Journal articles: 'Aerogele'

1

Fricke, Jochen. "Aerogele." Physik in unserer Zeit 17, no. 4 (1986): 101–6. http://dx.doi.org/10.1002/piuz.19860170401.

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Ziegler, Christoph, André Wolf, Wei Liu, Anne-Kristin Herrmann, Nikolai Gaponik, and Alexander Eychmüller. "Moderne Anorganische Aerogele." Angewandte Chemie 129, no. 43 (September 22, 2017): 13380–403. http://dx.doi.org/10.1002/ange.201611552.

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Eychmüller, Alexander. "Aerogele aus Halbleiter-Nanomaterialien." Angewandte Chemie 117, no. 31 (August 5, 2005): 4917–19. http://dx.doi.org/10.1002/ange.200501052.

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4

Fricke, J. "Internationales Symposium über Aerogele." Physik Journal 42, no. 2 (February 1986): 60. http://dx.doi.org/10.1002/phbl.19860420210.

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Bigall, Nadja C, Anne-Kristin Herrmann, Maria Vogel, Marcus Rose, Paul Simon, Wilder Carrillo-Cabrera, Dirk Dorfs, Stefan Kaskel, Nikolai Gaponik, and Alexander Eychmüller. "Hydrogele und Aerogele aus Edelmetallnanopartikeln." Angewandte Chemie 121, no. 51 (November 13, 2009): 9911–15. http://dx.doi.org/10.1002/ange.200902543.

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Liu, Wei, Anne-Kristin Herrmann, Dorin Geiger, Lars Borchardt, Frank Simon, Stefan Kaskel, Nikolai Gaponik, and Alexander Eychmüller. "Palladium-Aerogele für die hocheffiziente Elektrokatalyse." Angewandte Chemie 124, no. 23 (April 24, 2012): 5841–46. http://dx.doi.org/10.1002/ange.201108575.

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Dmitriev, Vladimir V., V. V. Zav'yalov, D. E. Zmeev, I. V. Kosarev, and N. Mulders. "Superfluid phases of ³He in aerogel." Uspekhi Fizicheskih Nauk 173, no. 4 (2003): 452. http://dx.doi.org/10.3367/ufnr.0173.200304h.0452.

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Wu, Zhen-Yu, Hai-Wei Liang, Bi-Cheng Hu, and Shu-Hong Yu. "Kohlenstoffnanofaser-Aerogele: Vergleich von Chemosynthese und Biosynthese." Angewandte Chemie 130, no. 48 (October 9, 2018): 15872–89. http://dx.doi.org/10.1002/ange.201802663.

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Hüsing, Nicola, and Ulrich Schubert. "Aerogele – luftige Materialien: Chemie, Struktur und Eigenschaften." Angewandte Chemie 110, no. 1-2 (January 16, 1998): 22–47. http://dx.doi.org/10.1002/(sici)1521-3757(19980116)110:1/2<22::aid-ange22>3.0.co;2-9.

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Zhao, Shanyu, Wim J. Malfait, Natalia Guerrero-Alburquerque, Matthias M. Koebel, and Gustav Nyström. "Biopolymer-Aerogele und -Schäume: Chemie, Eigenschaften und Anwendungen." Angewandte Chemie 130, no. 26 (May 28, 2018): 7704–33. http://dx.doi.org/10.1002/ange.201709014.

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11

Liu, Wei, Paramaconi Rodriguez, Lars Borchardt, Annette Foelske, Jipei Yuan, Anne-Kristin Herrmann, Dorin Geiger, et al. "Bimetall-Aerogele: hoch effiziente Elektrokatalysatoren für die Sauerstoffreduktion." Angewandte Chemie 125, no. 37 (July 22, 2013): 10033–37. http://dx.doi.org/10.1002/ange.201303109.

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12

Fricke, J. "Aerogele: Hochporöse, nanostrukturierte Materialien mit faszinierenden Eigenschaften und Anwendungen." Physik Journal 51, no. 10 (October 1995): 935–39. http://dx.doi.org/10.1002/phbl.19950511006.

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Wang, Jia Zhen, Jing Du, and Yun Bo Wang. "Fabrication and Measurement of Flexible Polymer Aerogel and Factors Affecting its Thermal Conductivity." Solid State Phenomena 324 (September 20, 2021): 133–38. http://dx.doi.org/10.4028/www.scientific.net/ssp.324.133.

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Silica aerogels are the most widely studied type of aerogel. However, its application still suffers from low mechanical strength and high production cost. The paper studies the use of recyclable PVC as the backbone material of the aerogel and introduces an economically friendly fabrication process of flexible PVC aerogel using sol-gel technique and ambient drying instead of the CO2 critical drying. Three different types of PVC powder with the molecule weight of 43000, 48000, and 80000 respectively are chosen and dissolved in DMF in five different concentrations-0.2, 0.4, 0.6, 0.8, and 1.0 g (mL)-1. The lowest thermal conductivity of the aerogel is measured using hot-wire method as 0.0323W(m*K)-1, which is made of PVC with molecule weight of 80000 in a concentration of 0.4g (mL)-1. The analysis based on SEM pictures shows that PVC type and concentration would greatly influence aerogel’s structure thus affecting its thermal conductivity. The optimal solution for producing low thermal conductivity aerogel is to use PVC powder with low molecule weight with a concentration between 0.2 and 0.6 g (mL)-1.

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14

Smirnova, I., P. Gurikov, D. Weinrich, S. Movahhed, V. Vogelsang, M. Fricke, and W. Lölsberg. "Entwicklung organischer Aerogele: der Weg von der Akademia in die Praxis." Chemie Ingenieur Technik 90, no. 9 (August 24, 2018): 1301. http://dx.doi.org/10.1002/cite.201855365.

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15

E, Lei, Wei Li, Jiaming Sun, Zhenwei Wu, and Shouxin Liu. "N-Doped Carbon Aerogels Obtained from APMP Fiber Aerogels Saturated with Rhodamine Dye and Their Application as Supercapacitor Electrodes." Applied Sciences 9, no. 4 (February 13, 2019): 618. http://dx.doi.org/10.3390/app9040618.

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We developed an efficient and environmentally friendly strategy for synthesizing an N-doped carbon aerogel by the carbonization of an alkaline peroxide mechanical pulp (APMP) fiber aerogel saturated with rhodamine B (RB) dyes. The APMP aerogel was prepared via cellulose extraction, sol-gel, and freeze drying. The resulting aerogel had a high adsorption capacity (250 mg g−1) and a fast adsorption rate (within 30 s) towards RB dyes. The saturated aerogel was used as a starting material for further carbonization to prepare N-doped carbon aerogels. SEM studies showed that the 3D network structure of the APMP aerogels was well preserved after RB adsorption and carbonization. The prepared carbon aerogel exhibited a graphitized structure, and N (2.15%) was doped at pyridinic N and pyrrolic N sites in the 3D carbon network. The specific capacitance of the N-doped carbon aerogel reached 185 F g−1 at a current density of 1 A g−1, which is higher than carbon aerogels (155 F g−1).

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Long, Linyu, Fenfen Li, Mengying Shu, Caili Zhang, and Yunxuan Weng. "Fabrication and Application of Carboxymethyl Cellulose-Carbon Nanotube Aerogels." Materials 12, no. 11 (June 9, 2019): 1867. http://dx.doi.org/10.3390/ma12111867.

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In this study, composite aerogels with excellent mechanical properties were prepared by using carboxymethyl cellulose (CMC) as raw materials, with carboxylic carbon nanotubes (CNTs) as reinforcement. By controlling the mass fraction of CNTs, composite aerogels with different CNTs were prepared, and the surface morphology, specific surface area, compressive modulus, density and adsorption capacities towards different oils were studied. Compared to the pure CMC aerogel, the specific surface areas of CMC/CNTs were decreased because of the agglomeration of CNTs. However, the densities of composite aerogels were lower than pure CMC aerogel. This is because the CNTs were first dispersed in water and then added to CMC solution. The results indicated that it was easy for the low CMC initial concentration to be converted to low density aerogel. The compressive modulus was increased from 0.3 MPa of pure CMC aerogel to 0.5 MPa of 5 wt % CMC/CNTs aerogel. Meanwhile, the prepared aerogels showed promising properties as the adsorption materials. Because of the high viscosity, liquid possesses strong adhesion to the pore wall, the adsorption capacity of the CMC aerogel to the liquid increases as the viscosity of the liquid increases.

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17

Sun, Chen Cheng, Zi Jun Hu, Tong Qi Li, Hong Bo Zhang, Zhi Jie Sun, and Zuo Guang Zhang. "Preparation and Properties of Ceramic Tiles for Heat Insulation." Materials Science Forum 546-549 (May 2007): 2157–62. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.2157.

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The bulk tiles of ceramic fibers reinforced aerogel were prepared from two reinforcements, evenly dispersed ceramic fibers and sintered tiles. It has been found that ceramic fiber-reinforced aerogels showed higher thermal conductivity than aerogel itself. Shrinkage of aerogels in chopped fiber reinforced aerogel composites showed similar tendency as pure aerogel during gelation, but the shrinkage was prohibited during supercritical drying. By contrary, in the case of sintered tile reinforced aerogel, shrinkage of aerogel was completely limited in both gelation and drying processes. Average of about 50% increase of compressive strengths of the sintered tile reinforced aerogel to sintered tiles were obtained with an average density increase of about 36%, their thermal conductivity depressed slightly.

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18

Wang, Yixin, Fei Xiang, Wei Wang, Weiling Wang, Yuehong Su, Fatang Jiang, Sheng Chen, and Saffa Riffat. "Sound absorption characteristics of KGM-based aerogel." International Journal of Low-Carbon Technologies 15, no. 3 (April 7, 2020): 450–57. http://dx.doi.org/10.1093/ijlct/ctaa005.

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Abstract This study presents the preparation and property characterization of biomass aerogels as sound absorption materials. Biomasses were chosen to prepare aerogels through the freeze-drying method. Results indicated that four components may have different effects on the aerogel pore structure, and the aerogel formula was thus optimized to reach the best sound absorption. Within the experimental range, biomass aerogel with the optimized formula had an average sound efficiency 0.352, density 0.047 g/cm3 and porosity 94.46 ± 0.04%. It shows better sound absorption performance than traditional sound absorption cotton. These results demonstrate the high sound absorption potential of biomass aerogels for building applications.

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19

Yeo, Jeong Gu, Jeong Min Hong, Churl Hee Cho, Sharad D. Bhagat, Yong Ha Kim, and Young Soo Ahn. "Inorganic Aerogel Granules Dried at Atmospheric-Pressure." Solid State Phenomena 124-126 (June 2007): 675–78. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.675.

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Silica aerogels using sodium silicates was synthesized by atmospheric-pressure drying. Granulation of silica aerogels was carried out in sequence of hydrogel formation, aging, surface modification, and drying. Rapidly prepared aerogels showed good properties in case aging and surface modification was done within 1 day. Drying is critical to aerogel granulation and the BET area of aerogel dried for a short duration had decreasing with time. It is suggested that sodium silicate-based aerogels granulation could be prepared within less than 5 days, half of initial processing. Aerogel granules had the average diameter of 1 mm and nearly spherical shape. It has very low thermal conductivity of 0.010 W/m⋅K, very light-weight and nanoporous structure with a porosity of upto 95%.

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20

Yao, Rui, Jinshan Ju, and Zhengjun Yao. "Novel 3-D hierarchical multiconfiguration graphene/polyaniline-based aerogels with directed higher performances." Cellular Polymers 39, no. 1 (October 31, 2019): 42–53. http://dx.doi.org/10.1177/0262489319885031.

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Novel three-dimensional (3-D) hierarchical multiconfiguration graphene/polyaniline-based aerogels were synthesized via in situ polymerization and directed freeze-drying method. The composite aerogels enhanced excellent thermal and electrical performances, at the same time, their 3-D hierarchical multiconfiguration was robust and stable, which made them more beneficial to be applied to thermal or electrical fields. Graphene oxide/polyaniline (GO/AP) and reduced graphene oxide (RGO/AP) were prepared. The multiconfiguration structure can be apparently observed through scanning electron microscopy image of GO/AP aerogel: the aerogels were composed of skeleton structure with paralleled open holes; the skeleton structure was made up by hierarchical GO sheet with AP network; and the AP network consisted of AP skeleton and nanopores. GO/AP aerogels showed higher heat resistance than single AP aerogel. In addition, compared with GO/AP and AP aerogels, RGO/AP aerogel had the best electrical performances (vertical electrical conductivity: 1.23 S cm−1 and specific capacitance: 580 F g−1). What is more, attributed to the multiconfiguration structure, the composite aerogels exhibited excellent performances in holes extending direction.

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21

Zhao, Mengke, Sufeng Zhang, Guigan Fang, Chen Huang, and Ting Wu. "Directionally-Grown Carboxymethyl Cellulose/Reduced Graphene Oxide Aerogel with Excellent Structure Stability and Adsorption Capacity." Polymers 12, no. 10 (September 27, 2020): 2219. http://dx.doi.org/10.3390/polym12102219.

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A novel three-dimensional carboxymethyl cellulose (CMC)/reduced graphene oxide (rGO) composite aerogel crosslinked by poly (methyl vinyl ether-co-maleic acid)/poly (ethylene glycol) system via a directional freezing technique exhibits high structure stability while simultaneously maintaining its excellent adsorption capacity to remove organic dyes from liquid. A series of crosslinked aerogels with different amounts of GO were investigated for their adsorption capacity of methylene blue (MB), which were found to be superb adsorbents, and the maximum adsorption capacity reached 520.67 mg/g with the incorporation of rGO. The adsorption kinetics and isotherm studies revealed that the adsorption process followed the pseudo-second-order model and the Langmuir adsorption model, and the adsorption was a spontaneous process. Furthermore, the crosslinked aerogel can be easily recycled after washing with dilute HCl solution, which could retain over 97% of the adsorption capacity after recycling five times. These excellent properties endow the crosslinked CMC/rGO aerogel’s potential in wastewater treatment and environment protection.

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22

Esquivel-Castro, Tzipatly A., Antonia Martínez-Luévanos, Luis Alfonso García-Cerda, Juan C. Contreras-Esquivel, Pascual Bartolo Pérez, and Elsa Nadia Aguilera González. "Effect of the drying on morphology and texture of aerogels and zirconia cryogels." MRS Advances 4, no. 64 (2019): 3513–21. http://dx.doi.org/10.1557/adv.2019.450.

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ABSTRACTDue to their excellent properties, aerogel has attracted the attention of the scientific community to use it in the biomedical area as a drug delivery system. This work reports on the synthesis and characterization of ZrO2 aerogels and cryogels obtained by the sol-gel method. The influence of different cetyltrimethylammonium bromide (CTAB) and the type of drying on structural, morphological and texture properties of ZrO2 aerogels and cryogels was investigated. SEM images reveal that a porous interconnected three-dimensional network was formed into aerogels due to supercritical drying. Zirconia aerogel sample has a specific surface area (SBET) larger than zirconia cryogels. Therefore, our results indicate that zirconia aerogel is an adequate material for applications in drug delivery systems.

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Kow, Kien Woh, Rozita Yusoff, A. R. Abdul Aziz, and E. C. Abdullah. "Thermal Insulative Performance of Bamboo Leaf Aerogel Opacified Using Activated Carbon Compared with Carbon Black." Advanced Materials Research 941-944 (June 2014): 2482–85. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.2482.

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Silica aerogel with extremely low thermal conductivity has great potential to be used as thermal insulating material. Opacification using carbon black is normally applied to reduce radiative heat loss in silica aerogel. This work attempted to replace carbon black with activated carbon as opacifer. Both the silica aerogel and activated carbon were synthesized via bamboo leaf. Effects of carbon loading and temperatures on the thermal conductivity of opacified aerogel were studied. The results show that an optimal carbon loading that minimized the thermal conductivity present at different temperatures. Such optimal loading increased as temperature applied to the opacified aerogel increased. Properties of aerogels opacified with activated carbon were also compared with aerogels opacified with carbon black.

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Bi, Yu Tie, Hong Bo Ren, and Lin Zhang. "Synthesis of a Low-Density Copper Oxide Monolithic Aerogel Using Inorganic Salt Precursor." Advanced Materials Research 217-218 (March 2011): 1165–69. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.1165.

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Copper oxide monolithic aerogel was prepared by sol–gel method using inorganic salt as precursor, ethanol as the solvent, and propylene oxide as the gelation agent. Calcination of the as-prepared aerogels at different temperatures induced a phase change which resulted in the formation of a mesoporous copper oxide aerogels. Field emission scanning electron microscopy (FESEM), Highresolution transmission electron microscopy (HRTEM), and Brunauer-Emmett-Teller(BET) methods were used to characterize the as-prepared aerogels. The combined results indicated that the as-prepared CuO aerogel has high porosity, high surface area, and low density. The X-ray diffraction (XRD) patterns show that the as-prepared CuO aerogel is highly crystalline and is identified to be predominantly copper chloride hydroxide, Cu2Cl(OH)3。

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Yin, Fen, Xuejiao Zhang, Dongna Li, and Xiaojun Ma. "Preparation and characterization of poly (3-hydroxy-butyrate-co-4-hydroxybutyrate)/porous cellulose aerogel biocomposites." BioResources 14, no. 2 (April 26, 2019): 4748–59. http://dx.doi.org/10.15376/biores.14.2.4748-4759.

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A green biocomposite of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) and cellulose aerogels was developed. Cellulose gel was prepared from NaOH/urea aqueous solution, and subsequent regenerating by Na2SO4 solution and freeze-drying resulted in porous cellulose aerogels. The P34HB/cellulose aerogel biocomposite was fabricated by immersion of porous cellulose in a polymer solution and hot-pressing. The morphology, crystallization, thermal, mechanical, and barrier properties (H2O) of biocomposite were investigated. The cellulose aerogels matrix exhibited a three-dimensional network structure with porosity and a wide pore size distribution, contributing to the change of the glass transition temperature and cold crystallization temperature of biocomposites. Compared with cellulose aerogels, the tensile strength and elongation at break of biocomposites were increased by as much as 48% and 25.1%, respectively. Moreover, biocomposites demonstrated an increased contact angle and water vapor permeability coefficient compared with the cellulose aerogel. The results revealed the potential of P34HB/cellulose aerogel biocomposites for practical application as packaging materials.

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Wei, Wei, Jing Yi Zhang, Li Ping Wu, and Guo Tong Qin. "Effects of Preparation Conditions on Characters of Hydrophobic Silica Granular Aerogel and its Applications." Advanced Materials Research 600 (November 2012): 190–93. http://dx.doi.org/10.4028/www.scientific.net/amr.600.190.

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The hydrophobic silica granular aerogels were synthesized via sol-gel synthesis followed by ambient pressure drying. The tetraethyloxylane (TEOS) was used as original precursor. The aerogels were analyzed using nitrogen adsorption, scanning electron microscopy (SEM) and laser particle size analyzer. It was found that the aerogel was mesoporous material with high surface area. The aerogels were prepared in grain form by dipping into disperse solution in order to adsorption application. The average particle size of the aerogel was controlled by pH and disperse solution volume. The pH also affected gel time. The aerogels were used to absorb phenol from water. The saturated adsorption amount could reach up to 145 mg•g-1.

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27

Zubair, Nur Afifah, Ebrahim Abouzari-Lotf, Mohamed Mahmoud Nasef, and Ezzat Chan Abdullah. "Aerogel-based materials for adsorbent applications in material domains." E3S Web of Conferences 90 (2019): 01003. http://dx.doi.org/10.1051/e3sconf/20199001003.

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Aerogels are considered to be promising materials in various applications due to their exclusive properties. Over the last decades, the potential of organic, inorganic, or hybrid aerogels has been practically exploited in different fields of use. Some aerogel compositions have been patented recently but their application in the area of adsorption remains limited. This review intends to discuss the potential of aerogels as adsorbents, which is summarised from the more recent progressive research and their capabilities. Furthermore, the potential of aerogels as viable absorbents for environmental remediation is also discussed. After a short introduction covering the aerogel properties, preparation procedures, and their possible classification options, the review is structured based on their possible use as adsorbents.

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Shi, Jian Jun, Ling Bin Lu, and Jing Ying Zhang. "An Environment-Friendly Thermal Insulation Material from Porous Cellulose Aerogel." Advanced Materials Research 773 (September 2013): 487–91. http://dx.doi.org/10.4028/www.scientific.net/amr.773.487.

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Cellulose hydrogel was prepared by using the NaOH/ Thiourea/ H2O as solvent system, cellulose aerogels were obtained by freeze-drying technology. The results showed that cellulose aerogel had porous network structure. Freeze-drying method was an effective way to prepare cellulose aerogel, and the volume shrinkage was 20.41%-28.36%. Bulk cellulose aerogel had low density, high porosity and fine mechanical strength. The density was low to 0.233g/cm3, and the porosity was up to 84.88%. The compressive strength was 5.7-8.2MPa. Cellulose aerogel had good heat insulation performance and thermal conductivity could be as low as 0.029 W/ (m·K). This work provided a foundation for the possibility of applying cellulose aerogels in the insulating material field.

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Erkhova, Ludmila V., Igor A. Presniakov, Michail I. Afanasov, Dmitry A. Lemenovskiy, Haojie Yu, Li Wang, Mati Danilson, and Mihkel Koel. "Ferrocene Introduced into 5-Methylresorcinol-Based Organic Aerogels." Polymers 12, no. 7 (July 16, 2020): 1582. http://dx.doi.org/10.3390/polym12071582.

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The polycondensation sol–gel reaction of 5-methylresocinol and formaldehyde with additional compounds in reaction media is a relatively simple way to produce modified aerogels. In order to obtain aerogels with a large surface area and high porosity, the conditions for gel formation, the solvent exchange process before drying, and the supercritical drying process were optimized. A successful attempt was made to introduce ferrocene units into 5-methylresocinol-formaldehyde-based aerogels. The resulting aerogels are amorphous substrates, and no aggregated ferrocene units were found in their structures. All of the aerogel samples that were obtained are structurally similar despite differences in the original ferrocene units and their initial concentration. It was found that the inclusion limit of ferrocene structural blocks into an aerogel is ~6% wt. The structures of the inclusions in which all of the Fe atoms in the aerogel substrates were present in ferrocene/ferrocenium at an approximate ratio of 60/40 to 55/45 were confirmed by X-ray photoelectron spectroscopy and Mössbauer spectroscopy. Aerogels with ferrocene/ferrocenium inclusions are likely to exhibit reversible redox activity in reactions with gaseous reagents.

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Santos-Rosales, Víctor, Inés Ardao, Carmen Alvarez-Lorenzo, Nilza Ribeiro, Ana Oliveira, and Carlos García-González. "Sterile and Dual-Porous Aerogels Scaffolds Obtained through a Multistep Supercritical CO2-Based Approach." Molecules 24, no. 5 (March 1, 2019): 871. http://dx.doi.org/10.3390/molecules24050871.

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Aerogels from natural polymers are endowed with attractive textural and biological properties for biomedical applications due to their high open mesoporosity, low density, and reduced toxicity. Nevertheless, the lack of macroporosity in the aerogel structure and of a sterilization method suitable for these materials restrict their use for regenerative medicine purposes and prompt the research on getting ready-to-implant dual (macro + meso)porous aerogels. In this work, zein, a family of proteins present in materials for tissue engineering, was evaluated as a sacrificial porogen to obtain macroporous starch aerogels. This approach was particularly advantageous since it could be integrated in the conventional aerogel processing method without extra leaching steps. Physicochemical, morphological, and mechanical characterization were performed to study the effect of porogen zein at various proportions (0:1, 1:2, and 1:1 zein:starch weight ratio) on the properties of the obtained starch-based aerogels. From a forward-looking perspective for its clinical application, a supercritical CO2 sterilization treatment was implemented for these aerogels. The sterilization efficacy and the influence of the treatment on the aerogel final properties were evaluated mainly in terms of absence of microbial growth, cytocompatibility, as well as physicochemical, structural, and mechanical modifications.

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Wang, Zhe, Wenkai Zhu, Runzhou Huang, Yang Zhang, Chong Jia, Hua Zhao, Wei Chen, and Yuanyuan Xue. "Fabrication and Characterization of Cellulose Nanofiber Aerogels Prepared via Two Different Drying Techniques." Polymers 12, no. 11 (November 3, 2020): 2583. http://dx.doi.org/10.3390/polym12112583.

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Studies on the influence of drying processes on cellulose nanofiber (CNF) aerogel performance has always been a great challenge. In this study, CNF aerogels were prepared via two different drying techniques. The CNF solution was prepared via existing chemical methods, and the resultant aerogel was fabricated through supercritical CO2 drying and liquid nitrogen freeze-drying techniques. The microstructure, shrinkage, specific surface area, pore volume, density, compression strength, and isothermal desorption curves of CNF aerogel were characterized. The aerogel obtained from the liquid nitrogen freeze-drying method showed a relatively higher shrinkage, higher compression strength, lower specific surface area, higher pore volume, and higher density. The N2 adsorption capacity and pore diameter of the aerogel obtained via the liquid nitrogen freeze-drying method were lower than the aerogel that underwent supercritical CO2 drying. However, the structures of CNF aerogels obtained from these two drying methods were extremely similar.

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32

JAWAD, NAEEM, MAZARI ADNAN, AKCAGUN ENGIN, and KUS ZDENEK. "SIO2 aerogels and its application in firefighter protective clothing." Industria Textila 69, no. 01 (March 1, 2018): 50–54. http://dx.doi.org/10.35530/it.069.01.1399.

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This article focuses our attention on utility of silica based aerogel as insulation materials in protective clothing especially for fire fighters at higher temperature. In past, aerogels were employed for insulation of buildings, aeronautics and aerospace applications. Later on, researchers determined the utility of aerogels as insulated substrate in protective clothing. Several investigations revealed insulation properties of aerogel at elevated temperature. There are several different types of aerogel but in this article, the main emphasis is on silica based aerogel because of its excellent insulation and outstanding flame proof properties along with thermal stability at raised temperature. By applying suitable coating techniques, aerogel can be impregnated into nonwoven substrates, which can be employed as thermal barriers resulting in enhancement of the protective capability of multilayered clothing at higher temperature. All these characteristics make aerogel a potential candidate to be used as insulation material in protective clothing at elevated temperature.

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Shi, Fei, Lu Nan Bai, Jing Xiao Liu, Xiao Li Dong, Jia Yu Luo, Chen Chen, and Xiu Fang Zhang. "Preparation and Characterization of SiO₂-WO₃ Composite Aerogel by Ambient Pressure Drying Process." Advanced Materials Research 534 (June 2012): 205–8. http://dx.doi.org/10.4028/www.scientific.net/amr.534.205.

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Using sodium tungsten and industrial water glass as raw materials, SiO2-WO3 composite aerogels were prepared by ambient pressure drying process. The hexamethyldisilazane(HMDSZ)/hexamethyldisiloxane(HMDSO)/hexane mixing solution was used to modify the sol-gel-derived SiO2-WO3 wet gel. The microstructure, morphology and pore characteristics of the obtained SiO2-WO3 composite aerogels were investigated by XRD, SEM, FTIR and BET N2 adsorption-desorption analysis. The adsorption/photocatalytic degradation for Rhodamine B of SiO2-WO3 composite aerogel was investigated. The results indicate that mesoporous SiO2-WO3 composite aerogel with specific surface area 660.8 m2/g and pore volume 1.94 cm3/g could be prepared by using HMDSZ/HMDSO/hexane mixing solution to modify the wet gel. The obtained SiO2-WO3 composite aerogels have good adsorption/photocatalytic degradation for Rhodamine B than that of pure WO3 aerogel.

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Bheekhun, Nadiir, Abd Rahim Abu Talib, and Mohd Roshdi Hassan. "Aerogels in Aerospace: An Overview." Advances in Materials Science and Engineering 2013 (2013): 1–18. http://dx.doi.org/10.1155/2013/406065.

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Aerogels are highly porous structures prepared via a sol-gel process and supercritical drying technology. Among the classes of aerogels, silica aerogel exhibits the most remarkable physical properties, possessing lower density, thermal conductivity, refractive index, and dielectric constant than any solids. Its acoustical property is such that it can absorb the sound waves reducing speed to 100 m/s compared to 332 m/s for air. However, when it comes to commercialization, the result is not as expected. It seems that mass production, particularly in the aerospace industry, has dawdled behind. This paper highlights the evolution of aerogels in general and discusses the functions and significances of silica aerogel in previous astronautical applications. Future outer-space applications have been proposed as per the current research trend. Finally, the implementation of conventional silica aerogel in aeronautics is argued with an alternative known as Maerogel.

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Xu, Lin, Yong Gang Jiang, Jun Zong Feng, and Jian Feng. "Influence of Ethyl Acetoacetate on the Structure and Thermal Stability of Alumina Aerogel." Materials Science Forum 816 (April 2015): 157–62. http://dx.doi.org/10.4028/www.scientific.net/msf.816.157.

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Alumina aerogels were prepared from aluminum sect-butoxide via sol-gel process and supercritical drying. The influence of Ethyl acetoacetate (Etac) on the aerogel properties, microstructure, and thermal stability was systematically studied. At the same time, reaction mechanism was also investigated. The results show that, without and with Etac addition, the alumina aerogels are consisted of crystalline boehmite and amorphous network, respectively. When nEtac/nAl molar ratio is 0.01~0.15:1, Al2O3 aerogels have larger surface area (71~98 m2/g) than pure alumina aerogel (61m2/g) after heated at 1200°C, a proper ratio of Etac is helpful to increases the gelation time and stability of alumina sol, and is useful to improve the thermal stability of Al2O3 aerogels.

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Tang, Shiyun, Jingyu Ran, Junjiang Guo, and Anjiang Tang. "Preparation of Highly Stable and Effective N-Doped TiO2@SiO2 Aerogel Catalyst for Degradation of Organic Pollutants by Visible Light Catalysis." Journal of Chemistry 2019 (November 3, 2019): 1–10. http://dx.doi.org/10.1155/2019/8587949.

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To obtain high stable and effective TiO2 photocatalyst, nano-N-doped TiO2@SiO2 (TiO2−xNx@SiO2, 0 ≤ x ≤ 2) composite aerogels were synthesized by the sol-gel method combined with supercritical drying and direct oxidation process. The adsorption/photocatalytic degradation efficiency of TiO2−xNx@SiO2 aerogels was evaluated by the degradation of RhB in aqueous solution under visible light irradiation. The physiochemical properties of the aerogels were examined by XRD, FT-IR, TEM, SEM, TG/DTA, and BET methods. It was found that the specific surface areas of all TiO2−xNx@SiO2 samples exceeded 700 m2/g and exhibited a honeycomb porous structure with fine particulate morphology. Photocatalytic activity tests show that the 500-TiO2@SiO2 composite aerogel exhibits the best adsorption/photocatalytic degradation rate for RhB, which obtained about 80% of the degradation rate in 30 min under visible light and over 95% after 120 min. On the one hand, the SiO2 aerogels can significantly inhibit the phase transition of TiO2, and the nano TiO2 can be highly dispersed in the SiO2 aerogels; On the other hand, if the oxidation temperature is selected properly, the N-doped TiO2−xNx@SiO2 aerogel can be obtained by simple TiN@SiO2 aerogel oxidation.

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Li, Kang, Xuejie Zhang, Yan Qin, and Ying Li. "Construction of the Cellulose Nanofibers (CNFs) Aerogel Loading TiO2 NPs and Its Application in Disposal of Organic Pollutants." Polymers 13, no. 11 (June 2, 2021): 1841. http://dx.doi.org/10.3390/polym13111841.

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Aerogels have been widely used in the adsorption of pollutants because of their large specific surface area. As an environmentally friendly natural polysaccharide, cellulose is a good candidate for the preparation of aerogels due to its wide sources and abundant polar groups. In this paper, an approach to construct cellulose nanofibers aerogels with both the good mechanical property and the high pollutants adsorption capability through chemical crosslinking was explored. On this basis, TiO2 nanoparticles were loaded on the aerogel through the sol-gel method followed by the hydrothermal method, thereby the enriched pollutants in the aerogel could be degraded synchronously. The chemical cross-linker not only helps build the three-dimensional network structure of aerogels, but also provides loading sites for TiO2. The degradation efficiency of pollutants by the TiO2@CNF Aerogel can reach more than 90% after 4 h, and the efficiency is still more than 70% after five cycles. The prepared TiO2@CNF Aerogels have high potential in the field of environmental management, because of the high efficiency of treating organic pollutes and the sustainability of the materials. The work also provides a choice for the functional utilization of cellulose, offering a valuable method to utilize the large amount of cellulose in nature.

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Osaki, Toshihiko, and Toshiaki Mori. "The Catalysis of NiO-Al₂O₃ Aerogels for the Methane Reforming by Carbon Dioxide." Advances in Science and Technology 45 (October 2006): 2137–42. http://dx.doi.org/10.4028/www.scientific.net/ast.45.2137.

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The aerogels of nickel-alumina system have been synthesized from aluminum triisoprppoxide and nickel glycoxide by sol-gel and subsequent supercritical drying, and the catalysis of NiO-Al2O3 aerogels for the methane reforming by carbon dioxide have been examined. The aerogel catalysts showed higher activity for the reforming than the impregnation catalysts prepared by a conventional impregnation method, on the other hand, the carbon deposition was much less significant on the aerogel catalysts than on the impregnation catalysts. By TEM and XRD observations, it was found for aerogel catalysts that fine nickel particles were formed throughout the alumina aerogel support with high dispersion. This resulted in not only higher catalytic reforming activity but also much less coking activity. The suppression of catalyst deactivation during the reforming was ascribed to the retardation of both carbon deposition and sintering of nickel particles on alumina aerogel support.

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Liu, Jing Xiao, Lu Nan Bai, Fei Shi, Zhi Qiang Hu, Yan Yan Jiang, and Ting Zhao. "Pore Structure Characterization of TiO₂-SiO₂ Composite Aerogel Prepared via Ambient Pressure Drying by Sol Pre-Modification Process." Advanced Materials Research 534 (June 2012): 101–5. http://dx.doi.org/10.4028/www.scientific.net/amr.534.101.

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In this paper, TiO2-SiO2composite aerogels were prepared via ambient pressure drying by sol-gel and sol pre-modification method. The pre-modification solution consists of hexamethyldisiloxane (HMDSO) as buffering agent, trimethylchlorosilane (TMCS) as modifier and hexane as organic solvent. The pore structure of TiO2-SiO2composite aerogels was characterized by N2adsorption-desorption method. The effects of HMDSO/TMCS volume ratio on the pore structure and properties of TiO2-SiO2composite aerogel were studied. The results indicate that the pre-modification of TiO2-SiO2composite sol by adding HMDSO/TMCS/Hexane solution could shorten the preparation period. Increasing the amount of HMDSO is favorable for obtaining TiO2-SiO2composite aerogel with higher specific surface area and pore volume. The best volume ratio of HMDSO/TMCS/composite sol for preparing mesoporous TiO2-SiO2composite aerogels were 12:6:120 and 12:12:120, with which the specific surface area and pore volume of the obtained TiO2-SiO2composite aerogel are 425.2～645.4 m2/g and 0.80～2.85 m3/g, respectively.

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Li, Jiajia, Sicong Tan, and Zhaoyang Xu. "Anisotropic Nanocellulose Aerogel Loaded with Modified UiO-66 as Efficient Adsorbent for Heavy Metal Ions Removal." Nanomaterials 10, no. 6 (June 5, 2020): 1114. http://dx.doi.org/10.3390/nano10061114.

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Currently, the preparation of outstanding adsorbents has attracted public concern in environmentally friendly and sustainable pollutant redress. Herein, we report a directional freeze-drying method to prepare a strong and reusable adsorbent by introducing metal-organic framework which modified by ethylene diamine tetraacetic acid (named UiO-66-EDTA) into cellulose nanofiber (CNF) aerogel. Compared to traditional aerogels, the fabricated adsorbent showed a good flexibility and reusability by forming a homogeneous three-dimensional structure. By controlling the concentration of a crosslinkable carboxymethyl cellulose (CMC) solution, we produced aerogels with different pore structures and fibrillar, columnar, and lamellar morphologies. The obtained UiO-66-EDTA/CNF/CMC aerogel (U-EDTACCA) showed an excellent adsorption performance for a total of nine types of heavy metal ions, as the removal efficiency could reach 91%. Moreover, the aerogels could retain 88% of their original shape after five cycles. The aerogel may be an appropriate material for the adsorption of heavy metal ions.

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Long, Lin-Yu, Fen-Fen Li, Yun-Xuan Weng, and Yu-Zhong Wang. "Effects of Sodium Montmorillonite on the Preparation and Properties of Cellulose Aerogels." Polymers 11, no. 3 (March 4, 2019): 415. http://dx.doi.org/10.3390/polym11030415.

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In this study, first, a green and efficient NaOH/urea aqueous solution system was used to dissolve cellulose. Second, the resulting solution was mixed with sodium montmorillonite. Third, a cellulose/montmorillonite aerogel with a three-dimensional porous structure was prepared via a sol-gel process, solvent exchange and freeze-drying. The viscoelastic analysis results showed that the addition of montmorillonite accelerated the sol-gel process in the cellulose solution. During this process, montmorillonite adhered to the cellulose substrate surface via hydrogen bonding and then became embedded in the pore structure of the cellulose aerogel. As a result, the pore diameter of the aerogel decreased and the specific surface area of the aerogel increased. Furthermore, the addition of montmorillonite increased the compressive modulus and density of the cellulose aerogel and reduced volume shrinkage during the preparation process. In addition, the oil/water adsorption capacities of cellulose aerogels and cellulose/montmorillon aerogels were investigated.

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Xu, Qinfeng, Jiayi Zhu, Xuan Luo, Zhaodong Chen, Hongbo Ren, Yutie Bi, and Lin Zhang. "Theoretical Evalution and Experimental Research on Thermal Insulation Performance of Graphitic Carbon-Doped Silica Aerogels." International Journal of Nanoscience 18, no. 05 (July 24, 2019): 1850028. http://dx.doi.org/10.1142/s0219581x1850028x.

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Graphitic carbon-doped silica aerogels, including graphite-doped and graphene-doped silica aerogels, were fabricated by the sol–gel method. Thermal resistance was a significant comprehensive parameter which could reflect the ability to prevent the heat transfer. In order to give a direct evaluation of the thermal insulation performance, the calculated formula of thermal resistance for graphitic carbon-doped silica aerogel thermal insulation layers had been given through theoretic analysis on the basis of the thermal conductivity and the aerogel-based heat insulation layers showed good thermal insulation performance. It was expected that theoretical evaluation and experimental research could provide a reference for the reliability and performance in the field of the aerogel-based insulation layers.

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Paraskevopoulou, Patrina, Irina Smirnova, Tamara Athamneh, Maria Papastergiou, Despoina Chriti, Gregor Mali, Tomaž Čendak, Grigorios Raptopoulos, and Pavel Gurikov. "Polyurea-crosslinked biopolymer aerogel beads." RSC Advances 10, no. 67 (2020): 40843–52. http://dx.doi.org/10.1039/d0ra07337g.

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Cheng, Zhihan, Kimberly DeGracia, and David Schiraldi. "Sustainable, Low Flammability, Mechanically-Strong Poly(vinyl alcohol) Aerogels." Polymers 10, no. 10 (October 5, 2018): 1102. http://dx.doi.org/10.3390/polym10101102.

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Poly(vinyl alcohol) (PVA), tannic acid (TA) and sodium hydroxide (NaOH) were used to prepare low-flammability, mechanically-strong aerogels via an environmentally-friendly freeze-drying method. Because of the strong interaction between TA and PVA through hydrogen bonds, PVA/TA/NaOH aerogels exhibited compressive moduli as high as 12.7 MPa, 20 times that of the control PVA aerogel. The microstructure of the aerogels in this study showed that the addition of NaOH disrupted the typical “card of house” aerogel structure, while the samples with TA showed a stereoscopic uniform structure. The thermal stabilities of aerogels were tested by thermogravimetric analysis, showing both a decrease on the onset of decomposition temperature, and a reduction in decomposition rate after initial char formation. The peak heat release rate and total heat release, as measured by cone calorimetry, dropped by 69% and 54%, respectively, after adding TA and NaOH.

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Illera, Danny, Jaime Mesa, Humberto Gomez, and Heriberto Maury. "Cellulose Aerogels for Thermal Insulation in Buildings: Trends and Challenges." Coatings 8, no. 10 (September 28, 2018): 345. http://dx.doi.org/10.3390/coatings8100345.

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Cellulose-based aerogels hold the potential to become a cost-effective bio-based solution for thermal insulation in buildings. Low thermal conductivities (<0.025 W·m−1·K−1) are achieved through a decrease in gaseous phase contribution, exploiting the Knudsen effect. However, several challenges need to be overcome: production energy demand and cost, moisture sensitivity, flammability, and thermal stability. Herein, a description and discussion of current trends and challenges in cellulose aerogel research for thermal insulation are presented, gathered from studies reported within the last five years. The text is divided into three main sections: (i) an overview of thermal performance of cellulose aerogels, (ii) an identification of challenges and possible solutions for cellulose aerogel thermal insulation, and (iii) a brief description of cellulose/silica aerogels.

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Kim, Hyung Min, Hyun Su Kim, Seong Yun Kim, and Jae Ryoun Youn. "Silica aerogel/epoxy composites with preserved aerogel pores and low thermal conductivity." e-Polymers 15, no. 2 (March 1, 2015): 111–17. http://dx.doi.org/10.1515/epoly-2014-0165.

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AbstractThe thermal conductivity of aerogel/epoxy composite based on the inexpensive powder form of silica aerogels by using water glass under ambient drying conditions was evaluated to investigate the relationship between the internal structure and the thermal conductivity of the composite. A high thermal conductivity was obtained for the composite fabricated by the typical liquid epoxy processing because the pores of the aerogels became filled with the epoxy resin during the processing of the composite. A new processing method for preserving the aerogel pores was then developed using ethanol evaporation, which lowered the thermal conductivity of the composite. The lowest thermal conductivity of 0.04 W/m K was obtained for the composite containing the as-received aerogel of 75 vol% with preserved pores. The preserved aerogel pores in the composite were the most significant physical factor in determining the thermal conductivity of the composite.

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Eangpayung, Supattra, Supan Yodyingyong, and Darapond Triampo. "Preparation of Silica Aerogels Monoliths from Hydrophobic Silica Gels and Pluronic10R5 via Sol–Gel Process." Science of Advanced Materials 12, no. 2 (February 1, 2020): 206–11. http://dx.doi.org/10.1166/sam.2020.3627.

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Silica aerogel, the most common type of aerogels, comprised of 95% air in its structure which made the aerogel has a high surface area, high porosity, low density, and low thermal conductivity. Because of its structure and high porosity, one of its major weakness compared to other materials is being very brittle. This study aims at strengthening the connection points between silica nanoparticles using Pluronic10R5 (poly(propylene oxide)8–poly(ethylene oxide)22–poly(propylene oxide)8) where the Pluronic10R5 was used to reduce phase separation during the silica condensation reaction in the sol–gel process. Silica aerogel monoliths were prepared via a sol–gel process from hydrophobic silica gels and Pluronic10R5 with an ambient pressure drying (APD) process. Results from the compression test showed that the Pluronic10R5/silica aerogels have improved mechanical property by ten times that of unmodified silica aerogels. A thermogravimetric analysis (TGA) showed a mass loss at 300–400 °C that is attributed to the surface methyl group, while a mass loss at 200 °C refers to the loss of Pluronic10R5 which confirms the incorporation of Pluronic10R5 into the monolith. Moreover, infrared (IR) images revealed that the top surface temperature of Pluronic10R5/silica aerogels monolith is about 80 °C differs from the bottom heat source temperature of 160 °C.

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Zhang, Ran, and Yan Zhao. "Preparation and Electrocatalysis Application of Pure Metallic Aerogel: A Review." Catalysts 10, no. 12 (November 25, 2020): 1376. http://dx.doi.org/10.3390/catal10121376.

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Nanomaterials are widely used in electrocatalysts due to their quantum size effect and high utilization efficiency. There are two ways to improve the activity of nanoelectrocatalysts: increasing the number of active sites and improving the inherent activity of each catalytic site. The structure of the catalyst itself can be improved by increasing the number of exposed active sites per unit mass. The high porosity and three-dimensional network structure enable aerogels to have the characteristics of a large specific surface area, exposing many active sites and bringing structural stability through the self-supporting nature of aerogels. Thus, by adjusting the compositions of aerogels, the synergetic effect introduced by alloy elements can be utilized to further improve the single-site activity. In this review, we summarized the basic preparation strategy of aerogels and extended it to the preparation of alloys and special structure aerogels. Moreover, through the eight electrocatalysis cases, the outstanding catalytic performances and broad applicability of aerogel electrocatalysts are emphasized. Finally, we predict the future development of pure metallic aerogel electrocatalysts from the perspective of preparation to application.

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Liu, Guang Wu, and Yan Gang Liu. "Synthesis and Characterization of Silica Aerogel Materials Doped with TiO₂ Powder for Thermal Insulation." Key Engineering Materials 723 (December 2016): 492–96. http://dx.doi.org/10.4028/www.scientific.net/kem.723.492.

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Super insulation and hydrophobic silica-based aerogels doped with TiO2 powder (8wt %) were successfully synthesized by using cost effective processing from Tetraeth oxysilane (TEOS). After aging and washing of wet gel, surface modification were modified using trimethylchlorosilane (TMCS) via one-step solvent exchange and surface modification. And the proper molar ratio of TMCS to pore water is 0.02. The microstructure and morphology of the ultralow density silica aerogels were characterized by the specific surface area, SBET, SEM, and the pore size distribution techniques. From the results, the obtained aerogel doped with TiO2 powder exhibited excellent physical properties with less than 10% volume shrinkage, extremely high specific surface area (652 m2/g) and super hydrophobicity (contact angle of~145°). It should be noted that TiO2 powders are physically embedded by SiO2 aerogel, and there is an obvious Ti–O–Ti and Si–O–Si bonding group based on structural analysis. The thermal properties of silica aerogel were determined using the Hot Disk device, composite aerogel exhibited thermal conductivities of 0.0426 W/m·K at 700°C, TiO2 powders effectively suppressed the intensified thermal radiations at high temperatures to achieve ultralow thermal conductivities. These results have important implications for designing novel structure of porous materials of high performance for silica aerogels.

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Hsieh, Tsung-Han, Yau-Shian Huang, and Ming-Yuan Shen. "Dynamic properties of carbon aerogel/epoxy nanocomposite and carbon fiber-reinforced composite beams." Journal of Reinforced Plastics and Composites 36, no. 23 (August 25, 2017): 1745–55. http://dx.doi.org/10.1177/0731684417728585.

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Carbon aerogels are a promising candidate for vibration insulation due to their three-dimensional networked structures interconnected with carbon nanoparticles. However, the effect of adding carbon aerogels to polymer-based composites on their dynamic properties remains unclear. In this study, an epoxy polymer matrix was modified with carbon aerogels, and this modified matrix was used to manufacture nanocomposite plates and carbon fiber-reinforced polymer composite laminates to investigate its dynamic properties. Force vibration tests were performed on cantilever beams of the composite beams. The frequency responses of the composite beams were measured experimentally and analytically; the half-power method was used to calculate the damping ratio for each vibration mode. According to the experimental results, the presence of carbon aerogel in the nanocomposites and laminates steadily increased the natural frequencies. Differences within 10% of the natural frequencies were obtained between the experimental and numerically. Furthermore, the damping ratios of the nanocomposite and laminate beams increased significantly with the increase in aerogel loading. For a nanocomposite with 0.3 wt% aerogel, a damping ratio approximately 44% greater than that of unmodified nanocomposite was obtained. The maximum damping ratio was 4.682% for the laminate with 0.5 wt% aerogel—an 88% increase compared with the unmodified laminate.

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Journal articles on the topic 'Aerogele'

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