of wearable applications.

scholarly journals Robust Silica-Bacterial Cellulose Composite Aerogel Fibers for Thermal Insulation Textile

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 145
Author(s):  
Huazheng Sai ◽  
Meijuan Wang ◽  
Changqing Miao ◽  
Qiqi Song ◽  
Yutong Wang ◽  
...  
Keyword(s):  
Bacterial Cellulose ◽  
Thermal Insulation ◽  
High Performance ◽  
Specific Area ◽  
Decomposition Temperature ◽  
Composite Aerogel ◽  
Shaping Process ◽  
The Matrix ◽  
Composite Aerogels ◽  
Novel Method

Aerogels are nanoporous materials with excellent properties, especially super thermal insulation. However, owing to their serious high brittleness, the macroscopic forms of aerogels are not sufficiently rich for the application in some fields, such as thermal insulation clothing fabric. Recently, freeze spinning and wet spinning have been attempted for the synthesis of aerogel fibers. In this study, robust fibrous silica-bacterial cellulose (BC) composite aerogels with high performance were synthesized in a novel way. Silica sol was diffused into a fiber-like matrix, which was obtained by cutting the BC hydrogel and followed by secondary shaping to form a composite wet gel fiber with a nanoscale interpenetrating network structure. The tensile strength of the resulting aerogel fibers reached up to 5.4 MPa because the quantity of BC nanofibers in the unit volume of the matrix was improved significantly by the secondary shaping process. In addition, the composite aerogel fibers had a high specific area (up to 606.9 m2/g), low density (less than 0.164 g/cm3), and outstanding hydrophobicity. Most notably, they exhibited excellent thermal insulation performance in high-temperature (210 °C) or low-temperature (−72 °C) environments. Moreover, the thermal stability of CAFs (decomposition temperature was about 330 °C) was higher than that of natural polymer fiber. A novel method was proposed herein to prepare aerogel fibers with excellent performance to meet the requirements of wearable applications.

scholarly journals Preparation and Properties of SiBCO Aerogel and Its Composites

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 40 ◽  
Author(s):  
Xiafei Li ◽  
Junzong Feng ◽  
Jie Yin ◽  
Yonggang Jiang ◽  
Jian Feng
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Thermal Insulation ◽  
Phenylboronic Acid ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Supercritical Drying ◽  
Temperature Resistance ◽  
Mullite Fiber ◽  
Boron Source

To obtain new high-temperature resistant composites that can meet the requirements of aircraft development for thermal insulation and mechanical properties, SiBCO aerogel composites were prepared by sol-gel, supercritical drying and high-temperature pyrolysis with trimethyl borate (TMB) or phenylboronic acid (PBA) as the boron source and mullite fiber as reinforcement. The structure and composition of the SiBCO aerogel and its composites were characterized with SEM, FT-IR, ICP and nitrogen adsorption tests. The specific surface area of the SiBCO aerogel is 293.22 m2/g, and the pore size is concentrated in the range of 10–150 nm. The mechanical properties, the thermal insulation properties and the temperature resistance were also studied. Due to the introduction of boron, the temperature resistance of SiBCO aerogel composites is improved greatly, and the service temperature of composites reached 1773 K. When n (TMB)/n (TEOS) = 1/1, the temperature resistance of the composites is the best. After heating in air at 1773 K for 30 min, the shrinkage of SiBCO aerogel composites is only 2.45%, and the thermal conductivity of the composites is 0.138 W/(m·K) at 1773 K. In addition, the type and amount of catalyst also have certain effects on the mechanical properties and temperature resistance of the composites.

Effect of hybrid hollow microspheres on thermal insulation performance and mechanical properties of silicone rubber composites

2017 ◽  
Vol 135 (11) ◽  
pp. 46025 ◽  
Author(s):  
Xiong-Wei Zhao ◽  
Chong-Guang Zang ◽  
Ya-Lun Sun ◽  
Yu-Long Zhang ◽  
Yu-Quan Wen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Insulation ◽  
Silicone Rubber ◽  
Hollow Microspheres ◽  
Rubber Composites ◽  
Insulation Performance

Fabrication and properties of carbon/carbon-carbon foam composites

2019 ◽  
Vol 89 (21-22) ◽  
pp. 4452-4460
Author(s):  
Bin Wang ◽  
Bugao Xu ◽  
Hejun Li
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Bonding Strength ◽  
Carbon Foam ◽  
Shear Load ◽  
Foam Composite ◽  
Final Failure ◽  
Carbon Foams ◽  
Insulation Performance

This paper was focused on the development of a new composite for high thermal insulation applications with carbon/carbon (C/C) composites, carbon foams and an interlayer of phenolic-based carbon. The microstructure, mechanical properties, fracture mechanism and thermal insulation performance of the composite was investigated. The experiment results showed that the bonding strength of the C/C-carbon foam composite was 4.31 MPa, and that the fracture occurred and propagated near the interface of the carbon foam and the phenolic-based carbon interlayer due to the relatively weak bonding. The shear load-displacement curves were characterized by alternated linear slopes and serrated plateaus before a final failure. he experiment revealed that the thermal conductivity of the C/C-carbon foam composite was 1.55 W·m−1ċK−1 in 800℃, which was 95.8% lower than that of C/C composites, proving that the thermal insulation of the new foam composite was greatly enhanced by the carbon foam with its porous hollow microstructure.

Robust and superhydrophobic thiourethane bridged polysilsesquioxane aerogels as potential thermal insulation materials

2016 ◽  
Vol 4 (28) ◽  
pp. 10801-10805 ◽  
Author(s):  
Fangxin Zou ◽  
Peng Yue ◽  
Xinghua Zheng ◽  
Dawei Tang ◽  
Wenxin Fu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Sol Gel ◽  
Vacuum Drying ◽  
Drying Method ◽  
Low Thermal Conductivity ◽  
Insulation Materials ◽  
Sol Gel Process ◽  
Bridged Polysilsesquioxane

Novel thiourethane bridged polysilsesquioxane aerogels prepared by a sol–gel process and vacuum drying method exhibit extraordinary mechanical properties and low thermal conductivity.

scholarly journals Phenolic Resin Foam Composites Reinforced by Acetylated Poplar Fiber with High Mechanical Properties, Low Pulverization Ratio, and Good Thermal Insulation and Flame Retardant Performance

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 148 ◽  
Author(s):  
Jian Liu ◽  
Liuliu Wang ◽  
Wei Zhang ◽  
Yanming Han
Keyword(s):  
Mechanical Properties ◽  
Flame Retardant ◽  
Thermal Insulation ◽  
Cell Structure ◽  
Value Added ◽  
Chemical Structures ◽  
Phenolic Foam ◽  
Flame Retardant Properties ◽  
Novel Strategy ◽  
Insulation Performance

Phenolic foam composites (PFs) are of substantial interest due to their uniform closed-cell structure, low thermal conductivity, and good thermal insulation performance. However, their disadvantages of a high pulverization rate and poor mechanical properties restrict their application in building exterior insulation. Therefore, the toughening of these composites is necessary. In this paper, poplar fiber was treated with an acetylation reagent, and the acetylated fiber was used to prepare modified phenolic foams (FTPFs); this successfully solved the phenomenon of the destruction of the foam structure due to the agglomeration of poplar fiber in the resin substrate. The foam composites were comprehensively evaluated via the characterization of their chemical structures, surface morphologies, mechanical properties, thermal conductivities, and flame retardant properties. It was found that the compressive strength and compressive modulus of FTPF-5% respectively increased by 28.5% and 37.9% as compared with those of PF. The pulverization ratio was reduced by 32.3%, and the thermal insulation performance and flame retardant performance (LOI) were improved. Compared with other toughening methods for phenolic foam composites, the phenolic foam composites modified with surface-compatibilized poplar fiber offer a novel strategy for the value-added utilization of woody fiber, and improve the toughness and industrial viability of phenolic foam.

Fabrication of Infrared Opacifiers Loaded Al2O3 Aerogel-SiO2 Fiber Mat Composites with High Thermal Resistance

2020 ◽  
Vol 19 (03) ◽  
pp. 1950021
Author(s):  
Shangyan Wen ◽  
Jiayi Zhu ◽  
Qiang Yin ◽  
Yutie Bi ◽  
Hongbo Ren ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Thermal Insulation ◽  
Sol Gel ◽  
Doping Content ◽  
Low Thermal Conductivity ◽  
Sic Particles ◽  
Sol Gel Process ◽  
High Thermal Resistance ◽  
Insulation Performance

The infrared opacifiers loaded Al2O3 aerogel-SiO2 fiber mat composites were fabricated by the sol–gel process. The effects of the content of the TiO2 and SiC particles on thermal insulation performance of the Al2O3 aerogel-SiO2 fiber mat composites were studied. The results showed that the optimum doping content of TiO2 and SiC for Al2O3 aerogel-SiO2 fiber mat composites were 10[Formula: see text]mol.% and 0.5[Formula: see text]mol.%, respectively. The optimum TiO2-Al2O3 aerogel-SiO2 fiber mat composite had the low thermal conductivity of 0.021[Formula: see text]W/(m[Formula: see text][Formula: see text][Formula: see text]K) at 35∘C and 0.031[Formula: see text]W/(m[Formula: see text][Formula: see text][Formula: see text]K) at 600∘C. Meanwhile, the SiC-Al2O3 aerogel-SiO2 fiber mat composite also had the low thermal conductivity of 0.022[Formula: see text]W/(m[Formula: see text][Formula: see text][Formula: see text]K) at 35∘C and 0.025[Formula: see text]W/(m[Formula: see text][Formula: see text][Formula: see text]K) at 600∘C.

scholarly journals New BN/SiOC aerogel composites fabricated by the sol-gel method with excellent thermal insulation performance at high temperature

2020 ◽  
Vol 185 ◽  
pp. 108217 ◽  
Author(s):  
Haixia Yang ◽  
Chunming Li ◽  
Xiandong Yue ◽  
Jianchun Huo ◽  
Feng Ye ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Insulation ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Insulation Performance

scholarly journals Polysiloxane Bonded Silica Aerogel with Enhanced Thermal Insulation and Strength

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2046
Author(s):  
Weilin Wang ◽  
Zongwei Tong ◽  
Ran Li ◽  
Dong Su ◽  
Huiming Ji
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Thermal Insulation ◽  
High Specific Surface Area ◽  
Comprehensive Properties ◽  
Composite Aerogels ◽  
Complex Forms ◽  
Application Fields ◽  
Silicon Based ◽  
Inorganic Composite

In order to improve the mechanical properties of SiO2 aerogels, PHMS/VTES-SiO2 composite aerogels (P/V-SiO2) were prepared. Using vinyltriethoxysilane (VTES) as a coupling agent, the PHMS/VTES complex was prepared by conducting an addition reaction with polyhydromethylsiloxane (PHMS) and VTES and then reacting it with inorganic silica sol to prepare the organic–inorganic composite aerogels. The PHMS/VTES complex forms a coating structure on the aerogel particles, enhancing the network structure of the composite aerogels. The composite aerogels can maintain the high specific surface area and excellent thermal insulation properties, and they have better mechanical properties. We studied the reaction mechanism during preparation and discussed the effects of the organic components on the structure and properties of the composite aerogels. The composite aerogels we prepared have a thermal conductivity of 0.03773 W·m−1·K−1 at room temperature and a compressive strength of 1.87 MPa. The compressive strength is several times greater than that of inorganic SiO2 aerogels. The organic–inorganic composite aerogels have excellent comprehensive properties, which helps to expand the application fields of silicon-based aerogels.

scholarly journals Microstructure and Thermal Insulation Property of Silica Composite Aerogel

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 993 ◽  
Author(s):  
Lei Shang ◽  
Yang Lyu ◽  
Wenbo Han
Keyword(s):  
Thermal Insulation ◽  
Silica Aerogel ◽  
Infrared Radiation ◽  
Performance Test ◽  
Heat Insulation ◽  
Insulation Material ◽  
Cold Surface ◽  
Composite Aerogel ◽  
Aerogel Composite ◽  
Insulation Performance

Tetraethyl orthosilicate was selected as a matrix of heat insulating materials among three silanes, and an anti-infrared radiation fiber was chosen as a reinforcement for silica aerogel insulation composite. The silica aerogel was combined well and evenly distributed in the anti-infrared radiation fiber. The heat insulation effect was improved with the increase in thickness of the aerogel insulation material, as determined by the self-made aerospace insulation material insulation performance test equipment. The 15 mm and 30 mm thick thermal insulation material heated at 250 °C for 3 h, the temperatures at the cold surface were about 80 °C and 60 °C, respectively, and the temperatures at 150 mm above the cold surface were less than 60 °C and 50 °C, respectively. The silica aerogel composites with various thicknesses showed good thermal insulation stability. The silica insulation composite with a thickness of 15 mm exhibited good heat insulation performance, meets the thermal insulation requirements of general equipment compartments under low-temperature and long-term environmental conditions. The thermal conductivity of prepared silica aerogel composite was 0.0191 W·m−1·k−1 at room temperature and 0.0489 W·m−1·k−1 at 500 °C.

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