Aerogel Insulation Systems for Space Launch Applications

NASA Technical Reports Server (NTRS)

Fesmire, James E.

2005-01-01

New developments in materials science in the areas of solution gelation processes and nanotechnology have led to the recent commercial production of aerogels. Concurrent with these advancements has been the development of new approaches to cryogenic thermal insulation systems. For example, thermal and physical characterizations of aerogel beads under cryogenic-vacuum conditions have been performed at the Cryogenics Test Laboratory of the NASA Kennedy Space Center. Aerogel-based insulation system demonstrations have also been conducted to improve performance for space launch applications. Subscale cryopumping experiments show the thermal insulating ability of these fully breathable nanoporous materials. For a properly executed thermal insulation system, these breathable aerogel systems are shown to not cryopump beyond the initial cooldown and thermal stabilization phase. New applications are being developed to augment the thermal protection systems of space launch vehicles, including the Space Shuttle External Tank. These applications include a cold-boundary temperature of 90 K with an ambient air environment in which both weather and flight aerodynamics are important considerations. Another application is a nitrogen-purged environment with a cold-boundary temperature of 20 K where both initial cooldown and launch ascent profiles must be considered. Experimental results and considerations for these flight system applications are discussed.

Fabrication and characterization of Aerogel-Polydimethyl siloxane (PDMS) Insulation Film

NASA Astrophysics Data System (ADS)

Noh, Yeoung ah; Song, Sinae; Taik Kim, Hee

2018-03-01

The building has a large impact on the space heating demand and the indoor environment is affected by climate or daylight. Hence, silica aerogel has generally used as a film to reduce the coefficient of the window in the building. Silica aerogel is a suitable material to apply for insulation material with lower thermal conductivity than that of air to save interior energy. However expensive precursor and drying process were the main issue of the silica aerogel synthesis and practical usage. We attempt to fabricate aerogel insulation film for energy saving through the economic process under ambient pressure. Silica aerogel was synthesized from rice husk ash, which was an agricultural waste to be able to recycle. Taguchi design was used to optimize the parameters (amount of rice husk ash, pH, aging time) controlling the surface area of silica aerogel. The silica aerogel is prepared by sol-gel processing through acidic treatment and aging. The silica aerogel was obtained by modification of silica hydrogel surface and dry at ambient pressure. Finally, aerogel film was respectively fabricated by the different content of aerogel in polydimethylsiloxane (PDMS). Silica aerogel obtained 21 – 24nm average particle size was analyzed by SEM and silica aerogel with high surface area (832.26 m2/g), pore size ( 3.30nm ) was characterized by BET. Then silica Aerogel – PDMS insulation film with thermal conductivity (0.002 W/mK) was analyzed by thermal wave system. The study demonstrates an eco-friendly and low-cost route toward silica – PDMS insulation film with low thermal conductivity (0.002 W/mK).

Preparation and properties of the multi-layer aerogel thermal insulation composites

NASA Astrophysics Data System (ADS)

Wang, Miao; Feng, Junzong; Jiang, Yonggang; Zhang, Zhongming; Feng, Jian

2018-03-01

Multi-layer insulation materials possess low radiation thermal conductivity, and excellent thermal insulation property in a vacuum environment. However, the spacers of the traditional multi-layer insulation materials are mostly loose fibers, which lead to more sensitive to the vacuum environmental of serviced. With the vacuum degree declining, gas phases thermal convection increase obviously, and the reflective screen will be severe oxidation, all of these make the thermal insulation property of traditional multi-layer insulation deteriorate, thus limits its application scope. In this paper, traditional multi-layer insulation material is combined with aerogel and obtain a new multi-layer aerogel thermal insulation composite, and the effects of the number, thickness and type of the reflective screens on the thermal insulation properties of the multi-layer composites are also studied. The result is that the thermal insulation property of the new type multi-layer aerogel composites is better than the pure aerogel composites and the traditional multi-layer insulation composites. When the 0.01 mm stainless steel foil as the reflective screen, and the aluminum silicate fiber and silica aerogel as the spacer layer, the layer density of composite with the best thermal insulation property is one layer per millimeter at 1000 °C.

Low-Density, Aerogel-Filled Thermal-Insulation Tiles

NASA Technical Reports Server (NTRS)

Santos, Maryann; Heng, Vann; Barney, Andrea; Oka, Kris; Droege, Michael

2005-01-01

Aerogel fillings have been investigated in a continuing effort to develop low-density thermal-insulation tiles that, relative to prior such tiles, have greater dimensional stability (especially less shrinkage), equal or lower thermal conductivity, and greater strength and durability. In preparation for laboratory tests of dimensional and thermal stability, prototypes of aerogel-filled versions of recently developed low-density tiles have been fabricated by impregnating such tiles to various depths with aerogel formations ranging in density from 1.5 to 5.6 lb/ft3 (about 53 to 200 kg/cu m). Results available at the time of reporting the information for this article showed that the thermal-insulation properties of the partially or fully aerogel- impregnated tiles were equivalent or superior to those of the corresponding non-impregnated tiles and that the partially impregnated tiles exhibited minimal (<1.5 percent) shrinkage after multiple exposures at a temperature of 2,300 F (1,260 C). Latest developments have shown that tiles containing aerogels at the higher end of the density range are stable after multiple exposures at the said temperature.

Thin Aerogel as a Spacer in Multilayer Insulation

NASA Technical Reports Server (NTRS)

Moroz, Nancy

2015-01-01

Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on real-world tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

Thin Aerogel as a Spacer in Multilayer Insulation

NASA Technical Reports Server (NTRS)

Moroz, Nancy

2015-01-01

Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on rea-lworld tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

Polyolefin-Based Aerogels

NASA Technical Reports Server (NTRS)

Lee, Je Kyun; Gould, George

2012-01-01

An organic polybutadiene (PB) rubberbased aerogel insulation material was developed that will provide superior thermal insulation and inherent radiation protection, exhibiting the flexibility, resiliency, toughness, and durability typical of the parent polymer, yet with the low density and superior insulation properties associated with the aerogels. The rubbery behaviors of the PB rubber-based aerogels are able to overcome the weak and brittle nature of conventional inorganic and organic aerogel insulation materials. Additionally, with higher content of hydrogen in their structure, the PB rubber aerogels will also provide inherently better radiation protection than those of inorganic and carbon aerogels. Since PB rubber aerogels also exhibit good hydrophobicity due to their hydrocarbon molecular structure, they will provide better performance reliability and durability as well as simpler, more economic, and environmentally friendly production over the conventional silica or other inorganic-based aerogels, which require chemical treatment to make them hydrophobic. Inorganic aerogels such as silica aerogels demonstrate many unusual and useful properties. There are several strategies to overcoming the drawbacks associated with the weakness and brittleness of silica aerogels. Development of the flexible fiber-reinforced silica aerogel composite blanket has proven one promising approach, providing a conveniently fielded form factor that is relatively robust toward handling in industrial environments compared to silica aerogel monoliths. However, the flexible silica aerogel composites still have a brittle, dusty character that may be undesirable, or even intolerable, in certain applications. Although the cross-linked organic aerogels such as resorcinol-formaldehyde (RF), polyisocyanurate, and cellulose aerogels show very high impact strength, they are also very brittle with little elongation (i.e., less rubbery). Also, silica and carbon aerogels are less efficient

Using of Aerogel to Improve Thermal Insulating Properties of Windows

NASA Astrophysics Data System (ADS)

Valachova, Denisa; Zdrazilova, Nada; Panovec, Vladan; Skotnicova, Iveta

2018-06-01

For the best possible thermal-technical properties of building structures it is necessary to use materials with very low thermal conductivity. Due to the increasing thermal-technical requirements for building structures, the insulating materials are developed. One of the modern thermal insulating materials is so-called aerogel. Unfortunately, this material is not used in the field of external thermal insulation composite systems because of its price and its properties. The aim of this paper is to present possibilities of using this insulating material in the civil engineering - specifically a usage of aerogel in the production of windows.

Thermal Performance Of Space Suit Elements With Aerogel Insulation For Moon And Mars Exploration

NASA Technical Reports Server (NTRS)

Tang, Henry H.; Orndoff, Evelyne S.; Trevino, Luis A.

2006-01-01

Flexible fiber-reinforced aerogel composites were studied for use as insulation materials of a future space suit for Moon and Mars exploration. High flexibility and good thermal insulation properties of fiber-reinforced silica aerogel composites at both high and low vacuum conditions make it a promising insulation candidate for the space suit application. This paper first presents the results of a durability (mechanical cycling) study of these aerogels composites in the context of retaining their thermal performance. The study shows that some of these Aerogels materials retained most of their insulation performance after up to 250,000 cycles of mechanical flex cycling. This paper also examines the problem of integrating these flexible aerogel composites into the current space suit elements. Thermal conductivity evaluations are proposed for different types of aerogels space suit elements to identify the lay-up concept that may have the best overall thermal performance for both Moon and Mars environments. Potential solutions in mitigating the silica dusting issue related to the application of these aerogels materials for the space suit elements are also discussed.

Heat insulation performance, mechanics and hydrophobic modification of cellulose-SiO2 composite aerogels.

PubMed

Shi, Jianjun; Lu, Lingbin; Guo, Wantao; Zhang, Jingying; Cao, Yang

2013-10-15

Cellulose-SiO2 composite hydrogel was prepared by combining the NaOH/thiourea/H2O solvent system and the immersion method with controlling the hydrolysis-fasculation rate of tetraethyl orthosilicate (TEOS). The hydrophobic composite aerogels were obtained through the freeze-drying technology and the cold plasma modification technology. Composite SiO2 could obviously reduce the thermal conductivity of cellulose aerogel. The thermal conductivity could be as low as 0.026 W/(mK). The thermal insulation mechanism of the aerogel material was discussed. Composite SiO2 reduced hydrophilicity of cellulose aerogel, but environmental humidity had a significant influence on heat insulation performance. After hydrophobic modification using CCl4 as plasma was conducted, the surface of composite aerogel was changed from hydrophilic to hydrophobic and water contact angle was as high as 132°. The modified composite aerogel still kept good heat insulation performance. This work provided a foundation for the possibility of applying cellulose-SiO2 composite aerogel in the insulating material field. Copyright © 2013 Elsevier Ltd. All rights reserved.

Thin Thermal-Insulation Blankets for Very High Temperatures

NASA Technical Reports Server (NTRS)

Choi, Michael K.

2003-01-01

Thermal-insulation blankets of a proposed type would be exceptionally thin and would endure temperatures up to 2,100 C. These blankets were originally intended to protect components of the NASA Solar Probe spacecraft against radiant heating at its planned closest approach to the Sun (a distance of 4 solar radii). These blankets could also be used on Earth to provide thermal protection in special applications (especially in vacuum chambers) for which conventional thermal-insulation blankets would be too thick or would not perform adequately.

Multilayer insulation blanket, fabricating apparatus and method

DOEpatents

Gonczy, John D.; Niemann, Ralph C.; Boroski, William N.

1992-01-01

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Method of fabricating a multilayer insulation blanket

DOEpatents

Gonczy, John D.; Niemann, Ralph C.; Boroski, William N.

1993-01-01

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Method of fabricating a multilayer insulation blanket

DOEpatents

Gonczy, J.D.; Niemann, R.C.; Boroski, W.N.

1993-07-06

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Multilayer insulation blanket, fabricating apparatus and method

DOEpatents

Gonczy, J.D.; Niemann, R.C.; Boroski, W.N.

1992-09-01

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel. 7 figs.

Insulation Blankets for High-Temperature Use

NASA Technical Reports Server (NTRS)

Goldstein, H.; Leiser, D.; Sawko, P. M.; Larson, H. K.; Estrella, C.; Smith, M.; Pitoniak, F. J.

1986-01-01

Insulating blanket resists temperatures up to 1,500 degrees F (815 degrees C). Useful where high-temperature resistance, flexibility, and ease of installation are important - for example, insulation for odd-shaped furnaces and high-temperature ducts, curtains for furnace openings and fire control, and conveyor belts in hot processes. Blanket is quilted composite consisting of two face sheets: outer one of silica, inner one of silica or other glass cloth with center filling of pure silica glass felt sewn together with silica glass threads.

Prototype Aerogel Insulation for Melamine-Foam Substitute: Critical Space Station Express Rack Technology

NASA Technical Reports Server (NTRS)

Noever, David A.; Sibille, Laurent; Smith, David; Cronise, Raymond

1998-01-01

There is a current lack of environmentally acceptable foams to insulate Long-Duration Human Spaceflight Missions, including the experimental Express Rack for the Space Station. A recent 60-day manned test in a sealed chamber at Johnson Space Center (JSC) was nearly aborted, because of persistently high formaldehyde concentrations in the chamber. Subsequent investigation showed that the source was melamine foam (used extensively for acoustic insulation). The thermal and acoustic potential for melamine-foam substitutes is evaluated for scale-up to a silica-based foam and aerogel, which is environmentally benign for long duration space flight. These features will be discussed in reference to an aerogel prototype to: 1) assemble material strength data for various formulated aerogels, both silica and organic carbon aerogels; 2) assemble the aerogel into panels of mylar/vacuum-encapsulated rigid boards which can be molded in various shapes and rigidities; and 3) describe a process for space applications for formaldehyde-free, long duration thermal and acoustic insulators.

Composite flexible blanket insulation

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A. (Inventor); Lowe, David M. (Inventor)

1994-01-01

An improved composite flexible blanket insulation is presented comprising top silicon carbide having an interlock design, wherein the reflective shield is composed of single or double aluminized polyimide and wherein the polyimide film has a honeycomb pattern.

Thermal insulating conformal blanket

NASA Technical Reports Server (NTRS)

Barney, Andrea (Inventor); Whittington, Charles A (Inventor); Eilertson, Bryan (Inventor); Siminski, Zenon (Inventor)

2003-01-01

The conformal thermal insulating blanket may have generally rigid batting material covered by an outer insulating layer formed of a high temperature resistant woven ceramic material and an inner insulating layer formed of a woven ceramic fiber material. The batting and insulating layers may be fastened together by sewing or stitching using an outer mold layer thread fabricated of a high temperature resistant material and an inner mold layer thread of a ceramic fiber material. The batting may be formed to a composite structure that may have a firmness factor sufficient to inhibit a pillowing effect after the stitching to not more than 0.03 inch. The outer insulating layer and an upper portion of the batting adjacent the outer insulating layer may be impregnated with a ceramic coating material.

Fabrication of Cellulose Nanofiber/AlOOH Aerogel for Flame Retardant and Thermal Insulation

PubMed Central

Fan, Bitao; Chen, Shujun; Yao, Qiufang; Sun, Qingfeng; Jin, Chunde

2017-01-01

Cellulose nanofiber/AlOOH aerogel for flame retardant and thermal insulation was successfully prepared through a hydrothermal method. Their flame retardant and thermal insulation properties were investigated. The morphology image of the cellulose nanofiber/AlOOH exhibited spherical AlOOH with an average diameter of 0.5 μm that was wrapped by cellulose nanofiber or adhered to them. Cellulose nanofiber/AlOOH composite aerogels exhibited excellent flame retardant and thermal insulation properties through the flammability test, which indicated that the as-prepared composite aerogels would have a promising future in the application of some important areas such as protection of lightweight construction materials. PMID:28772670

Thin Thermal-Insulation Blankets for Very High Temperatures

NASA Technical Reports Server (NTRS)

Choi, Michael K.

2003-01-01

Thermal-insulation blankets of a proposed type would be exceptionally thin and would endure temperatures up to 2,100 C. These blankets were originally intended to protect components of the NASA Solar Probe spacecraft against radiant heating at its planned closest approach to the Sun (a distance of 4 solar radii). These blankets could also be used on Earth to provide thermal protection in special applications (especially in vacuum chambers) for which conventional thermal-insulation blankets would be too thick or would not perform adequately. A blanket according to the proposal (see figure) would be made of molybdenum, titanium nitride, and carbon- carbon composite mesh, which melt at temperatures of 2,610, 2,930, and 2,130 C, respectively. The emittance of molybdenum is 0.24, while that of titanium nitride is 0.03. Carbon-carbon composite mesh is a thermal insulator. Typically, the blanket would include 0.25-mil (.0.00635-mm)-thick hot-side and cold-side cover layers of molybdenum. Titanium nitride would be vapor-deposited on both surfaces of each cover layer. Between the cover layers there would be 10 inner layers of 0.15-mil (.0.0038-mm)-thick molybdenum with vapor-deposited titanium nitride on both sides of each layer. The thickness of each titanium nitride coat would be about 1,000 A. The cover and inner layers would be interspersed with 0.25-mil (0.00635-mm)-thick layers of carbon-carbon composite mesh. The blanket would have total thickness of 4.75 mils (approximately equal to 0.121 mm) and an areal mass density of 0.7 kilograms per square meter. One could, of course, increase the thermal- insulation capability of the blanket by increasing number of inner layers (thereby unavoidably increasing the total thickness and mass density).

Fire-Retardant and Thermally Insulating Phenolic-Silica Aerogels.

PubMed

Yu, Zhi-Long; Yang, Ning; Apostolopoulou-Kalkavoura, Varvara; Qin, Bing; Ma, Zhi-Yuan; Xing, Wei-Yi; Qiao, Chan; Bergström, Lennart; Antonietti, Markus; Yu, Shu-Hong

2018-04-16

Energy efficient buildings require materials with a low thermal conductivity and a high fire resistance. Traditional organic insulation materials are limited by their poor fire resistance and inorganic insulation materials are either brittle or display a high thermal conductivity. Herein we report a mechanically resilient organic/inorganic composite aerogel with a thermal conductivity significantly lower than expanded polystyrene and excellent fire resistance. Co-polymerization and nanoscale phase separation of the phenol-formaldehyde-resin (PFR) and silica generate a binary network with domain sizes below 20 nm. The PFR/SiO 2 aerogel can resist a high-temperature flame without disintegration and prevents the temperature on the non-exposed side from increasing above the temperature critical for the collapse of reinforced concrete structures. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sprayable Aerogel Bead Compositions With High Shear Flow Resistance and High Thermal Insulation Value

NASA Technical Reports Server (NTRS)

Ou, Danny; Trifu, Roxana; Caggiano, Gregory

2013-01-01

A sprayable aerogel insulation has been developed that has good mechanical integrity and lower thermal conductivity than incumbent polyurethane spray-on foam insulation, at similar or lower areal densities, to prevent insulation cracking and debonding in an effort to eliminate the generation of inflight debris. This new, lightweight aerogel under bead form can be used as insulation in various thermal management systems that require low mass and volume, such as cryogenic storage tanks, pipelines, space platforms, and launch vehicles.

Monte Carlo Study on Carbon-Gradient-Doped Silica Aerogel Insulation.

PubMed

Zhao, Y; Tang, G H

2015-04-01

Silica aerogel is almost transparent for wavelengths below 8 µm where significant energy is transferred by thermal radiation. The radiative heat transfer can be restricted at high temperature if doped with carbon powder in silica aerogel. However, different particle sizes of carbon powder doping have different spectral extinction coefficients and the doped carbon powder will increase the solid conduction of silica aerogel. This paper presents a theoretical method for determining the optimal carbon doping in silica aerogel to minimize the energy transfer. Firstly we determine the optimal particle size by combining the spectral extinction coefficient with blackbody radiation and then evaluate the optimal doping amount between heat conduction and radiation. Secondly we develop the Monte Carlo numerical method to study radiative properties of carbon-gradient-doped silica aerogel to decrease the radiative heat transfer further. The results indicate that the carbon powder is able to block infrared radiation and thus improve the thermal insulating performance of silica aerogel effectively.

Impact Verification of Aerogel Insulation Paint on Historic Brick Facades

NASA Astrophysics Data System (ADS)

Ganobjak, Michal; Kralova, Eva

2017-10-01

Increasing the sustainability of existing buildings is being motivated by reduction of their energy demands. It is the above all the building envelope and its refurbishment by substitution or addition of new materials that makes the opportunity for reduction of energy consumption. A special type of refurbishment is conservation of historical buildings. Preservation of historic buildings permits also application of innovative methods and materials in addition to the original materials if their effects are known and the gained experience ensures their beneficial effect. On the market, there are new materials with addition of silica aerogel in various forms of products. They are also potentially useful in conservation of monuments. However, the effects of aerogel application in these cases are not known. For refurbishment is commercially available additional transparent insulation paint - Nansulate Clear Coat which is containing aerogel and can be used for structured surfaces such as bricks. A series of experiments examined the thermo-physical manifestation of an ultra-thin insulation coating of Nansulate Clear Coat containing silica aerogel on a brick facade. The experiments of active and passive thermography have observed effects of application on the small-scale samples of the brick façade of a protected historical building. Through a series of experiments were measured thermal insulation effect and influence on the aesthetic characteristics such as change in colour and gloss. The treated samples were compared to a reference. Results have shown no thermal-insulating manifestation of the recommended three layers of insulation paint. The three layers recommended by the manufacturer did not significantly affect the appearance of the brick facade. Color and gloss were not significantly changed. Experiments showed the absence of thermal insulation effect of Nansulate transparent triple coating. The thermal insulation effect could likely be reached by more layers of

Polyurea-Based Aerogel Monoliths and Composites

NASA Technical Reports Server (NTRS)

Lee, Je Kyun

2012-01-01

aerogel insulation material was developed that will provide superior thermal insulation and inherent radiation protection for government and commercial applications. The rubbery polyureabased aerogel exhibits little dustiness, good flexibility and toughness, and durability typical of the parent polyurea polymer, yet with the low density and superior insulation properties associated with aerogels. The thermal conductivity values of polyurea-based aerogels at lower temperature under vacuum pressures are very low and better than that of silica aerogels. Flexible, rubbery polyurea-based aerogels are able to overcome the weak and brittle nature of conventional inorganic and organic aerogels, including polyisocyanurate aerogels, which are generally prepared with the one similar component to polyurethane rubber aerogels. Additionally, with higher content of hydrogen in their structures, the polyurea rubber-based aerogels will also provide inherently better radiation protection than those of inorganic and carbon aerogels. The aerogel materials also demonstrate good hydrophobicity due to their hydrocarbon molecular structure. There are several strategies to overcoming the drawbacks associated with the weakness and brittleness of silica aerogels. Development of the flexible fiber-reinforced silica aerogel composite blanket has proven to be one promising approach, providing a conveniently fielded form factor that is relatively robust in industrial environments compared to silica aerogel monoliths. However, the flexible, silica aerogel composites still have a brittle, dusty character that may be undesirable, or even intolerable, in certain application environments. Although the cross - linked organic aerogels, such as resorcinol- formaldehyde (RF), polyisocyanurate, and cellulose aerogels, show very high impact strength, they are also very brittle with little elongation (i.e., less rubbery). Also, silica and carbon aerogels are less efficient radiation shielding materials due

Foam/Aerogel Composite Materials for Thermal and Acoustic Insulation and Cryogen Storage

NASA Technical Reports Server (NTRS)

Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Sass, Jared P. (Inventor); Weiser, Erik S. (Inventor)

2011-01-01

The invention involves composite materials containing a polymer foam and an aerogel. The composite materials have improved thermal insulation ability, good acoustic insulation, and excellent physical mechanical properties. The composite materials can be used, for instance, for heat and acoustic insulation on aircraft, spacecraft, and maritime ships in place of currently used foam panels and other foam products. The materials of the invention can also be used in building construction with their combination of light weight, strength, elasticity, ability to be formed into desired shapes, and superior thermal and acoustic insulation power. The materials have also been found to have utility for storage of cryogens. A cryogenic liquid or gas, such as N.sub.2 or H.sub.2, adsorbs to the surfaces in aerogel particles. Thus, another embodiment of the invention provides a storage vessel for a cryogen.

Foam/aerogel composite materials for thermal and acoustic insulation and cryogen storage

NASA Technical Reports Server (NTRS)

Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Williams, Martha K. (Inventor); Sass, Jared P. (Inventor); Weiser, Erik S. (Inventor)

2010-01-01

The invention involves composite materials containing a polymer foam and an aerogel. The composite materials have improved thermal insulation ability, good acoustic insulation, and excellent physical mechanical properties. The composite materials can be used, for instance, for heat and acoustic insulation on aircraft, spacecraft, and maritime ships in place of currently used foam panels and other foam products. The materials of the invention can also be used in building construction with their combination of light weight, strength, elasticity, ability to be formed into desired shapes, and superior thermal and acoustic insulation power. The materials have also been found to have utility for storage of cryogens. A cryogenic liquid or gas, such as N.sub.2 or H.sub.2, adsorbs to the surfaces in aerogel particles. Thus, another embodiment of the invention provides a storage vessel for a cryogen.

Advanced Aerogel Technology

NASA Technical Reports Server (NTRS)

Jones, Steven

2013-01-01

The JPL Aerogel Laboratory has made aerogels for NASA flight missions, e.g., Stardust, 2003 Mars Exploration Rovers and the 2011 Mars Science Laboratory, as well as NASA research projects for the past 14 years. During that time it has produced aerogels of a range of shapes, sizes, densities and compositions. Research is ongoing in the development of aerogels for future sample capture and return missions and for thermal insulation for both spacecraft and scientific instruments. For the past several years, the JPL Aerogel Laboratory has been developing, producing and testing a new composite material for use as the high temperature thermal insulation in the Advanced Sterling Radioisotope Generator (ASRG) being developed by Lockheed Martin and NASA. The composite is made up of a glass fiber felt, silica aerogel, Titania powder, and silica powder. The oxide powders are included to reduce irradiative heat transport at elevated temperatures. These materials have thermal conductivity values that are the same as the best commercially produced high temperature insulation materials, and yet are 40% lighter. By greatly reducing the amount of oxide powder in the composite, the density, and therefore for the value of the thermal conductivity, would be reduced. The JPL Aerogel Laboratory has experimented with using glass fiber felt, expanded glass fiber felt and loose fibers to add structural integrity to silica aerogels. However, this work has been directed toward high temperature applications. By conducting a brief investigation of the optimal combination of fiber reinforcement and aerogel density, a durable, extremely efficient thermal insulation material for ambient temperature applications would be produced. If a transparent thermal insulation is desired, then aerogel is an excellent candidate material. At typical ambient temperatures, silica aerogel prevents the transport of heat via convection and conduction due to its highly porous nature. To prevent irradiative thermal

Ambient Dried Aerogels

NASA Technical Reports Server (NTRS)

Jones, Steven M.; Paik, Jong-Ah

2013-01-01

A method has been developed for creating aerogel using normal pressure and ambient temperatures. All spacecraft, satellites, and landers require the use of thermal insulation due to the extreme environments encountered in space and on extraterrestrial bodies. Ambient dried aerogels introduce the possibility of using aerogel as thermal insulation in a wide variety of instances where supercritically dried aerogels cannot be used. More specifically, thermoelectric devices can use ambient dried aerogel, where the advantages are in situ production using the cast-in ability of an aerogel. Previously, aerogels required supercritical conditions (high temperature and high pressure) to be dried. Ambient dried aerogels can be dried at room temperature and pressure. This allows many materials, such as plastics and certain metal alloys that cannot survive supercritical conditions, to be directly immersed in liquid aerogel precursor and then encapsulated in the final, dried aerogel. Additionally, the metalized Mylar films that could not survive the previous methods of making aerogels can survive the ambient drying technique, thus making multilayer insulation (MLI) materials possible. This results in lighter insulation material as well. Because this innovation does not require high-temperature or high-pressure drying, ambient dried aerogels are much less expensive to produce. The equipment needed to conduct supercritical drying costs many tens of thousands of dollars, and has associated running expenses for power, pressurized gasses, and maintenance. The ambient drying process also expands the size of the pieces of aerogel that can be made because a high-temperature, high-pressure system typically has internal dimensions of up to 30 cm in diameter and 60 cm in height. In the case of this innovation, the only limitation on the size of the aerogels produced would be in the ability of the solvent in the wet gel to escape from the gel network.

Mechanically Strong, Polymer Cross-linked Aerogels (X-Aerogels)

NASA Technical Reports Server (NTRS)

Leventis, Nicholas

2006-01-01

Aerogels comprise a class of low-density, high porous solid objects consisting of dimensionally quasi-stable self-supported three-dimensional assemblies of nanoparticles. Aerogels are pursued because of properties above and beyond those of the individual nanoparticles, including low thermal conductivity, low dielectric constant and high acoustic impedance. Possible applications include thermal and vibration insulation, dielectrics for fast electronics, and hosting of functional guests for a wide variety of optical, chemical and electronic applications. Aerogels, however, are extremely fragile materials, hence they have found only limited application in some very specialized environments, for example as Cerenkov radiation detectors in certain types of nuclear reactors, aboard spacecraft as collectors of hypervelocity particles (refer to NASA's Stardust program) and as thermal insulators on planetary vehicles on Mars (refer to Sojourner Rover in 1997 and Spirit and Opportunity in 2004). Along these lines, the X-Aerogel is a new NASA-developed strong lightweight material that has resolved the fragility problem of traditional (native) aerogels. X-Aerogels are made by applying a conformal polymer coating on the surfaces of the skeletal nanoparticles of native aerogels (see Scanning Electron Micrographs). Since the relative amounts of the polymeric crosslinker and the backbone are comparable, X-Aerogels can be viewed either as aerogels modified by the templated accumulation of polymer on the skeletal nanoparticles, or as nanoporous polymers made by remplated casting of polymer on a nanostructured framework. The most striking feature of X-Aerogels is that for a nominal 3-fold increase in density (still a ultralighweight material), the mechanical strength can be up to 300 times higher than the strength of the underlying native aerogel. Thus, X-Aerogels combine a multiple of the specific compressive strength of steel, with the the thermal conductivity of styrofoam. X-Aerogels

Development of a new multi-layer insulation blanket with non-interlayer-contact spacer for space cryogenic mission

NASA Astrophysics Data System (ADS)

Miyakita, Takeshi; Hatakenaka, Ryuta; Sugita, Hiroyuki; Saitoh, Masanori; Hirai, Tomoyuki

2014-11-01

For conventional Multi-Layer Insulation (MLI) blankets, it is difficult to control the layer density and the thermal insulation performance degrades due to the increase in conductive heat leak through interlayer contacts. At low temperatures, the proportion of conductive heat transfer through MLI blankets is large compared to that of radiative heat transfer, hence the decline in thermal insulation performance is significant. A new type of MLI blanket using new spacers; the Non-Interlayer-Contact Spacer MLI (NICS MLI) has been developed. This new MLI blanket uses small discrete spacers and can exclude uncertain interlayer contact between films. It is made of polyetheretherketone (PEEK) making it suitable for space use. The cross-sectional area to length ratio of the spacer is 1.0 × 10-5 m with a 10 mm diameter and 4 mm height. The insulation performance is measured with a boil-off calorimeter. Because the NICS MLI blanket can exclude uncertain interlayer contact, the test results showed good agreement with estimations. Furthermore, the NICS MLI blanket shows significantly good insulation performance (effective emissivity is 0.0046 at ordinary temperature), particularly at low temperatures, due to the high thermal resistance of this spacer.

Nearly Seamless Vacuum-Insulated Boxes

NASA Technical Reports Server (NTRS)

Stepanian, Christopher J.; Ou, Danny; Hu, Xiangjun

2010-01-01

applied across the thickness, in particular, when the space between the face sheets is evacuated, causing the core material to be squeezed between the face sheets by atmospheric pressure. Fabrication of a typical vacuum-insulated box according to the proposal would begin with fabrication of a cross-shaped polymer-modified aerogel blanket. The dimensions of the cross would be chosen so that (1) the central rectangular portion of the cross would form the core for the back of the box and (2) the arms of the cross could be folded 90 from the back plane to form the cores of the adjacent four sides of the box. Optionally, the blanket could include tabs for joining the folded sides of the blanket along mating edges and tabs that could serve as hinges for the door. Vacuum bags in the form of similar five-sided boxes would be made of a suitable polymeric film, one bag to fit the outer core surface, the other to fit the inner core surface. By use of commercially available film-sealing equipment, these box-shaped bags would be seamed together to form a single vacuum bag encasing the box-shaped core. Also, a one-way valve would be sealed to the bag. Through this valve, the interior of the bag would be evacuated to a pressure between 1 and 10 torr (approximately between 0.13 and 1.3 kPa). The polymer-modified aerogel core material is known to perform well as a thermal insulator in such a partial vacuum.

Using Aerogel-Based Insulation Material To Prevent Foam Loss on the Liquid-Hydrogen Intertank

NASA Technical Reports Server (NTRS)

2008-01-01

Uninsulated areas on cryogenic propellant tanks and feedlines cause moisture in the air to condense or ice to form. Flange joints, bracket supports, expansion bellows, and other cavities are uninsulated by design. These areas cannot be sealed because conventional thermal insulation materials would restrict mechanical articulations. Aerogel-based thermal insulation systems are able to seal critical locations such as the liquid-oxygen (LO2) feedline bellows. A new thermal insulation system was also necessary between the intertank wall, flange, and the liquid-hydrogen (LH2) tank dome, where there is a cavity (or crevice) with an exposed 20-K surface. When nitrogen gas is used for purging within the intertank volume, it condenses on this cold surface. Some solid nitrogen may also form on the colder side of the crevice. Voids or discontinuities within the foam can pressurize and cause areas of foam to weaken and break off, reducing thermal efficiency and creating potentially dangerous debris. To prevent this foam loss, we developed a thermal insulation system using bulk-fill aerogel material and demonstrated it with a one-tenth-scale model of the LH2 intertank flange area

Compression molding of aerogel microspheres

DOEpatents

Pekala, Richard W.; Hrubesh, Lawrence W.

1998-03-24

An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50-800 kg/m.sup.3 (0.05-0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization.

Composite Aerogel Multifoil Protective Shielding

NASA Technical Reports Server (NTRS)

Jones, Steven M.

2013-01-01

New technologies are needed to survive the temperatures, radiation, and hypervelocity particles that exploration spacecraft encounter. Multilayer insulations (MLIs) have been used on many spacecraft as thermal insulation. Other materials and composites have been used as micrometeorite shielding or radiation shielding. However, no material composite has been developed and employed as a combined thermal insulation, micrometeorite, and radiation shielding. By replacing the scrims that have been used to separate the foil layers in MLIs with various aerogels, and by using a variety of different metal foils, the overall protective performance of MLIs can be greatly expanded to act as thermal insulation, radiation shielding, and hypervelocity particle shielding. Aerogels are highly porous, low-density solids that are produced by the gelation of metal alkoxides and supercritical drying. Aerogels have been flown in NASA missions as a hypervelocity particle capture medium (Stardust) and as thermal insulation (2003 MER). Composite aerogel multifoil protective shielding would be used to provide thermal insulation, while also shielding spacecraft or components from radiation and hypervelocity particle impacts. Multiple layers of foil separated by aerogel would act as a thermal barrier by preventing the transport of heat energy through the composite. The silica aerogel would act as a convective and conductive thermal barrier, while the titania powder and metal foils would absorb and reflect the radiative heat. It would also capture small hypervelocity particles, such as micrometeorites, since it would be a stuffed, multi-shock Whipple shield. The metal foil layers would slow and break up the impacting particles, while the aerogel layers would convert the kinetic energy of the particles to thermal and mechanical energy and stop the particles.

Compression molding of aerogel microspheres

DOEpatents

Pekala, R.W.; Hrubesh, L.W.

1998-03-24

An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner is disclosed. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50--800 kg/m{sup 3} (0.05--0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization. 4 figs.

System and method for suppressing sublimation using opacified aerogel

NASA Technical Reports Server (NTRS)

Sakamoto, Jeff S. (Inventor); Snyder, G. Jeffrey (Inventor); Calliat, Thierry (Inventor); Fleurial, Jean-Pierre (Inventor); Jones, Steven M. (Inventor); Palk, Jong-Ah (Inventor)

2008-01-01

The present invention relates to a castable, aerogel-based, ultra-low thermal conductivity opacified insulation to suppress sublimation. More specifically, the present invention relates to an aerogel opacified with various opacifying or reflecting constituents to suppress sublimation and provide thermal insulation in thermoelectric modules. The opacifying constituent can be graded within the aerogel for increased sublimation suppression, and the density of the aerogel can similarly be graded to achieve optimal thermal insulation and sublimation suppression.

The efficiency of night insulation using aerogel-filled polycarbonate panels during the heating season

NASA Astrophysics Data System (ADS)

Adelsberger, Kathleen

Energy is the basis for modern life. All modern technology from a simple coffee maker to massive industrial facilities is powered by energy. While the demand for energy is increasing, our planet is suffering from the consequences of using fossil fuels to generate electricity. Therefore, the world is looking at clean energy and solar power to minimize this effect on our environment. However, saving energy is extremely important even for clean energy. The more we save the less we have to generate. Heat retention in buildings is one step towards achieving passive heating. Therefore, efforts are made to prevent heat from escaping buildings through the glass during cold nights. Movable insulation is a way to increase the insulation value of the glass to reduce heat loss towards the outdoor. This thesis examines the performance of the aerogel-filled polycarbonate movable panels in the Ecohawks building, a building located on the west campus of The University of Kansas. Onsite tests were performed using air and surface temperature sensors to determine the effectiveness of the system. Computer simulations were run by Therm 7.2 simulation software to explore alternative design options. A cost analysis was also performed to evaluate the feasibility of utilizing movable insulation to reduce the heating bills during winter. Results showed that sealed movable insulation reduces heat loss through the glazing by 67.5%. Replacing aerogel with XPS panels reduces this percentage to 64.3%. However, it reduces the cost of the insulation material by 98%.

Tailorable advanced blanket insulation using aluminoborosilicate and alumina batting

NASA Technical Reports Server (NTRS)

Calamito, Dominic P.

1989-01-01

Two types of Tailorable Advanced Blanket Insulation (TABI) flat panels for Advanced Space Transportation Systems were produced. Both types consisted of integrally woven, 3-D fluted core having parallel faces and connecting ribs of Nicalon yarns. The triangular cross section flutes of one type was filled with mandrels of processed Ultrafiber (aluminoborosilicate) stitchbonded Nextel 440 fibrous felt, and the second type wall filled with Saffil alumina fibrous felt insulation. Weaving problems were minimal. Insertion of the fragile insulation mandrels into the fabric flutes was improved by using a special insertion tool. An attempt was made to weave fluted core fabrics from Nextel 440 yarns but was unsuccessful because of the yarn's fragility. A small sample was eventually produced by an unorthodox weaving process and then filled with Saffil insulation. The procedures for setting up and weaving the fabrics and preparing and inserting insulation mandrels are discussed. Characterizations of the panels produced are also presented.

Cellulose as an adhesion agent for the synthesis of lignin aerogel with strong mechanical performance, Sound-absorption and thermal Insulation

PubMed Central

Wang, Chao; Xiong, Ye; Fan, Bitao; Yao, Qiufang; Wang, Hanwei; Jin, Chunde; Sun, Qingfeng

2016-01-01

The lignin aerogels that are both high porosity and compressibility would have promising implications for bioengineering field to sound-adsorption and damping materials; however, creating this aerogel had a challenge to adhesive lignin. Here we reported cellulose as green adhesion agent to synthesize the aerogels with strong mechanical performance. Our approach—straightforwardly dissolved in ionic liquids and simply regenerated in the deionized water—causes assembly of micro-and nanoscale and even molecule level of cellulose and lignin. The resulting lignin aerogels exhibit Young’s modulus up to 25.1 MPa, high-efficiency sound-adsorption and excellent thermal insulativity. The successful synthesis of this aerogels developed a path for lignin to an advanced utilization. PMID:27562532

Optically Transparent Thermally Insulating Silica Aerogels for Solar Thermal Insulation.

PubMed

Günay, A Alperen; Kim, Hannah; Nagarajan, Naveen; Lopez, Mateusz; Kantharaj, Rajath; Alsaati, Albraa; Marconnet, Amy; Lenert, Andrej; Miljkovic, Nenad

2018-04-18

Rooftop solar thermal collectors have the potential to meet residential heating demands if deployed efficiently at low solar irradiance (i.e., 1 sun). The efficiency of solar thermal collectors depends on their ability to absorb incoming solar energy and minimize thermal losses. Most techniques utilize a vacuum gap between the solar absorber and the surroundings to eliminate conduction and convection losses, in combination with surface coatings to minimize reradiation losses. Here, we present an alternative approach that operates at atmospheric pressure with simple, black, absorbing surfaces. Silica based aerogels coated on black surfaces have the potential to act as simple and inexpensive solar thermal collectors because of their high transmission to solar radiation and low transmission to thermal radiation. To demonstrate their heat-trapping properties, we fabricated tetramethyl orthosilicate-based silica aerogels. A hydrophilic aerogel with a thickness of 1 cm exhibited a solar-averaged transmission of 76% and thermally averaged transmission of ≈1% (at 100 °C). To minimize unwanted solar absorption by O-H groups, we functionalized the aerogel to be hydrophobic, resulting in a solar-averaged transmission of 88%. To provide a deeper understanding of the link between aerogel properties and overall efficiency, we developed a coupled radiative-conductive heat transfer model and used it to predict solar thermal performance. Instantaneous solar thermal efficiencies approaching 55% at 1 sun and 80 °C were predicted. This study sheds light on the applicability of silica aerogels on black coatings for solar thermal collectors and offers design priorities for next-generation solar thermal aerogels.

Heat Loads Due to Small Penetrations in Multilayer Insulation Blankets

NASA Technical Reports Server (NTRS)

Johnson, W. L.; Heckle, K. W.; Fesmire, J. E.

2017-01-01

The main penetrations (supports and piping) through multilayer insulation systems for cryogenic tanks have been previously addressed by heat flow measurements. Smaller penetrations due to fasteners and attachments are now experimentally investigated. The use of small pins or plastic garment tag fasteners to each the handling and construction of multilayer insulation (MLI) blankets goes back many years. While it has long been understood that penetrations and other discontinuities degrade the performance of the MLI blanket, quantification of this degradation has generally been lumped into gross performance multipliers (often called degradation factors or scale factors). Small penetrations contribute both solid conduction and radiation heat transfer paths through the blanket. The conduction is down the stem of the structural element itself while the radiation is through the hole formed during installation of the pin or fastener. Analytical models were developed in conjunction with MLI perforation theory and Fouriers Law. Results of the analytical models are compared to experimental testing performed on a 10 layer MLI blanket with approximately 50 small plastic pins penetrating the test specimen. The pins were installed at 76-mm spacing inches in both directions to minimize the compounding of thermal effects due to localized compression or lateral heat transfer. The testing was performed using a liquid nitrogen boil-off calorimeter (Cryostat-100) with the standard boundary temperatures of 293 K and 78 K. Results show that the added radiation through the holes is much more significant than the conduction down the fastener. The results are shown to be in agreement with radiation theory for perforated films.

Heat Loads Due To Small Penetrations In Multilayer Insulation Blankets

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Heckle, K. W.; E Fesmire, J.

2017-12-01

The main penetrations (supports and piping) through multilayer insulation systems for cryogenic tanks have been previously addressed by heat flow measurements. Smaller penetrations due to fasteners and attachments are now experimentally investigated. The use of small pins or plastic garment tag fasteners to ease the handling and construction of multilayer insulation (MLI) blankets goes back many years. While it has long been understood that penetrations and other discontinuities degrade the performance of the MLI blanket, quantification of this degradation has generally been lumped into gross performance multipliers (often called degradation factors or scale factors). Small penetrations contribute both solid conduction and radiation heat transfer paths through the blanket. The conduction is down the stem of the structural element itself while the radiation is through the hole formed during installation of the pin or fastener. Analytical models were developed in conjunction with MLI perforation theory and Fourier’s Law. Results of the analytical models are compared to experimental testing performed on a 10 layer MLI blanket with approximately 50 small plastic pins penetrating the test specimen. The pins were installed at ∼76-mm spacing inches in both directions to minimize the compounding of thermal effects due to localized compression or lateral heat transfer. The testing was performed using a liquid nitrogen boil-off calorimeter (Cryostat-100) with the standard boundary temperatures of 293 K and 78 K. Results show that the added radiation through the holes is much more significant than the conduction down the fastener. The results are shown to be in agreement with radiation theory for perforated films.

Influence of Aerogel Morphology and Reinforcement Architecture on Gas Convection in Aerogel Composites

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.; Meyer, Matthew; Guo, Haiquan; Rogers, Richard B.; DeMange, Jeffrey J.; Richardson, Hayley

2016-01-01

A variety of thermal protection applications require lightweight insulation capable of withstanding temperatures well above 900 C. Aerogels offer extremely low-density thermal insulation due to their mesoporous structure, which inhibits both gas convection and solid conduction. Silica aerogel systems are limited to use temperatures of 600-700 C, above which they sinter. Alumina aerogels maintain a porous structure to higher temperatures than silica, before transforming to -alumina and densifying. We have synthesized aluminosilicate aerogels capable of maintaining higher surface areas at temperatures above 1100 C than an all-alumina aerogel using -Boehmite as the aluminum source and tetraethoxysilane (TEOS) as the silicon source. The pore structure of these aerogels varies with thermal exposure temperature and time, as the aluminosilicate undergoes a variety of phase changes to form transition aluminas. Transformation to -alumina is inhibited by incorporation of silica into the alumina lattice. The aerogels are fragile, but can be reinforced using a large variety of ceramic papers, felts or fabrics. The objective of the current study is to characterize the influence of choice of reinforcement and architecture on gas permeability of the aerogel composites in both the as fabricated condition and following thermal exposure, as well as understand the effects of incorporating hydrophobic treatments in the composites.

Improved Silica Aerogel Composite Materials

NASA Technical Reports Server (NTRS)

Paik, Jong-Ah; Sakamoto, Jeffrey; Jones, Steven

2008-01-01

A family of aerogel-matrix composite materials having thermal-stability and mechanical- integrity properties better than those of neat aerogels has been developed. Aerogels are known to be excellent thermal- and acoustic-insulation materials because of their molecular-scale porosity, but heretofore, the use of aerogels has been inhibited by two factors: (1) Their brittleness makes processing and handling difficult. (2) They shrink during production and shrink more when heated to high temperatures during use. The shrinkage and the consequent cracking make it difficult to use them to encapsulate objects in thermal-insulation materials. The underlying concept of aerogel-matrix composites is not new; the novelty of the present family of materials lies in formulations and processes that result in superior properties, which include (1) much less shrinkage during a supercritical-drying process employed in producing a typical aerogel, (2) much less shrinkage during exposure to high temperatures, and (3) as a result of the reduction in shrinkage, much less or even no cracking.

Aerogel: Tile Composites Toughen a Brittle Superinsulation

NASA Technical Reports Server (NTRS)

White, Susan; Rasky, Daniel; Arnold, James O. (Technical Monitor)

1998-01-01

Pure aerogels, though familiar in the laboratory for decades as exotic lightweight insulators with unusual physical properties, have had limited industrial applications due to their low strength and high brittleness. Composites formed of aerogels and the ceramic fiber matrices like those used as space shuttle tiles bypass the fragility of pure aerogels and can enhance the performance of space shuttle tiles in their harsh operating environment. Using a layer of aerogel embedded in a tile may open up a wide range of applications where thermal insulation, gas convection control and mechanical strength matter.

Aerogel: Tile Composites Toughen a Brittle Superinsulation

NASA Technical Reports Server (NTRS)

White, Susan; Rasky, Daniel; Arnold, James O. (Technical Monitor)

1998-01-01

Pure aerogels, though familiar in the laboratory for decades as exotic lightweight insulators with unusual physical properties, have had limited industrial applications due to their low strength and high brittleness. Composites formed of aerogels and the ceramic fiber matrices used as space shuttle tiles bypass the fragility of pure aerogels and can enhance the performance of space shuttle tiles in their harsh operating environment. Using a layer of aerogel embedded in a tile may open up a wide range of applications where thermal insulation, gas convection control and mechanical strength matter.

High surface area aerogels for energy storage and efficiency

NASA Astrophysics Data System (ADS)

Maloney, Ryan Patrick

The dissertation is divided into two main chapters, each focused on a different application for aerogel. The first chapter concerns the development of silica aerogel for thermal insulation. It begins with initial characterization of a silica aerogel insulation for a next-generation Advanced Radioisotope Stirling Generator for space vehicles. While the aerogel as made performs well, it is apparent that further improvements in mechanical strength and durability are necessary. The chapter then continues with the exploration of chlorotrimethysilane surface modification, which somewhat surprisingly provides a drastic increase in mechanical properties, allowing the inherently brittle silica network to deform plastically to >80% strain. It is hypothesized that the hydrophobic surface groups reduce capillary forces during drying, lowering the number of microcracks that may form and weaken the gel. This surface modification scheme is then implemented in a fiber-reinforced, opacified aerogel insulation for a prototypical thermoelectric generator for automotive waste heat recovery. This is the first known report of aerogel insulation for thermoelectrics. The aerogel insulation is able to increase the efficiency of the thermoelectric generator by 40% compared with commercial high-temperature insulating wool. Unfortunately, the supercritical drying process adds significant cost to the aerogel insulation, limiting its commercial viability. The chapter then culminates in the development and characterization of an Ambiently Dried Aerogel Insulation (ADAI) that eliminates the need for expensive supercritical drying. It is believed that this report represents the first aerogel insulation that can be dried without undergoing a large volume change before "springing back" to near its original volume, which allows it to be cast into place into complex geometries and around rigid inclusions. This reduces a large barrier to the commercial viability of aerogel insulation. The advantages of

Cryogenic Thermal Performance Testing of Bulk-Fill and Aerogel Insulation Materials

NASA Astrophysics Data System (ADS)

Scholtens, B. E.; Fesmire, J. E.; Sass, J. P.; Augustynowicz, S. D.; Heckle, K. W.

2008-03-01

Thermal conductivity testing under actual-use conditions is a key to understanding how cryogenic thermal insulation systems perform in regard to engineering, economics, and materials factors. The Cryogenics Test Laboratory at NASA's Kennedy Space Center tested a number of bulk-fill insulation materials, including aerogel beads, glass bubbles, and perlite powder, using a new cylindrical cryostat. Boundary temperatures for the liquid nitrogen boiloff method were 78 K and 293 K. Tests were performed as a function of cold vacuum pressure under conditions ranging from high vacuum to no vacuum. Results were compared with those from complementary test methods in the range of 20 K to 300 K. Various testing techniques are required to completely understand the operating performance of a material and to provide data for answers to design engineering questions.

The monolithic carbon aerogels and aerogel composites for electronics and thermal protection applications

NASA Astrophysics Data System (ADS)

Lu, Sheng; Guo, Hui; Zhou, Yugui; Liu, Yuanyuan; Jin, Zhaoguo; Liu, Bin; Zhao, Yingmin

2017-09-01

Monolithic carbon aerogels have been prepared by condensation polymerization and high temperature pyrolysis. The morphology of carbon aerogels are characterized by SEM. The pore structure is characterized by N2 adsorption-desorption technique. Monolithic carbon aerogels are mesoporous nanomaterials. Carbon fiber reinforced carbon aerogel composites are prepared by in-situ sol-gel process. Fiber reinforced carbon aerogel composites are of high mechanical strength. The thermal response of the fiber reinforced aerogel composite samples are tested in an arc plasma wind tunnel. Carbon aerogel composites show good thermal insulation capability and high temperature resistance in inert atmosphere even at ultrahigh temperature up to 1800 °C. The results show that they are suitable for applications in electrodes for supercapacitors/ Lithium-ion batteries and aerospace thermal protection area.

Hybrid aerogel rigid ceramic fiber insulation and method of producing same

NASA Technical Reports Server (NTRS)

Barney, Andrea O. (Inventor); Heng, Vann (Inventor); Oka, Kris Shigeko (Inventor); Santos, Maryann (Inventor); Zinn, Alfred A. (Inventor); Droege, Michael (Inventor)

2004-01-01

A hybrid insulation material comprises of porous ceramic substrate material impregnated with nanoporous material and method of making the same is the topic of this invention. The porous substrate material has bulk density ranging from 6 to 20 lb/ft.sup.3 and is composed of about 60 to 80 wt % silica (SiO.sub.2) 20 to 40 wt % alumina (Al.sub.2 O.sub.3) fibers, and with about 0.1 to 1.0 wt % boron-containing constituent as the sintering agent. The nanoporous material has density ranging from 1.0 to 10 lb/ft.sup.3 and is either fully or partially impregnated into the substrate to block the pores, resulting in substantial reduction in conduction via radiation and convention. The nanoporous material used to impregnate the fiber substrate is preferably formed from a precursor of alkoxysilane, alcohol, water, and an acid or base catalyst for silica aerogels, and from a precursor of aluminum alkoxide, alcohol, water, and an acid or base catalyst for alumina aerogels.

Application of Nanofiber Technology to Nonwoven Thermal Insulation

DTIC Science & Technology

2006-11-01

polyester high-loft insulations, meltblown pitch carbon fiber, electrospun polyacrylonitrile, and silica aerogel -impregnated flexible fibrous insulation...supported flexible aerogels have polymer or carbon fibers dispersed in an aerogel matrix. Silica aerogels are transparent to thermal radiation, and do

Cryogenic Thermal Performance Testing of Bulk-Fill and Aerogel Insulation Materials

NASA Technical Reports Server (NTRS)

Scholtens, B. E.; Fesmire, J. E.; Sass, J. P.; Augustynowicz, S. D.; Heckle, K. W.

2007-01-01

The research testing and demonstration of new bulk-fill materials for cryogenic thermal insulation systems was performed by the Cryogenics Test Laboratory at NASA Kennedy Space Center. Thermal conductivity testing under actual-use cryogenic conditions is a key to understanding the total system performance encompassing engineering, economics, and materials factors. A number of bulk fill insulation materials, including aerogel beads, glass bubbles, and perlite powder, were tested using a new cylindrical cryostat. Boundary temperatures for the liquid nitrogen boil-off method were 293 K and 78 K. Tests were performed as a function of cold vacuum pressure from high vacuum to no vacuum conditions. Results are compared with other complementary test methods in the range of 300 K to 20 K. Various testing techniques are shown to be required to obtain a complete understanding of the operating performance of a material and to provide data for answers to design engineering questions.

Thermal Performance of Composite Flexible Blanket Insulations for Hypersonic Aerospace Vehicles

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A.

1993-01-01

This paper describes the thermal performance of a Composite Flexible Blanket Insulation (C.F.B.I.) considered for potential use as a thermal protection system or thermal insulation for future hypersonic vehicles such as the National Aerospace Plane (N.A.S.P.). Thermophysical properties for these insulations were also measured including the thermal conductivity at various temperatures and pressures and the emissivity of the fabrics used in the flexible insulations. The thermal response of these materials subjected to aeroconvective heating from a plasma arc is also described. Materials tested included two surface variations of the insulations, and similar insulations coated with a Protective Ceramic Coating (P.C.C.). Surface and backface temperatures were measured in the flexible insulations and on Fibrous Refractory Composite Insulation (F.R.C.I.) used as a calibration model. The uncoated flexible insulations exhibited good thermal performance up to 35 W/sq cm. The use of a P.C.C. to protect these insulations at higher heating rates is described. The results from a computerized thermal analysis model describing thermal response of those materials subjected to the plasma arc conditions are included. Thermal and optical properties were determined including thermal conductivity for the rigid and flexible insulations and emissivity for the insulation fabrics. These properties were utilized to calculate the thermal performance of the rigid and flexible insulations at the maximum heating rate.

Aerogel/polymer composite materials

NASA Technical Reports Server (NTRS)

Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Roberson, Luke B. (Inventor); Clayton, LaNetra M. (Inventor)

2010-01-01

The invention provides new composite materials containing aerogels blended with thermoplastic polymer materials at a weight ratio of aerogel to thermoplastic polymer of less than 20:100. The composite materials have improved thermal insulation ability. The composite materials also have better flexibility and less brittleness at low temperatures than the parent thermoplastic polymer materials.

Aerogel / Polymer Composite Materials

NASA Technical Reports Server (NTRS)

Smith, Trent M. (Inventor); Clayton, LaNetra M. (Inventor); Fesmire, James E. (Inventor); Williams, Martha K. (Inventor); Roberson, Luke B. (Inventor)

2017-01-01

The invention provides new composite materials containing aerogels blended with thermoplastic polymer materials at a weight ratio of aerogel to thermoplastic polymer of less than 20:100. The composite materials have improved thermal insulation ability. The composite materials also have better flexibility and less brittleness at low temperatures than the parent thermoplastic polymer materials.

Novel load responsive multilayer insulation with high in-atmosphere and on-orbit thermal performance

NASA Astrophysics Data System (ADS)

Dye, S.; Kopelove, A.; Mills, G. L.

2012-04-01

Aerospace cryogenic systems require lightweight, high performance thermal insulation to preserve cryopropellants both pre-launch and on-orbit. Current technologies have difficulty meeting all requirements, and advances in insulation would benefit cryogenic upper stage launch vehicles, LH2 fueled aircraft and ground vehicles, and provide capabilities for sub-cooled cryogens for space-borne instruments and orbital fuel depots. This paper reports the further development of load responsive multilayer insulation (LRMLI) that has a lightweight integrated vacuum shell and provides high thermal performance both in-air and on-orbit. LRMLI is being developed by Quest Product Development and Ball Aerospace under NASA contract, with prototypes designed, built, installed and successfully tested. A 3-layer LRMLI blanket (0.63 cm thick, 77 K cold, 295 K hot) had a measured heat leak of 6.6 W/m2 in vacuum and 40.6 W/m2 in air at one atmosphere. In-air LRMLI has an 18× advantage over Spray On Foam Insulation (SOFI) in heat leak per thickness and a 16× advantage over aerogel. On-orbit LRMLI has a 78× lower heat leak than SOFI per thickness and 6× lower heat leak than aerogel. The Phase II development of LRMLI is reported with a modular, flexible, thin vacuum shell and improved on-orbit performance. Structural and thermal analysis and testing results are presented. LRMLI mass and thermal performance is compared to SOFI, aerogel and MLI over SOFI.

Process for forming transparent aerogel insulating arrays

DOEpatents

Tewari, Param H.; Hunt, Arlon J.

1986-01-01

An improved supercritical drying process for forming transparent silica aerogel arrays is described. The process is of the type utilizing the steps of hydrolyzing and condensing aloxides to form alcogels. A subsequent step removes the alcohol to form aerogels. The improvement includes the additional step, after alcogels are formed, of substituting a solvent, such as CO.sub.2, for the alcohol in the alcogels, the solvent having a critical temperature less than the critical temperature of the alcohol. The resulting gels are dried at a supercritical temperature for the selected solvent, such as CO.sub.2, to thereby provide a transparent aerogel array within a substantially reduced (days-to-hours) time period. The supercritical drying occurs at about 40.degree. C. instead of at about 270.degree. C. The improved process provides increased yields of large scale, structurally sound arrays. The transparent aerogel array, formed in sheets or slabs, as made in accordance with the improved process, can replace the air gap within a double glazed window, for example, to provide a substantial reduction in heat transfer. The thus formed transparent aerogel arrays may also be utilized, for example, in windows of refrigerators and ovens, or in the walls and doors thereof or as the active material in detectors for analyzing high energy elementry particles or cosmic rays.

Process for forming transparent aerogel insulating arrays

DOEpatents

Tewari, P.H.; Hunt, A.J.

1985-09-04

An improved supercritical drying process for forming transparent silica aerogel arrays is described. The process is of the type utilizing the steps of hydrolyzing and condensing aloxides to form alcogels. A subsequent step removes the alcohol to form aerogels. The improvement includes the additional step, after alcogels are formed, of substituting a solvent, such as CO/sub 2/, for the alcohol in the alcogels, the solvent having a critical temperature less than the critical temperature of the alcohol. The resulting gels are dried at a supercritical temperature for the selected solvent, such as CO/sub 2/, to thereby provide a transparent aerogel array within a substantially reduced (days-to-hours) time period. The supercritical drying occurs at about 40/sup 0/C instead of at about 270/sup 0/C. The improved process provides increased yields of large scale, structurally sound arrays. The transparent aerogel array, formed in sheets or slabs, as made in accordance with the improved process, can replace the air gap within a double glazed window, for example, to provide a substantial reduction in heat transfer. The thus formed transparent aerogel arrays may also be utilized, for example, in windows of refrigerators and ovens, or in the walls and doors thereof or as the active material in detectors for analyzing high energy elementary particles or cosmic rays.

Flexible aerogel composite for mechanical stability and process of fabrication

DOEpatents

Coronado, Paul R.; Poco, John F.

2000-01-01

A flexible aerogel and process of fabrication. An aerogel solution is mixed with fibers in a mold and allowed to gel. The gel is then processed by supercritical extraction, or by air drying, to produce a flexible aerogel formed to the shape of the mold. The flexible aerogel has excellent thermal and acoustic properties, and can be utilized in numerous applications, such as for energy absorption, insulation (temperature and acoustic), to meet the contours of aircraft shapes, and where space is limited since an inch of aerogel is a 4-5 times better insulator than an inch of fiberglass. The flexible aerogel may be of an inorganic (silica) type or an organic (carbon) type, but containing fibers, such as glass or carbon fibers.

Flexible aerogel composite for mechanical stability and process of fabrication

DOEpatents

Coronado, Paul R.; Poco, John F.

1999-01-01

A flexible aerogel and process of fabrication. An aerogel solution is mixed with fibers in a mold and allowed to gel. The gel is then processed by supercritical extraction, or by air drying, to produce a flexible aerogel formed to the shape of the mold. The flexible aerogel has excellent thermal and acoustic properties, and can be utilized in numerous applications, such as for energy absorption, insulation (temperature and acoustic), to meet the contours of aircraft shapes, and where space is limited since an inch of aerogel is a 4-5 times better insulator than an inch of fiberglass. The flexible aerogel may be of an inorganic (silica) type or an organic (carbon) type, but containing fibers, such as glass or carbon fibers.

Clay Nanocomposite/Aerogel Sandwich Structures for Cryotanks

NASA Technical Reports Server (NTRS)

Miller, Sandi; Leventis, Nicholas; Johnston, J. Chris; Meador, Michael

2006-01-01

GRC research has led to the development of epoxy-clay nanocomposites with 60-70% lower gas permeability than the base epoxy resin. Filament wound carbon fiber reinforced tanks made with this nanocomposite had a five-fold lower helium leak rate than the corresponding tanks made without clay. More recent work has produced new composites with more than a 100-fold reduction in helium permeability. Use of these advanced, high barrier composites would eliminate the need for a liner in composite cryotanks, thereby simplifying construction and reducing propellant leakage. Aerogels are attractive materials for use as cryotank insulation because of their low density and low thermal conductivity. However, aerogels are fragile and have poor environmental stability, which have limited their use to certain applications in specialized environments (e.g., in certain types of nuclear reactors as Cerenkov radiation detectors, and as thermal insulators aboard space rovers on Mars). New GRC developed polymer crosslinked aerogels (X-Aerogels) retain the low density of conventional aerogels, but they demonstrate a 300-fold increase in their mechanical strength. Currently, our strongest materials combine a density of approx. 0.45 g/cc, a thermal conductivity of approx. 0.04 W/mK and a compressive strength of 185 MPa. Use of these novel aerogels as insulation materials/structural components in combination with the low permeability of epoxy-clay nanocomposites could significantly reduce cryotank weight and improve durability.

Improvements to the Synthesis of Polyimide Aerogels

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B.; Nguyen, Baochau N.; Guo, Haiquan; Vivod, Stephanie; He, Zuhui; Malow, Ericka; Silva, Rebecca

2011-01-01

Cross-linked polyimide aerogels are viable approach to higher temperature, flexible insulation for inflatable decelerators. Results indicate that the all-polyimide aerogels are as strong or stronger than polymer reinforced silica aerogels at the same density. Currently, examining use of carbon nanofiber and clay nanoparticles to improve performance. Flexible, polyimide aerogels have potential utility in other applications such as space suits, habitats, shelter applications, etc. where low dusting is desired

Toward a benchmark material in aerogel development

NASA Astrophysics Data System (ADS)

Sibille, Laurent; Cronise, Raymond J.; Noever, David A.; Hunt, Arlon J.

1996-03-01

Discovered in the thirties, aerogels constitute today the lightest solids known while exhibiting outstanding thermal and noise insulation properties in air and vacuum. In a far-reaching collaboration, the Space Science Laboratory at NASA Marshall Space Flight Center and the Microstructured Materials Group at Lawrence Berkeley National Laboratory are engaged in a two-fold research effort aiming at characterizing the microstructure of silica aerogels and the development of benchmark samples through the use of in-orbit microgravity environment. Absence of density-driven convection flows and sedimentation is sought to produce aerogel samples with narrow distribution of pore sizes, thus largely improving transparency of the material in the visible range. Furthermore, highly isotropic distribution of doping materials are attainable even in large gels grown in microgravity. Aerospace companies (cryogenic tanks insulation and high temperature insulation of space vehicles), insulation manufacturers (household and industrial applications) as well as pharmaceutical companies (biosensors) are potential end-users of this rapidly developing technology.

Synthesis, Processing, and Characterization of Inorganic-Organic Hybrid Cross-Linked Silica, Organic Polyimide, and Inorganic Aluminosilicate Aerogels

NASA Technical Reports Server (NTRS)

Nguyen, Baochau N.; Guo, Haiquan N.; McCorkle, Linda S.

2014-01-01

As aerospace applications become ever more demanding, novel insulation materials with lower thermal conductivity, lighter weight and higher use temperature are required to fit the aerospace application needs. Having nanopores and high porosity, aerogels are superior thermal insulators, among other things. The use of silica aerogels in general is quite restricted due to their inherent fragility, hygroscopic nature, and poor mechanical properties, especially in extereme aerospace environments. Our research goal is to develop aerogels with better mechanical and environmental stability for a variety of aeronautic and space applications including space suit insulation for planetary surface missions, insulation for inflatable structures for habitats, inflatable aerodynamic decelerators for entry, descent and landing (EDL) operations, and cryotank insulation for advance space propulsion systems. Different type of aerogels including organic-inorganic polymer reinforced (hybrid) silica-based aerogels, polyimide aerogels and inorganic aluminosilicate aerogels have been developed and examined.

Improvements of reinforced silica aerogel nanocomposites thermal properties for architecture applications.

PubMed

Saboktakin, Amin; Saboktakin, Mohammad Reza

2015-01-01

An 1,4-cis polybutadiene rubber/carboxymethyl starch (CMS)-based silica aerogel nanocomposites as a insulation material was developed that will provide superior thermal insulation properties, flexibility, toughness, durability of the parent polymer, yet with the low density and superior insulation properties associated with the aerogels. In this study, reinforced 1,4-cis polybutadiene-CMS-silica aerogel nanocomposites were prepared from a silica aerogel with a surface area 710 m(2) g(-1), a pore size of 25.3 nm and a pore volume of 4.7 cm(3) g(-1). The tensile properties and dynamic mechanical properties of 1,4-cis polybutadiene/CMS nanocomposites were systematically enhanced at low silica loading. Similar improvements in tensile modulus and strength have been observed for 1,4-cis polybutadiene/CMS mesoporous silica aerogel nanocomposites. Copyright © 2014 Elsevier B.V. All rights reserved.

Protective Skins for Aerogel Monoliths

NASA Technical Reports Server (NTRS)

Leventis, Nicholas; Johnston, James C.; Kuczmarski, Maria A.; Meador, Ann B.

2007-01-01

A method of imparting relatively hard protective outer skins to aerogel monoliths has been developed. Even more than aerogel beads, aerogel monoliths are attractive as thermal-insulation materials, but the commercial utilization of aerogel monoliths in thermal-insulation panels has been inhibited by their fragility and the consequent difficulty of handling them. Therefore, there is a need to afford sufficient protection to aerogel monoliths to facilitate handling, without compromising the attractive bulk properties (low density, high porosity, low thermal conductivity, high surface area, and low permittivity) of aerogel materials. The present method was devised to satisfy this need. The essence of the present method is to coat an aerogel monolith with an outer polymeric skin, by painting or spraying. Apparently, the reason spraying and painting were not attempted until now is that it is well known in the aerogel industry that aerogels collapse in contact with liquids. In the present method, one prevents such collapse through the proper choice of coating liquid and process conditions: In particular, one uses a viscous polymer precursor liquid and (a) carefully controls the amount of liquid applied and/or (b) causes the liquid to become cured to the desired hard polymeric layer rapidly enough that there is not sufficient time for the liquid to percolate into the aerogel bulk. The method has been demonstrated by use of isocyanates, which, upon exposure to atmospheric moisture, become cured to polyurethane/polyurea-type coats. The method has also been demonstrated by use of commercial epoxy resins. The method could also be implemented by use of a variety of other resins, including polyimide precursors (for forming high-temperature-resistant protective skins) or perfluorinated monomers (for forming coats that impart hydrophobicity and some increase in strength).

An environmentally benign route for the development of compressible, thermally insulating and fire retardant aerogels through self-assembling the silk fibroin biopolymer inside the silica structure - An approach towards 3D printing of aerogels.

PubMed

Maleki, Hajar; Montes, Susan; Hayati-Roodbari, Nastaran; Putz, Florian; Huesing, Nicola

2018-06-04

Thanks to the exceptional materials properties of silica aerogels, this fascinating highly porous material has found high performance and real-life applications in various modern industries. However, a requirement for a broadening of these applications is based on the further improvement of their properties especially with regard to mechanical strength and post-synthesis processability with minimum compromise to the other physical properties. Here, we report an entirely novel, simple and aqueous based synthesis approach to prepare mechanically robust aerogel hybrids by co-gelation of silk fibroin (SF) biopolymer, extracted from silkworm cocoons. The synthesis is based on a one-step sequential processes of acid catalysis (physical) crosslinking of the SF biopolymer and simultaneous polycondensation of tetramethyl orthosilicate (TMOS), in the presence of 5-(trimethoxysilyl)pentanoic acid (TMSPA) as a coupling agent and subsequent solvent exchange and supercritical drying. Extensive characterizations by solid-state 1H-NMR, 29Si-NMR, and 2D 1H-29Si heteronuclear correlation (HETCOR) MAS NMR spectroscopy as well as various microscopic techniques (SEM, TEM) and mechanical assessment, confirmed the molecular-level homogeneity of the hybrid nanostructure. The developed silica-SF aerogel hybrids contained an improved set of material properties, such as low density (ρb, average = 0.11 - 0.2 g cm-3), high porosity (~90%), high specific surface area (~ 400-800 m2 g-1), excellent flexibility in compression (up to 80% of strain) with three-order of magnitude improvement in the Young's modulus over that of pristine silica aerogels. In addition, the silica-SF hybrid aerogels are fire retardant and demonstrated excellent thermal insulation performance with thermal conductivities (λ) of (0.033-0.039 Wm-1 K-1). As a further advantage, the formulated hybrid silica-SF aerogel showed an excellent printability in the wet state using a micro-extrusion based 3D printing approach. The

Aerogel/Particle Composites for Thermoelectric Devices

NASA Technical Reports Server (NTRS)

Paik, Jong-Ah; Sakamoto, Jeffrey; Jones, Steven

2006-01-01

Optimizing solution chemistry and the addition of titania and fumed silica powder reduces shrinkage. These materials would serve to increase thermal efficiency by providing thermal insulation to suppress lateral heat leaks. They would also serve to prolong operational lifetime by suppressing sublimation of certain constituents of thermoelectric materials (e.g., sublimation of Sb from CoSb3) at typical high operating temperatures. [The use of pure silica aerogels as cast-in-place thermal-insulation and sublimation-suppression materials was described in "Aerogels for Thermal Insulation of Thermoelectric Devices" (NPO-40630), NASA Tech Briefs, Vol. 30, No. 7 (July 2006), page 50.] A silica aerogel is synthesized in a solgel process that includes preparation of a silica sol, gelation of the sol, and drying of the gel in a solvent at a supercritical temperature and pressure. The utility of pure silica aerogel is diminished by a tendency to shrink (and, therefore, also to crack) during the gelation and supercritical-drying stages. Moreover, to increase suppression of sublimation, it is advantageous to make an aerogel having greater density, but shrinkage and cracking tend to increase with density. A composite material of the type under investigation consists mostly of titania oxide powder particles and a small addition of fumed silica powder, which are mixed into the sol along with other ingredients prior to the gelation stage of processing. The silica aerogel and fumed silica act as a binder, gluing the titania particles together. It is believed that the addition of fumed silica stiffens the aerogel network and reduces shrinkage during the supercritical-drying stage. Minimization of shrinkage enables establishment of intimate contact between thermoelectric legs and the composite material, thereby maximizing the effectiveness of the material for thermal insulation and suppression of sublimation. To some extent, the properties of the composite can be tailored via the

Development of tailorable advanced blanket insulation for advanced space transportation systems

NASA Technical Reports Server (NTRS)

Calamito, Dominic P.

1987-01-01

Two items of Tailorable Advanced Blanket Insulation (TABI) for Advanced Space Transportation Systems were produced. The first consisted of flat panels made from integrally woven, 3-D fluted core having parallel fabric faces and connecting ribs of Nicalon silicon carbide yarns. The triangular cross section of the flutes were filled with mandrels of processed Q-Fiber Felt. Forty panels were prepared with only minimal problems, mostly resulting from the unavailability of insulation with the proper density. Rigidizing the fluted fabric prior to inserting the insulation reduced the production time. The procedures for producing the fabric, insulation mandrels, and TABI panels are described. The second item was an effort to determine the feasibility of producing contoured TABI shapes from gores cut from flat, insulated fluted core panels. Two gores of integrally woven fluted core and single ply fabric (ICAS) were insulated and joined into a large spherical shape employing a tadpole insulator at the mating edges. The fluted core segment of each ICAS consisted of an Astroquartz face fabric and Nicalon face and rib fabrics, while the single ply fabric segment was Nicalon. Further development will be required. The success of fabricating this assembly indicates that this concept may be feasible for certain types of space insulation requirements. The procedures developed for weaving the ICAS, joining the gores, and coating certain areas of the fabrics are presented.

Coated Aerogel Beads

NASA Technical Reports Server (NTRS)

Littman, Howard (Inventor); Plawsky, Joel L. (Inventor); Paccione, John D. (Inventor)

2014-01-01

Methods and apparatus for coating particulate material are provided. The apparatus includes a vessel having a top and a bottom, a vertically extending conduit having an inlet in the vessel and an outlet outside of the vessel, a first fluid inlet in the bottom of the vessel for introducing a transfer fluid, a second fluid inlet in the bottom of the vessel for introducing a coating fluid, and a fluid outlet from the vessel. The method includes steps of agitating a material, contacting the material with a coating material, and drying the coating material to produce a coated material. The invention may be adapted to coat aerogel beads, among other materials. A coated aerogel bead and an aerogel-based insulation material are also disclosed.

Protection against cold in prehospital care-thermal insulation properties of blankets and rescue bags in different wind conditions.

PubMed

Henriksson, Otto; Lundgren, J Peter; Kuklane, Kalev; Holmér, Ingvar; Bjornstig, Ulf

2009-01-01

In a cold, wet, or windy environment, cold exposure can be considerable for an injured or ill person. The subsequent autonomous stress response initially will increase circulatory and respiratory demands, and as body core temperature declines, the patient's condition might deteriorate. Therefore, the application of adequate insulation to reduce cold exposure and prevent body core cooling is an important part of prehospital primary care, but recommendations for what should be used in the field mostly depend on tradition and experience, not on scientific evidence. The objective of this study was to evaluate the thermal insulation properties in different wind conditions of 12 different blankets and rescue bags commonly used by prehospital rescue and ambulance services. The thermal manikin and the selected insulation ensembles were setup inside a climatic chamber in accordance to the modified European Standard for assessing requirements of sleeping bags. Fans were adjusted to provide low (< 0.5 m/s), moderate (2-3 m/s) and high (8-9 m/s) wind conditions. During steady state thermal transfer, the total resultant insulation value, Itr (m2 C/Wclo; where C = degrees Celcius, and W = watts), was calculated from ambient air temperature (C), manikin surface temperature (C), and heat flux (W/m2). In the low wind condition, thermal insulation of the evaluated ensembles correlated to thickness of the ensembles, ranging from 2.0 to 6.0 clo (1 clo = 0.155 m2 C/W), except for the reflective metallic foil blankets that had higher values than expected. In moderate and high wind conditions, thermal insulation was best preserved for ensembles that were windproof and resistant to the compressive effect of the wind, with insulation reductions down to about 60-80% of the original insulation capacity, whereas wind permeable and/or lighter materials were reduced down to about 30-50% of original insulation capacity. The evaluated insulation ensembles might all be used for prehospital

Pectin-based nanocomposite aerogels for potential insulated food packaging application.

PubMed

Nešić, Aleksandra; Gordić, Milan; Davidović, Sladjana; Radovanović, Željko; Nedeljković, Jovan; Smirnova, Irina; Gurikov, Pavel

2018-09-01

Environmental-friendly pectin-TiO 2 nanocomposite aerogels were prepared via sol-gel process and subsequent drying under supercritical conditions. The first step includes dissolution of pectin in water, addition of proper amount of TiO 2 colloid and crosslinking reaction induced in the presence of tert-butanol and zinc ions. Then, the gels are subjected to the solvent exchange and supercritical CO 2 drying. The influence of TiO 2 nanoparticles on the textural, mechanical, thermal and antibacterial properties of aerogels was investigated. Results indicate that in the presence of TiO 2 nanoparticles (NPs) mechanical, thermal and antimicrobial properties of pectin-based aerogels are improved in comparison to the control pectin aerogels. It should be emphasized that the thermal conductivity of pectin-based aerogels (0.022-0.025 W m -1  K -1 ) is lower than the thermal conductivity of air. Generally, the results propose that the pectin-TiO 2 nanocomposite aerogels, as bio-based material, might have potential application for the storage of temperature-sensitive food. Copyright © 2018 Elsevier Ltd. All rights reserved.

Carbon Nanofiber Incorporated Silica Based Aerogels with Di-Isocyanate Cross-Linking

NASA Technical Reports Server (NTRS)

Vivod, Stephanie L.; Meador, Mary Ann B.; Capadona, Lynn A.; Sullivan, Roy M.; Ghosn, Louis J.; Clark, Nicholas; McCorkle, Linda

2008-01-01

Lightweight materials with excellent thermal insulating properties are highly sought after for a variety of aerospace and aeronautic applications. (1) Silica based aerogels with their high surface area and low relative densities are ideal for applications in extreme environments such as insulators for the Mars Rover battery. (2) However, the fragile nature of aerogel monoliths prevents their widespread use in more down to earth applications. We have shown that the fragile aerogel network can be cross-linked with a di-isocyanate via amine decorated surfaces to form a conformal coating. (3) This coating reinforces the neck regions between secondary silica particles and significantly strengthens the aerogels with only a small effect on density or porosity. Scheme 1 depicts the cross-linking reaction with the di-isocyanate and exhibits the stages that result in polymer cross-linked aerogel monoliths.

Method for producing metal oxide aerogels

DOEpatents

Tillotson, T.M.; Poco, J.F.; Hrubesh, L.W.; Thomas, I.M.

1995-04-25

A two-step hydrolysis-condensation method was developed to form metal oxide aerogels of any density, including densities of less than 0.003g/cm{sup 3} and greater than 0.27g/cm{sup 3}. High purity metal alkoxide is reacted with water, alcohol solvent, and an additive to form a partially condensed metal intermediate. All solvent and reaction-generated alcohol is removed, and the intermediate is diluted with a nonalcoholic solvent. The intermediate can be stored for future use to make aerogels of any density. The aerogels are formed by reacting the intermediate with water, nonalcoholic solvent, and a catalyst, and extracting the nonalcoholic solvent directly. The resulting monolithic aerogels are hydrophobic and stable under atmospheric conditions, and exhibit good optical transparency, high clarity, and homogeneity. The aerogels have high thermal insulation capacity, high porosity, mechanical strength and stability, and require shorter gelation times than aerogels formed by conventional methods. 8 figs.

Method for producing metal oxide aerogels

DOEpatents

Tillotson, Thomas M.; Poco, John F.; Hrubesh, Lawrence W.; Thomas, Ian M.

1995-01-01

A two-step hydrolysis-condensation method was developed to form metal oxide aerogels of any density, including densities of less than 0.003g/cm.sup.3 and greater than 0.27g/cm.sup.3. High purity metal alkoxide is reacted with water, alcohol solvent, and an additive to form a partially condensed metal intermediate. All solvent and reaction-generated alcohol is removed, and the intermediate is diluted with a nonalcoholic solvent. The intermediate can be stored for future use to make aerogels of any density. The aerogels are formed by reacting the intermediate with water, nonalcoholic solvent, and a catalyst, and extracting the nonalcoholic solvent directly. The resulting monolithic aerogels are hydrophobic and stable under atmospheric conditions, and exhibit good optical transparency, high clarity, and homogeneity. The aerogels have high thermal insulation capacity, high porosity, mechanical strength and stability, and require shorter gelation times than aerogels formed by conventional methods.

Biopolymer Aerogels and Foams: Chemistry, Properties, and Applications.

PubMed

Zhao, Shanyu; Malfait, Wim J; Guerrero-Alburquerque, Natalia; Koebel, Matthias M; Nyström, Gustav

2018-06-25

Biopolymer aerogels were among the first aerogels produced, but only in the last decade has research on biopolymer and biopolymer-composite aerogels become popular, motivated by sustainability arguments, their unique and tunable properties, and ease of functionalization. Biopolymer aerogels and open-cell foams have great potential for classical aerogel applications such as thermal insulation, as well as emerging applications in filtration, oil-water separation, CO 2 capture, catalysis, and medicine. The biopolymer aerogel field today is driven forward by empirical materials discovery at the laboratory scale, but requires a firmer theoretical basis and pilot studies to close the gap to market. This Review includes a database with over 3800 biopolymer aerogel properties, evaluates the state of the biopolymer aerogel field, and critically discusses the scientific, technological, and commercial barriers to the commercialization of these exciting materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composite Silica Aerogels Opacified with Titania

NASA Technical Reports Server (NTRS)

Paik, Jon-Ah; Sakamoto, Jeffrey; Jones, Steven; Fleurial, Jean-Pierre; DiStefano, Salvador; Nesmith, Bill

2009-01-01

A further improvement has been made to reduce the high-temperature thermal conductivities of the aerogel-matrix composite materials described in Improved Silica Aerogel Composite Materials (NPO-44287), NASA Tech Briefs, Vol. 32, No. 9 (September 2008), page 50. Because the contribution of infrared radiation to heat transfer increases sharply with temperature, the effective high-temperature thermal conductivity of a thermal-insulation material can be reduced by opacifying the material to reduce the radiative contribution. Therefore, the essence of the present improvement is to add an opacifying constituent material (specifically, TiO2 powder) to the aerogel-matrix composites.

Analyses of Hubble Space Telescope Aluminized-Teflon Multilayer Insulation Blankets Retrieved After 19 Years of Space Exposure

NASA Technical Reports Server (NTRS)

de Groh, Kim K.; Perry, Bruce A.; Mohammed, Jelila S.; Banks, Bruce

2015-01-01

Since its launch in April 1990, the Hubble Space Telescope (HST) has made many important observations from its vantage point in low Earth orbit (LEO). However, as seen during five servicing missions, the outer layer of multilayer insulation (MLI) has become increasingly embrittled and has cracked in many areas. In May 2009, during the 5th servicing mission (called SM4), two MLI blankets were replaced with new insulation and the space-exposed MLI blankets were retrieved for degradation analyses by teams at NASA Glenn Research Center (GRC) and NASA Goddard Space Flight Center (GSFC). The retrieved MLI blankets were from Equipment Bay 8, which received direct sunlight, and Equipment Bay 5, which received grazing sunlight. Each blanket was divided into several regions based on environmental exposure and/or physical appearance. The aluminized-Teflon (DuPont, Wilmington, DE) fluorinated ethylene propylene (Al-FEP) outer layers of the retrieved MLI blankets have been analyzed for changes in optical, physical, and mechanical properties, along with chemical and morphological changes. Pristine and as-retrieved samples (materials) were heat treated to help understand degradation mechanisms. When compared to pristine material, the analyses have shown how the Al-FEP was severely affected by the space environment. Most notably, the Al-FEP was highly embrittled, fracturing like glass at strains of 1 to 8 percent. Across all measured properties, more significant degradation was observed for Bay 8 material as compared to Bay 5 material. This paper reviews the tensile and bend-test properties, density, thickness, solar absorptance, thermal emittance, x-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) elemental composition measurements, surface and crack morphologies, and atomic oxygen erosion yields of the Al-FEP outer layer of the retrieved HST blankets after 19 years of space exposure.

Study on Thermal Conductivities of Aromatic Polyimide Aerogels.

PubMed

Feng, Junzong; Wang, Xin; Jiang, Yonggang; Du, Dongxuan; Feng, Jian

2016-05-25

Polyimide aerogels for low density thermal insulation materials were produced by 4,4'-diaminodiphenyl ether and 3,3',4,4'-biphenyltetracarboxylic dianhydride, cross-linked with 1,3,5-triaminophenoxybenzene. The densities of obtained polyimide aerogels are between 0.081 and 0.141 g cm(-3), and the specific surface areas are between 288 and 322 m(2) g(-1). The thermal conductivities were measured by a Hot Disk thermal constant analyzer. The value of the measured thermal conductivity under carbon dioxide atmosphere is lower than that under nitrogen atmosphere. Under pressure of 5 Pa at -130 °C, the thermal conductivity is the lowest, which is 8.42 mW (m K)(-1). The polyimide aerogels have lower conductivity [30.80 mW (m K)(-1)], compared to the value for other organic foams (polyurethane foam, phenolic foam, and polystyrene foam) with similar apparent densities under ambient pressure at 25 °C. The results indicate that polyimide aerogel is an ideal insulation material for aerospace and other applications.

Highly flexible cross-linked cellulose nanofibril sponge-like aerogels with improved mechanical property and enhanced flame retardancy.

PubMed

Guo, Limin; Chen, Zhilin; Lyu, Shaoyi; Fu, Feng; Wang, Siqun

2018-01-01

Cellulose nanofibril (CNF) aerogel is highly flammable and its mechanical strength is very soft, which is unfavourable due to safety concerns and impractical when used as the thermal insulation material. In this work, we used N-methylol dimethylphosphonopropionamide (MDPA) and 1,2,3,4-butanetetracarboxylic acid (BTCA) as co-additives and then prepared lightweight flame resistant CNF sponge-like aerogels via an eco-friendly freeze-drying and post cross-linking method. The CNF/BTCA/MDPA aerogel exhibited a better flame retardant performance, outstanding self-extinguishing behaviour and significantly increased char residue (by as much as 268%) compared with the neat CNF aerogel. Meanwhile, the resilience of the aerogel samples improved significantly as the flexibility decreased slightly. Furthermore, the aerogel samples still exhibited excellent thermal insulating properties with thermal conductivity as low as 0.03258W/(m k). The combination of these characteristics makes the CNF-based aerogel a promising insulation candidate for thermal protective equipment (e.g., fire-protection clothing or advanced spacesuit elements) in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silicon Oxycarbide Aerogels for High-Temperature Thermal Insulation

NASA Technical Reports Server (NTRS)

Evans, Owen; Rhine, Wendell; Coutinho, Decio

2010-01-01

This work has shown that the use of SOC-A35 leads to aerogel materials containing a significant concentration of carbidic species and limited amorphous free carbon. Substitution of the divalent oxide species in silica with tetravalent carbidic carbon has directly led to materials that exhibit increased network viscosity, reduced sintering, and limited densification. The SiOC aerogels produced in this work have the highest carbide content of any dense or porous SiOC glass reported in the literature at that time, and exhibit tremendous long-term thermal stability.

Gauge Measures Thicknesses Of Blankets

NASA Technical Reports Server (NTRS)

Hagen, George R.; Yoshino, Stanley Y.

1991-01-01

Tool makes highly repeatable measurements of thickness of penetrable blanket insulation. Includes commercial holder for replaceable knife blades, which holds needle instead of knife. Needle penetrates blanket to establish reference plane. Ballasted slider applies fixed preload to blanket. Technician reads thickness value on scale.

Strong, Thermally Superinsulating Biopolymer-Silica Aerogel Hybrids by Cogelation of Silicic Acid with Pectin.

PubMed

Zhao, Shanyu; Malfait, Wim J; Demilecamps, Arnaud; Zhang, Yucheng; Brunner, Samuel; Huber, Lukas; Tingaut, Philippe; Rigacci, Arnaud; Budtova, Tatiana; Koebel, Matthias M

2015-11-23

Silica aerogels are excellent thermal insulators, but their brittle nature has prevented widespread application. To overcome these mechanical limitations, silica-biopolymer hybrids are a promising alternative. A one-pot process to monolithic, superinsulating pectin-silica hybrid aerogels is presented. Their structural and physical properties can be tuned by adjusting the gelation pH and pectin concentration. Hybrid aerogels made at pH 1.5 exhibit minimal dust release and vastly improved mechanical properties while remaining excellent thermal insulators. The change in the mechanical properties is directly linked to the observed "neck-free" nanoscale network structure with thicker struts. Such a design is superior to "neck-limited", classical inorganic aerogels. This new class of materials opens up new perspectives for novel silica-biopolymer nanocomposite aerogels. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flexible transparent aerogels as window retrofitting films and optical elements with tunable birefringence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Qingkun; Frazier, Allister W.; Zhao, Xinpeng

Experimental realization of optically transparent, mechanically robust and flexible aerogels has been a longstanding challenge, which limits their practical applications in energy-saving devices, such as thermally insulating films for enhancing energy efficiency of windows. The poor transparency precluded even hypothetical consideration of the possibility of birefringent aerogels. We develop birefringent and optically isotropic aerogels that combine properties of thermal super-insulation, mechanical robustness and flexibility, and transparency to visible-spectrum light. This unusual combination of physical properties is achieved by combining liquid crystalline self-organization of cellulose nanofibers with polysiloxane cross-linking and control of the nanoscale porosity to form hybrid organic-inorganic mesostructured aerogels.more » Potential applications of these inexpensive materials range from single pane window retrofitting to smart fabrics.« less

Tailoring mechanical properties of aerogels for aerospace applications.

PubMed

Randall, Jason P; Meador, Mary Ann B; Jana, Sadhan C

2011-03-01

Silica aerogels are highly porous solid materials consisting of three-dimensional networks of silica particles and are typically obtained by removing the liquid in silica gels under supercritical conditions. Several unique attributes such as extremely low thermal conductivity and low density make silica aerogels excellent candidates in the quest for thermal insulation materials used in space missions. However, native silica aerogels are fragile at relatively low stresses. More durable aerogels with higher strength and stiffness are obtained by proper selection of silane precursors and by reinforcement with polymers. This paper first presents a brief review of the literature on methods of silica aerogel reinforcement and then discusses our recent activities in improving not only the strength but also the elastic response of polymer-reinforced silica aerogels. Several alkyl-linked bis-silanes were used in promoting flexibility of the silica networks in conjunction with polymer reinforcement by epoxy.

Composite Flexible Blanket Insulation

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A. (Inventor); Pitts, William C. (Inventor); Goldstein, Howard E. (Inventor); Sawko, Paul M. (Inventor)

1991-01-01

Composite flexible multilayer insulation systems (MLI) were evaluated for thermal performance and compared with the currently used fibrous silica (baseline) insulation system. The systems described are multilayer insulations consisting of alternating layers of metal foil and scrim ceramic cloth or vacuum metallized polymeric films quilted together using ceramic thread. A silicon carbide thread for use in the quilting and the method of making it are also described. These systems are useful in providing lightweight insulation for a variety of uses, particularly on the surface of aerospace vehicles subject to very high temperatures during flight.

Mechanical Properties of Aerogels

NASA Technical Reports Server (NTRS)

Parmenter, Kelly E.; Milstein, Frederick

1995-01-01

Aerogels are extremely low density solids that are characterized by a high porosity and pore sizes on the order of nanometers. Their low thermal conductivity and sometimes transparent appearance make them desirable for applications such as insulation in cryogenic vessels and between double paned glass in solar architecture. An understanding of the mechanical properties of aerogels is necessary before aerogels can be used in load bearing applications. In the present study, the mechanical behavior of various types of fiber-reinforced silica aerogels was investigated with hardness, compression, tension and shear tests. Particular attention was paid to the effects of processing parameters, testing conditions, storage environment, and age on the aerogels' mechanical response. The results indicate that the addition of fibers to the aerogel matrix generally resulted in softer, weaker materials with smaller elastic moduli. Furthermore, the testing environment significantly affected compression results. Tests in ethanol show an appreciable amount of scatter, and are not consistent with results for tests in air. In fact, the compression specimens appeared to crack and begin to dissolve upon exposure to the ethanol solution. This is consistent with the inherent hydrophobic nature of these aerogels. In addition, the aging process affected the aerogels' mechanical behavior by increasing their compressive strength and elastic moduli while decreasing their strain at fracture. However, desiccation of the specimens did not appreciably affect the mechanical properties, even though it reduced the aerogel density by removing trapped moisture. Finally, tension and shear test results indicate that the shear strength of the aerogels exceeds the tensile strength. This is consistent with the response of brittle materials. Future work should concentrate on mechanical testing at cryogenic temperatures, and should involve more extensive tensile tests. Moreover, before the mechanical response

Effects of Microgravity on the Formation of Aerogels

NASA Technical Reports Server (NTRS)

Hunt, A. J.; Ayers, M. R.; Sibille, L.; Cronise, R. J.; Noever, D. A.

1999-01-01

presence of poorly controlled microporosity in aerogel leads to material non-uniformity that gives rise to increased light scattering. Investigation of the effect of gravity driven solute flows within microclusters and their effect on condensation and agglomeration reactions will enable us to improve the preparation and properties of aerogel. Increased clarity of images viewed through aerogel and decreased scattering from the pores of aerogel will significantly improve the prospects for large-scale adoption of aerogel in such applications as transparent insulating windows, high performance thermal insulation, and Cherenkov detectors.

Polyimide Cellulose Nanocrystal Composite Aerogels

NASA Technical Reports Server (NTRS)

Nguyen, Baochau N.; Meador, Mary Ann; Rowan, Stuart; Cudjoe, Elvis; Sandberg, Anna

2014-01-01

Polyimide (PI) aerogels are highly porous solids having low density, high porosity and low thermal conductivity with good mechanical properties. They are ideal for various applications including use in antenna and insulation such as inflatable decelerators used in entry, decent and landing operations. Recently, attention has been focused on stimuli responsive materials such as cellulose nano crystals (CNCs). CNCs are environmentally friendly, bio-renewable, commonly found in plants and the dermis of sea tunicates, and potentially low cost. This study is to examine the effects of CNC on the polyimide aerogels. The CNC used in this project are extracted from mantle of a sea creature called tunicates. A series of polyimide cellulose nanocrystal composite aerogels has been fabricated having 0-13 wt of CNC. Results will be discussed.

Thermal Insulation Strips Conserve Energy

NASA Technical Reports Server (NTRS)

2009-01-01

Launching the space shuttle involves an interesting paradox: While the temperatures inside the shuttle s main engines climb higher than 6,000 F hot enough to boil iron for fuel, the engines use liquid hydrogen, the second coldest liquid on Earth after liquid helium. Maintained below 20 K (-423 F), the liquid hydrogen is contained in the shuttle s rust-colored external tank. The external tank also contains liquid oxygen (kept below a somewhat less chilly 90 K or -297 F) that combines with the hydrogen to create an explosive mixture that along with the shuttle s two, powdered aluminum-fueled solid rocket boosters allows the shuttle to escape Earth s gravity. The cryogenic temperatures of the main engines liquid fuel can cause ice, frost, or liquefied air to build up on the external tank and other parts of the numerous launch fueling systems, posing a possible debris risk when the ice breaks off during launch and causing difficulties in the transfer and control of these cryogenic liquid propellants. Keeping the fuel at the necessary ultra-cold temperatures while minimizing ice buildup and other safety hazards, as well as reducing the operational maintenance costs, has required NASA to explore innovative ways for providing superior thermal insulation systems. To address the challenge, the Agency turned to an insulating technology so effective that, even though it is mostly air, a thin sheet can prevent a blowtorch from igniting a match. Aerogels were invented in 1931 and demonstrate properties that make them the most extraordinary insulating materials known; a 1-inch-thick piece of aerogel provides the same insulation as layering 15 panes of glass with air pockets in between. Derived from silica, aluminum oxide, or carbon gels using a supercritical drying process - resulting in a composition of almost 99-percent air - aerogels are the world s lightest solid (among 15 other titles they hold in the Guinness World Records), can float indefinitely on water if treated to be

Ceramic insulation/multifoil composite for thermal protection of reentry spacecraft

NASA Technical Reports Server (NTRS)

Pitts, W. C.; Kourtides, D. A.

1989-01-01

A new type of insulation blanket called Composite Flexible Blanket Insulation is proposed for thermal protection of advanced spacecraft in regions where the maximum temperature is not excessive. The blanket is a composite of two proven insulation materials: ceramic insulation blankets from Space Shuttle technology and multilayer insulation blankets from spacecraft thermal control technology. A potential heatshield weight saving of up to 500 g/sq m is predicted. The concept is described; proof of concept experimental data are presented; and a spaceflight experiment to demonstrate its actual performance is discussed.

Organic aerogel microspheres

DOEpatents

Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

1999-01-01

Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

Distributing Radiant Heat in Insulation Tests

NASA Technical Reports Server (NTRS)

Freitag, H. J.; Reyes, A. R.; Ammerman, M. C.

1986-01-01

Thermally radiating blanket of stepped thickness distributes heat over insulation sample during thermal vacuum testing. Woven of silicon carbide fibers, blanket spreads heat from quartz lamps evenly over insulation sample. Because of fewer blanket layers toward periphery of sample, more heat initially penetrates there for more uniform heat distribution.

Method of low pressure and/or evaporative drying of aerogel

DOEpatents

Mayer, S.T.; Kaschmitter, J.L.; Pekala, R.W.

1995-05-30

A process is described whereby Resorcinol/Formaldehyde (RF) aerogel having a density of about 0.4--1.2 g/cc can be manufactured using a simple air drying procedure. This process is inherently simpler, quicker, and less expensive than the more conventional supercritical or subcritical CO{sub 2} extraction procedures. RF aerogels can be used as produced, such as in insulation applications, or pyrolyzed to form carbon aerogels with a density of about 0.9 g/cc for use in applications such as batteries, supercapacitors, etc.

Method of low pressure and/or evaporative drying of aerogel

DOEpatents

Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

1995-01-01

A process whereby Resorcinol/Formaldehyde (RF) aerogel having a density of about 0.4-1.2 g/cc can be manufactured using a simple air drying procedure. This process is inherently simpler, quicker, and less expensive than the more conventional supercritical or subcritical CO.sub.2 extraction procedures. RF aerogels can be used as produced, such as in insulation applications, or pyrolyzed to form carbon aerogels with a density of about 0.9 g/cc for use in applications such as batteries, supercapacitors, etc.

Influence of Boehmite Precursor on Aluminosilicate Aerogel Pore Structure, Phase Stability and Resistance to Densification at High Temperatures

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.; Guo, Haiquan; Newlin, Katy N.

2011-01-01

Aluminosilicate aerogels are of interest as constituents of thermal insulation systems for use at temperatures higher than those attainable with silica aerogels. It is anticipated that their effectiveness as thermal insulators will be influenced by their morphology, pore size distribution, physical and skeletal densities. The present study focuses on the synthesis of aluminosilicate aerogel from a variety of Boehmite (precursors as the Al source, and tetraethylorthosilicate (TEOS) as the Si source, and the influence of starting powder on pore structure and thermal stability.

Polyimide aerogels cross-linked through amine functionalized polyoligomeric silsesquioxane.

PubMed

Guo, Haiquan; Meador, Mary Ann B; McCorkle, Linda; Quade, Derek J; Guo, Jiao; Hamilton, Bart; Cakmak, Miko; Sprowl, Guilherme

2011-02-01

We report the first synthesis of polyimide aerogels cross-linked through a polyhedral oligomeric silsesquioxane, octa(aminophenyl)silsesquioxane (OAPS). Gels formed from polyamic acid solutions of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), bisaniline-p-xylidene (BAX) and OAPS were chemically imidized and dried using supercritical CO(2) extraction to give aerogels having density around 0.1 g/cm(3). The aerogels are greater than 90 % porous, have high surface areas (230 to 280 m(2)/g) and low thermal conductivity (14 mW/m-K at room temperature). Notably, the polyimide aerogels cross-linked with OAPS have higher modulus than polymer reinforced silica aerogels of similar density and can be fabricated as both monoliths and thin films. Thin films of the aerogel are flexible and foldable making them an ideal insulation for space suits, and inflatable structures for habitats or decelerators for planetary re-entry, as well as more down to earth applications.

Organic aerogel microspheres

DOEpatents

Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

1999-06-01

Organic aerogel microspheres are disclosed which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonstick gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

Polyimide Aerogels Using Triisocyanate as Cross-linker.

PubMed

Nguyen, Baochau N; Meador, Mary Ann B; Scheiman, Daniel; McCorkle, Linda

2017-08-16

A family of polyimide (PI)-based aerogels is produced using Desmodur N3300A, an inexpensive triisocyanate, as the cross-linker. The aerogels are prepared by cross-linking amine end-capped polyimide oligomers with the triisocyanate. The polyimide oligomers are formulated using 2,2'-dimethylbenzidine, 4,4'-oxydianiline, or mixtures of both diamines, combined with 3,3',4,4'-biphenyltetracarboxylic dianhydride, and are chemically imidized at room temperature. Depending on the backbone chemistry, chain length, and polymer concentration, density of the aerogels ranged from 0.06 to 0.14 g/cm 3 and Brunauer-Emmett-Teller surface areas ranged from 350 to 600 m 2 /g. Compressive moduli of these aerogels were as high as 225 MPa, which are comparable to, or higher than, those previously reported prepared with similar backbone structures but with other cross-linkers. Because of their lower cost and commercial availability as cross-linker, the aerogels may have further potential as insulation for building and construction, clothing, sporting goods, and automotive applications, although lower-temperature stability may limit their use in some aerospace applications.

Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, R.W.

1996-09-17

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes {<=}1,000{angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1,050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, Richard W.

1995-01-01

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes.ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, R.W.

1995-12-19

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes{<=}1000{angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, Richard W.

1996-01-01

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes .ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

Thermophysical investigations of nanotechnological insulation materials

NASA Astrophysics Data System (ADS)

Lakatos, Ákos

2017-07-01

Nowadays, to sufficiently reduce the heat loss through the wall structures with the so-called traditional insulations (polystyrene and fibrous slabs), huge thicknesses (20 - 25 cm) must be applied. In some cases there is no place for their applications e.g.: historical or heritage builfings, since the use of nano-insulation materials (aerogel, vacuum ceramic paints) takes place. They are said to be much more efficient insulations than the above mentioned ones, since they should be used in thinner forms. In this article the thermal insulating capability of solid brick wall covered with a silica-aerogel slab with 1.3 cm, moreover with a vacuum ceramic hollow contained paint with 2 mm thick are investigated. As well as a literature review about the thermal conductivity of nano-technological insulation materials will be given. Comparison of the atomic and thermal diffusion will be also presented.

Polymer/Carbon-Based Hybrid Aerogels: Preparation, Properties and Applications

PubMed Central

Zuo, Lizeng; Zhang, Youfang; Zhang, Longsheng; Miao, Yue-E; Fan, Wei; Liu, Tianxi

2015-01-01

Aerogels are synthetic porous materials derived from sol-gel materials in which the liquid component has been replaced with gas to leave intact solid nanostructures without pore collapse. Recently, aerogels based on natural or synthetic polymers, called polymer or organic aerogels, have been widely explored due to their porous structures and unique properties, such as high specific surface area, low density, low thermal conductivity and dielectric constant. This paper gives a comprehensive review about the most recent progresses in preparation, structures and properties of polymer and their derived carbon-based aerogels, as well as their potential applications in various fields including energy storage, adsorption, thermal insulation and flame retardancy. To facilitate further research and development, the technical challenges are discussed, and several future research directions are also suggested in this review. PMID:28793602

Mechanically Strong Lightweight Materials for Aerospace Applications (x-aerogels)

NASA Technical Reports Server (NTRS)

Leventis, Nicholas

2005-01-01

The X-Aerogel is a new NASA-developed strong lightweight material made by reacting the mesoporous surfaces of 3-D networks of inorganic nanoparticles with polymeric crosslinkers. Since the relative amount of the crosslinker and the backbone are comparable, X-Aerogels can be viewed either as aerogels modified by templated accumulation of polymer on the skeletal nanoparticles, or as nanoporous polymers made by templated casting of polymeric precursors on a nanostructured framework. The most striking feature of X-Aerogels is that for a nominal 3-fold increase in density (still a ultralightweight material), the mechanical strength can be up to 300 times higher than the strength of the underlying native aerogel. Thus, X-Aerogels combine a multiple of the specific compressive strength of steel, with the thermal conductivity of styrofoam. XAerogels have been demonstrated with several polymers such as polyurethanes/polyureas, epoxies and polyolefins, while crosslinking of approximately 35 different oxide aerogels yields a wide variety of dimensionally stable, porous lightweight materials with interesting structural, magnetic and optical properties. X-Aerogels are evaluated for cryogenic rocket fuel storage tanks and for Advanced EVA suits, where they will play the dual role of the thermal insulator/structural material. Along the same lines, major impact is also expected by the use of X-Aerogels in structural components/thermal protection for small satellites, spacecrafts, planetary vehicles and habitats.

Organic carbon aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, R.W.

1998-04-28

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes {<=}1000 {angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

Organic carbon aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, Richard W.

1998-04-28

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes .ltoreq.1000 .ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

Enhanced mechanical, thermal, and electric properties of graphene aerogels via supercritical ethanol drying and high-temperature thermal reduction.

PubMed

Cheng, Yehong; Zhou, Shanbao; Hu, Ping; Zhao, Guangdong; Li, Yongxia; Zhang, Xinghong; Han, Wenbo

2017-05-03

Graphene aerogels with high surface areas, ultra-low densities and thermal conductivities have been prepared to exploit their wide applications from pollution adsorption to energy storage, supercapacitor, and thermal insulation. However, the low mechanical properties, poor thermal stability and electric conductivity restrict these aerogels' applications. In this paper, we prepared mechanically strong graphene aerogels with large BET surface areas, low thermal conductivities, high thermal stability and electric conductivities via hydrothermal reduction and supercritical ethanol drying. Annealing at 1500 °C resulted in slightly increased thermal conductivity and further improvement in mechanical properties, oxidation temperature and electric conductivity of the graphene aerogel. The large BET surface areas, together with strong mechanical properties, low thermal conductivities, high thermal stability and electrical conductivities made these graphene aerogels feasible candidates for use in a number of fields covering from batteries to sensors, electrodes, lightweight conductor and insulation materials.

Synthesis and Properties of Cross-Linked Polyamide Aerogels

NASA Technical Reports Server (NTRS)

Williams, Jarrod C.; Meador, Mary Ann; McCorkle, Linda

2015-01-01

We report the first synthesis of cross-linked polyamide aerogels through step growth polymerization using a combination of diamines, diacid chloride and triacid chloride. Polyamide oligomers endcapped with amines are prepared as stable solutions in N-methylpyrrolidinone from several different diamine precursors and 1,3-benzenedicarbonyl dichloride. Addition of 1,3,5-benzenetricarbonyl trichloride yields gels which form in under five minutes according to the scheme shown. Solvent exchange of the gels into ethanol, followed by drying using supercritical CO2 extraction gives colorless aerogels with densities around 0.1 to 0.2 gcm3. Thicker monolithes of the polyamide aerogels are stiff and strong, while thin films of certain formulations are highly flexible, durable, and even translucent. These materials may have use as insulation for deployable space structures, rovers, habitats or extravehicular activity suits as well as in many terrestrial applications. Strucure property relationships of the aerogels, including surface area, mechanical properties, and thermal conductivity will be discussed.

Uncooled thin film pyroelectric IR detector with aerogel thermal isolation

DOEpatents

Ruffner, Judith A.; Bullington, Jeff A.; Clem, Paul G.; Warren, William L.; Brinker, C. Jeffrey; Tuttle, Bruce A.; Schwartz, Robert W.

1999-01-01

A monolithic infrared detector structure which allows integration of pyroelectric thin films atop low thermal conductivity aerogel thin films. The structure comprises, from bottom to top, a substrate, an aerogel insulating layer, a lower electrode, a pyroelectric layer, and an upper electrode layer capped by a blacking layer. The aerogel can offer thermal conductivity less than that of air, while providing a much stronger monolithic alternative to cantilevered or suspended air-gap structures for pyroelectric thin film pixel arrays. Pb(Zr.sub.0.4 Ti.sub.0.6)O.sub.3 thin films deposited on these structures displayed viable pyroelectric properties, while processed at 550.degree. C.

Comparative study of aerogels obtained from differently prepared nanocellulose fibers.

PubMed

Chen, Wenshuai; Li, Qing; Wang, Youcheng; Yi, Xin; Zeng, Jie; Yu, Haipeng; Liu, Yixing; Li, Jian

2014-01-01

This article describes the fabrication of nanocellulose fibers (NCFs) with different morphologies and surface properties from biomass resources as well as their self-aggregation into lightweight aerogels. By carefully modulating the nanofibrillation process, four types of NCFs could be readily fabricated, including long aggregated nanofiber bundles, long individualized nanofibers with surface C6 -carboxylate groups, short aggregated nanofibers, and short individualized nanofibers with surface sulfate groups. Free-standing lightweight aerogels were obtained from the corresponding aqueous NCF suspensions through freeze-drying. The structure of the aerogels could be controlled by manipulating the type of NCFs and the concentration of their suspensions. A possible mechanism for the self-aggregation of NCFs into two- or three-dimensional aerogel nanostructures was further proposed. Owing to web-like structure, high porosity, and high surface reactivity, the NCF aerogels exhibited high mechanical flexibility and ductility, and excellent properties for water uptake, removal of dye pollutants, and the use as thermal insulation materials. The aerogels also displayed sound-adsorption capability at high frequencies. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In vivo ultrasonic detection of polyurea crosslinked silica aerogel implants.

PubMed

Sabri, Firouzeh; Sebelik, Merry E; Meacham, Ryan; Boughter, John D; Challis, Mitchell J; Leventis, Nicholas

2013-01-01

Polyurea crosslinked silica aerogels are highly porous, lightweight, and mechanically strong materials with great potential for in vivo applications. Recent in vivo and in vitro studies have demonstrated the biocompatibility of this type of aerogel. The highly porous nature of aerogels allows for exceptional thermal, electric, and acoustic insulating capabilities that can be taken advantage of for non-invasive external imaging techniques. Sound-based detection of implants is a low cost, non-invasive, portable, and rapid technique that is routinely used and readily available in major clinics and hospitals. In this study the first in vivo ultrasound response of polyurea crosslinked silica aerogel implants was investigated by means of a GE Medical Systems LogiQe diagnostic ultrasound machine with a linear array probe. Aerogel samples were inserted subcutaneously and sub-muscularly in a) fresh animal model and b) cadaveric human model for analysis. For comparison, samples of polydimethylsiloxane (PDMS) were also imaged under similar conditions as the aerogel samples. Polyurea crosslinked silica aerogel (X-Si aerogel) implants were easily identified when inserted in either of the regions in both fresh animal model and cadaveric model. The implant dimensions inferred from the images matched the actual size of the implants and no apparent damage was sustained by the X-Si aerogel implants as a result of the ultrasonic imaging process. The aerogel implants demonstrated hyperechoic behavior and significant posterior shadowing. Results obtained were compared with images acquired from the PDMS implants inserted at the same location.

Modeling silica aerogel optical performance by determining its radiative properties

NASA Astrophysics Data System (ADS)

Zhao, Lin; Yang, Sungwoo; Bhatia, Bikram; Strobach, Elise; Wang, Evelyn N.

2016-02-01

Silica aerogel has been known as a promising candidate for high performance transparent insulation material (TIM). Optical transparency is a crucial metric for silica aerogels in many solar related applications. Both scattering and absorption can reduce the amount of light transmitted through an aerogel slab. Due to multiple scattering, the transmittance deviates from the Beer-Lambert law (exponential attenuation). To better understand its optical performance, we decoupled and quantified the extinction contributions of absorption and scattering separately by identifying two sets of radiative properties. The radiative properties are deduced from the measured total transmittance and reflectance spectra (from 250 nm to 2500 nm) of synthesized aerogel samples by solving the inverse problem of the 1-D Radiative Transfer Equation (RTE). The obtained radiative properties are found to be independent of the sample geometry and can be considered intrinsic material properties, which originate from the aerogel's microstructure. This finding allows for these properties to be directly compared between different samples. We also demonstrate that by using the obtained radiative properties, we can model the photon transport in aerogels of arbitrary shapes, where an analytical solution is difficult to obtain.

In Vivo Ultrasonic Detection of Polyurea Crosslinked Silica Aerogel Implants

PubMed Central

Sabri, Firouzeh; Sebelik, Merry E.; Meacham, Ryan; Boughter, John D.; Challis, Mitchell J.; Leventis, Nicholas

2013-01-01

Background Polyurea crosslinked silica aerogels are highly porous, lightweight, and mechanically strong materials with great potential for in vivo applications. Recent in vivo and in vitro studies have demonstrated the biocompatibility of this type of aerogel. The highly porous nature of aerogels allows for exceptional thermal, electric, and acoustic insulating capabilities that can be taken advantage of for non-invasive external imaging techniques. Sound-based detection of implants is a low cost, non-invasive, portable, and rapid technique that is routinely used and readily available in major clinics and hospitals. Methodology In this study the first in vivo ultrasound response of polyurea crosslinked silica aerogel implants was investigated by means of a GE Medical Systems LogiQe diagnostic ultrasound machine with a linear array probe. Aerogel samples were inserted subcutaneously and sub-muscularly in a) fresh animal model and b) cadaveric human model for analysis. For comparison, samples of polydimethylsiloxane (PDMS) were also imaged under similar conditions as the aerogel samples. Conclusion/significance Polyurea crosslinked silica aerogel (X-Si aerogel) implants were easily identified when inserted in either of the regions in both fresh animal model and cadaveric model. The implant dimensions inferred from the images matched the actual size of the implants and no apparent damage was sustained by the X-Si aerogel implants as a result of the ultrasonic imaging process. The aerogel implants demonstrated hyperechoic behavior and significant posterior shadowing. Results obtained were compared with images acquired from the PDMS implants inserted at the same location. PMID:23799093

Thermal Conductivity of Powder Insulations Below 180 K

NASA Astrophysics Data System (ADS)

Barrios, M. N.; Choi, Y. S.; Van Sciver, S. W.

2008-03-01

We have measured the thermal conductivity of aerogel beads and glass microspheres at average temperatures ranging from 30 K to 180 K. The measuring device consists of two closed, concentric cylinders suspended inside of a vacuum insulated cryostat. The insulation being tested occupies the annular space between the cylinders. A single stage Gifford-McMahon cryocooler, thermally anchored to the outer cylinder, cools the apparatus to a desired temperature range. A heater mounted on the inner cylinder generates uniform heat flux through the insulating material between the two cylinders. During each measurement, a temperature difference of roughly 10 K across the insulation is maintained. Fourier's law of heat conduction is used to relate the temperature difference between the two cylinders and the applied heating power to a bulk effective thermal conductivity of the powder insulation. Data were collected for aerogel beads between 30 K and 80 K and for glass bubbles between 30 K and 180 K. Results are compared to data from the literature.

Polyimide Aerogels with Three-Dimensional Cross-Linked Structure

NASA Technical Reports Server (NTRS)

Panek, John

2010-01-01

Polyimide aerogels with three-dimensional cross-linked structure are made using linear oligomeric segments of polyimide, and linked with one of the following into a 3D structure: trifunctional aliphatic or aromatic amines, latent reactive end caps such as nadic anhydride or phenylethynylphenyl amine, and silica or silsesquioxane cage structures decorated with amine. Drying the gels supercritically maintains the solid structure of the gel, creating a polyimide aerogel with improved mechanical properties over linear polyimide aerogels. Lightweight, low-density structures are desired for acoustic and thermal insulation for aerospace structures, habitats, astronaut equipment, and aeronautic applications. Aerogels are a unique material for providing such properties because of their extremely low density and small pore sizes. However, plain silica aerogels are brittle. Reinforcing the aerogel structure with a polymer (X-Aerogel) provides vast improvements in strength while maintaining low density and pore structure. However, degradation of polymers used in cross-linking tends to limit use temperatures to below 150 C. Organic aerogels made from linear polyimide have been demonstrated, but gels shrink substantially during supercritical fluid extraction and may have lower use temperature due to lower glass transition temperatures. The purpose of this innovation is to raise the glass transition temperature of all organic polyimide aerogel by use of tri-, tetra-, or poly-functional units in the structure to create a 3D covalently bonded network. Such cross-linked polyimides typically have higher glass transition temperatures in excess of 300 400 C. In addition, the reinforcement provided by a 3D network should improve mechanical stability, and prevent shrinkage on supercritical fluid extraction. The use of tri-functional aromatic or aliphatic amine groups in the polyimide backbone will provide such a 3D structure.

Fast and Minimal-Solvent Production of Superinsulating Silica Aerogel Granulate.

PubMed

Huber, Lukas; Zhao, Shanyu; Malfait, Wim J; Vares, Sirje; Koebel, Matthias M

2017-04-18

With their low thermal conductivity (λ), silica aerogels can reduce carbon emissions from heating and cooling demands, but their widespread adoption is limited by the high production cost. A one-pot synthesis for silica aerogel granulate is presented that drastically reduces solvent use, production time, and global warming potential. The inclusion of the hydrophobization agent prior to gelation with a post-gelation activation step, enables a complete production cycle of less than four hours at the lab scale for a solvent use close to the theoretical minimum, and limits the global warming potential. Importantly, the one-pot aerogel granulate retains the exceptional properties associated with silica aerogel, mostly λ=14.4±1.0 mW m -1 ⋅K -1 for the pilot scale materials, about half that of standing air (26 mW m -1 ⋅K -1 ). The resource-, time-, and cost-effective production will allow silica aerogels to break out of its niche into the mainstream building and industrial insulation markets. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lightweight Thermal Insulation for a Liquid-Oxygen Tank

NASA Technical Reports Server (NTRS)

Willen, G. Scott; Lock, Jennifer; Nieczkoski, Steve

2005-01-01

A proposed lightweight, reusable thermal-insulation blanket has been designed for application to a tank containing liquid oxygen, in place of a non-reusable spray-on insulating foam. The blanket would be of the multilayer-insulation (MLI) type and equipped with a pressure-regulated nitrogen purge system. The blanket would contain 16 layers in two 8-layer sub-blankets. Double-aluminized polyimide 0.3 mil (.0.008 mm) thick was selected as a reflective shield material because of its compatibility with oxygen and its ability to withstand ionizing radiation and high temperature. The inner and outer sub-blanket layers, 1 mil (approximately equals 0.025 mm) and 3 mils (approximately equals 0.076 mm) thick, respectively, would be made of the double-aluminized polyimide reinforced with aramid. The inner and outer layers would provide structural support for the more fragile layers between them and would bear the insulation-to-tank attachment loads. The layers would be spaced apart by lightweight, low-thermal-conductance netting made from polyethylene terephthalate.

Synthesis and Characterization of Poly(maleic Anhydride)s Cross-linked Polyimide Aerogels

NASA Technical Reports Server (NTRS)

Guo, Haiquan; Meador, Mary Ann B.

2015-01-01

With the development of technology for aerospace applications, new thermal insulation materials are required to be flexible and capable of surviving high heat flux. For instance, flexible insulation is needed for inflatable aerodynamic decelerators which are used to slow spacecraft for entry, descent and landing (EDL) operations. Polyimide aerogels have low density, high porosity, high surface area, and better mechanical properties than silica aerogels and can be made into flexible thin films, thus they are potential candidates for aerospace needs. The previously reported cross-linkers such as octa(aminophenyl)silsesquioxane (OAPS) and 1,3,5-triaminophenoxybenzene (TAB) are either expensive or not commercially available. Here, we report the synthesis of a series of polyimide aerogels cross-linked using various commercially available poly(maleic anhydride)s, as seen in Figure 1. The amine end capped polyimide oligomers were made with 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA) and diamine combinations of dimethylbenzidine (DMBZ) and 4, 4-oxydianiline (ODA). The resulting aerogels have low density (0.12 gcm3 to 0.16 gcm3), high porosity (90) and high surface area (380-554 m2g). The effect of the different poly(maleic anhydride) cross-linkers and polyimide backbone structures on density, shrinkage, porosity, surface area, mechanical properties, moisture resistance and thermal properties will be discussed.

Multipurpose insulation system for a radioisotope fueled Mini-Brayton Heat Source Assembly

NASA Technical Reports Server (NTRS)

Aller, P.; Saylor, W.; Schmidt, G.; Wein, D.

1976-01-01

The Mini-Brayton Heat Source Assembly (HSA) consists of a radioisotope fueled heat source, a heat exchanger, a multifoil thermal insulation blanket, and a hermetically sealed housing. The thermal insulation blanket is a multilayer wrap of thin metal foil separated by a sparsely coated oxide. The objectives of the insulation blanket are related to the effective insulation of the HSA during operation, the transfer of the full thermal inventory to the housing when the primary coolant is not flowing, and the transfer of the full thermal inventory to the housing in the event of a flow stoppage of the primary coolant. A description is given of the approaches which have been developed to make it possible for the insulation blanket to meet these requirements.

Structural heat pipe. [for spacecraft wall thermal insulation system

NASA Technical Reports Server (NTRS)

Ollendorf, S. (Inventor)

1974-01-01

A combined structural reinforcing element and heat transfer member is disclosed for placement between a structural wall and an outer insulation blanket. The element comprises a heat pipe, one side of which supports the outer insulation blanket, the opposite side of which is connected to the structural wall. Heat penetrating through the outer insulation blanket directly reaches the heat pipe and is drawn off, thereby reducing thermal gradients in the structural wall. The element, due to its attachment to the structural wall, further functions as a reinforcing member.

Facilitated fabrication of high strength silica aerogels using cellulose nanofibrils as scaffold.

PubMed

Fu, Jingjing; Wang, Siqun; He, Chunxia; Lu, Zexiang; Huang, Jingda; Chen, Zhilin

2016-08-20

Monolithic cellulose nanofibrils (CNF)-silica composite aerogels were successfully prepared by immersing CNF aerogels into a silica solution in a two-step sol-gel process (initial hydrolysis of tetraethyl orthosilicate (TEOS) followed by condensation of silica particles). Aerogels were characterized by SEM, BET surface area test, bulk density and silica content analysis, FTIR spectroscopy, and compression test. The form of SiO2 existing in the composite aerogel was the spherical individual particles coated on CNF fibrils. The pH value of condensation solution was found to have great influence on the properties of the composite aerogels. By varying the pH value of condensation atmosphere from 8 to 12, the bulk densities of composite aerogels were able to be linearly increased from 0.059gcm(-3) to 0.29gcm(-3)，and the silica content in the matrix sharply jumped from 3wt% to 79wt%. The porosities of the aerogels remained very high, between 85 and 96%, and the surface area of the composite aerogel reached up to 700.1m(2)g(-1). The compression properties of the composite aerogel improved greatly compared with those of the silica aerogel, about 8-30 times higher. Moreover, the compressive strength of the composite aerogel prepared in this work greatly exceeded the conventional insulation materials found in the recent commercial market, and without substantial increases in thermal conductivity. Hence, the findings of this research offer a promising application for composite aerogels and give a theoretical basis for developing new advanced materials. Copyright © 2016 Elsevier Ltd. All rights reserved.

Double layered tailorable advanced blanket insulation

NASA Technical Reports Server (NTRS)

Falstrup, D.

1983-01-01

An advanced flexible reusable surface insulation material for future space shuttle flights was investigated. A conventional fly shuttle loom with special modifications to weave an integral double layer triangular core fabric from quartz yarn was used. Two types of insulating material were inserted into the cells of the fabric, and a procedure to accomplish this was developed. The program is follow up of a program in which single layer rectangular cell core fabrics are woven and a single type of insulating material was inserted into the cells.

Pressure-Sensitive and Conductive Carbon Aerogels from Poplars Catkins for Selective Oil Absorption and Oil/Water Separation.

PubMed

Li, Lingxiao; Hu, Tao; Sun, Hanxue; Zhang, Junping; Wang, Aiqin

2017-05-31

Multifunctional carbon aerogels that are both highly compressible and conductive have broad potential applications in the range of sound insulator, sensor, oil absorption, and electronics. However, the preparation of such carbon aerogels has been proven to be very challenging. Here, we report fabrication of pressure-sensitive and conductive (PSC) carbon aerogels by pyrolysis of cellulose aerogels composed of poplars catkin (PC) microfibers with a tubular structure. The wet PC gels can be dried directly in an oven without any deformation, in marked contrast to the brittle nature of traditional carbon aerogels. The resultant PSC aerogels exhibit ultralow density (4.3 mg cm -3 ), high compressibility (80%), high electrical conductivity (0.47 S cm -1 ), and high absorbency (80-161 g g -1 ) for oils and organic liquids. The PSC aerogels have potential applications in various fields such as elastomeric conductors, absorption of oils from water and oil/water separation, as the PSC aerogels feature simple preparation process with low-cost biomass as the precursor.

Organic aerogel microspheres and fabrication method therefor

DOEpatents

Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

1996-04-16

Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

Organic aerogel microspheres and fabrication method therefor

DOEpatents

Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

1996-01-01

Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

Cryogenic Insulation Systems

NASA Technical Reports Server (NTRS)

Augustynowicz, S. D.; Fesmire, J. E.; Wikstrom, J. P.

1999-01-01

The results of a comparative study of cryogenic insulation systems performed are presented. The key aspects of thermal insulation relative to cryogenic system design, testing, manufacturing, and maintenance are discussed. An overview of insulation development from an energy conservation perspective is given. Conventional insulation materials for cryogenic applications provide three levels of thermal conductivity. Actual thermal performance of standard multilayer insulation (MLI) is several times less than laboratory performance and often 10 times worse than ideal performance. The cost-effectiveness of the insulation system depends on thermal performance; flexibility and durability; ease of use in handling, installation, and maintenance; and overall cost including operations, maintenance, and life cycle. Results of comprehensive testing of both conventional and novel materials such as aerogel composites using cryostat boil-off methods are given. The development of efficient, robust cryogenic insulation systems that operate at a soft vacuum level is the primary focus of this paper.

Lightweight, Thermally Insulating Structural Panels

NASA Technical Reports Server (NTRS)

Eisen, Howard J.; Hickey, Gregory; Wen, Liang-Chi; Layman, William E.; Rainen, Richard A.; Birur, Gajanana C.

1996-01-01

Lightweight, thermally insulating panels that also serve as structural members developed. Honeycomb-core panel filled with low-thermal-conductivity, opacified silica aerogel preventing convection and minimizes internal radiation. Copper coating on face sheets reduces radiation. Overall thermal conductivities of panels smaller than state-of-art commercial non-structurally-supporting foam and fibrous insulations. On Earth, panels suitable for use in low-air-pressure environments in which lightweight, compact, structurally supporting insulation needed; for example, aboard high-altitude aircraft or in partially evacuated panels in refrigerators.

Ultralight and fire-resistant ceramic nanofibrous aerogels with temperature-invariant superelasticity.

PubMed

Si, Yang; Wang, Xueqin; Dou, Lvye; Yu, Jianyong; Ding, Bin

2018-04-01

Ultralight aerogels that are both highly resilient and compressible have been fabricated from various materials including polymer, carbon, and metal. However, it has remained a great challenge to realize high elasticity in aerogels solely based on ceramic components. We report a scalable strategy to create superelastic lamellar-structured ceramic nanofibrous aerogels (CNFAs) by combining SiO 2 nanofibers with aluminoborosilicate matrices. This approach causes the random-deposited SiO 2 nanofibers to assemble into elastic ceramic aerogels with tunable densities and desired shapes on a large scale. The resulting CNFAs exhibit the integrated properties of flyweight densities of >0.15 mg cm -3 , rapid recovery from 80% strain, zero Poisson's ratio, and temperature-invariant superelasticity to 1100°C. The integral ceramic nature also provided the CNFAs with robust fire resistance and thermal insulation performance. The successful synthesis of these fascinating materials may provide new insights into the development of ceramics in a lightweight, resilient, and structurally adaptive form.

Ultralight and fire-resistant ceramic nanofibrous aerogels with temperature-invariant superelasticity

PubMed Central

Wang, Xueqin; Dou, Lvye; Yu, Jianyong

2018-01-01

Ultralight aerogels that are both highly resilient and compressible have been fabricated from various materials including polymer, carbon, and metal. However, it has remained a great challenge to realize high elasticity in aerogels solely based on ceramic components. We report a scalable strategy to create superelastic lamellar-structured ceramic nanofibrous aerogels (CNFAs) by combining SiO2 nanofibers with aluminoborosilicate matrices. This approach causes the random-deposited SiO2 nanofibers to assemble into elastic ceramic aerogels with tunable densities and desired shapes on a large scale. The resulting CNFAs exhibit the integrated properties of flyweight densities of >0.15 mg cm−3, rapid recovery from 80% strain, zero Poisson’s ratio, and temperature-invariant superelasticity to 1100°C. The integral ceramic nature also provided the CNFAs with robust fire resistance and thermal insulation performance. The successful synthesis of these fascinating materials may provide new insights into the development of ceramics in a lightweight, resilient, and structurally adaptive form. PMID:29719867

Advanced Polymer For Multilayer Insulating Blankets

NASA Technical Reports Server (NTRS)

Haghighat, R. Ross; Shepp, Allan

1996-01-01

Polymer resisting degradation by monatomic oxygen undergoing commercial development under trade name "Aorimide" ("atomic-oxygen-resistant imidazole"). Intended for use in thermal blankets for spacecraft in low orbit, useful on Earth in outdoor applications in which sunlight and ozone degrades other plastics. Also used, for example, to make threads and to make films coated with metals for reflectivity.

Perioperative thermal insulation.

PubMed

Sessler, D I; McGuire, J; Sessler, A M

1991-05-01

To determine the efficacy of passive insulators advocated for prevention of cutaneous heat loss, we determined heat loss in unanesthetized volunteers covered by one of the following: a cloth "split sheet" surgical drape; a Convertors disposable-paper split sheet; a Thermadrape disposable laparotomy sheet; an unheated Bair Hugger patient-warming blanket; 1.5-mil-thick plastic hamper bags; and a prewarmed, cotton hospital blanket. Cutaneous heat loss was measured using 10 area-weighted thermal flux transducers while volunteers were exposed to a 20.6 degrees C environment for 1 h. Heat loss decreased significantly from 100 +/- 3 W during the control periods to 69 +/- 6 W (average of all covers) after 1 h of treatment. Heat losses from volunteers insulated by the Thermadrape (61 +/- 6 W) and Bair Hugger covers (64 +/- 5 W) were significantly less than losses from those insulated by plastic bags (77 +/- 11 W). The paper drape (67 +/- 7 W) provided slightly, but not significantly, better insulation than the cloth drape (70 +/- 4 W). Coverage by prewarmed cotton blankets initially resulted in the least heat loss (58 +/- 8 W), but after 40 min, resulted in heat loss significantly greater than that for the Thermadrape (71 +/- 7 W). Regional heat loss was roughly proportional to surface area, and the distribution of regional heat loss remained similar with all covers. These data suggest that cost and convenience should be major factors when choosing among passive perioperative insulating covers. It is likely that the amount of skin surface covered is more important than the choice of skin region covered or the choice of insulating material.

Two Dimensional Heat Transfer around Penetrations in Multilayer Insulation

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.; Kelly, Andrew O.; Jumper, Kevin M.

2012-01-01

The objective of this task was to quantify thermal losses involving integrating MLI into real life situations. Testing specifically focused on the effects of penetrations (including structural attachments, electrical conduit/feedthroughs, and fluid lines) through MLI. While there have been attempts at quantifying these losses both analytically and experimentally, none have included a thorough investigation of the methods and materials that could be used in such applications. To attempt to quantify the excess heat load coming into the system due to the integration losses, a calorimeter was designed to study two dimensional heat transfer through penetrated MLI. The test matrix was designed to take as many variables into account as was possible with the limited test duration and system size. The parameters varied were the attachment mechanism, the buffer material (for buffer attachment mechanisms only), the thickness of the buffer, and the penetration material. The work done under this task is an attempt to measure the parasitic heat loads and affected insulation areas produced by system integration, to model the parasitic loads, and from the model produce engineering equations to allow for the determination of parasitic heat loads in future applications. The methods of integration investigated were no integration, using a buffer to thermally isolate the strut from the MLI, and temperature matching the MLI on the strut. Several materials were investigated as a buffer material including aerogel blankets, aerogel bead packages, cryolite, and even an evacuated vacuum space (in essence a no buffer condition).

Method for producing metal oxide aerogels having densities less than 0.02 g/cc

DOEpatents

Tillotson, Thomas M.; Poco, John F.; Hrubesh, Lawrence W.; Thomas, Ian M.

1994-01-01

A two-step method is described for making transparent aerogels which have a density of less than 0.003 g/cm.sup.3 to those with a density of more than 0.8 g/cm.sup.3, by a sol/gel process and supercritical extraction. Condensed metal oxide intermediate made with purified reagents can be diluted to produce stable aerogels with a density of less than 0.02 g/cm.sup.3. High temperature, direct supercritical extraction of the liquid phase of the gel produces hydrophobic aerogels which are stable at atmospheric moisture conditions. Monolithic, homogeneous silica aerogels with a density of less than 0.02 to higher than 0.8 g/cm.sup.3, with high thermal insulation capacity, improved mechanical strength and good optical transparency, are described.

Method for producing metal oxide aerogels having densities less than 0. 02 g/cc

DOEpatents

Tillotson, T.M.; Poco, J.F.; Hrubesh, L.W.; Thomas, I.M.

1994-01-04

A two-step method is described for making transparent aerogels which have a density of less than 0.003 g/cm[sup 3] to those with a density of more than 0.8 g/cm[sup 3], by a sol/gel process and supercritical extraction. Condensed metal oxide intermediate made with purified reagents can be diluted to produce stable aerogels with a density of less than 0.02 g/cm[sup 3]. High temperature, direct supercritical extraction of the liquid phase of the gel produces hydrophobic aerogels which are stable at atmospheric moisture conditions. Monolithic, homogeneous silica aerogels with a density of less than 0.02 to higher than 0.8 g/cm[sup 3], with high thermal insulation capacity, improved mechanical strength and good optical transparency, are described. 7 figures.

Polymer-Reinforced, Non-Brittle, Lightweight Cryogenic Insulation

NASA Technical Reports Server (NTRS)

Hess, David M.

2013-01-01

The primary application for cryogenic insulating foams will be fuel tank applications for fueling systems. It is crucial for this insulation to be incorporated into systems that survive vacuum and terrestrial environments. It is hypothesized that by forming an open-cell silica-reinforced polymer structure, the foam structures will exhibit the necessary strength to maintain shape. This will, in turn, maintain the insulating capabilities of the foam insulation. Besides mechanical stability in the form of crush resistance, it is important for these insulating materials to exhibit water penetration resistance. Hydrocarbon-terminated foam surfaces were implemented to impart hydrophobic functionality that apparently limits moisture penetration through the foam. During the freezing process, water accumulates on the surfaces of the foams. However, when hydrocarbon-terminated surfaces are present, water apparently beads and forms crystals, leading to less apparent accumulation. The object of this work is to develop inexpensive structural cryogenic insulation foam that has increased impact resistance for launch and ground-based cryogenic systems. Two parallel approaches will be pursued: a silica-polymer co-foaming technique and a post foam coating technique. Insulation characteristics, flexibility, and water uptake can be fine-tuned through the manipulation of the polyurethane foam scaffold. Silicate coatings for polyurethane foams and aerogel-impregnated polyurethane foams have been developed and tested. A highly porous aerogel-like material may be fabricated using a co-foam and coated foam techniques, and can insulate at liquid temperatures using the composite foam

Affordable Window Insulation with R-10/inch Rating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenifer Marchesi Redouane Begag; Je Kyun Lee; Danny Ou

2004-10-15

During the performance of contract DE-FC26-00-NT40998, entitled ''Affordable Window Insulation with R-10/inch Value'', research was conducted at Aspen Aerogels, Inc. to develop new transparent aerogel materials suitable for window insulation applications. The project requirements were to develop a formulation or multiple formulations that have high transparency (85-90%) in the visible region, are hydrophobic (will not opacify with exposure to water vapor or liquid), and have at least 2% resiliency (interpreted as recoverable 2% strain and better than 5% strain to failure in compression). Results from an unrelated project showed that silica aerogels covalently bonded to organic polymers exhibit excellent mechanicalmore » properties. At the outset of this project, we believed that such a route is the best to improve mechanical properties. We have applied Design of Experiment (DOE) techniques to optimize formulations including both silica aerogels and organically modified silica aerogels (''Ormosils''). We used these DOE results to optimize formulations around the local/global optimization points. This report documents that we succeeded in developing a number of formulations that meet all of the stated criteria. We successfully developed formulations utilizing a two-step approach where the first step involves acid catalyzed hydrolysis and the second step involves base catalyzed condensation to make the gels. The gels were dried using supercritical CO{sub 2} and we were able to make 1 foot x 1 foot x 0.5 inch panels that met the criteria established.« less

Thermal Failure Analysis of Fiber-Reinforced Silica Aerogels under Liquid Nitrogen Thermal Shock.

PubMed

Du, Ai; Liu, Mingfang; Huang, Shangming; Li, Conghang; Zhou, Bin

2018-06-24

Aerogel materials are recognized as promising candidates for the thermal insulator and have achieved great successes for the aerospace applications. However, the harsh environment on the exoplanet, especially for the tremendous temperature difference, tends to affect the tenuous skeleton and performances of the aerogels. In this paper, an evaluation method was proposed to simulate the environment of exoplanet and study the influence on the fiber-reinforced silica aerogels with different supercritical point drying (SPD) technology. Thermal conductivity, mechanical property and the microstructure were characterized for understanding the thermal failure mechanism. It was found that structure and thermal property were significantly influenced by the adsorbed water in the aerogels under the thermal shocks. The thermal conductivity of CO₂-SPD aerogel increased 35.5% after the first shock and kept in a high value, while that of the ethanol-SPD aerogel increased only 19.5% and kept in a relatively low value. Pore size distribution results showed that after the first shock the peak pore size of the CO₂-SPD aerogel increased from 18 nm to 25 nm due to the shrinkage of the skeleton, while the peak pore size of the ethanol-SPD aerogel kept at ~9 nm probably induced by the spring-back effect. An 80 °C treatment under vacuum was demonstrated to be an effective way for retaining the good performance of ethanol-SPD aerogels under the thermal shock. The thermal conductivity increases of the ethanol-SPD aerogels after 5 shocks decreased from ~30 to ~0% via vacuum drying, while the increase of the CO₂-SPD aerogels via the same treatments remains ~28%. The high-strain hardening and low-strain soften behaviors further demonstrated the skeleton shrinkage of the CO₂-SPD aerogel.

Effect of different types of surfactants on the microstructure of methyltrimethoxysilane-derived silica aerogels: A combined experimental and computational approach.

PubMed

Vareda, João P; Maximiano, Pedro; Cunha, Luís P; Ferreira, André F; Simões, Pedro N; Durães, Luísa

2018-02-15

Surfactants interfere with sol-gel particle/pore growth, influencing the structure and properties of silica aerogels. Their ability to induce microscopic changes in the aerogel's structure may be useful to improve/control the thermal insulation performance of aerogels. The influence of different types of surfactants (anionic, cationic and non-ionic) on the microstructural arrangement and macroscopic properties of methyltrimethoxysilane (MTMS)-based aerogels was evaluated for the first time, using an experimental and computational comparative approach. Molecular dynamics simulations were performed based on two representative silica molecular structures derived from MTMS, while the experimentally-obtained silica aerogels were characterized in terms of chemical/structural/mechanical/thermal insulation properties. The use of both hexadecyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS) led to a decrease in bulk density, thermal conductivity and average pore size of the aerogels, with notorious increase of their flexibility. The observed changes were due to microstructural arrangements, as evidenced by scanning electron microscopy (SEM). However, the non-ionic surfactant, Pluronic F-127, did not have a positive impact on the desired properties. Globally, the simulation results support the experimental findings, suggesting differentiated microstructural changes induced by the use of cationic or anionic surfactants. The addition of CTAB and SDS generally resulted in smaller or larger silica aggregates, respectively. Copyright © 2017 Elsevier Inc. All rights reserved.

Improved multilayer insulation applications. [spacecraft thermal control

NASA Technical Reports Server (NTRS)

Mikk, G.

1982-01-01

Multilayer insulation blankets used for the attenuation of radiant heat transfer in spacecraft are addressed. Typically, blanket effectiveness is degraded by heat leaks in the joints between adjacent blankets and by heat leaks caused by the blanket fastener system. An approach to blanket design based upon modular sub-blankets with distributed seams and upon an associated fastener system that practically eliminates the through-the-blanket conductive path is described. Test results are discussed providing confirmation of the approach. The specific case of the thermal control system for the optical assembly of the Space Telescope is examined.

Aerogel Development

NASA Technical Reports Server (NTRS)

Sahai, Rashmi K.

2005-01-01

Aerogel is one of the most promising materials of the future. It's unique properties, including high porosity, transparency, very high thermal tolerance, and environmental friendliness give it the potential of replacing many different products used in society today. However, the market for aerogel is still very limited because of the cost of producing the material and its fragility. The principle objective of my project has been to find new ways to apply aerogel in order to increase its practicality and appeal to different aspects of society. More specifically, I have focused on finding different chemicals that will coat aerogel and increase its durability. Because aerogel is so fragile and will crumble under the pressure of most coatings this has been no easy task. However, by experimenting with many different coatings and combinations of aerogel properties, I have made several significant discoveries. Aerogel (ideally, high density and hydrophobic) can be coated with several acrylic polymers, including artist's gel and nail polish. These materials provide a protective layering around the aerogel and keep it from breaking as easily. Because fragility is one of the main reasons applications of aerogel are limited, these discoveries will hopefully aid in finding future applications for this extraordinary material.

Aerogels in Chemical Engineering: Strategies Toward Tailor-Made Aerogels.

PubMed

Smirnova, Irina; Gurikov, Pavel

2017-06-07

The present review deals with recent advances in the rapidly growing field of aerogel research and technology. The major focus of the review lies in approaches that allow tailoring of aerogel properties to meet application-driven requirements. The decisive properties of aerogels are discussed with regard to existing and potential application areas. Various tailoring strategies, such as modulation of the pore structure, coating, surface modification, and post-treatment, are illustrated by results of the last decade. In view of commercialization of aerogel-based products, a panorama of current industrial aerogel suppliers is given, along with a discussion of possible alternative sources for raw materials and precursors. Finally, growing points and perspectives of the aerogel field are summarized.

Simulation of energy- efficient building prototype using different insulating materials

NASA Astrophysics Data System (ADS)

Ouhaibi, Salma; Belouaggadia, Naoual; Lbibb, Rachid; Ezzine, Mohammed

2018-05-01

The objective of this work is to analyze the energetic efficiency of an individual building including an area of 130 m2 multi-zone, located in the region of FEZ which is characterized by a very hot and dry climate in summer and a quite cold one in winter, by incorporating insulating materials. This study was performed using TRNSYS V16 simulation software during a typical year of the FEZ region. Our simulation consists in developing a comparative study of two types of polystyrene and silica-aerogel insulation materials, in order to determine the best thermal performance. The results show that the thermal insulation of the building envelope is among the most effective solutions that give a significant reduction in energy requirements. Similarly, the use of silica-aerogels gives a good thermal performance, and therefore a good energy gain.

High Temperature Aerogels in the Al2O3-SiO2 System

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.; Aranda, Denisse V.; Gallagher, Meghan E.

2008-01-01

Al2O3-SiO2 aerogels are of interest as constituents of thermal insulation systems for use at high temperatures. Al2O3 and mullite aerogels are expected to crystallize at higher temperatures than their SiO2 counterparts, hence avoiding the shrinkages that accompany the formation of lower temperature SiO2 phases and preserving pore structures into higher temperature regimes. The objective of this work is to determine the influence of processing parameters on shrinkage, gel structure (including surface area, pore size and distribution) and pyrolysis behavior.

Electron penetration of spacecraft thermal insulation

NASA Technical Reports Server (NTRS)

Powers, W. L.; Adams, B. F.; Inouye, G. T.

1981-01-01

The external thermal blanket with 13 mils of polyethylene which has the known range and stopping power as a function of electron energy is investiated. The most recent omnidirectional peak Jovian electron flux at 5 Jupiter radii is applied, the electron current penetrating the thermal blanket is calculated and allowed to impinge on a typical 20 mil polyethylene insulator surrounding a wire. The radiation dose rate to the insulator is then calculated and the electrical conductivity found. The results demonstrate that the increased electronic mobility is sufficient to keep the maximum induced electric field two orders of magnitude below the critical breakdown strength.

Heat Transfer in the LCCM Thermal Reserve Battery

DTIC Science & Technology

2009-09-01

and Molded Sheet 3M Corporation, Elkhart IN 46516 Microtherm Sheet Microtherm Inc., Alcoa TN 37701 AR5401 Flexible Blanket Aspen Aerogels, Inc...heated Microtherm side wall and axial thermal insulation 90.9 GPS9I 04/27/07 All batteries after GPS9H used six silicone rubber gaskets to form...pressure before ignition. Thin Microtherm side wrap next to cell stack. No pre- compression of any side wall insulation or side wall heat paper (– 40

Surface modified aerogel monoliths

NASA Technical Reports Server (NTRS)

Leventis, Nicholas (Inventor); Johnston, James C. (Inventor); Kuczmarski, Maria A. (Inventor); Meador, Mary Ann B. (Inventor)

2013-01-01

This invention comprises reinforced aerogel monoliths such as silica aerogels having a polymer coating on its outer geometric surface boundary, and to the method of preparing said aerogel monoliths. The polymer coatings on the aerogel monoliths are derived from polymer precursors selected from the group consisting of isocyanates as a precursor, precursors of epoxies, and precursors of polyimides. The coated aerogel monoliths can be modified further by encapsulating the aerogel with the polymer precursor reinforced with fibers such as carbon or glass fibers to obtain mechanically reinforced composite encapsulated aerogel monoliths.

Vibration Considerations for Cryogenic Tanks Using Glass Bubbles Insulation

NASA Technical Reports Server (NTRS)

Werlink, Rudolph J.; Fesmire, James E.; Sass, Jared P.

2011-01-01

The use of glass bubbles as an efficient and practical thermal insulation system has been previously demonstrated in cryogenic storage tanks. One such example is a spherical, vacuum-jacketed liquid hydrogen vessel of 218,000 liter capacity where the boiloff rate has been reduced by approximately 50 percent. Further applications may include non-stationary tanks such as mobile tankers and tanks with extreme duty cycles or exposed to significant vibration environments. Space rocket launch events and mobile tanker life cycles represent two harsh cases of mechanical vibration exposure. A number of bulk fill insulation materials including glass bubbles, perlite powders, and aerogel granules were tested for vibration effects and mechanical behavior using a custom design holding fixture subjected to random vibration on an Electrodynamic Shaker. The settling effects for mixtures of insulation materials were also investigated. The vibration test results and granular particle analysis are presented with considerations and implications for future cryogenic tank applications. A thermal performance update on field demonstration testing of a 218,000 L liquid hydrogen storage tank, retrofitted with glass bubbles, is presented. KEYWORDS: Glass bubble, perlite, aerogel, insulation, liquid hydrogen, storage tank, mobile tanker, vibration.

Highly Porous, Rigid-Rod Polyamide Aerogels with Superior Mechanical Properties and Unusually High Thermal Conductivity.

PubMed

Williams, Jarrod C; Nguyen, Baochau N; McCorkle, Linda; Scheiman, Daniel; Griffin, Justin S; Steiner, Stephen A; Meador, Mary Ann B

2017-01-18

We report here the fabrication of polyamide aerogels composed of poly-p-phenylene-terephthalamide, the same backbone chemistry as DuPont's Kevlar. The all-para-substituted polymers gel without the use of cross-linker and maintain their shape during processing-an improvement over the meta-substituted cross-linked polyamide aerogels reported previously. Solutions containing calcium chloride (CaCl 2 ) and para-phenylenediamine (pPDA) in N-methylpyrrolidinone (NMP) at low temperature are reacted with terephthaloyl chloride (TPC). Polymerization proceeds over the course of 5 min resulting in gelation. Removal of the reaction solvent via solvent exchange followed by extraction with supercritical carbon dioxide provides aerogels with densities ranging from 0.1 to 0.3 g/cm 3 , depending on the concentration of calcium chloride, the formulated number of repeat units, n, and the concentration of polymer in the reaction mixture. These variables were assessed in a statistical experimental study to understand their effects on the properties of the aerogels. Aerogels made using at least 30 wt % CaCl 2 had the best strength when compared to aerogels of similar density. Furthermore, aerogels made using 30 wt % CaCl 2 exhibited the lowest shrinkage when aged at elevated temperatures. Notably, whereas most aerogel materials are highly insulating (thermal conductivities of 10-30 mW/m K), the polyamide aerogels produced here exhibit remarkably high thermal conductivities (50-80 mW/(m K)) at the same densities as other inorganic and polymer aerogels. These high thermal conductivities are attributed to efficient phonon transport by the rigid-rod polymer backbone. In conjunction with their low cost, ease of fabrication with respect to other polymer aerogels, low densities, and high mass-normalized strength and stiffness properties, these aerogels are uniquely valuable for applications such as lightweighting in consumer electronics, automobiles, and aerospace where weight reduction is

Low RF Reflectivity Spacecraft Thermal Blanket by Using High-Impedance Surface Absorbers

NASA Astrophysics Data System (ADS)

Costa, F.; Monorchio, A.; Carrubba, E.; Zolesi, V.

2012-05-01

A technique for designing a low-RF reflectivity thermal blanket is presented. Multi-layer insulation (MLI) blankets are employed to stabilize the temperature on spacecraft unit but they can be responsible of passive intermodulation products and high-mutual coupling between antennas since they are realized with metallic materials. The possibility to replace the last inner layer of a MLI blanket with an ultra-thin absorbing layer made of high-impedance surface absorber is discussed.

Method for nanoencapsulation of aerogels and nanoencapsulated aerogels produced by such method

NASA Technical Reports Server (NTRS)

Sullivan, Thomas A. (Inventor)

2007-01-01

A method for increasing the compressive modulus of aerogels comprising: providing aerogel substrate comprising a bubble matrix in a chamber; providing monomer to the chamber, the monomer comprising vapor phase monomer which polymerizes substantially free of polymerization byproducts; depositing monomer from the vapor phase onto the surface of the aerogel substrate under deposition conditions effective to produce a vapor pressure sufficient to cause the vapor phase monomer to penetrate into the bubble matrix and deposit onto the surface of the aerogel substrate, producing a substantially uniform monomer film; and, polymerizing the substantially uniform monomer film under polymerization conditions effective to produce polymer coated aerogel comprising a substantially uniform polymer coating substantially free of polymerization byproducts.Polymer coated aerogel comprising aerogel substrate comprising a substantially uniform polymer coating, said polymer coated aerogel comprising porosity and having a compressive modulus greater than the compressive modulus of the aerogel substrate, as measured by a 100 lb. load cell at 1 mm/minute in the linear range of 20% to 40% compression.

X-Aerogels for Structural Components and High Temperature Applications

NASA Technical Reports Server (NTRS)

2005-01-01

Future NASA missions and space explorations rely on the use of materials that are strong ultra lightweight and able to withstand extreme temperatures. Aerogels are low density (0.01-0.5 g/cu cm) high porosity materials that contain a glass like structure formed through standard sol-gel chemistry. As a result of these structural properties, aerogels are excellent thermal insulators and are able to withstand temperatures in excess of l,000 C. The open structure of aerogels, however, renders these materials extremely fragile (fracturing at stress forces less than 0.5 N/sq cm). The goal of NASA Glenn Research Center is to increase the strength of these materials by templating polymers and metals onto the surface of an aerogel network facilitating the use of this material for practical applications such as structural components of space vehicles used in exploration. The work this past year focused on two areas; (1) the research and development of new templated aerogels materials and (2) process development for future manufacturing of structural components. Research and development occurred on the production and characterization of new templating materials onto the standard silica aerogel. Materials examined included polymers such as polyimides, fluorinated isocyanates and epoxies, and, metals such as silver, gold and platinum. The final properties indicated that the density of the material formed using an isocyanate is around 0.50 g/cc with a strength greater than that of steel and has low thermal conductivity. The process used to construct these materials is extremely time consuming and labor intensive. One aspect of the project involved investigating the feasibility of shortening the process time by preparing the aerogels in the templating solvent. Traditionally the polymerization used THF as the solvent and after several washes to remove any residual monomers and water, the solvent around the aerogels was changed to acetonitrile for the templating step. This process

Predicting spacecraft multilayer insulation performance from heat transfer measurements

NASA Technical Reports Server (NTRS)

Stimpson, L. D.; Hagemeyer, W. A.

1974-01-01

Multilayer insulation (MLI) ideally consists of a series of radiation shields with low-conductivity spacers. When MLI blankets were installed on cryogenic tanks or spacecraft, a large discrepancy between the calorimeter measurements and the performance of the installed blankets was discovered. It was found that discontinuities such as exposed edges coupled with high lateral heat transfer created 'heat leaks' which overshadowed the basic heat transfer of the insulation. Approaches leading to improved performance predictions of MLI units are discussed.

Progress on DCLL Blanket Concept

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, Clement; Abdou, M.; Katoh, Yutai

2013-09-01

Under the US Fusion Nuclear Science and Technology Development program, we have selected the Dual Coolant Lead Lithium concept (DCLL) as a reference blanket, which has the potential to be a high performance DEMO blanket design with a projected thermal efficiency of >40%. Reduced activation ferritic/martensitic (RAF/M) steel is used as the structural material. The self-cooled breeder PbLi is circulated for power conversion and for tritium breeding. A SiC-based flow channel insert (FCI) is used as a means for magnetohydrodynamic pressure drop reduction from the circulating liquid PbLi and as a thermal insulator to separate the high-temperature PbLi (~700°C) frommore » the helium-cooled RAF/M steel structure. We are making progress on related R&D needs to address critical Fusion Nuclear Science and Facility (FNSF) and DEMO blanket development issues. When performing the function as the Interface Coordinator for the DCLL blanket concept, we had been developing the mechanical design and performing neutronics, structural and thermal hydraulics analyses of the DCLL TBM module. We had estimated the necessary ancillary equipment that will be needed at the ITER site and a detailed safety impact report has been prepared. This provided additional understanding of the DCLL blanket concept in preparation for the FNSF and DEMO. This paper will be a summary report on the progress of the DCLL TBM design and R&Ds for the DCLL blanket concept.« less

Polyolefin-based aerogels

NASA Technical Reports Server (NTRS)

Gould, Gerogle L. (Inventor); Lee, Je Kyun (Inventor)

2010-01-01

The present invention relates to cross-linked polyolefin aerogels in simple and fiber-reinforced composite form. Of particular interest are polybutadiene aerogels. Especially aerogels derived from polybutadienes functionalized with anhydrides, amines, hydroxyls, thiols, epoxies, isocyanates or combinations thereof.

Crystalline boron nitride aerogels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.

This disclosure provides methods and materials related to boron nitride aerogels. For example, one aspect relates to a method for making an aerogel comprising boron nitride, comprising: (a) providing boron oxide and an aerogel comprising carbon; (b) heating the boron oxide to melt the boron oxide and heating the aerogel; (c) mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide; and (d) converting at least a portion of the carbon to boron nitride to obtain the aerogel comprising boron nitride. Another aspect relates to a method for making an aerogel comprising boron nitride, comprising heating boron oxidemore » and an aerogel comprising carbon under flow of a nitrogen-containing gas, wherein boron oxide vapor and the nitrogen-containing gas convert at least a portion of the carbon to boron nitride to obtain the aerogel comprising boron nitride.« less

A Co-Precursor Approach Coupled with a Supercritical Modification Method for Constructing Highly Transparent and Superhydrophobic Polymethylsilsesquioxane Aerogels.

PubMed

Lei, Chaoshuai; Li, Junning; Sun, Chencheng; Yang, Hailong; Xia, Tao; Hu, Zijun; Zhang, Yue

2018-03-30

Polymethylsilsesquioxane (PMSQ) aerogels obtained from methyltrimethoxysilane (MTMS) are well-known high-performance porous materials. Highly transparent and hydrophobic PMSQ aerogel would play an important role in transparent vacuum insulation panels. Herein, the co-precursor approach and supercritical modification method were developed to prepare the PMSQ aerogels with high transparency and superhydrophobicity. Firstly, benefiting from the introduction of tetramethoxysilane (TMOS) in the precursor, the pore structure became more uniform and the particle size was decreased. As the TMOS content increased, the light transmittance increased gradually from 54.0% to 81.2%, whereas the contact angle of water droplet decreased from 141° to 99.9°, ascribed to the increase of hydroxyl groups on the skeleton surface. Hence, the supercritical modification method utilizing hexamethyldisilazane was also introduced to enhance the hydrophobic methyl groups on the aerogel's surface. As a result, the obtained aerogels revealed superhydrophobicity with a contact angle of 155°. Meanwhile, the developed surface modification method did not lead to any significant changes in the pore structure resulting in the superhydrophobic aerogel with a high transparency of 77.2%. The proposed co-precursor approach and supercritical modification method provide a new horizon in the fabrication of highly transparent and superhydrophobic PMSQ aerogels.

Method of patterning an aerogel

DOEpatents

Reed, Scott T [Edgewood, NM

2012-07-24

A method for producing a pattern in an aerogel disposed as a coating on a substrate comprises exposing the aerogel coating to the vapors of a hydrophobic silane compound, masking the aerogel coating with a shadow photomask and irradiating the aerogel coating with ultraviolet (UV) irradiation. The exposure to UV through the shadow mask creates a pattern of hydrophobic and hydrophilic regions in the aerogel coating. Etching away the hydrophilic regions of the aerogel coating, preferably with a 1 molar solution of sodium hydroxide, leaves the unwetted and unetched hydrophobic regions of the aerogel layer on the substrate, replicating the pattern of the photomask. The hydrophobic aerogel pattern can be further exposed to UV irradiation if desired, to create a hydrophilic aerogel pattern.

Graphene aerogels

DOEpatents

Pauzauskie, Peter J; Worsley, Marcus A; Baumann, Theodore F; Satcher, Jr., Joe H; Biener, Juergen

2015-03-31

Graphene aerogels with high conductivity and surface areas including a method for making a graphene aerogel, including the following steps: (1) preparing a reaction mixture comprising a graphene oxide suspension and at least one catalyst; (2) curing the reaction mixture to produce a wet gel; (3) drying the wet gel to produce a dry gel; and (4) pyrolyzing the dry gel to produce a graphene aerogel. Applications include electrical energy storage including batteries and supercapacitors.

Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage

NASA Astrophysics Data System (ADS)

Prakash, Sai S.; Brinker, C. Jeffrey; Hurd, Alan J.; Rao, Sudeep M.

1995-03-01

HIGHLY porous inorganic films have potential applications as dielectric materials, reflective and anti-reflective coatings, flat-panel displays, sensors, catalyst supports and super-insulating architectural glazings1-3. Aerogels4 are the most highly porous solids known, and can now be prepared from inorganic5 and organic6,7 precursors with volume-fraction porosities of up to 99.9% (ref. 8). Aerogels are normally prepared by supercritical extraction of the pore fluid from a wet gel1, which prevents the network collapse that is otherwise induced by capillary forces. But supercritical processing is expensive, hazardous and incompatible with the processing requirements of many potential applications,thus severely restricting the commercial exploitation of aerogels. Here we describe a means of preparing aerogels by a simple dip-coating method at ambient pressure without the need for supercriti-cal extraction. We add surface groups to the inorganic gel which make drying shrinkage reversible9: as the solvent is withdrawn, the gel springs back to a porous state. We can generate aerogel films with 98.5% porosity using this approach. We anticipate that it will greatly expand the commercial applications of these materials.

Aerogel-clad optical fiber

DOEpatents

Sprehn, Gregory A.; Hrubesh, Lawrence W.; Poco, John F.; Sandler, Pamela H.

1997-01-01

An optical fiber is surrounded by an aerogel cladding. For a low density aerogel, the index of refraction of the aerogel is close to that of air, which provides a high numerical aperture to the optical fiber. Due to the high numerical aperture, the aerogel clad optical fiber has improved light collection efficiency.

Polyimide Aerogel Thin Films

NASA Technical Reports Server (NTRS)

Meador, Mary Ann; Guo, Haiquan

2012-01-01

Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

Aerogel-clad optical fiber

DOEpatents

Sprehn, G.A.; Hrubesh, L.W.; Poco, J.F.; Sandler, P.H.

1997-11-04

An optical fiber is surrounded by an aerogel cladding. For a low density aerogel, the index of refraction of the aerogel is close to that of air, which provides a high numerical aperture to the optical fiber. Due to the high numerical aperture, the aerogel clad optical fiber has improved light collection efficiency. 4 figs.

Automotive Insulation

NASA Technical Reports Server (NTRS)

1997-01-01

Under a Space Act Agreement between Boeing North America and BSR Products, Space Shuttle Thermal Protection System (TPS) materials are now used to insulate race cars. BSR has created special TPS blanket insulation kits for use on autos that take part in NASCAR events, and other race cars through its nationwide catalog distribution system. Temperatures inside a race car's cockpit can soar to a sweltering 140 to 160 degrees, with the extreme heat coming through the engine firewall, transmission tunnel, and floor. It is common for NASCAR drivers to endure blisters and burns due to the excessive heat. Tests on a car insulated with the TPS material showed a temperature drop of some 50 degrees in the driver's cockpit. BSR-TPS Products, Inc. now manufactures insulation kits for distribution to race car teams around the world.

Integrated Multilayer Insulation

NASA Technical Reports Server (NTRS)

Dye, Scott

2009-01-01

Integrated multilayer insulation (IMLI) is being developed as an improved alternative to conventional multilayer insulation (MLI), which is more than 50 years old. A typical conventional MLI blanket comprises between 10 and 120 metallized polymer films separated by polyester nets. MLI is the best thermal- insulation material for use in a vacuum, and is the insulation material of choice for spacecraft and cryogenic systems. However, conventional MLI has several disadvantages: It is difficult or impossible to maintain the desired value of gap distance between the film layers (and consequently, it is difficult or impossible to ensure consistent performance), and fabrication and installation are labor-intensive and difficult. The development of IMLI is intended to overcome these disadvantages to some extent and to offer some additional advantages over conventional MLI. The main difference between IMLI and conventional MLI lies in the method of maintaining the gaps between the film layers. In IMLI, the film layers are separated by what its developers call a micro-molded discrete matrix, which can be loosely characterized as consisting of arrays of highly engineered, small, lightweight, polymer (typically, thermoplastic) frames attached to, and placed between, the film layers. The term "micro-molded" refers to both the smallness of the frames and the fact that they are fabricated in a process that forms precise small features, described below, that are essential to attainment of the desired properties. The term "discrete" refers to the nature of the matrix as consisting of separate frames, in contradistinction to a unitary frame spanning entire volume of an insulation blanket.

Aerogel-supported filament

DOEpatents

Wuest, Craig R.; Tillotson, Thomas M.; Johnson, III, Coleman V.

1995-01-01

The present invention is a thin filament embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine filament or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces.

Influence of HF acid catalyst concentration on properties of aerogel low-k thin films

NASA Astrophysics Data System (ADS)

Gaikwad, A. S.; Gupta, S. A.; Mahajan, A. M.

2016-08-01

The effect of hydrofluoric acid (HF) catalyst concentration in coating solution on chemical, physical and structural properties of silica aerogel thin films was investigated. The aerogel films were synthesized by using a sol-gel spin coating method followed by aging in ethanol and CO2 supercritical drying. The refractive index (RI) is observed to be reduced from 1.32 to 1.13 and porosity percentage increased from 30.21% to 71.64% in accordance with increasing HF concentration. Deposition of silica aerogel was confirmed from Fourier transform infrared spectroscopy measurement. The nanoporous nature of deposited films was confirmed from field effect scanning electron microscopy and observed pore diameter is in the range of 3.33 to 6.69 nm. The nanoporous nature of the film was also validated from atomic force microscopy and root mean square roughness was observed to be increased from 2.31 nm to 3.2 nm with increasing acid catalyst concentration in the coating solution. The calculated dielectric constant from CV measurement of fabricated metal-insulator-semiconductor structure for the silica aerogel formed at 0.8 ml HF concentration is observed to be 1.73. These deposited nanoporous silica aerogel low-k films with lower k value and smaller pore size have application as interlayer dielectric materials to minimize the disadvantages of porous materials.

Evaluation of low cost/high temperature insulation, July 1974 - June 1975

NASA Technical Reports Server (NTRS)

Strauss, E. L.

1975-01-01

Six fiber products and six insulation blankets comprising silica, alumina, zirconia, mullite, and mixed ceramic systems were subjected to furnace exposures up to 500 hours at temperatures of 1000 to 1600 C and evaluated for chemical and dimensional stability and for changes in thermal conductivity. Alumina, zirconia, and mullite fibers were fabricated into reusable surface insulation (RSI) tile by water-felting and reimpregnation with ethyl silicate. Specimens were exposed to 25 thermal cycles at 1200 C and 1400 C and a pressure of 10 and 32 torr, respectively. Production costs for 930 sq m (10,000 sq ft) of blanket insulation and of alumina RSI tile were developed.

Method for producing hydrophobic aerogels

DOEpatents

Hrubesh, Lawrence W.; Poco, John F.; Coronado, Paul R.

1999-01-01

A method for treating a dried monolithic aerogel containing non-dispersed particles, with an organometallic surface modifying agent to produce hydrophobic aerogels. The dried, porous hydrophobic aerogels contain a protective layer of alkyl groups, such as methyl groups, on the modified surfaces of the pores of the aerogel. The alkyl groups at the aerogel surface typically contain at least one carbon-metal bond per group.

High-Tech, Low-Temp Insulation

NASA Technical Reports Server (NTRS)

1998-01-01

Under an SBIR (Small Business Innovative Research) contract with Ames, S.D. Miller & Associates developed new manufacturing methods for multi-layer metal spacecraft insulation that could significantly reduce launch weight and launch costs. The new honeycomb structure is more efficient than fibers for insulation. Honeycombs can be made from metals for high temperature uses, even plastic insulation from recycled milk bottles. Under development are blankets made from recycled milk bottles which will be field tested by the Red Cross and ambulance companies. Currently available are honeycomb mittens based on the same technology.

Ultralight nanofibre-assembled cellular aerogels with superelasticity and multifunctionality.

PubMed

Si, Yang; Yu, Jianyong; Tang, Xiaomin; Ge, Jianlong; Ding, Bin

2014-12-16

Three-dimensional nanofibrous aerogels (NFAs) that are both highly compressible and resilient would have broad technological implications for areas ranging from electrical devices and bioengineering to damping materials; however, creating such NFAs has proven extremely challenging. Here we report a novel strategy to create fibrous, isotropically bonded elastic reconstructed (FIBER) NFAs with a hierarchical cellular structure and superelasticity by combining electrospun nanofibres and the fibrous freeze-shaping technique. Our approach causes the intrinsically lamellar deposited electrospun nanofibres to assemble into elastic bulk aerogels with tunable densities and desirable shapes on a large scale. The resulting FIBER NFAs exhibit densities of >0.12 mg cm(-3), rapid recovery from deformation, efficient energy absorption and multifunctionality in terms of the combination of thermal insulation, sound absorption, emulsion separation and elasticity-responsive electric conduction. The successful synthesis of such fascinating materials may provide new insights into the design and development of multifunctional NFAs for various applications.

Particle Tracks in Aerogel

NASA Image and Video Library

2005-11-03

In an experiment using a special air gun, particles are shot into aerogel at high velocities. Closeup of particles leaving a carrot-shaped trail in the aerogel are shown here. Aerogel was used on NASA Stardust spacecraft.

Aerogel-supported filament

DOEpatents

Wuest, C.R.; Tillotson, T.M.; Johnson, C.V. III

1995-05-16

The present invention is a thin filament embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine filament or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces. 6 Figs.

Evaluation of Fire Test Methods for Aircraft Thermal Acoustical Insulation

DOT National Transportation Integrated Search

1997-09-01

This report presents the results of laboratory round robin flammability testing performed on thermal acoustical insulation blankets and the films used as insulation coverings. This work was requested by the aircraft industry as a result of actual inc...

Fast synthesis of transparent and hydrophobic silica aerogels using polyethoxydisiloxane and methyltrimethoxysilane in one-step drying process

NASA Astrophysics Data System (ADS)

Zhu, Xingqun; Naz, Hina; Nauman Ali, Rai; Yang, Yongfei; Zheng, Zhou; Xiang, Bin; Cui, Xudong

2018-04-01

We have successfully synthesized the transparent and hydrophobic silica aerogels by a one-step drying process using appropriate amount of Polyethoxydisiloxane and methyltrimethoxysilane. With an introduction of modified rapid supercritical extraction technique, the synthesis process time was shortened down to one hour for a 4 L solution reaction. The observed transmittance of as-synthesized product is larger than 80% within the wavelength range of 500–1000 nm, and the contact angle is confirmed to be over 135°. Our results provide a path way to the fast synthesis of hydrophobic and transparent aerogels in near future for window insulator applications.

Testing Seam Concepts for Advanced Multilayer Insulation

NASA Technical Reports Server (NTRS)

Chato, D. J.; Johnson, W. L.; Alberts, Samantha J.

2017-01-01

Multilayer insulation (MLI) is considered the state of the art insulation for cryogenic propellant tanks in the space environment. MLI traditionally consists of multiple layers of metalized films separated by low conductivity spacers. In order to better understand some of the details within MLI design and construction, GRC has been investigating the heat loads caused by multiple types of seams. To date testing has been completed with 20 layer and 50 layer blankets. Although a truly seamless blanket is not practical, a blanket lay-up where each individual layer was overlapped and tapped together was used as a baseline for the other seams tests. Other seams concepts tested included: an overlap where the complete blanket was overlapped on top of itself; a butt joint were the blankets were just trimmed and butted up against each other, and a staggered butt joint where the seam in the out layers is offset from the seam in the inner layers. Measured performance is based on a preliminary analysis of rod calibration tests conducted prior to the start of seams testing. Baseline performance for the 50 layer blanket showed a measured heat load of 0.46 Watts with a degradation to about 0.47 Watts in the seamed blankets. Baseline performance for the 20 layer blanket showed a measured heat load of 0.57 Watts. Heat loads for the seamed tests are still begin analyzed. So far analysis work has suggested the need for corrections due to heat loads from both the heater leads and the instrumentation wires. A careful re-examination of the calibration test results with these factors accounted for is also underway. This presentation will discuss the theory of seams in MLI, our test results to date, and the uncertainties in our measurements.

Surge current and electron swarm tunnel tests of thermal blanket and ground strap materials

NASA Technical Reports Server (NTRS)

Hoffmaster, D. K.; Inouye, G. T.; Sellen, J. M., Jr.

1977-01-01

The results are described of a series of current conduction tests with a thermal control blanket to which grounding straps have been attached. The material and the ground strap attachment procedure are described. The current conduction tests consisted of a surge current examination of the ground strap and a dilute flow, energetic electron deposition and transport through the bulk of the insulating film of this thermal blanket material. Both of these test procedures were used previously with thermal control blanket materials.

Super-hydrophobic fluorine containing aerogels

DOEpatents

Coronado, Paul R [Livermore, CA; Poco, John F [Livermore, CA; Hrubesh, Lawrence W [Pleasanton, CA

2007-05-01

An aerogel material with surfaces containing fluorine atoms which exhibits exceptional hydrophobicity, or the ability to repel liquid water. Hydrophobic aerogels are efficient absorbers of solvents from water. Solvents miscible with water are separated from it because the solvents are more volatile than water and they enter the porous aerogel as a vapor across the liquid water/solid interface. Solvents that are immisicble with water are separated from it by selectively wetting the aerogel. The hydrophobic property is achieved by formulating the aerogel using fluorine containing molecules either directly by addition in the sol-gel process, or by treating a standard dried aerogel using the vapor of fluorine containing molecules.

Comparative Investigation on Thermal Insulation of Polyurethane Composites Filled with Silica Aerogel and Hollow Silica Microsphere.

PubMed

Liu, Chunyuan; Kim, Jin Seuk; Kwon, Younghwan

2016-02-01

This paper presents a comparative study on thermal conductivity of PU composites containing open-cell nano-porous silica aerogel and closed-cell hollow silica microsphere, respectively. The thermal conductivity of PU composites is measured at 30 degrees C with transient hot bridge method. The insertion of polymer in pores of silica aerogel creates mixed interfaces, increasing the thermal conductivity of resulting composites. The measured thermal conductivity of PU composites filled with hollow silica microspheres is estimated using theoretical models, and is in good agreement with Felske model. It appears that the thermal conductivity of composites decreases with increasing the volume fraction (phi) when hollow silica microsphere (eta = 0.916) is used.

Design and Development of Aerogel-Based Antennas for Aerospace Applications: A Final Report to the NARI Seedling

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B.; Miranda, Felix A.

2014-01-01

As highly porous solids possessing low density and low dielectric permittivity combined with good mechanical properties, polyimide (PI) aerogels offer great promise as an enabling technology for lightweight aircraft antenna systems. While they have been aggressively explored for thermal insulation, barely any effort has been made to leverage these materials for antennas or other applications that take advantage of their aforementioned attributes. In Phase I of the NARI Seedling Project, we fabricated PI aerogels with properties tailored to enable new antenna concepts with performance characteristics (wide bandwidth and high gain) and material properties (low density, environmental stability, and robustness) superior to the state of practice (SOP). We characterized electromagnetic properties, including permittivity, reflectivity, and propagation losses for the aerogels. Simple, prototype planar printed circuit patch antennas from down-selected aerogel formulations were fabricated by molding the aerogels to net shapes and by gold-metalizing the pattern onto the templates via electron beam evaporation in a clean room environment. These aerogel based antennas were benchmarked against current antenna SOP, and exhibited both broader bandwidth and comparable or higher gain performance at appreciably lower mass. Phase II focused on the success of the Phase I results pushing the PI aerogel based antenna technology further by exploring alternative antenna design (i.e., slot coupled antennas) and by examining other techniques for fabricating the antennas including ink jet printing with the goal of optimizing antenna performance and simplifying production. We also examined new aerogel formulations with better moisture and solvent resistance to survive processing conditions. In addition, we investigated more complex antenna designs including passive phased arrays such as 2x4 and 4x8 element arrays to assess the scalability of the aerogel antenna concept. Furthermore, we

Benzimidazole Based Aerogel Materials

NASA Technical Reports Server (NTRS)

Rhine, Wendell E. (Inventor); Mihalcik, David (Inventor)

2016-01-01

The present invention provides aerogel materials based on imidazoles and polyimidazoles. The polyimidazole based aerogel materials can be thermally stable up to 500 C or more, and can be carbonized to produce a carbon aerogel having a char yield of 60% or more, specifically 70% or more. The present invention also provides methods of producing polyimidazole based aerogel materials by reacting at least one monomer in a suitable solvent to form a polybenzimidazole gel precursor solution, casting the polybenzimidazole gel precursor solution into a fiber reinforcement phase, allowing the at least one gel precursor in the precursor solution to transition into a gel material, and drying the gel materials to remove at least a portion of the solvent, to obtain an polybenzimidazole-based aerogel material.

Method of manufacturing aerogel composites

DOEpatents

Cao, W.; Hunt, A.J.

1999-03-09

Disclosed herewith is a process of forming an aerogel composite which comprises introducing a gaseous material into a formed aerogel monolith or powder, and causing decomposition of said gaseous material in said aerogel in amounts sufficient to cause deposition of the decomposition products of the gas on the surfaces of the pores of the said aerogel.

Method of manufacturing aerogel composites

DOEpatents

Cao, Wanqing; Hunt, Arlon Jason

1999-01-01

Disclosed herewith is a process of forming an aerogel composite which comprises introducing a gaseous material into a formed aerogel monolith or powder, and causing decomposition of said gaseous material in said aerogel in amounts sufficient to cause deposition of the decomposition products of the gas on the surfaces of the pores of the said aerogel.

Multiplier, moderator, and reflector materials for advanced lithium?vanadium fusion blankets

NASA Astrophysics Data System (ADS)

Gohar, Y.; Smith, D. L.

2000-12-01

The self-cooled lithium-vanadium fusion blanket concept has several attractive operational and environmental features. In this concept, liquid lithium works as the tritium breeder and coolant to alleviate issues of coolant breeder compatibility and reactivity. Vanadium alloy (V-4Cr-4Ti) is used as the structural material because of its superior performance relative to other alloys for this application. However, this concept has poor attenuation characteristics and energy multiplication for the DT neutrons. An advanced self-cooled lithium-vanadium fusion blanket concept has been developed to eliminate these drawbacks while maintaining all the attractive features of the conventional concept. An electrical insulator coating for the coolant channels, spectral shifter (multiplier, and moderator) and reflector were utilized in the blanket design to enhance the blanket performance. In addition, the blanket was designed to have the capability to operate at average loading conditions of 2 MW/m 2 surface heat flux and 10 MW/m 2 neutron wall loading. This paper assesses the spectral shifter and the reflector materials and it defines the technological requirements of this advanced blanket concept.

Nano-casted Metal Oxide Aerogels as Dual Purpose Structural Components for Space Exploration

NASA Technical Reports Server (NTRS)

Vassilaras, Plousia E.

2004-01-01

NASA missions and space exploration rely on strong, ultra lightweight materials. Such materials are needed for building up past and present space vehicles such as the Sojourner Rover (1997) or the two MERs (2003), but also for a number of components and/or systems including thermal insulators, Solar Sails, Rigid Aeroshells, and Ballutes. The purpose of my internship here at Glenn Research Center is to make dual purpose materials; materials that in addition to being lightweight have electronic, photophysical and magnetic properties and, therefore, act as electronic components and sensors as well as structural components. One type of ultra lightweight material of great interest is aerogels, which have densities ranging from 0.003 g/cc to 0.8 g/cc . However, aerogels are extremely fragile and, as a result, have limited practical applications. Recently, Glenn Research Center has developed a process of nano-casting polymers onto the inorganic network of silica-based aerogels increasing the strength 300 fold while only increasing the density 3 fold. By combining the process of nano-casting polymers with inorganic oxide networks other than silica, we are actively pursuing lightweight dual purpose materials. To date, thirty different inorganic oxide aerogels have been prepared using either standard sol-gel chemistry or a non-alkoxide method involving metal chloride precursors and an epoxide; epichlorohydrin, propylene oxide or trimethylene oxide, as proton scavengers. More importantly, preliminary investigations show that the residual surface hydroxyl groups on each of these inorganic oxide aerogels can be successfully crosslinked with urethane. In addition to characterizing physical and mechanical properties such as density, strength and flexibility, each of these metal oxide aerogels are being characterized for thermal and electronic conductivity and magnetic and optical properties.

Multiplier, moderator, and reflector materials for lithium-vanadium fusion blankets.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gohar, Y.; Smith, D. L.

1999-10-07

The self-cooled lithium-vanadium fusion blanket concept has several attractive operational and environmental features. In this concept, liquid lithium works as the tritium breeder and coolant to alleviate issues of coolant breeder compatibility and reactivity. Vanadium alloy (V-4Cr-4Ti) is used as the structural material because of its superior performance relative to other alloys for this application. However, this concept has poor attenuation characteristics and energy multiplication for the DT neutrons. An advanced self-cooled lithium-vanadium fusion blanket concept has been developed to eliminate these drawbacks while maintaining all the attractive features of the conventional concept. An electrical insulator coating for the coolantmore » channels, spectral shifter (multiplier, and moderator) and reflector were utilized in the blanket design to enhance the blanket performance. In addition, the blanket was designed to have the capability to operate at high loading conditions of 2 MW/m{sup 2} surface heat flux and 10 MW/m{sup 2} neutron wall loading. This paper assesses the spectral shifter and the reflector materials and it defines the technological requirements of this advanced blanket concept.« less

Lightweight, Mesoporous, and Highly Absorptive All-Nanofiber Aerogel for Efficient Solar Steam Generation.

PubMed

Jiang, Feng; Liu, He; Li, Yiju; Kuang, Yudi; Xu, Xu; Chen, Chaoji; Huang, Hao; Jia, Chao; Zhao, Xinpeng; Hitz, Emily; Zhou, Yubing; Yang, Ronggui; Cui, Lifeng; Hu, Liangbing

2018-01-10

The global fresh water shortage has driven enormous endeavors in seawater desalination and wastewater purification; among these, solar steam generation is effective in extracting fresh water by efficient utilization of naturally abundant solar energy. For solar steam generation, the primary focus is to design new materials that are biodegradable, sustainable, of low cost, and have high solar steam generation efficiency. Here, we designed a bilayer aerogel structure employing naturally abundant cellulose nanofibrils (CNFs) as basic building blocks to achieve sustainability and biodegradability as well as employing a carbon nanotube (CNT) layer for efficient solar utilization with over 97.5% of light absorbance from 300 to 1200 nm wavelength. The ultralow density (0.0096 g/cm 3 ) of the aerogel ensures that minimal material is required, reducing the production cost while at the same time satisfying the water transport and thermal-insulation requirements due to its highly porous structure (99.4% porosity). Owing to its rationally designed structure and thermal-regulation performance, the bilayer CNF-CNT aerogel exhibits a high solar-energy conversion efficiency of 76.3% and 1.11 kg m -2 h -1 at 1 kW m -2 (1 Sun) solar irradiation, comparable or even higher than most of the reported solar steam generation devices. Therefore, the all-nanofiber aerogel presents a new route for designing biodegradable, sustainable, and scalable solar steam generation devices with superb performance.

High surface area silicon carbide-coated carbon aerogel

DOEpatents

Worsley, Marcus A; Kuntz, Joshua D; Baumann, Theodore F; Satcher, Jr, Joe H

2014-01-14

A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust. Carbon aerogels can be coated with sol-gel silica and the silica can be converted to silicone carbide, improved the thermal stability of the carbon aerogel.

Aerogel Projects Ongoing in MSFC's Engineering Directorate

NASA Technical Reports Server (NTRS)

Shular, D. A.; Smithers, G. A.; Plawsky, J. L.

2001-01-01

When we speak of an aerogel material, we are referring more to process and structure than to a specific substance. Aerogel, considered the lightest solid material, has been made from silica for seventy years. Resorcinol-formaldehyde, organic aerogels have been developed more recently. However, aerogel can be made from almost any type of substance, even lead. Because an aerogel is mostly air (about 99%), the solid substance used will affect the weight very little. The problem with aerogels is their low tensile strength and lack of elasticity. Therefore, the challenge is to find ways to make the stronger or ways to circumvent the strength issue. Organic aerogels have slightly higher strength than base silica aerogels, while the carbonized version has three to five times the break strength of the base aerogel.

Melamine-formaldehyde aerogels

DOEpatents

Pekala, Richard W.

1992-01-01

Organic aerogels that are transparent and essentially colorless are prepa from the aqueous, sol-gel polymerization of melamine with formaldehyde. The melamine-formaldehyde (MF) aerogels have low densities, high surface areas, continuous porsity, ultrafine cell/pore sizes, and optical clarity.

Investigation of Insulation Materials for Future Radioisotope Power Systems

NASA Technical Reports Server (NTRS)

Cornell, Peggy A.; Hurwitz, Frances I.; Ellis, David L.; Schmitz, Paul C.

2013-01-01

NASA's Radioisotope Power Systems (RPS) Technology Advancement Project is developing next generation high-temperature insulation materials that directly benefit thermal management and improve performance of RPS for future science missions. Preliminary studies on the use of multilayer insulation (MLI) for Stirling convertors used on the Advanced Stirling Radioisotope Generator (ASRG) have shown the potential benefits of MLI for space vacuum applications in reducing generator size and increasing specific power (W/kg) as compared to the baseline Microtherm HT (Microtherm, Inc.) insulation. Further studies are currently being conducted at NASA Glenn Research Center on candidate MLI foils and aerogel composite spacers. This paper presents the method of testing of foils and spacers and experimental results to date.

Melamine-formaldehyde aerogels

DOEpatents

Pekala, R.W.

1992-01-14

Organic aerogels that are transparent and essentially colorless are prepared from the aqueous, sol-gel polymerization of melamine with formaldehyde. The melamine-formaldehyde (MF) aerogels have low densities, high surface areas, continuous porosity, ultrafine cell/pore sizes, and optical clarity. 3 figs.

Study of multilayer thermal insulation by inverse problems method

NASA Astrophysics Data System (ADS)

Alifanov, O. M.; Nenarokomov, A. V.; Gonzalez, V. M.

2009-11-01

The purpose of this paper is to introduce a new method in the research of radiative and thermal properties of materials with further applications in the design of thermal control systems (TCS) of spacecrafts. In this paper the radiative and thermal properties (emissivity and thermal conductance) of a multilayered thermal-insulating blanket (MLI), which is a screen-vacuum thermal insulation as a part of the TCS for perspective spacecrafts, are estimated. Properties of the materials under study are determined in the result of temperature and heat flux measurement data processing based on the solution of the inverse heat transfer problem (IHTP) technique. Given are physical and mathematical models of heat transfer processes in a specimen of the multilayered thermal-insulating blanket located in the experimental facility. A mathematical formulation of the inverse heat conduction problem is presented as well. The practical approves were made for specimen of the real MLI.

Towards an aerogel-based coating for aerospace applications: reconstituting aerogel particles via spray drying

NASA Astrophysics Data System (ADS)

Bheekhun, N.; Abu Talib, A. R.; Mustapha, S.; Ibrahim, R.; Hassan, M. R.

2016-10-01

Silica aerogel is an ultralight and highly porous nano-structured ceramic with its thermal conductivity being the lowest than any solids. Although aerogels possess fascinating physical properties, innovative solutions to tackle today's problems were limited due to their relative high manufacturing cost in comparison to conventional materials. Recently, some producers have brought forward quality aerogels at competitive costs, and thereby opening a panoply of applied research in this field. In this paper, the feasibility of spray-drying silica aerogel to tailor its granulometric property is studied for thermal spraying, a novel application of aerogels that is never tried before in the academic arena. Aerogel-based slurries with yttria stabilised zirconia as a secondary ceramic were prepared and spray-dried according to modified T aguchi experimental design in order to appreciate the effect of both the slurry formulation and drying conditions such as the solid content, the ratio of yttria stabilised zirconia:aerogel added, the amount of dispersant and binder, inlet temperature, atomisation pressure and feeding rate on the median particle size of the resulting spray-dried powder. The latter was found to be affected by all the aforementioned independent variables at different degree of significance and inclination. Based on the derived relationships, an optimised condition to achieve maximum median particle size was then predicted.

Flammability and oxidation kinetics of hydrophobic silica aerogels.

PubMed

Li, Zhi; Cheng, Xudong; Shi, Long; He, Song; Gong, Lunlun; Li, Congcong; Zhang, Heping

2016-12-15

Silica aerogels (SAs) present great application prospects especially on thermal insulation, but their flammability is usually ignored. A combined study on the combustion behaviors and oxidation kinetics of hydrophobic silica aerogels prepared by ambient pressure drying (SA-apd) and supercritical drying (SA-sd) was performed by employing cone calorimeter and thermal analysis. The whole combustion process for SAs could be divided into three stages in which a fire propagation phenomenon was observed with the radial propagation velocity of 6.6-8.3cms -1 . Current investigations forcefully demonstrated that hydrophobic SAs were combustible and easy to flashover when exposed to a heat flux higher than 25kWm -2 . Compared between the two SAs, the SA-sd owned a less fire risk with presenting a less fire hazard and a lower smoke toxicity than those of SA-apd. The oxidation kinetics by Ozawa-Flynn-Wall method revealed that SA-sd had larger apparent activation energies than those of SA-apd which conformed to the thermal stability analysis by TG-DSC. Furthermore, a two-step combustion mechanism was proposed to explain the combustion behaviors of SAs. Copyright © 2016 Elsevier B.V. All rights reserved.

Study of the surfactant role in latex-aerogel systems by scanning transmission electron microscopy on aqueous suspensions.

PubMed

Perret, A; Foray, G; Masenelli-Varlot, K; Maire, E; Yrieix, B

2018-01-01

For insulation applications, boards thinner than 2 cm are under design with specific thermal conductivities lower than 15 mW m -1  K -1 . This requires binding slightly hydrophobic aerogels which are highly nanoporous granular materials. To reach this step and ensure insulation board durability at the building scale, it is compulsory to design, characterise and analyse the microstructure at the nanoscale. It is indeed necessary to understand how the solid material is formed from a liquid suspension. This issue is addressed in this paper through wet-STEM experiments carried out in an Environmental Scanning Electron Microscope (ESEM). Latex-surfactant binary blends and latex-surfactant-aerogel ternary systems are studied, with two different surfactants of very different chemical structures. Image analysis is used to distinguish the different components and get quantitative morphological parameters which describe the sample architecture. The evolution of such morphological parameters during water evaporation permits a good understanding of the role of the surfactant. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Silica aerogel core waveguide.

PubMed

Grogan, M D W; Leon-Saval, S G; England, R; Birks, T A

2010-10-11

We have selectively filled the core of hollow photonic crystal fibre with silica aerogel. Light is guided in the aerogel core, with a measured attenuation of 0.2 dB/cm at 1540 nm comparable to that of bulk aerogel. The structure guides light by different mechanisms depending on the wavelength. At long wavelengths the effective index of the microstructured cladding is below the aerogel index of 1.045 and guidance is by total internal reflection. At short wavelengths, where the effective cladding index exceeds 1.045, a photonic bandgap can guide the light instead. There is a small region of crossover, where both index- and bandgap-guided modes were simultaneously observed.

Wood-Derived Ultrathin Carbon Nanofiber Aerogels.

PubMed

Li, Si-Cheng; Hu, Bi-Cheng; Ding, Yan-Wei; Liang, Hai-Wei; Li, Chao; Yu, Zi-You; Wu, Zhen-Yu; Chen, Wen-Shuai; Yu, Shu-Hong

2018-06-11

Carbon aerogels with 3D networks of interconnected nanometer-sized particles exhibit fascinating physical properties and show great application potential. Efficient and sustainable methods are required to produce high-performance carbon aerogels on a large scale to boost their practical applications. An economical and sustainable method is now developed for the synthesis of ultrathin carbon nanofiber (CNF) aerogels from the wood-based nanofibrillated cellulose (NFC) aerogels via a catalytic pyrolysis process, which guarantees high carbon residual and well maintenance of the nanofibrous morphology during thermal decomposition of the NFC aerogels. The wood-derived CNF aerogels exhibit excellent electrical conductivity, a large surface area, and potential as a binder-free electrode material for supercapacitors. The results suggest great promise in developing new families of carbon aerogels based on the controlled pyrolysis of economical and sustainable nanostructured precursors. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method of casting aerogels

DOEpatents

Poco, J.F.

1993-09-07

The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm[sup 3] to 0.6 g/cm[sup 3]. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of aerogel which occurs during the drying step of supercritical extraction of solvent. 2 figures.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, KSC employee Duane Williams prepares the blanket insulation to be installed on the body flap on orbiter Discovery. The blankets are part of the Orbiter Thermal Protection System, thermal shields to protect against temperatures as high as 3,000° Fahrenheit, which are produced during descent for landing. Discovery is scheduled to fly on mission STS-121 to the International Space Station.

NASA Image and Video Library

2003-12-09

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, KSC employee Duane Williams prepares the blanket insulation to be installed on the body flap on orbiter Discovery. The blankets are part of the Orbiter Thermal Protection System, thermal shields to protect against temperatures as high as 3,000° Fahrenheit, which are produced during descent for landing. Discovery is scheduled to fly on mission STS-121 to the International Space Station.

Heat transfer correlations for multilayer insulation systems

NASA Astrophysics Data System (ADS)

Krishnaprakas, C. K.; Badari Narayana, K.; Dutta, Pradip

2000-01-01

Multilayer insulation (MLI) blankets are extensively used in spacecrafts as lightweight thermal protection systems. Heat transfer analysis of MLI is sometimes too complex to use in practical design applications. Hence, for practical engineering design purposes, it is necessary to have simpler procedures to evaluate the heat transfer rate through MLI. In this paper, four different empirical models for heat transfer are evaluated by fitting against experimentally observed heat flux through MLI blankets of various configurations, and the results are discussed.

Reusable Surface Insulation

NASA Technical Reports Server (NTRS)

1997-01-01

Advanced Flexible Reusable Surface Insulation, developed by Ames Research Center, protects the Space Shuttle from the searing heat that engulfs it on reentry into the Earth's atmosphere. Initially integrated into the Space Shuttle by Rockwell International, production was transferred to Hi-Temp Insulation Inc. in 1974. Over the years, Hi-Temp has created many new technologies to meet the requirements of the Space Shuttle program. This expertise is also used commercially, including insulation blankets to cover aircrafts parts, fire barrier material to protect aircraft engine cowlings and aircraft rescue fire fighter suits. A Fire Protection Division has also been established, offering the first suit designed exclusively by and for aircraft rescue fire fighters. Hi-Temp is a supplier to the Los Angeles City Fire Department as well as other major U.S. civil and military fire departments.

Aerogel composites and method of manufacture

DOEpatents

Cao, Wanqing; Hunt, Arlon Jason

1999-01-01

Disclosed herewith is a process of forming an aerogel composite which comprises introducing a gaseous material into a formed aerogel monolith or powder, and causing decomposition of said gaseous material in said aerogel in amounts sufficient to cause deposition of the decomposition products of the gas on the surfaces of the pores of the said aerogel. Also disclosed are the composites made by the process.

Parameter Identification Of Multilayer Thermal Insulation By Inverse Problems

NASA Astrophysics Data System (ADS)

Nenarokomov, Aleksey V.; Alifanov, Oleg M.; Gonzalez, Vivaldo M.

2012-07-01

The purpose of this paper is to introduce an iterative regularization method in the research of radiative and thermal properties of materials with further applications in the design of Thermal Control Systems (TCS) of spacecrafts. In this paper the radiative and thermal properties (heat capacity, emissivity and thermal conductance) of a multilayered thermal-insulating blanket (MLI), which is a screen-vacuum thermal insulation as a part of the (TCS) for perspective spacecrafts, are estimated. Properties of the materials under study are determined in the result of temperature and heat flux measurement data processing based on the solution of the Inverse Heat Transfer Problem (IHTP) technique. Given are physical and mathematical models of heat transfer processes in a specimen of the multilayered thermal-insulating blanket located in the experimental facility. A mathematical formulation of the IHTP, based on sensitivity function approach, is presented too. The practical testing was performed for specimen of the real MLI. This paper consists of recent researches, which developed the approach suggested at [1].

Investigation of Insulation Materials for Future Radioisotope Power Systems (RPS)

NASA Technical Reports Server (NTRS)

Cornell, Peggy A.; Hurwitz, Frances I.; Ellis, David L.; Schmitz, Paul C.

2013-01-01

NASA's Radioisotope Power System (RPS) Technology Advancement Project is developing next generation high temperature insulation materials that directly benefit thermal management and improve performance of RPS for future science missions. Preliminary studies on the use of multilayer insulation (MLI) for Stirling convertors used on the Advanced Stirling Radioisotope Generator (ASRG) have shown the potential benefits of MLI for space vacuum applications in reducing generator size and increasing specific power (W/kg) as compared to the baseline Microtherm HT (Microtherm, Inc.) insulation. Further studies are currently being conducted at NASA Glenn Research Center (GRC) on candidate MLI foils and aerogel composite spacers. This paper presents the method of testing of foils and spacers and experimental results to date.

Monolayer coated aerogels and method of making

DOEpatents

Zemanian, Thomas Samuel [Richland, WA; Fryxell, Glen [Kennwick, WA; Ustyugov, Oleksiy A [Spokane, WA

2006-03-28

Aerogels having a monolayer coating are described. The aerogel and a monolayer forming precursor are provided in a supercritical fluid, whereupon the aerogel and the monolayer forming precursor are reacted in said supercritical fluid to form a covalent bond between the aerogel and the monolayer forming precursor. Suitable aerogels are ceramic oxides such as silica, alumina, aluminosilicate, and combinations thereof. Suitable monolayer forming precursors include alkyl silanes, chlorosilanes, boranes, chloroboranes, germanes, and combinations thereof. The method may also include providing a surface preparation agent such as water, or hydroetching an aerogel to enhance the coating of the monolayer.

Aerogel volatiles concentrator and analyzer (AVCA) - Collection and concentration of trace volatile organics in aerogel for spectroscopic detection

NASA Astrophysics Data System (ADS)

Tsapin, A.; Jones, S.; Petkov, M.; Borchardt, D.; Anderson, M.

2017-03-01

A study was conducted to determine the efficacy of using silica aerogel to collect and concentrate ambient trace organics for spectroscopic analysis. Silica aerogel was exposed to atmospheres containing trace amounts of polycyclic aromatic and aliphatic hydrocarbons. The organics present were concentrated in the aerogels by factors varying from 10 to more than 1000 over the levels found in the atmospheres, depending on the specific organic present. Since silica aerogel is transparent over a wide range of optical and near infrared wavelengths, UV-induced fluorescence, Raman and infrared spectroscopies were used to detect and identify the organics collected by the aerogel. Measurements were conducted to determine the sensitivity of these spectroscopic methods for determining organics concentrated by aerogels and the effectiveness of this method for identifying systems containing multiple organic species. Polycyclic aromatic hydrocarbons (PAHs) were added to simulated Mars regolith and then vaporized by modest heating in the presence of aerogel. The aerogels adsorbed and concentrated the PAHs, which were detected by induced fluorescence and Raman and FTIR spectroscopies.

Ultralight, Recoverable, and High-Temperature-Resistant SiC Nanowire Aerogel.

PubMed

Su, Lei; Wang, Hongjie; Niu, Min; Fan, Xingyu; Ma, Mingbo; Shi, Zhongqi; Guo, Sheng-Wu

2018-04-24

Ultralight ceramic aerogels with the property combination of recoverable compressibility and excellent high-temperature stability are attractive for use in harsh environments. However, conventional ceramic aerogels are usually constructed by oxide ceramic nanoparticles, and their practical applications have always been limited by the brittle nature of ceramics and volume shrinkage at high temperature. Silicon carbide (SiC) nanowire offers the integrated properties of elasticity and flexibility of one-dimensional (1D) nanomaterials and superior high-temperature thermal and chemical stability of SiC ceramics, which makes it a promising building block for compressible ceramic nanowire aerogels (NWAs). Here, we report the fabrication and properties of a highly porous three-dimensional (3D) SiC NWA assembled by a large number of interweaving 3C-SiC nanowires of 20-50 nm diameter and tens to hundreds of micrometers in length. The SiC NWA possesses ultralow density (∼5 mg cm -3 ), excellent mechanical properties of large recoverable compression strain (>70%) and fatigue resistance, refractory property, oxidation and high-temperature resistance, and thermal insulating property (0.026 W m -1 K -1 at room temperature in N 2 ). When used as absorbents, the SiC NWAs exhibit an adsorption selectivity of low-viscosity organic solvents with high absorption capacity (130-237 g g -1 ). The successful fabrication of such an attractive material may provide promising perspectives to the design and fabrication of other compressible and multifunctional ceramic NWAs.

Multipurpose Thermal Insulation Test Apparatus

NASA Technical Reports Server (NTRS)

Fesmire, James E. (Inventor); Augustynowicz, Stanislaw D. (Inventor)

2002-01-01

A multi-purpose thermal insulation test apparatus is used for testing insulation materials, or other components. The test apparatus is a fluid boil-off calorimeter system for calibrated measurement of the apparent thermal conductivity (k-value) of a specimen material at a fixed vacuum level. The apparatus includes an inner vessel for receiving a fluid with a normal boiling point below ambient temperature, such as liquid nitrogen, enclosed within a vacuum chamber. A cold mass assembly, including the inner vessel and thermal guards, is suspended from the top of the vacuum chamber. Handling tools attach to the cold mass assembly for convenient manipulation of the assembly and for the installation or wrapping of insulation test materials. Liquid nitrogen is typically supplied to the inner vessel using a fill tube with funnel. A single port through the top of the vacuum chamber facilitates both filling and venting. Aerogel composite stacks with reflective films are fastened to the top and the bottom of the inner vessel as thermal guards. The comparative k-value of the insulation material is determined by measuring the boil-off flow rate of gas, the temperature differential across the insulation thickness, and the dimensions (length and diameters) of the test specimen.

Vibration and Thermal Cycling Effects on Bulk-fill Insulation Materials for Cryogenic Tanks

NASA Astrophysics Data System (ADS)

Fesmire, J. E.; Augustynowicz, S. D.; Nagy, Z. F.; Sojourner, S. J.; Morris, D. L.

2006-04-01

Large-scale (1,000,000 liters or more) cryogenic storage tanks are typically perlite-insulated double-walled vessels. Associated problems with perlite, such as mechanical compaction and settling, could be greatly reduced by using newer bulk-fill materials such as glass bubbles or aerogel beads. Using the newer materials should translate to lower life cycle costs and improved system reliability. NASA Kennedy Space Center is leveraging its experience in the areas of materials development, insulation testing, and cryogenic systems design to develop an insulation retrofit option that will meet both industry and NASA requirements. A custom 10-liter dewar test apparatus, developed by the KSC Cryogenics Test Laboratory, was used to determine the vibration and thermal cycling effects on different bulk-fill insulation materials for cryogenic tanks. The testing included liquid-nitrogen boiloff testing and thermal cycling (with vibration) of a number of test dewars. Test results show that glass bubbles have better thermal performance and less mechanical compaction compared to perlite powder. The higher cost of the bulk material should be offset by reduced commodity loss from boiloff and improvements in material handling, evacuation, and vacuum retention. The long-term problem with settling and compaction of perlite should also be eliminated. Aerogel beads are superior for the no-vacuum condition and can now be considered in some applications. Further studies on large-scale systems are presently being pursued.

Highly stretchable carbon aerogels.

PubMed

Guo, Fan; Jiang, Yanqiu; Xu, Zhen; Xiao, Youhua; Fang, Bo; Liu, Yingjun; Gao, Weiwei; Zhao, Pei; Wang, Hongtao; Gao, Chao

2018-02-28

Carbon aerogels demonstrate wide applications for their ultralow density, rich porosity, and multifunctionalities. Their compressive elasticity has been achieved by different carbons. However, reversibly high stretchability of neat carbon aerogels is still a great challenge owing to their extremely dilute brittle interconnections and poorly ductile cells. Here we report highly stretchable neat carbon aerogels with a retractable 200% elongation through hierarchical synergistic assembly. The hierarchical buckled structures and synergistic reinforcement between graphene and carbon nanotubes enable a temperature-invariable, recoverable stretching elasticity with small energy dissipation (~0.1, 100% strain) and high fatigue resistance more than 10 6 cycles. The ultralight carbon aerogels with both stretchability and compressibility were designed as strain sensors for logic identification of sophisticated shape conversions. Our methodology paves the way to highly stretchable carbon and neat inorganic materials with extensive applications in aerospace, smart robots, and wearable devices.

Silver-Loaded Aluminosilicate Aerogels As Iodine Sorbents.

PubMed

Riley, Brian J; Kroll, Jared O; Peterson, Jacob A; Matyáš, Josef; Olszta, Matthew J; Li, Xiaohong; Vienna, John D

2017-09-27

In this paper, aluminosilicate aerogels were used as scaffolds for silver nanoparticles to capture I 2 (g). The starting materials for these scaffolds included Na-Al-Si-O and Al-Si-O aerogels, both synthesized from metal alkoxides. The Ag 0 particles were added by soaking the aerogels in aqueous AgNO 3 solutions followed by drying and Ag + reduction under H 2 /Ar to form Ag 0 crystallites within the aerogel matrix. In some cases, aerogels were thiolated with 3-(mercaptopropyl)trimethoxysilane as an alternative method for binding Ag + . During the Ag + -impregnation steps, for the Na-Al-Si-O aerogels, Na was replaced with Ag, and for the Al-Si-O aerogels, Si was replaced with Ag. The Ag-loading of thiolated versus nonthiolated Na-Al-Si-O aerogels was comparable at ∼35 atomic %, whereas the Ag-loading in unthiolated Al-Si-O aerogels was significantly lower at ∼7 atomic % after identical treatment. Iodine loadings in both thiolated and unthiolated Ag 0 -functionalized Na-Al-Si-O aerogels were >0.5 m I m s -1 (denoting the mass of iodine captured per starting mass of the sorbent) showing almost complete utilization of the Ag through chemisorption to form AgI. Iodine loading in the thiolated and Ag 0 -functionalized Al-Si-O aerogel was 0.31 m I m s -1 . The control of Ag uptake over solution residence time and [Ag] demonstrates the ability to customize the Ag-loading in the base sorbent to regulate the loading capacity of iodine.

Comet Ejecta in Aerogel

NASA Image and Video Library

2006-02-21

This image from NASA shows a particle impact on the aluminum frame that holds the aerogel tiles. The debris from the impact shot into the adjacent aerogel tile producing the explosion pattern of ejecta framents captured in the material.

Slotted Polyimide-Aerogel-Filled-Waveguide Arrays

NASA Technical Reports Server (NTRS)

Rodriguez-Solis, Rafael A.; Pacheco, Hector L.; Miranda, Felix A.; Meador, Mary Ann B.

2013-01-01

This presentation discussed the potential advantages of developing Slotted Waveguide Arrays using polyimide aerogels. Polyimide (PI) aerogels offer great promise as an enabling technology for lightweight aerospace antenna systems. PI aerogels are highly porous solids possessing low density and low dielectric permittivity combined with good mechanical properties. For slotted waveguide array applications, there are significant advantages in mass that more than compensate for the slightly higher loss of the aerogel filled waveguide when compared to state of practice commercial waveguide.

Synthesis and characterization of a nanocrystalline diamond aerogel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.

2011-07-06

Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel's void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Time-resolved photoluminescence measurements of recovered material revealmore » the formation of both nitrogen- and silicon- vacancy point-defects, suggesting a broad range of applications for this nanocrystalline diamond aerogel.« less

Chitin Liquid-Crystal-Templated Oxide Semiconductor Aerogels.

PubMed

Chau, Trang The Lieu; Le, Dung Quang Tien; Le, Hoa Thi; Nguyen, Cuong Duc; Nguyen, Long Viet; Nguyen, Thanh-Dinh

2017-09-13

Chitin nanocrystals have been used as a liquid crystalline template to fabricate layered oxide semiconductor aerogels. Anisotropic chitin liquid crystals are transformed to sponge-like aerogels by hydrothermally cross-linked gelation and lyophilization-induced solidification. The hydrothermal gelation of chitin aqueous suspensions then proceeds with peroxotitanate to form hydrogel composites that recover to form aerogels after freeze-drying. The homogeneous peroxotitanate/chitin composites are calcined to generate freestanding titania aerogels that exhibit the nanostructural integrity of layered chitin template. Our extended investigations show that coassembling chitin nanocrystals with other metal-based precursors also yielded semiconductor aerogels of perovskite BaTiO 3 and CuO x nanocrystals. The potential of these materials is great to investigate these chitin sponges for biomedicine and these semiconductor aerogels for photocatalysis, gas sensing, and other applications. Our results present a new aerogel templating method of highly porous, ultralight materials with chitin liquid crystals.

The Aerogel Mesh Contamination Collector

DTIC Science & Technology

1993-07-01

patent pending 2.1 Introduction The new method of contamination prevention and collection described herein employs ultra-low density silica aerogel and a... silica aerogel and the Section 2.2 presents the fabrication of the acrogel me:sh contamination collector (AMCC). The device is a heterostructure...monolithic photonic devices and lightweight optics). This report series will focus on silica aerogels almost exclusively. It is also of interest to note that

Analysis of thermal performance of penetrated multi-layer insulation

NASA Technical Reports Server (NTRS)

Foster, Winfred A., Jr.; Jenkins, Rhonald M.; Yoo, Chai H.; Barrett, William E.

1988-01-01

Results of research performed for the purpose of studying the sensitivity of multi-layer insulation blanket performance caused by penetrations through the blanket are presented. The work described in this paper presents the experimental data obtained from thermal vacuum tests of various penetration geometries similar to those present on the Hubble Space Telescope. The data obtained from these tests is presented in terms of electrical power required sensitivity factors referenced to a multi-layer blanket without a penetration. The results of these experiments indicate that a significant increase in electrical power is required to overcome the radiation heat losses in the vicinity of the penetrations.

Preparation and Characterization of Silica Aerogel Microspheres

PubMed Central

Chen, Qifeng; Wang, Hui; Sun, Luyi

2017-01-01

Silica aerogel microspheres based on alkali silica sol were synthesized using the emulsion method. The experimental results revealed that the silica aerogel microspheres (4–20 µm in diameter) were mesoporous solids with an average pore diameter ranging from 6 to 35 nm. The tapping densities and specific surface areas of the aerogel microspheres are in the range of 0.112–0.287 g/cm3 and 207.5–660.6 m2/g, respectively. The diameter of the silica aerogel microspheres could be tailored by varying the processing conditions including agitation rate, water/oil ratio, mass ratio of Span 80: Tween 80, and emulsifier concentration. The effects of these parameters on the morphology and textural properties of the synthesized silica aerogel microspheres were systematically investigated. Such silica aerogel microspheres can be used to prepare large-scale silica aerogels at an ambient pressure for applications in separation and high efficiency catalysis, which requires features of high porosity and easy fill and recovery. PMID:28772795

Preparation and Characterization of Silica Aerogel Microspheres.

PubMed

Chen, Qifeng; Wang, Hui; Sun, Luyi

2017-04-20

Silica aerogel microspheres based on alkali silica sol were synthesized using the emulsion method. The experimental results revealed that the silica aerogel microspheres (4-20 µm in diameter) were mesoporous solids with an average pore diameter ranging from 6 to 35 nm. The tapping densities and specific surface areas of the aerogel microspheres are in the range of 0.112-0.287 g/cm³ and 207.5-660.6 m²/g, respectively. The diameter of the silica aerogel microspheres could be tailored by varying the processing conditions including agitation rate, water/oil ratio, mass ratio of Span 80: Tween 80, and emulsifier concentration. The effects of these parameters on the morphology and textural properties of the synthesized silica aerogel microspheres were systematically investigated. Such silica aerogel microspheres can be used to prepare large-scale silica aerogels at an ambient pressure for applications in separation and high efficiency catalysis, which requires features of high porosity and easy fill and recovery.

21 CFR 182.1711 - Silica aerogel.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having...

21 CFR 182.1711 - Silica aerogel.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having...

Mechanical performance and thermal stability of glass fiber reinforced silica aerogel composites based on co-precursor method by freeze drying

NASA Astrophysics Data System (ADS)

Zhou, Ting; Cheng, Xudong; Pan, Yuelei; Li, Congcong; Gong, Lunlun; Zhang, Heping

2018-04-01

In order to maintain the integrity, glass fiber (GF) reinforced silica aerogel composites were synthesized using methltrimethoxysilane (MTMS) and water glass co-precursor by freeze drying method. The composites were characterized by scanning electron microscopy, Brunauer-Emmett-Teller analysis, uniaxial compressive test, three-point bending test, thermal conductivity analysis, contact angle test, TG-DSC analysis. It was found that the molar ratio of MTMS/water glass could significantly affect the properties of composites. The bulk density and thermal conductivity first decreased and then increased with the increasing molar ratio. The composites showed remarkable mechanical strength and flexibility compared with pure silica aerogel. Moreover, when the molar ratio is 1.8, the composites showed high specific surface area (870.9 m2/g), high contact angle (150°), great thermal stability (560 °C) and low thermal conductivity (0.0248 W/m·K). These outstanding properties indicate that GF/aerogels have broad prospects in the field of thermal insulation.

Space environment durability of beta cloth in LDEF thermal blankets

NASA Technical Reports Server (NTRS)

Linton, Roger C.; Whitaker, Ann F.; Finckenor, Miria M.

1993-01-01

Beta cloth performance for use on long-term space vehicles such as Space Station Freedom (S.S. Freedom) requires resistance to the degrading effects of the space environment. The major issues are retention of thermal insulating properties through maintaining optical properties, preserving mechanical integrity, and generating minimal particulates for contamination-sensitive spacecraft surfaces and payloads. The longest in-flight test of beta cloth's durability was on the Long Duration Exposure Facility (LDEF), where it was exposed to the space environment for 68 months. The LDEF contained 57 experiments which further defined the space environment and its effects on spacecraft materials. It was deployed into low-Earth orbit (LEO) in Apr. 1984 and retrieved Jan. 1990 by the space shuttle. Among the 10,000 plus material constituents and samples onboard were thermal control blankets of multilayer insulation with a beta cloth outer cover and Velcro attachments. These blankets were exposed to hard vacuum, thermal cycling, charged particles, meteoroid/debris impacts, ultraviolet (UV) radiation, and atomic oxygen (AO). Of these space environmental exposure elements, AO appears to have had the greatest effect on the beta cloth. The beta cloth analyzed in this report came from the MSFC Experiment S1005 (Transverse Flat-Plate Heat Pipe) tray oriented approximately 22 deg from the leading edge vector of the LDEF satellite. The location of the tray on LDEF and the placement of the beta cloth thermal blankets are shown. The specific space environment exposure conditions for this material are listed.

Silver-Loaded Aluminosilicate Aerogels As Iodine Sorbents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riley, Brian J.; Kroll, Jared O.; Peterson, Jacob A.

This paper discusses the development of aluminosilicates aerogels as scaffolds for Ag0 nanoparticles used for chemisorption of I2(g). The starting materials for these scaffolds included both Na-Al-Si-O and Al-Si-O aerogels, both synthesized from metal alkoxides. The Ag0 particles are added by soaking the aerogels in AgNO3 followed by drying and flowing under H2/Ar to reduce Ag+ → Ag0. In some cases, samples were soaked in 3-(mercaptopropyl)trimethoxysilane under supercritical CO2 to add –SH tethers to the aerogel surfaces for more effective binding of Ag+. During the Ag+-impregnation steps, for the Na-Al-Si-O aerogels, Na was replaced with Ag, and for the Al-Si-Omore » aerogel, Si was replaced with Ag. The Ag-loading of thiolated versus non-thiolated Na-Al-Si-O aerogels was comparable at ~35 at% whereas the Ag-loading in unthiolated Al-Si-O aerogels was significantly lower at ~ 7 at% after identical treatment. Iodine loadings in both thiolated and unthiolated Ag0-functionalized Na-Al-Si-O aerogels were > 0.5 g g-1 showing almost complete utilization of the Ag through chemisorption to form AgI. Iodine loading in the thiolated Al-Si-O aerogel was 0.31 g g-1. The control of Ag uptake over solution residence time and [AgNO3] demonstrates the ability to customize the Ag-loading in the base sorbent to regulate the capacity of iodine chemisorption. Consolidation experimental results are also presented.« less

Processing and Mechanical Characterization of Polyurea Aerogels

DTIC Science & Technology

2011-01-01

PROCESSING AND MECHANICAL CHARACTERIZATION OF POLYUREA AEROGELS by JARED MICHAEL LOEBS A THESIS Presented to the Faculty of the Graduate School of...SUBTITLE Processing and Mechanical Characterization of Polyurea Aerogels 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...suggest otherwise. This thesis outlines the processing and major mechanical properties of a relatively new type of aerogel, polyurea aerogel, that shows

Design, Manufacture, and Experimental Serviceability Validation of ITER Blanket Components

NASA Astrophysics Data System (ADS)

Leshukov, A. Yu.; Strebkov, Yu. S.; Sviridenko, M. N.; Safronov, V. M.; Putrik, A. B.

2017-12-01

In 2014, the Russian Federation and the ITER International Organization signed two Procurement Arrangements (PAs) for ITER blanket components: 1.6.P1ARF.01 "Blanket First Wall" of February 14, 2014, and 1.6.P3.RF.01 "Blanket Module Connections" of December 19, 2014. The first PA stipulates development, manufacture, testing, and delivery to the ITER site of 179 Enhanced Heat Flux (EHF) First Wall (FW) Panels intended for withstanding the heat flux from the plasma up to 4.7MW/m2. Two Russian institutions, NIIEFA (Efremov Institute) and NIKIET, are responsible for the implementation of this PA. NIIEFA manufactures plasma-facing components (PFCs) of the EHF FW panels and performs the final assembly and testing of the panels, and NIKIET manufactures FW beam structures, load-bearing structures of PFCs, and all elements of the panel attachment system. As for the second PA, NIKIET is the sole official supplier of flexible blanket supports, electrical insulation key pads (EIKPs), and blanket module/vacuum vessel electrical connectors. Joint activities of NIKIET and NIIEFA for implementing PA 1.6.P1ARF.01 are briefly described, and information on implementation of PA 1.6.P3.RF.01 is given. Results of the engineering design and research efforts in the scope of the above PAs in 2015-2016 are reported, and results of developing the technology for manufacturing ITER blanket components are presented.

21 CFR 182.1711 - Silica aerogel.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered...

Synthesis and characterization of a nanocrystalline diamond aerogel

PubMed Central

Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.; Laurence, Ted A.; Kilcoyne, A. L. David; Wang, Yinmin; Willey, Trevor M.; Visbeck, Kenneth S.; Fakra, Sirine C.; Evans, William J.; Zaug, Joseph M.; Satcher, Joe H.

2011-01-01

Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel’s void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Time-resolved photoluminescence measurements of recovered material reveal the formation of both nitrogen- and silicon- vacancy point-defects, suggesting a broad range of applications for this nanocrystalline diamond aerogel. PMID:21555550

Composition containing aerogel substrate loaded with tritium

DOEpatents

Ashley, Carol S.; Brinker, C. Jeffrey; Ellefson, Robert E.; Gill, John T.; Reed, Scott; Walko, Robert J.

1992-01-01

The invention provides a process for loading an aerogel substrate with tritium and the resultant compositions. According to the process, an aerogel substrate is hydrolyzed so that surface OH groups are formed. The hydrolyzed aerogel is then subjected to tritium exchange employing, for example, a tritium-containing gas, whereby tritium atoms replace H atoms of surface OH groups. OH and/or CH groups of residual alcohol present in the aerogel may also undergo tritium exchange.

Durable polymer-aerogel based superhydrophobic coatings, a composite material

DOEpatents

Kissel, David J; Brinker, Charles Jeffrey

2014-03-04

Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

Durable polymer-aerogel based superhydrophobic coatings: a composite material

DOEpatents

Kissel, David J.; Brinker, Charles Jeffrey

2016-02-02

Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

Tapered fibers embedded in silica aerogel.

PubMed

Xiao, Limin; Grogan, Michael D W; Leon-Saval, Sergio G; Williams, Rhys; England, Richard; Wadsworth, Willam J; Birks, Tim A

2009-09-15

We have embedded thin tapered fibers (with diameters down to 1 microm) in silica aerogel with low loss. The aerogel is rigid but behaves refractively like air, protecting the taper without disturbing light propagation along it. This enables a new class of fiber devices exploiting volume evanescent interactions with the aerogel itself or with dopants or gases in the pores.

Aerogel Projects Ongoing in MSFC's Engineering Directorate

NASA Technical Reports Server (NTRS)

Shular, David A.; Smithers, Gweneth A.; Plawsky, Joel L.; Whitaker, Ann F. (Technical Monitor)

2000-01-01

When we speak of an aerogel material, we are referring more to process and structure am to a specific substance. Aerogel, considered the lightest solid material, has been made from silica for seventy years. Resorcinol-formaldehyde, organic aerogels have been developed more recently. However, aerogel can be made from almost any type of substance, even lead. Because an aerogel is mostly air (about 99 %), the solid substance used will affect the weight very little. The term "aerogel" connotes the sol-gel process used to manufacture the material. The aerogel begins as a liquid "sol," becomes a solid "alcogel," and is then dried to become an "aerogel." The final product has a unique structure, useful for exploitation. It is an "open pore" system with nano-sized particles and pores, has very high surface area, and is highly interconnected. Besides low weight, aerogels have ultimate (lowest) values in other properties: thermal conductivity, refractive index, sound speed, and dielectric constant. Aerogels were first prepared in 1931 by Steven Kistler, who used a supercritical drying step to replace the liquid in a gel with air, preserving the structure (1). Kistler's procedure involved a water-to-alcohol exchange step; in the 1970's, this step was eliminated when a French investigator introduced the use of tetramethylorthosilicate. Still, alcohol drying involved dangerously high temperatures and pressures. In the 1980's, the Microstructured Materials Group at Berkeley Laboratory found that the alcohol in the gel could be replaced with liquid carbon dioxide before supercritical drying, which greatly improved safety (2). 'Me most recent major contribution has been that of Deshpande, Smith and Brinker in New Mexico, who are working to eliminate the supercritical drying step (3). When aerogels were first being developed, they were evaporatively dried. However, the wet gel, when dried, underwent severe shrinkage and cracking; this product was termed "xerogel." When the

Low density, resorcinol-formaldehyde aerogels

DOEpatents

Pekala, R.W.

1989-10-10

The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer clusters. The covalent crosslinking of these clusters produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density [<=]100 mg/cc; cell size [<=]0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 [angstrom]. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.

How We 3D-Print Aerogel

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

A new type of graphene aerogel will make for better energy storage, sensors, nanoelectronics, catalysis and separations. Lawrence Livermore National Laboratory researchers have made graphene aerogel microlattices with an engineered architecture via a 3D printing technique known as direct ink writing. The research appears in the April 22 edition of the journal, Nature Communications. The 3D printed graphene aerogels have high surface area, excellent electrical conductivity, are lightweight, have mechanical stiffness and exhibit supercompressibility (up to 90 percent compressive strain). In addition, the 3D printed graphene aerogel microlattices show an order of magnitude improvement over bulk graphene materials and muchmore » better mass transport.« less

Ultralight Conductive Silver Nanowire Aerogels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, Fang; Lan, Pui Ching; Freyman, Megan C.

Low-density metal foams have many potential applications in electronics, energy storage, catalytic supports, fuel cells, sensors, and medical devices. Here in this work, we report a new method for fabricating ultralight, conductive silver aerogel monoliths with predictable densities using silver nanowires. Silver nanowire building blocks were prepared by polyol synthesis and purified by selective precipitation. Silver aerogels were produced by freeze-casting nanowire aqueous suspensions followed by thermal sintering to weld the nanowire junctions. As-prepared silver aerogels have unique anisotropic microporous structures, with density precisely controlled by the nanowire concentration, down to 4.8 mg/cm 3 and an electrical conductivity up tomore » 51 000 S/m. Lastly, mechanical studies show that silver nanowire aerogels exhibit “elastic stiffening” behavior with a Young’s modulus up to 16 800 Pa.« less

Ultralight Conductive Silver Nanowire Aerogels

DOE PAGES

Qian, Fang; Lan, Pui Ching; Freyman, Megan C.; ...

2017-09-05

Low-density metal foams have many potential applications in electronics, energy storage, catalytic supports, fuel cells, sensors, and medical devices. Here in this work, we report a new method for fabricating ultralight, conductive silver aerogel monoliths with predictable densities using silver nanowires. Silver nanowire building blocks were prepared by polyol synthesis and purified by selective precipitation. Silver aerogels were produced by freeze-casting nanowire aqueous suspensions followed by thermal sintering to weld the nanowire junctions. As-prepared silver aerogels have unique anisotropic microporous structures, with density precisely controlled by the nanowire concentration, down to 4.8 mg/cm 3 and an electrical conductivity up tomore » 51 000 S/m. Lastly, mechanical studies show that silver nanowire aerogels exhibit “elastic stiffening” behavior with a Young’s modulus up to 16 800 Pa.« less

Nanoencapsulated aerogels produced by monomer vapor deposition and polymerization

NASA Technical Reports Server (NTRS)

Sullivan, Thomas A. (Inventor)

2011-01-01

Polymer coated aerogel comprising aerogel substrate comprising a substantially uniform polymer coating. In an embodiment, the polymer coated aerogel is comprised of a porosity and has a compressive modulus greater than the compressive modulus of the aerogel substrate.

Low density, resorcinol-formaldehyde aerogels

DOEpatents

Pekala, Richard W.

1991-01-01

The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "Clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density.ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100.circle.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.

Low density, resorcinol-formaldehyde aerogels

DOEpatents

Pekala, Richard W.

1989-01-01

The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density .ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 .ANG.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.

High Temperature Aerogels for Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.; Mbah, Godfrey C.

2008-01-01

High temperature aerogels in the Al2O3-SiO2 system are being investigated as possible constituents for lightweight integrated thermal protection system (TPS) designs for use in supersonic and hypersonic applications. Gels are synthesized from ethoxysilanes and AlCl3.6H2O, using an epoxide catalyst. The influence of Al:Si ratio, solvent, water to metal and water to alcohol ratios on aerogel composition, morphology, surface area, and pore size distribution were examined, and phase transformation on heat treatment characterized. Aerogels have been fabricated which maintain porous, fractal structures after brief exposures to 1000 C. Incorporation of nanofibers, infiltration of aerogels into SiC foams, use of polymers for crosslinking the aerogels, or combinations of these, offer potential for toughening and integration of TPS with composite structure. Woven fabric composites having Al2O3-SiO2 aerogels as a matrix also have been fabricated. Continuing work is focused on reduction in shrinkage and optimization of thermal and physical properties.

Cryogenic Testing of Different Seam Concepts for Multilayer Insulation Systems

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.; Fesmire, J. E.

2009-01-01

Recent testing in a cylindrical, comparative cryostat at the Cryogenics Test Laboratory has focused on various seam concepts for multilayer insulation systems. Three main types of seams were investigated: straight overlap, fold-over, and roll wrapped. Each blanket was comprised of 40 layer pairs of reflector and spacer materials. The total thickness was approximately 12.5-mm, giving an average layer density of 32 layers per centimeter. The blankets were tested at high vacuum, soft vacuum, and no vacuum using liquid nitrogen to maintain the cold boundary temperature at 77 K. Test results show that all three seam concepts are all close in thermal performance; however the fold-over method provides the lowest heat flux. For the first series of tests, seams were located 120 degrees around the circumference of the cryostat from the previous seam. This technique appears to have lessened the degradation of the blanket due to the seams. In a follow-on test, a 20 layer blanket was tested in a roll wrapped configuration and then cut down the side of the cylinder, taped together, and re-tested. This test result shows the thermal performance impact of having the seams all in one location versus having the seams clocked around the vessel. This experimental investigation indicates that the method of joining the seams in multilayer insulation systems is not as critical as the quality of the installation process.

Conversion of a room temperature NaK loop to a high temperature MHD facility for Li/V blanket testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reed, C.B.; Haglund, R.C.; Miller, M.E.

1996-12-31

The Vanadium/Lithium system has been the recent focus of ANL`s Blanket Technology Program, and for the last several years, ANL`s Liquid Metal Blanket activities have been carried out in direct support of the ITER (International Thermonuclear Experimental Reactor) breeding blanket task area. A key feasibility issue for the ITER Vanadium/Lithium breeding blanket is the development of insulator coatings. Design calculations, Hua and Gohar, show that an electrically insulating layer is necessary to maintain an acceptably low magnetohydrodynamic (MHD) pressure drop in the current ITER design. Consequently, the decision was made to convert Argonne`s Liquid Metal EXperiment (ALEX) from a 200{degree}Cmore » NaK facility to a 350{degree}C lithium facility. The upgraded facility was designed to produce MHD pressure drop data, test section voltage distributions, and heat transfer data for mid-scale test sections and blanket mockups at Hartmann numbers (M) and interaction parameters (N) in the range of 10{sup 3} to 10{sup 5} in lithium at 350{degree}C. Following completion of the upgrade work, a short performance test was conducted, followed by two longer, multiple-hour, MHD tests, all at 230{degree}C. The modified ALEX facility performed up to expectations in the testing. MHD pressure drop and test section voltage distributions were collected at Hartmann numbers of 1000. 4 refs., 2 figs.« less

Emerging Hierarchical Aerogels: Self-Assembly of Metal and Semiconductor Nanocrystals.

PubMed

Cai, Bin; Sayevich, Vladimir; Gaponik, Nikolai; Eychmüller, Alexander

2018-06-19

Aerogels assembled from colloidal metal or semiconductor nanocrystals (NCs) feature large surface area, ultralow density, and high porosity, thus rendering them attractive in various applications, such as catalysis, sensors, energy storage, and electronic devices. Morphological and structural modification of the aerogel backbones while maintaining the aerogel properties enables a second stage of the aerogel research, which is defined as hierarchical aerogels. Different from the conventional aerogels with nanowire-like backbones, those hierarchical aerogels are generally comprised of at least two levels of architectures, i.e., an interconnected porous structure on the macroscale and a specially designed configuration at local backbones at the nanoscale. This combination "locks in" the inherent properties of the NCs, so that the beneficial genes obtained by nanoengineering are retained in the resulting monolithic hierarchical aerogels. Herein, groundbreaking advances in the design, synthesis, and physicochemical properties of the hierarchical aerogels are reviewed and organized in three sections: i) pure metallic hierarchical aerogels, ii) semiconductor hierarchical aerogels, and iii) metal/semiconductor hybrid hierarchical aerogels. This report aims to define and demonstrate the concept, potential, and challenges of the hierarchical aerogels, thereby providing a perspective on the further development of these materials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid phase microextraction device using aerogel

DOEpatents

Miller, Fred S.; Andresen, Brian D.

2005-06-14

A sample collection substrate of aerogel and/or xerogel materials bound to a support structure is used as a solid phase microextraction (SPME) device. The xerogels and aerogels may be organic or inorganic and doped with metals or other compounds to target specific chemical analytes. The support structure is typically formed of a glass fiber or a metal wire (stainless steel or kovar). The devices are made by applying gel solution to the support structures and drying the solution to form aerogel or xerogel. Aerogel particles may be attached to the wet layer before drying to increase sample collection surface area. These devices are robust, stable in fields of high radiation, and highly effective at collecting gas and liquid samples while maintaining superior mechanical and thermal stability during routine use. Aerogel SPME devices are advantageous for use in GC/MS analyses due to their lack of interfering background and tolerance of GC thermal cycling.

Ultra-Low Density Aerogel Mirror Substrates

DTIC Science & Technology

1993-04-01

Silica aerogel materials were fabricated by both the high temperature and low temperature methods at the Lawrence Livermore National Laboratory in...evaporation techniques were used to planarize the silica aerogel with SiO 2 prior to metalization. The PECVD was performed at the Cornell University...incident hv. Defect Physics Silica aerogel is an amorphous SiO, matrix of high porosity (or a low density disordered material). The amorphous r~ature of

Nano-sized Ni-doped carbon aerogel for supercapacitor.

PubMed

Lee, Yoon Jae; Jung, Ji Chul; Park, Sunyoung; Seo, Jeong Gil; Baeck, Sung-Hyeon; Yoon, Jung Rag; Yi, Jongheop; Song, In Kyu

2011-07-01

Carbon aerogel was prepared by polycondensation of resorcinol with formaldehyde using sodium carbonate as a catalyst in ambient conditions. Nano-sized Ni-doped carbon aerogel was then prepared by a precipitation method in an ethanol solvent. In order to elucidate the effect of nickel content on electrochemical properties, Ni-doped carbon aerogels (21, 35, 60, and 82 wt%) were prepared and their performance for supercapacitor electrode was investigated. Electrochemical properties of Ni-doped carbon aerogel electrodes were measured by cyclic voltammetry at a scan rate of 10 mV/sec and charge/discharge test at constant current of 1 A/g in 6 M KOH electrolyte. Among the samples prepared, 35 wt% Ni-doped carbon aerogel (Ni/CA-35) showed the highest capacitance (110 F/g) and excellent charge/discharge behavior. The enhanced capacitance of Ni-doped carbon aerogel was attributed to the faradaic redox reactions of nano-sized nickel oxide. Moreover, Ni-doped carbon aerogel exhibited quite stable cyclability, indicating long-term electrochemical stability.

Synthesis and Characterization of Highly Crystalline Graphene Aerogels

DOE PAGES

Worsley, Marcus A.; Pham, Thang T.; Yan, Aiming; ...

2014-10-06

Aerogels are used in a broad range of scientific and industrial applications due to their large surface areas, ultrafine pore sizes, and extremely low densities. Recently, a large number of reports have described graphene aerogels based on the reduction of graphene oxide (GO). Though these GO-based aerogels represent a considerable advance relative to traditional carbon aerogels, they remain significantly inferior to individual graphene sheets due to their poor crystallinity. Here, we report a straightforward method to synthesize highly crystalline GO-based graphene aerogels via high-temperature processing common in commercial graphite production. The crystallization of the graphene aerogels versus annealing temperature ismore » characterized using Raman and X-ray absorption spectroscopy, X-ray diffraction, and electron microscopy. Nitrogen porosimetry shows that the highly crystalline graphene macrostructure maintains a high surface area and ultrafine pore size. Because of their enhanced crystallinity, these graphene aerogels exhibit a ~200 °C improvement in oxidation temperature and an order of magnitude increase in electrical conductivity.« less

Analyses of Hubble Space Telescope Aluminized-Teflon Insulation Retrieved After 19 Years of Space Exposure

NASA Technical Reports Server (NTRS)

deGroh, Kim K.; Waters, Deborah L.; Mohammed, Jelila S.; Perry, Bruce A.; Banks, Bruce A.

2012-01-01

Since its launch in April 1990, the Hubble Space Telescope (HST) has made many important observations from its vantage point in low Earth orbit (LEO). However, as seen during five servicing missions, the outer layer of multilayer insulation (MLI) has become successively more embrittled and has cracked in many areas. In May 2009, during the 5th servicing mission (called SM4), two MLI blankets were replaced with new insulation pieces and the space-exposed MLI blankets were retrieved for degradation analyses by teams at NASA Glenn Research Center (GRC) and NASA Goddard Space Flight Center (GSFC). The MLI blankets were from Equipment Bay 8, which received direct sunlight, and Equipment Bay 5, which received grazing sunlight. Each blanket contained a range of unique regions based on environmental exposure and/or physical appearance. The retrieved MLI blanket s aluminized-Teflon (DuPont) fluorinated ethylene propylene (Al-FEP) outer layers have been analyzed for changes in optical, physical, and mechanical properties, along with space induced chemical and morphological changes. When compared to pristine material, the analyses have shown how the Al-FEP was severely affected by the space environment. This paper reviews tensile properties, solar absorptance, thermal emittance, x-ray photoelectron spectroscopy (XPS) data and atomic oxygen erosion values of the retrieved HST blankets after 19 years of space exposure.

Carbon aerogels by pyrolysis of TEMPO-oxidized cellulose

NASA Astrophysics Data System (ADS)

Zhang, Sizhao; Feng, Jian; Feng, Junzong; Jiang, Yonggang; Ding, Feng

2018-05-01

Although carbon aerogels derived from naturally occurring materials have been developed extensively, a reasonable synthetic approach using cellulose-resource remains unclear. Here, we report a strategy to prepare carbon aerogels originated from cellulose position-selectively oxidized by TEMPO-oxidized process. Contrary to non-TEMPO-oxidized cellulose-derived carbon aerogels (NCCA) with relative loose structure, TEMPO-oxidized cellulose-derived carbon aerogels (TCCA) with tight fibrillar-continuous network are monitored, suggesting the importance of TEMPO-oxidized modification towards creating the architecture of subsequently produced carbon aerogels. TCCA endows a higher BET area despite owning slightly dense bulk density comparing with that of NCCA. The structural texture of TCCA could be maintained in a way in comparison to TEMPO-oxidized cellulose-derived aerogel, due to the integration and aggregation effect by losing the electric double layer repulsion via ionization of the surface carboxyl groups. FTIR and XPS analyses signify the evidence of non-functionalized carbon-skeleton network formation in terms of TCCA. Further, the mechanism concerning the creation of carbon aerogels is also established. These findings not only provide new insights into the production of carbon aerogels but also open up a new opportunity in the field of functional carbon materials.

An emerging platform for drug delivery: aerogel based systems.

PubMed

Ulker, Zeynep; Erkey, Can

2014-03-10

Over the past few decades, advances in "aerogel science" have provoked an increasing interest for these materials in pharmaceutical sciences for drug delivery applications. Because of their high surface areas, high porosities and open pore structures which can be tuned and controlled by manipulation of synthesis conditions, nanostructured aerogels represent a promising class of materials for delivery of various drugs as well as enzymes and proteins. Along with biocompatible inorganic aerogels and biodegradable organic aerogels, more complex systems such as surface functionalized aerogels, composite aerogels and layered aerogels have also been under development and possess huge potential. Emphasis is given to the details of the aerogel synthesis and drug loading methods as well as the influence of synthesis parameters and loading methods on the adsorption and release of the drugs. Owing to their ability to increase the bioavailability of low solubility drugs, to improve both their stability and their release kinetics, there are an increasing number of research articles concerning aerogels in different drug delivery applications. This review presents an up to date overview of the advances in all kinds of aerogel based drug delivery systems which are currently under investigation. Copyright © 2014 Elsevier B.V. All rights reserved.

Horowitz shows off the hand-crafted thermal insulation he made for the HST

NASA Image and Video Library

1997-02-18

S82-E-5686 (17 Feb. 1997) --- Astronaut Scott J. Horowitz, STS-82 pilot, shows the hand-crafted thermal insulation blanket to support the goal of the final Extravehicular Activity (EVA) to cover tears in Hubble Space Telescope's (HST) insulation caused by changes in thermal conditions. This view was taken with an Electronic Still Camera (ESC).

Low density, resorcinol-formaldehyde aerogels

DOEpatents

Pekala, R.W.

1988-05-26

The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer ''clusters''. The covalent crosslinking of these ''clusters'' produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density less than or equal to100 mg/cc; cell size less than or equal to0.1 microns). The aerogels are transparent,dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 A/degree/. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron. 1 fig., 1 tab.

The conversion of a room temperature NaK loop to a high temperature MHD facility for Li/V blanket testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reed, C.B.; Haglund, R.C.; Miller, M.E.

1996-12-31

The Vanadium/Lithium system has been the recent focus of ANL`s Blanket Technology Pro-ram, and for the last several years, ANL`s Liquid Metal Blanket activities have been carried out in direct support of the ITER (International Thermonuclear Experimental Reactor) breeding blanket task area. A key feasibility issue for the ITER Vanadium/Lithium breeding blanket is the Near the development of insulator coatings. Design calculations, Hua and Gohar, show that an electrically insulating layer is necessary to maintain an acceptably low magneto-hydrodynamic (MHD) pressure drop in the current ITER design. Consequently, the decision was made to convert Argonne`s Liquid Metal EXperiment (ALEX) frommore » a 200{degrees}C NaK facility to a 350{degrees}C lithium facility. The upgraded facility was designed to produce MHD pressure drop data, test section voltage distributions, and heat transfer data for mid-scale test sections and blanket mockups at Hartmann numbers (M) and interaction parameters (N) in the range of 10{sup 3} to 10{sup 5} in lithium at 350{degrees}C. Following completion of the upgrade work, a short performance test was conducted, followed by two longer multiple-hour, MHD tests, all at 230{degrees}C. The modified ALEX facility performed up to expectations in the testing. MHD pressure drop and test section voltage distributions were collected at Hartmann numbers of 1000.« less

Multiscale Computer Simulation of Tensile and Compressive Strain in Polymer- Coated Silica Aerogels

NASA Technical Reports Server (NTRS)

Good, Brian

2009-01-01

While the low thermal conductivities of silica aerogels have made them of interest to the aerospace community as lightweight thermal insulation, the application of conformal polymer coatings to these gels increases their strength significantly, making them potentially useful as structural materials as well. In this work we perform multiscale computer simulations to investigate the tensile and compressive strain behavior of silica and polymer-coated silica aerogels. Aerogels are made up of clusters of interconnected particles of amorphous silica of less than bulk density. We simulate gel nanostructure using a Diffusion Limited Cluster Aggregation (DLCA) procedure, which produces aggregates that exhibit fractal dimensions similar to those observed in real aerogels. We have previously found that model gels obtained via DLCA exhibited stress-strain curves characteristic of the experimentally observed brittle failure. However, the strain energetics near the expected point of failure were not consistent with such failure. This shortcoming may be due to the fact that the DLCA process produces model gels that are lacking in closed-loop substructures, compared with real gels. Our model gels therefore contain an excess of dangling strands, which tend to unravel under tensile strain, producing non-brittle failure. To address this problem, we have incorporated a modification to the DLCA algorithm that specifically produces closed loops in the model gels. We obtain the strain energetics of interparticle connections via atomistic molecular statics, and abstract the collective energy of the atomic bonds into a Morse potential scaled to describe gel particle interactions. Polymer coatings are similarly described. We apply repeated small uniaxial strains to DLCA clusters, and allow relaxation of the center eighty percent of the cluster between strains. The simulations produce energetics and stress-strain curves for looped and nonlooped clusters, for a variety of densities and

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R

NASA Astrophysics Data System (ADS)

Stochl, Robert J.; Knoll, Richard H.

1991-06-01

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on a 87.6 in diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure.

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R

NASA Astrophysics Data System (ADS)

Stochl, Robert J.; Knoll, Richard H.

1991-06-01

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on an 87.6 in. diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr, respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure.

Crystalline boron nitride aerogels

DOEpatents

Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

2017-04-04

This disclosure provides methods and materials related to boron nitride aerogels. In one aspect, a material comprises an aerogel comprising boron nitride. The boron nitride has an ordered crystalline structure. The ordered crystalline structure may include atomic layers of hexagonal boron nitride lying on top of one another, with atoms contained in a first layer being superimposed on atoms contained in a second layer.

Demonstration of Hybrid Multilayer Insulation for Fixed Thickness Applications

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Fesmire, J. E.; Heckle, K. W.

2015-12-01

Cryogenic multilayer insulation (MLI) systems provide both conductive and radiative thermal insulation performance. The use of radiation shields with low conductivity spacers in between are required. By varying the distance and types of the spacers between the radiation shields, the relative radiation and conduction heat transfers can be manipulated. However, in most systems, there is a fixed thickness or volume allocated to the insulation. To understand how various combinations of different multilayer insulation (MLI) systems work together and to further validate thermal models of hybrid MLI systems, test data are needed. The MLI systems include combinations of Load-Bearing MLI (LB-MLI) and traditional MLI (tMLI). To further simulate the space launch vehicle case wherein both ambient pressure and vacuum environments are addressed, different cold-side thermal insulation substrates were included for select tests. The basic hybrid construction consists of some number of layers of LB-MLI on the cold side of the insulation system followed by layers of tMLI on the warm side of the system. The advantages of LB-MLI on the cold side of the insulation blanket are that its low layer density (0.5 - 0.6 layer/mm) is better suited for lower temperature applications and is a structural component to support heat interception shields that may be placed within the blanket. The advantage of tMLI systems on the warm side is that radiation is more dominant than conduction at warmer temperatures, so that a higher layer density is desired (2 - 3 layer/mm) and less effort need be put into minimizing conduction heat transfer. Liquid nitrogen boiloff test data using a cylindrical calorimeter are presented along with analysis for spacecraft tank applications.

Preparation of Silica Aerogel from TEOS

PubMed

Tamon; Kitamura; Okazaki

1998-01-15

Silica alcogels were synthesized by the sol-gel polymerization of tetraethylorthosilicate (TEOS). In the synthesis, HCl and NH3 were used as hydrolysis and condensation catalysts. The gelation time became short and the visible light transmittance increased with increasing the amount of HCl or lengthening the hydrolysis time. The alcogels were dried under supercritical conditions with carbon dioxide, and silica aerogels were obtained. As a result of characterization by visible light transmission and N2 adsorption, the aerogels are mesoporous materials with high surface areas. The experimental results suggest that the aerogel properties are not influenced by the drying conditions such as extraction temperature, extraction time, depressurizing temperature, and depressurizing rate. On the other hand, the properties are changed under the conditions of sol-gel polymerization. In the preparation of highly transparent aerogels with high surface areas and large pore volumes, it is necessary to synthesize highly transparent alcogels. It is found that the visible light transmittance of alcogels is an index for preparing aerogels from TEOS. Copyright 1998 Academic Press. Copyright 1998Academic Press

Hydrogen crystallization in low-density aerogels.

PubMed

Kucheyev, S O; Van Cleve, E; Johnston, L T; Gammon, S A; Worsley, M A

2015-04-07

Crystallization of liquids confined in disordered low-density nanoporous scaffolds is poorly understood. Here, we use relaxation calorimetry to study the liquid-solid phase transition of H2 in a series of silica and carbon (nanotube- and graphene-based) aerogels with porosities ≳94%. Results show that freezing temperatures of H2 inside all the aerogels studied are depressed but do not follow predictions of the Gibbs-Thomson theory based on average pore diameters measured by conventional gas sorption techniques. Instead, we find that, for each material family investigated, the depression of average freezing temperatures scales linearly with the ratio of the internal surface area (measured by gas sorption) and the total pore volume derived from the density of aerogel monoliths. The slope of such linear dependences is, however, different for silica and carbon aerogels, which we attribute to microporosity of carbons and the presence of macropores in silica aerogels. Our results have important implications for the analysis of pore size distributions of low-density nanoporous materials and for controlling crystallization of fuel layers in targets for thermonuclear fusion energy applications.

Structure of starch aerogel as affected by crosslinking and feasibility assessment of the aerogel for an anti-fungal volatile release.

PubMed

Abhari, Negar; Madadlou, Ashkan; Dini, Ali

2017-04-15

Starch suspensions were crosslinked with trisodium citrate for either 0 or 17h, gelled and then freeze-dried to corresponding aerogels. The aerogel from the 17h-crosslinked suspension was loaded with the antifungal compound, trans-2-hexenal, and coated with the surfactant, sorbitan monooleate. Aerogel hardness was increased by the citrate-mediated crosslinking, whereas its adhesiveness decreased. Starch gelation decreased the crystallinity index (CrI) from 59% to ≈23%; however, the pre-gelation crosslinking resulted in a higher CrI value (i.e. ≈38%) for the aerogel. The voids at the internal microstructure of the 17h-crosslinked aerogel were more uniform and coating with surfactant closed the surface openings. The latter accordingly resulted in a more sustained release of the volatile, trans-2-hexenal, from the crosslinked starch aerogel and led to slower lethality of Aspergillus parasiticus cells inoculated on pistachio nuts compared with the non-coated condition. Copyright © 2016 Elsevier Ltd. All rights reserved.

Composite flexible insulation for thermal protection of space vehicles

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A.; Tran, Huy K.; Chiu, S. Amanda

1991-01-01

A composite flexible blanket insulation (CFBI) system considered for use as a thermal protection system for space vehicles is described. This flexible composite insulation system consists of an outer layer of silicon carbide fabric, followed by alumina mat insulation, and alternating layers of aluminized polyimide film and aluminoborosilicate scrim fabric. A potential application of this composite insulation would be as a thermal protection system for the aerobrake of the aeroassist space transfer vehicle (ASTV). It would also apply to other space vehicles subject to high convective and radiative heating during atmospheric entry. The thermal performance of this composite insulation as exposed to a simulated atmospheric entry environment in a plasma arc test facility is described. Other thermophysical properties which affect the thermal response of this composite insulation is included. It shows that this composite insulation is effective as a thermal protection system at total heating rates up to 30.6 W/sq cm.

Composite flexible insulation for thermal protection of space vehicles

NASA Astrophysics Data System (ADS)

Kourtides, Demetrius A.; Tran, Huy K.; Chiu, S. Amanda

1992-09-01

A composite flexible blanket insulation (CFBI) system considered for use as a thermal protection system for space vehicles is described. This flexible composite insulation system consists of an outer layer of silicon carbide fabric, followed by alumina mat insulation, and alternating layers of aluminized polyimide film and aluminoborosilicate scrim fabric. A potential application of this composite insulation would be as a thermal protection system for the aerobrake of the Aeroassist Space Transfer Vehicle (ASTV). It would also apply to other space vehicles subject to high convective and radiative heating during atmospheric entry. The thermal performance of this composite insulation as exposed to a simulated atmospheric entry environment in a plasma arc test facility is described. Other thermophysical properties which affect the thermal response of this system are also described. Analytical modeling describing the thermal performance of this composite insulation is included. It shows that this composite insulation is effective as a thermal protection system at total heating rates up to 30.6 W/sq cm.

High strength air-dried aerogels

DOEpatents

Coronado, Paul R.; Satcher, Jr., Joe H.

2012-11-06

A method for the preparation of high strength air-dried organic aerogels. The method involves the sol-gel polymerization of organic gel precursors, such as resorcinol with formaldehyde (RF) in aqueous solvents with R/C ratios greater than about 1000 and R/F ratios less than about 1:2.1. Using a procedure analogous to the preparation of resorcinol-formaldehyde (RF) aerogels, this approach generates wet gels that can be air dried at ambient temperatures and pressures. The method significantly reduces the time and/or energy required to produce a dried aerogel compared to conventional methods using either supercritical solvent extraction. The air dried gel exhibits typically less than 5% shrinkage.

Method of casting aerogels

DOEpatents

Poco, John F.

1993-01-01

The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm.sup.3 to 0.6 g/cm.sup.3. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of alcogel which occurs during the drying step of supercritical extraction of solvent.

Comparison of thermal insulation performance of fibrous materials for the advanced space suit.

PubMed

Paul, Heather L; Diller, Kenneth R

2003-10-01

The current multi-layer insulation used in the extravehicular mobility unit (EMU) will not be effective in the atmosphere of Mars due to the presence of interstitial gases. Alternative thermal insulation means have been subjected to preliminary evaluation by NASA to attempt to identify a material that will meet the target conductivity of 0.005 W/m-K. This study analyzes numerically the thermal conductivity performance for three of these candidate insulating fiber materials in terms of various denier (size), interstitial void fractions, interstitial void media, and orientations to the applied temperature gradient to evaluate their applicability for the new Mars suit insulation. The results demonstrate that the best conductive insulation is achieved for a high-void-fraction configuration with a grooved fiber cross section, aerogel void medium, and the fibers oriented normal to the heat flux vector. However, this configuration still exceeds the target thermal conductivity by a factor of 1.5.

Polymer-Attached Functional Inorganic-Organic Hybrid Nano-Composite Aerogels

DTIC Science & Technology

2003-01-01

drugs. The chemistry to synthesize polyamino- siloxane based aerogel composite was discussed. In addition, two approaches to synthesize PHEMA aerogel... Composite Aerogels DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the following report: TITLE: Materials...Proc. Vol. 740 © 2003 Materials Research Society 112.24 Polymer-Attached Functional Inorganic-Organic Hybrid Nano- composite Aerogels Xipeng Liu, Mingzhe

Highly compressible 3D periodic graphene aerogel microlattices

PubMed Central

Zhu, Cheng; Han, T. Yong-Jin; Duoss, Eric B.; Golobic, Alexandra M.; Kuntz, Joshua D.; Spadaccini, Christopher M.; Worsley, Marcus A.

2015-01-01

Graphene is a two-dimensional material that offers a unique combination of low density, exceptional mechanical properties, large surface area and excellent electrical conductivity. Recent progress has produced bulk 3D assemblies of graphene, such as graphene aerogels, but they possess purely stochastic porous networks, which limit their performance compared with the potential of an engineered architecture. Here we report the fabrication of periodic graphene aerogel microlattices, possessing an engineered architecture via a 3D printing technique known as direct ink writing. The 3D printed graphene aerogels are lightweight, highly conductive and exhibit supercompressibility (up to 90% compressive strain). Moreover, the Young's moduli of the 3D printed graphene aerogels show an order of magnitude improvement over bulk graphene materials with comparable geometric density and possess large surface areas. Adapting the 3D printing technique to graphene aerogels realizes the possibility of fabricating a myriad of complex aerogel architectures for a broad range of applications. PMID:25902277

Highly compressible 3D periodic graphene aerogel microlattices

DOE PAGES

Zhu, Cheng; Han, T. Yong-Jin; Duoss, Eric B.; ...

2015-04-22

Graphene is a two-dimensional material that offers a unique combination of low density, exceptional mechanical properties, large surface area and excellent electrical conductivity. Recent progress has produced bulk 3D assemblies of graphene, such as graphene aerogels, but they possess purely stochastic porous networks, which limit their performance compared with the potential of an engineered architecture. Here we report the fabrication of periodic graphene aerogel microlattices, possessing an engineered architecture via a 3D printing technique known as direct ink writing. The 3D printed graphene aerogels are lightweight, highly conductive and exhibit supercompressibility (up to 90% compressive strain). Moreover, the Young’s modulimore » of the 3D printed graphene aerogels show an order of magnitude improvement over bulk graphene materials with comparable geometric density and possess large surface areas. Ultimately, adapting the 3D printing technique to graphene aerogels realizes the possibility of fabricating a myriad of complex aerogel architectures for a broad range of applications.« less

Thermal Performance Testing of Cryogenic Insulation Systems

NASA Technical Reports Server (NTRS)

Fesmire, James E.; Augustynowicz, Stan D.; Scholtens, Brekke E.

2007-01-01

Efficient methods for characterizing thermal performance of materials under cryogenic and vacuum conditions have been developed. These methods provide thermal conductivity data on materials under actual-use conditions and are complementary to established methods. The actual-use environment of full temperature difference in combination with vacuum-pressure is essential for understanding insulation system performance. Test articles include solids, foams, powders, layered blankets, composite panels, and other materials. Test methodology and apparatus design for several insulation test cryostats are discussed. The measurement principle is liquid nitrogen boil-off calorimetry. Heat flux capability ranges from approximately 0.5 to 500 watts per square meter; corresponding apparent thermal conductivity values range from below 0.01 up to about 60 mW/m- K. Example data for different insulation materials are also presented. Upon further standardization work, these patented insulation test cryostats can be available to industry for a wide range of practical applications.

Hydrogen Crystallization in Low-Density Aerogels

DOE PAGES

Kucheyev, S. O.; Van Cleve, E.; Johnston, L. T.; ...

2015-03-17

Crystallization of liquids confined in disordered low-density nanoporous scaffolds is poorly understood. Here in this work, we use relaxation calorimetry to study the liquid–solid phase transition of H 2 in a series of silica and carbon (nanotube- and graphene-based) aerogels with porosities ≳94%. Results show that freezing temperatures of H 2 inside all the aerogels studied are depressed but do not follow predictions of the Gibbs–Thomson theory based on average pore diameters measured by conventional gas sorption techniques. Instead, we find that, for each material family investigated, the depression of average freezing temperatures scales linearly with the ratio of themore » internal surface area (measured by gas sorption) and the total pore volume derived from the density of aerogel monoliths. The slope of such linear dependences is, however, different for silica and carbon aerogels, which we attribute to microporosity of carbons and the presence of macropores in silica aerogels. In conclusion, our results have important implications for the analysis of pore size distributions of low-density nanoporous materials and for controlling crystallization of fuel layers in targets for thermonuclear fusion energy applications.« less

Chemical modification of graphene aerogels for electrochemical capacitor applications.

PubMed

Hong, Jin-Yong; Wie, Jeong Jae; Xu, Yu; Park, Ho Seok

2015-12-14

Graphene aerogel is a relatively new type of aerogel that is ideal for energy storage applications because of its large surface area, high electrical conductivity and good chemical stability. Also, three dimensional interconnected macropores offer many advantages such as low density, fast ion and mass transfer, and easy access to storage sites. Such features allow graphene aerogels to be intensively applied for electrochemical capacitor applications. Despite the growing interest in graphene aerogel-based electrochemical capacitors, however, the graphene aerogels still suffer from their low capacitive performances and high fragility. Both relatively low capacitance and brittleness of physically crosslinked graphene aerogels remain a critical challenge. Until now, a number of alternative attempts have been devoted to overcome these shortcomings. In this perspective, we summarize the recent research progress towards the development of advanced graphene aerogel-based electrochemical capacitors according to the different approaches (e.g. porosity, composition and structure controls). Then, the recently proposed chemical strategies to improve the capacitive performances and mechanical durability of graphene aerogels for practical applications are highlighted. Finally, the current challenges and perspectives in this emerging material are also discussed.

Ultralight boron nitride aerogels via template-assisted chemical vapor deposition

PubMed Central

Song, Yangxi; Li, Bin; Yang, Siwei; Ding, Guqiao; Zhang, Changrui; Xie, Xiaoming

2015-01-01

Boron nitride (BN) aerogels are porous materials with a continuous three-dimensional network structure. They are attracting increasing attention for a wide range of applications. Here, we report the template-assisted synthesis of BN aerogels by catalyst-free, low-pressure chemical vapor deposition on graphene-carbon nanotube composite aerogels using borazine as the B and N sources with a relatively low temperature of 900 °C. The three-dimensional structure of the BN aerogels was achieved through the structural design of carbon aerogel templates. The BN aerogels have an ultrahigh specific surface area, ultralow density, excellent oil absorbing ability, and high temperature oxidation resistance. The specific surface area of BN aerogels can reach up to 1051 m2 g−1, 2-3 times larger than the reported BN aerogels. The mass density can be as low as 0.6 mg cm−3, much lower than that of air. The BN aerogels exhibit high hydrophobic properties and can absorb up to 160 times their weight in oil. This is much higher than porous BN nanosheets reported previously. The BN aerogels can be restored for reuse after oil absorption simply by burning them in air. This is because of their high temperature oxidation resistance and suggests broad utility as water treatment tools. PMID:25976019

Ultralight boron nitride aerogels via template-assisted chemical vapor deposition.

PubMed

Song, Yangxi; Li, Bin; Yang, Siwei; Ding, Guqiao; Zhang, Changrui; Xie, Xiaoming

2015-05-15

Boron nitride (BN) aerogels are porous materials with a continuous three-dimensional network structure. They are attracting increasing attention for a wide range of applications. Here, we report the template-assisted synthesis of BN aerogels by catalyst-free, low-pressure chemical vapor deposition on graphene-carbon nanotube composite aerogels using borazine as the B and N sources with a relatively low temperature of 900 (°)C. The three-dimensional structure of the BN aerogels was achieved through the structural design of carbon aerogel templates. The BN aerogels have an ultrahigh specific surface area, ultralow density, excellent oil absorbing ability, and high temperature oxidation resistance. The specific surface area of BN aerogels can reach up to 1051 m(2) g(-1), 2-3 times larger than the reported BN aerogels. The mass density can be as low as 0.6 mg cm(-3), much lower than that of air. The BN aerogels exhibit high hydrophobic properties and can absorb up to 160 times their weight in oil. This is much higher than porous BN nanosheets reported previously. The BN aerogels can be restored for reuse after oil absorption simply by burning them in air. This is because of their high temperature oxidation resistance and suggests broad utility as water treatment tools.

Multipurpose hardened spacecraft insulation

NASA Technical Reports Server (NTRS)

Steimer, Carlos H.

1990-01-01

A Multipurpose Hardened Spacecraft Multilayer Insulation (MLI) system was developed and implemented to meet diverse survivability and performance requirements. Within the definition and confines of a MLI assembly (blanket), the design: (1) provides environmental protection from natural and induced nuclear, thermal, and electromagnetic radiation; (2) provides adequate electrostatic discharge protection for a geosynchronous satellite; (3) provides adequate shielding to meet radiated emission needs; and (4) will survive ascent differential pressure loads between enclosed volume and space. The MLI design is described which meets these requirements and design evolution and verification is discussed. The application is for MLI blankets which closeout the area between the laser crosslink subsystem (LCS) equipment and the DSP spacecraft cabin. Ancillary needs were implemented to ease installation at launch facility and to survive ascent acoustic and vibration loads. Directional venting accommodations were also incorporated to avoid contamination of LCS telescope, spacecraft sensors, and second surface mirrors (SSMs).

High specific surface area aerogel cryoadsorber for vacuum pumping applications

DOEpatents

Hill, Randal M.; Fought, Eric R.; Biltoft, Peter J.

2000-01-01

A cryogenic pumping system is provided, comprising a vacuum environment, an aerogel sorbent formed from a carbon aerogel disposed within the vacuum environment, and cooling means for cooling the aerogel sorbent sufficiently to adsorb molecules from the vacuum environment onto the aerogel sorbent. Embodiments of the invention include a liquid refrigerant cryosorption pump, a compressed helium cryogenic pump, a cryopanel and a Meissner coil, each of which uses carbon aerogel as a sorbent material.

Nitrogen-doped carbon aerogels for electrical energy storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, Patrick; Montalvo, Elizabeth; Baumann, Theodore F.

Disclosed here is a method for making a nitrogen-doped carbon aerogel, comprising: preparing a reaction mixture comprising formaldehyde, at least one nitrogen-containing resorcinol analog, at least one catalyst, and at least one solvent; curing the reaction mixture to produce a wet gel; drying the wet gel to produce a dry gel; and thermally annealing the dry gel to produce the nitrogen-doped carbon aerogel. Also disclosed is a nitrogen-doped carbon aerogel obtained according to the method and a supercapacitor comprising the nitrogen-doped carbon aerogel.

Aerogels Derived from Polymer Nanofibers and Their Applications.

PubMed

Qian, Zhenchao; Wang, Zhen; Zhao, Ning; Xu, Jian

2018-03-08

Aerogels are gels in which the solvent is supplanted by air while the pores and networks are largely maintained. Owing to their low bulk density, high porosity, and large specific surface area (SSA), aerogels are promising for many applications. Various inorganic aerogels, e.g., silica aerogels, are intensively studied. However, the mechanical brittleness of common inorganic aerogels has seriously restricted their applications. In the past decade, nanofibers have been developed as building blocks for the construction of aerogels to improve their mechanical property. Unlike traditional frameworks constructed by interconnected particles, nanofibers can form chemically cross-linked and/or physically entangled 3D skeletons, thus showing flexibility instead of brittleness. Therefore, excellent elasticity and toughness, ultralow density, high SSA, and tunable chemical composition can be expected for the polymer nanofiber-derived aerogels (PNAs). In this review, recent research progress in the fabrication, properties, and applications of PNAs is summarized. Various nanofibers, including nanocelluloses, nanochitins, and electrospun nanofibers are included, as well as carbon nanofibers from the corresponding organic precursors. Typical applications in supercapacitors, electrocatalysts for oxygen reduction reaction, flexible electrodes, oil absorbents, adsorbents, tissue engineering, stimuli-responsive materials, and catalyst carriers, are presented. Finally, the challenges and future development of PNAs are discussed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composite ceria-coated aerogels and methods of making the same

DOEpatents

Eyring, Edward M; Ernst, Richard D; Turpin, Gregory C; Dunn, Brian C

2013-05-07

Ceria-coated aerogels can include an aerogel support material having a stabilized ceria coating thereon. The ceria coating can be formed by solution or vapor deposition of alcogels or aerogels. Additional catalytic metal species can also be incorporated into the coating to form multi-metallic compounds having improved catalytic activity. Further, the ceria coated aerogels retain high surface areas at elevated temperatures. Thus, improvements in catalytic activity and thermal stability can be achieved using these ceria-coated composite aerogels.

The Structural Heat Intercept-Insulation-Vibration Evaluation Rig (SHIVER)

NASA Technical Reports Server (NTRS)

Johnson, W. L.; Zoeckler, J. G.; Best-Ameen, L. M.

2015-01-01

NASA is currently investigating methods to reduce the boil-off rate on large cryogenic upper stages. Two such methods to reduce the total heat load on existing upper stages are vapor cooling of the cryogenic tank support structure and integration of thick multilayer insulation systems to the upper stage of a launch vehicle. Previous efforts have flown a 2-layer MLI blanket and shown an improved thermal performance, and other efforts have ground-tested blankets up to 70 layers thick on tanks with diameters between 2 3 meters. However, thick multilayer insulation installation and testing in both thermal and structural modes has not been completed on a large scale tank. Similarly, multiple vapor cooled shields are common place on science payload helium dewars; however, minimal effort has gone into intercepting heat on large structural surfaces associated with rocket stages. A majority of the vapor cooling effort focuses on metallic cylinders called skirts, which are the most common structural components for launch vehicles. In order to provide test data for comparison with analytical models, a representative test tank is currently being designed to include skirt structural systems with integral vapor cooling. The tank is 4 m in diameter and 6.8 m tall to contain 5000 kg of liquid hydrogen. A multilayer insulation system will be designed to insulate the tank and structure while being installed in a representative manner that can be extended to tanks up to 10 meters in diameter. In order to prove that the insulation system and vapor cooling attachment methods are structurally sound, acoustic testing will also be performed on the system. The test tank with insulation and vapor cooled shield installed will be tested thermally in the B2 test facility at NASAs Plumbrook Station both before and after being vibration tested at Plumbrooks Space Power Facility.

Measurements of rates of cooling of a manikin insulated with different mountain rescue casualty bags.

PubMed

Press, Christopher; Duffy, Christopher; Williams, Jonathan; Cooper, Ben; Chapman, Neil

2017-01-01

Accidental hypothermia is common in those who sustain injuries in remote environments. This is unpleasant and associated with adverse effects on subsequent patient outcomes. To minimise further heat loss, a range of insulating systems are available to mountain rescue teams although the most effective and cost-efficient have yet to be determined. Under ambient, still, dry, air conditions, a thermal manikin was filled with water at a temperature of 42 °C and then placed into a given insulation system. Water temperature was then continuously observed via an in-dwelling temperature sensor linked to a PROPAQ 100 series monitor and recorded every 10 min for 130 min. This method was repeated for each insulating package. The vacuum mattress/Pertex©/fibrepile blanket system, either on its own or coupled with the Wiggy bag, was the most efficient with water temperatures only decreasing by 3.2 °C over 130 min. This was followed by the heavy-weight casualty bags without the vacuum mattress/Pertex©/fibrepile blanket system, decreasing by 4.2-4.3 °C. With the Blizzard bag, a decline in water temperature of 5.4 °C was seen over the study duration while a decrease of 9.5 °C was noted when the plastic survival bag was employed. Under the still-air conditions of the study, the vacuum mattress/Pertex©/fibrepile blanket was seen to offer comparable insulation effectiveness compared to be both heavy-weight casualty bags. In turn, these three systems appeared more efficient at insulating the manikin than the Blizzard bag or plastic survival bag.

Thermal Performance of Cryogenic Multilayer Insulation at Various Layer Spacings

NASA Technical Reports Server (NTRS)

Johnson, Wesley Louis

2010-01-01

Multilayer insulation (MLI) has been shown to be the best performing cryogenic insulation system at high vacuum (less that 10 (exp 3) torr), and is widely used on spaceflight vehicles. Over the past 50 years, many investigations into MLI have yielded a general understanding of the many variables that are associated with MLI. MLI has been shown to be a function of variables such as warm boundary temperature, the number of reflector layers, and the spacer material in between reflectors, the interstitial gas pressure and the interstitial gas. Since the conduction between reflectors increases with the thickness of the spacer material, yet the radiation heat transfer is inversely proportional to the number of layers, it stands to reason that the thermal performance of MLI is a function of the number of layers per thickness, or layer density. Empirical equations that were derived based on some of the early tests showed that the conduction term was proportional to the layer density to a power. This power depended on the material combination and was determined by empirical test data. Many authors have graphically shown such optimal layer density, but none have provided any data at such low densities, or any method of determining this density. Keller, Cunnington, and Glassford showed MLI thermal performance as a function of layer density of high layer densities, but they didn't show a minimal layer density or any data below the supposed optimal layer density. However, it was recently discovered that by manipulating the derived empirical equations and taking a derivative with respect to layer density yields a solution for on optimal layer density. Various manufacturers have begun manufacturing MLI at densities below the optimal density. They began this based on the theory that increasing the distance between layers lowered the conductive heat transfer and they had no limitations on volume. By modifying the circumference of these blankets, the layer density can easily be

Evaluating Dimethyldiethoxysilane for use in Polyurethane Crosslinked Silica Aerogels

NASA Technical Reports Server (NTRS)

Randall, Jason P.; Meador, Mary Ann B.; Jana, Sadhan C.

2008-01-01

Silica aerogels are highly porous materials which exhibit exceptionally low density and thermal conductivity. Their "pearl necklace" nanostructure, however, is inherently weak; most silica aerogels are brittle and fragile. The strength of aerogels can be improved by employing an additional crosslinking step using isocyanates. In this work, dimethyldiethoxysilane (DMDES) is evaluated for use in the silane backbone of polyurethane crosslinked aerogels. Approximately half of the resulting aerogels exhibited a core/shell morphology of hard crosslinked aerogel surrounding a softer, uncrosslinked center. Solid state NMR and scanning electron microscopy results indicate the DMDES incorporated itself as a conformal coating around the outside of the secondary silica particles, in much the same manner as isocyanate crosslinking. Response surface curves were generated from compression data, indicating levels of reinforcement comparable to that in previous literature, despite the core/shell morphology.

Production of hollow aerogel microspheres

DOEpatents

Upadhye, Ravindra S.; Henning, Sten A.

1993-01-01

A method is described for making hollow aerogel microspheres of 800-1200 .mu. diameter and 100-300 .mu. wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

Venting through multiple-layer insulation on Space Station Freedom. II - Ascent rate pressure chamber testing

NASA Technical Reports Server (NTRS)

Sharp, Jeffrey B.; Buitekant, Alan; Fay, John F.; Holladay, Jon B.

1993-01-01

A test was conducted to determine the venting characteristics of the multiple-layer insulation (MLI) to be installed on the Space Station Freedom (SSF). A full MLI blanket with inter-blanket joints was installed onto a model of a section of the SSF pressure wall, support structure, and debris shield. Data were taken from this test and were used to predict the venting of the actual Space Station pressure-wall/MLI/debris-shield assemply during launch and possible re-entry. It was found that the pressure differences across the debris shields and MLI blankets were well within the specified limits in all cases.

Ambient pressure process for preparing aerogel thin films reliquified sols useful in preparing aerogel thin films

DOEpatents

Brinker, Charles Jeffrey; Prakash, Sai Sivasankaran

1999-01-01

A method for preparing aerogel thin films by an ambient-pressure, continuous process. The method of this invention obviates the use of an autoclave and is amenable to the formation of thin films by operations such as dip coating. The method is less energy intensive and less dangerous than conventional supercritical aerogel processing techniques.

Evaluation of supercritical CO2 dried cellulose aerogels as nano-biomaterials

NASA Astrophysics Data System (ADS)

Lee, Sinah; Kang, Kyu-Young; Jeong, Myung-Joon; Potthast, Antje; Liebner, Falk

2017-10-01

Cellulose is the renewable, biodegradable and abundant resource and is suggested as an alternative material to silica due to the high price and environmental load of silica. The first step for cellulose aerogel production is to dissolve cellulose, and hydrated calcium thiocyanate molten salt is one of the most effective solvents for preparing porous material. Cellulose aerogels were prepared from dissolved cellulose samples of different degree of polymerization (DP) and drying methods, and tested with shrinkage, density and mechanical strength. Supercritical CO2 dried cellulose aerogels shrank less compared to freeze-dried cellulose aerogels, whereas the densities were increased according to the DP increases in both cellulose aerogels. Furthermore, scanning electron microscope (SEM) images showed that the higher DP cellulose aerogels were more uniform with micro-porous structure. Regarding the mechanical strength of cellulose aerogels, supercritical CO2 dried cellulose aerogels with higher molecular weight were much more solid.

Slotted Polyimide-Aerogel-Filled-Waveguide Arrays

NASA Technical Reports Server (NTRS)

Rodriguez-Solis, Rafael A.; Pacheco, Hector L.; Miranda, Felix A.; Meador, Mary Ann B.

2013-01-01

Polyimide aerogels were considered to serve as a filling for millimeter-wave waveguides. While these waveguides present a slightly higher loss than hollow waveguides, they have less losses than Duroid substrate integrated waveguides (less than 0.15 dB at Ka-band, in a 20 mm section), and exhibit an order of magnitude of mass reduction when compared to commercial waveguides. A Ka-band slotted aerogel-filled-waveguide array was designed, which provided the same gain (9 dBi) as its standard waveguide counterpart, and a slotted aerogel-filled-waveguide array using folded-slots was designed for comparison, obtaining a gain of 9 dB and a bandwidth of 590 MHz.

Benefit from NASA

NASA Image and Video Library

1997-03-05

Scientists at Marshall Space Flight Center (MSFC) have been studying the properties of Aerogel for several years. Aerogel, the lightest solid known to man, has displayed a high quality for insulation. Because of its smoky countenance, it has yet to be used as an insulation on windows, but has been used in the space program on the rover Sojourner, and has been used as insulation in the walls of houses and in automobile engine compartments. As heat is applied to Aerogel, scientist Dr. David Noever of Space Sciences Laboratory, Principal Investigator of Aerogel, studies for its properties trying to uncover the secret to making Aerogel a clear substance. Once found, Aerogel will be a major component in the future of glass insulation.

Water extractable arabinoxylan aerogels prepared by supercritical CO2 drying.

PubMed

Marquez-Escalante, Jorge; Carvajal-Millan, Elizabeth; Miki-Yoshida, Mario; Alvarez-Contreras, Lorena; Toledo-Guillén, Alma Rosa; Lizardi-Mendoza, Jaime; Rascón-Chu, Agustín

2013-05-14

Water extractable arabinoxylan (WEAX) aerogels were prepared by extracting the solvent from the alcogels (WEAX hydrogels with an alcohol as the solvent) with carbon dioxide under supercritical conditions. WEAX aerogels were characterized using scanning electron microscopy and adsorption and desorption nitrogen isotherms. The micrographs indicate a heterogeneous porous network structure in WEAX aerogel. Adsorption/desorption nitrogen isotherms of this material were type IV, which confirm that this material possess a mesoporous structure. WEAX aerogels rehydration capability was evaluated and the water absorption mechanism was determined. The WEAX aerogels water absorption mechanism was non-Fickian (n = 0.54).

Mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogels

DOEpatents

Worsley, Marcus A.; Baumann, Theodore F.; Satcher, Jr., Joe H.

2016-10-04

Disclosed here is a device comprising a porous carbon aerogel or composite thereof as an energy storage material, catalyst support, sensor or adsorbent, wherein the porous carbon aerogel comprises a network of interconnected struts comprising carbon nanotube bundles covalently crosslinked by graphitic carbon nanoparticles, wherein the carbon nanotubes account for 5 to 95 wt. % of the aerogel and the graphitic carbon nanoparticles account for 5 to 95 wt. % of the aerogel, and wherein the aerogel has an electrical conductivity of at least 10 S/m and is capable of withstanding strains of more than 10% before fracture.

Conductivity enhancement of carbon aerogel by modified gelation using self additive

NASA Astrophysics Data System (ADS)

Singh, Ashish; Kohli, D. K.; Bhartiya, Sushmita; Singh, Rashmi; Rajak, Gaurav; Singh, M. K.; Karnal, A. K.

2018-04-01

Carbon aerogels having high surface area and open pore structure are being studied for many electrochemical applications such as fuel cells and super capacitors. Moderate electrical conductivity of resorcinol - formaldehyde (R-F) derived carbon aerogel limits its utility in these applications. The current manuscript briefs about the synthesis of composite carbon aerogel using carbon aerogel itself as additive during gelation of water based carbon aerogel and study the effect on its conductivity and surface properties. The additive carbon aerogel was synthesized and pre-treated at higher temperature to achieve enhancement in conductivity. The composite carbon aerogel (CCA) samples were characterized for surface area properties, morphology, electrical conductivity and specific capacitance. The surface area properties of CCA showed improvement and specific surface area of ˜1798 m2/g with total pore volume of 1.7 cm3/g. was obtained. The electrical conductivity of the composite carbon aerogel with 5 wt % additive showed improvement over the plain carbon aerogel with respective values of 144 S/m and 128 S/m. The specific capacitance evaluated for CA and CCA are 102 and 118 F/g at scan rate of 10mV/s with improvement of ˜16%.

Thio-,amine-,nitro-,and macrocyclic containing organic aerogels & xerogels

DOEpatents

Fox, Glenn A.; Tillotson, Thomas M.

2005-08-02

An organic aerogel or xerogel formed by a sol-gel reaction using starting materials that exhibit similar reactivity to the most commonly used resorcinol starting material. The new starting materials, including thio-, amine- and nitro-containing molecules and functionalized macrocyclic molecules will produce organic xerogels and aerogels that have improved performance in the areas of detection and sensor technology, as well as water stream remediation. Also, further functionalization of these new organic aerogels or xerogels will yield material that can be extracted with greater facility than current organic aerogels.

21 CFR 182.1711 - Silica aerogel.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Silica aerogel. 182.1711 Section 182.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1711 Silica aerogel. (a) Product....

21 CFR 182.1711 - Silica aerogel.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1711 Silica aerogel. (a) Product....

Design of Multilayer Insulation for the Multipurpose Hydrogen Test Bed

NASA Technical Reports Server (NTRS)

Marlow, Weston A.

2011-01-01

Multilayer insulation (MLI) is a critical component for future, long term space missions. These missions will require the storage of cryogenic fuels for extended periods of time with little to no boil-off and MLI is vital due to its exceptional radiation shielding properties. Several MLI test articles were designed and fabricated which explored methods of assembling and connecting blankets, yielding results for evaluation. Insight gained, along with previous design experience, will be used in the design of the replacement blanket for the Multipurpose Hydrogen Test Bed (MHTB), which is slated for upcoming tests. Future design considerations are discussed which include mechanical testing to determine robustness of such a system, as well as cryostat testing of samples to give insight to the loss of thermal performance of sewn panels in comparison to the highly efficient, albeit laborious application of the original MHTB blanket.

Aerogel materials with periodic structures imprinted with cellulose nanocrystals.

PubMed

Xu, Yi-Tao; Dai, Yiling; Nguyen, Thanh-Dinh; Hamad, Wadood Y; MacLachlan, Mark J

2018-02-22

Novel aerogel materials with periodic structures derived from chiral nematic liquid crystalline cellulose nanocrystals (CNCs) are reported. The liquid crystalline structure of phase-separated CNCs is locked by a simple solvent exchange method or silica condensation. Both cellulose and silica/cellulose aerogel materials were obtained after critical point drying, and subsequent calcination of the silica/cellulose composite afforded a silica aerogel with periodic order. Gas adsorption and electron microscopy studies revealed that these materials have high surface areas and a unique chiral nematic structure imparted from the helicoidal CNC template. This is a new, scalable approach to aerogel materials with highly anisotropic structures. The high porosity and periodic, chiral features of these new materials may make them suitable for applications that require anisotropic properties or as hard templates for the construction of other ordered aerogels.

Preparation and application of nanoglued binary titania-silica aerogel.

PubMed

Luo, Liang; Cooper, Adrienne T; Fan, Maohong

2009-01-15

Nanoglued binary titania (TiO2)-silica (SiO2) aerogel, as a novel type of photocatalyst, has been synthesized on glass substrates. Using an about-to-gel SiO2 sol as nanoglue, anatase TiO2 aerogel was immobilized into a three-dimensional mesoporous network of the SiO2. Factorial designs were employed to optimize both TiO2 aerogel and binary TiO2-SiO2 aerogel synthesis. Characterization of the as-prepared TiO2 and binary samples by surface area, porosity, and surface chemical composition showed that the photocatalysts were high-surface-area nanoporous materials, with a Ti4+ valency. The binary aerogel exhibited high photocatalytic activity for the degradation of methylene blue (MB) under simulated solar light; the reaction followed the pseudo first-order Langmuir-Hinshelwood (L-H) kinetic model. Fluorescence spectroscopy revealed that the hydroxyl (*OH) radical was formed during the illumination of the binary TiO2-SiO2 aerogel in a solution of probe molecules, which corroborates the probable mechanism of hydroxyl radical oxidation of contaminants in photocatalytic reactions.

Tailoring Advanced Nanoscale Materials Through Synthesis of Composite Aerogel Architectures

DTIC Science & Technology

2000-01-01

silica aerogel nanocomposites retain the characteristic yellow-green photoluminescence of ZnO nanocrystals (also illustrated by Deng, et al., for ZnO...aerogel relative to the mechanical durability of pure silica aerogel , even without thermally densifying[16b] the com- posite. 3. Chemical and...mediate to the values for the silica and guest particulate. Pure silica aerogel (~1 % dense) has a pore volume of ~4.4 cm3/g; silica-based composite

21 CFR 582.1711 - Silica aerogel.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1711 Silica aerogel. (a) Product. Silica...

21 CFR 582.1711 - Silica aerogel.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1711 Silica aerogel. (a) Product. Silica...

21 CFR 582.1711 - Silica aerogel.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1711 Silica aerogel. (a) Product. Silica...

21 CFR 582.1711 - Silica aerogel.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1711 Silica aerogel. (a) Product. Silica...

21 CFR 582.1711 - Silica aerogel.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1711 Silica aerogel. (a) Product. Silica...

Load responsive multilayer insulation performance testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dye, S.; Kopelove, A.; Mills, G. L.

Cryogenic insulation designed to operate at various pressures from one atmosphere to vacuum, with high thermal performance and light weight, is needed for cryogenically fueled space launch vehicles and aircraft. Multilayer insulation (MLI) performs well in a high vacuum, but the required vacuum shell for use in the atmosphere is heavy. Spray-on foam insulation (SOFI) is often used in these systems because of its light weight, but can have a higher heat flux than desired. We report on the continued development of Load Responsive Multilayer Insulation (LRMLI), an advanced thermal insulation system that uses dynamic beam discrete spacers that providemore » high thermal performance both in atmosphere and vacuum. LRMLI consists of layers of thermal radiation barriers separated and supported by micromolded polymer spacers. The spacers have low thermal conductance, and self-support a thin, lightweight vacuum shell that provides internal high vacuum in the insulation. The dynamic load responsive spacers compress to support the external load of a vacuum shell in one atmosphere, and decompress under reduced atmospheric pressure for lower heat leak. Structural load testing was performed on the spacers with various configurations. LRMLI was installed on a 400 liter tank and boil off testing with liquid nitrogen performed at various chamber pressures from one atmosphere to high vacuum. Testing was also performed with an MLI blanket on the outside of the LRMLI.« less

Load responsive multilayer insulation performance testing

NASA Astrophysics Data System (ADS)

Dye, S.; Kopelove, A.; Mills, G. L.

2014-01-01

Cryogenic insulation designed to operate at various pressures from one atmosphere to vacuum, with high thermal performance and light weight, is needed for cryogenically fueled space launch vehicles and aircraft. Multilayer insulation (MLI) performs well in a high vacuum, but the required vacuum shell for use in the atmosphere is heavy. Spray-on foam insulation (SOFI) is often used in these systems because of its light weight, but can have a higher heat flux than desired. We report on the continued development of Load Responsive Multilayer Insulation (LRMLI), an advanced thermal insulation system that uses dynamic beam discrete spacers that provide high thermal performance both in atmosphere and vacuum. LRMLI consists of layers of thermal radiation barriers separated and supported by micromolded polymer spacers. The spacers have low thermal conductance, and self-support a thin, lightweight vacuum shell that provides internal high vacuum in the insulation. The dynamic load responsive spacers compress to support the external load of a vacuum shell in one atmosphere, and decompress under reduced atmospheric pressure for lower heat leak. Structural load testing was performed on the spacers with various configurations. LRMLI was installed on a 400 liter tank and boil off testing with liquid nitrogen performed at various chamber pressures from one atmosphere to high vacuum. Testing was also performed with an MLI blanket on the outside of the LRMLI.

Fabrication and characterization of silica aerogel as synthetic tissues for medical imaging phantoms

NASA Astrophysics Data System (ADS)

In, Eunji; Naguib, Hani

2015-05-01

Medical imaging plays an important role in the field of healthcare industry both in clinical settings and in research and development. It is used in prevention, early detection of disease, in choosing the optimal treatment, during surgical interventions and monitoring of the treatment effects. Despite much advancement in the last few decades, rapid change on its technology development and variety of imaging parameters that differ with the manufacturer restrict its further development. Imaging phantom is a calibrating medium that is scanned or imaged in the field of medical imaging to evaluate, analyze and tune the performance of various imaging devices. A phantom used to evaluate an imaging device should respond in a similar manner to how human tissue and organs would act in that specific imaging modality. There has been many research on the phantom materials; however, there has been no attempt to study on the material that mimics the structure of lung or fibrous tissue. So with the need for development of gel with such structure, we tried to mimic this structure with aerogel. Silica aerogels have unique properties that include low density (0.003g/cm) and mesoporosity (pore size 2-50nm), with a high thermal insulation value (0.005W/mK) and high surface area (500-1200m-2/g).] In this study, we cross-linked with di-isocyanate, which is a group in polyurethane to covalently bond the polymer to the surface of silica aerogel to enhance the mechanical properties. By formation of covalent bonds, the structure can be reinforced by widening the interparticle necks while minimally reducing porosity.

Aerogel Algorithm for Shrapnel Penetration Experiments

NASA Astrophysics Data System (ADS)

Tokheim, R. E.; Erlich, D. C.; Curran, D. R.; Tobin, M.; Eder, D.

2004-07-01

To aid in assessing shrapnel produced by laser-irradiated targets, we have performed shrapnel collection "BB gun" experiments in aerogel and have developed a simple analytical model for deceleration of the shrapnel particles in the aerogel. The model is similar in approach to that of Anderson and Ahrens (J. Geophys. Res., 99 El, 2063-2071, Jan. 1994) and accounts for drag, aerogel compaction heating, and the velocity threshold for shrapnel ablation due to conductive heating. Model predictions are correlated with the BB gun results at impact velocities up to a few hundred m/s and with NASA data for impact velocities up to 6 km/s. The model shows promising agreement with the data and will be used to plan and interpret future experiments.

Thermally insulating and fire-retardant lightweight anisotropic foams based on nanocellulose and graphene oxide.

PubMed

Wicklein, Bernd; Kocjan, Andraž; Salazar-Alvarez, German; Carosio, Federico; Camino, Giovanni; Antonietti, Markus; Bergström, Lennart

2015-03-01

High-performance thermally insulating materials from renewable resources are needed to improve the energy efficiency of buildings. Traditional fossil-fuel-derived insulation materials such as expanded polystyrene and polyurethane have thermal conductivities that are too high for retrofitting or for building new, surface-efficient passive houses. Tailored materials such as aerogels and vacuum insulating panels are fragile and susceptible to perforation. Here, we show that freeze-casting suspensions of cellulose nanofibres, graphene oxide and sepiolite nanorods produces super-insulating, fire-retardant and strong anisotropic foams that perform better than traditional polymer-based insulating materials. The foams are ultralight, show excellent combustion resistance and exhibit a thermal conductivity of 15 mW m(-1) K(-1), which is about half that of expanded polystyrene. At 30 °C and 85% relative humidity, the foams retained more than half of their initial strength. Our results show that nanoscale engineering is a promising strategy for producing foams with excellent properties using cellulose and other renewable nanosized fibrous materials.

Sensitivity of dual-wall structures under hypervelocity impact to multi-layer thermal insulation thickness and placement

NASA Astrophysics Data System (ADS)

Schonberg, William P.

1993-04-01

Results are presented from an experimental study in which Al dual-wall structures were tested, under various high-speed impact conditions, with a view to the effect of multilayer insulation thickness and location on perforation resistance. Attention is given to comparisons of the damage sustained by dual-wall systems with multilayer insulation blankets of various thicknesses and at various locations within the dual-wall system, under comparable impact loading conditions. The placement of the insulation has a significant effect on the ballistic limit of the dual-wall structures considered, while reducing insulation thickness by as much as a third did not.

Study of Hygrothermal Processes in External Walls with Internal Insulation

NASA Astrophysics Data System (ADS)

Biseniece, Edite; Freimanis, Ritvars; Purvins, Reinis; Gravelsins, Armands; Pumpurs, Aivars; Blumberga, Andra

2018-03-01

Being an important contributor to the final energy consumption, historic buildings built before 1945 have high specific heating energy consumption compared to current energy standards and norms. However, they often cannot be insulated from the outside due to their heritage and culture value. Internal insulation is an alternative. However internal insulation faces challenges related to hygrothermal behaviour leading to mold growth, freezing, deterioration and other risks. The goal of this research is to link hygrothermal simulation results with experimental results for internally insulated historic brick masonry to assess correlation between simulated and measured data as well as the most influential parameters. The study is carried out by both a mathematical simulation tool and laboratory tests of historic masonry with internal insulation with four insulation materials (mineral wool, EPS, wood fiber and granulated aerogel) in a cold climate (average 4000 heating degree days). We found disparity between measured and simulated hygrothermal performance of studied constructions due to differences in material parameters and initial conditions of materials. The latter plays a more important role than material parameters. Under a steady state of conditions, the condensate tolerating system varies between 72.7 % and 80.5 % relative humidity, but in condensate limiting systems relative humidity variates between 73.3 % and 82.3 %. The temperature between the masonry wall and all insulation materials has stabilized on average at +10 °C. Mold corresponding to Mold index 3 was discovered on wood fiber mat.

Fabrication and thermal properties of tetradecanol/graphene aerogel form-stable composite phase change materials.

PubMed

Mu, Boyuan; Li, Min

2018-06-11

In this study, tetradecanol/graphene aerogel form-stable composite phase change materials were prepared by physical absorption. Two kinds of graphene aerogels were prepared using vitamin C and ethylenediamine to enhance the thermal conductivity of tetradecanol and prevent its leakage during phase transition. The form-stable composite phase change material exhibited excellent thermal energy storage capacity. The latent heat of the tetradecanol/graphene aerogel composite phase change materials with 5 wt.% graphene aerogel was similar to the theoretical latent heat of pure tetradecanol. The thermal conductivity of the tetradecanol/graphene aerogel composite phase change material improved gradually as the graphene aerogel content increased. The prepared tetradecanol/graphene aerogel composite phase change materials exhibited good thermal reliability and thermal stability, and no chemical reaction occurred between tetradecanol and the graphene aerogel. In addition, the latent heat and thermal conductivity of the tetradecanol/ethylenediamine-graphene aerogel composites were higher than those of tetradecanol/vitamin C-graphene aerogel composites, and the flexible shape of the ethylenediamine-graphene aerogel is suitable for application of the tetradecanol/ethylenediamine-graphene aerogel composite.

Aerogel sorbents

DOEpatents

Begag, Redouane; Rhine, Wendell E.; Dong, Wenting

2018-04-03

The current invention describes methods and compositions of various sorbents based on aerogels of various silanes and their use as sorbent for carbon dioxide. Methods further provide for optimizing the compositions to increase the stability of the sorbents for prolonged use as carbon dioxide capture matrices.

Aerogel sorbents

DOEpatents

Begag, Redouane; Rhine, Wendell E; Dong, Wenting

2016-04-05

The current invention describes methods and compositions of various sorbents based on aerogels of various silanes and their use as sorbent for carbon dioxide. Methods further provide for optimizing the compositions to increase the stability of the sorbents for prolonged use as carbon dioxide capture matrices.

Preparation and characterization of silica aerogels from diatomite via ambient pressure drying

NASA Astrophysics Data System (ADS)

Wang, Baomin; Ma, Hainan; Song, Kai

2014-07-01

The silica aerogels were successfully fabricated under ambient pressure from diatomite. The influence of different dilution ratios of diatomite filtrate on physical properties of aerogels were studied. The microstructure, surface functional groups, thermal stability, morphology and mechanical properties of silica aerogels based on diatomite were investigated by BET adsorption, FT-IR, DTA-TG, FESEM, TEM, and nanoindentation methods. The results indicate that the filtrate diluted with distilled water in a proportion of 1: 2 could give silica aerogels in the largest size with highest transparency. The obtained aerogels with density of 0.122-0.203 g/m3 and specific surface area of 655.5-790.7 m2/g are crack free amorphous solids and exhibited a sponge-like structure. Moreover, the peak pore size resided at 9 nm. The initial aerogels were hydrophobic, when being heat-treated around 400°C, the aerogels were transformed into hydrophilic ones. The obtained aerogel has good mechanical properties.

Silica-Aerogel Composites Opacified with La(0.7)Sr(0.3)MnO3

NASA Technical Reports Server (NTRS)

Rhine, Wendell; Polli, Andrew; Deshpande, Kiranmayi

2009-01-01

As part of an effort to develop improved lightweight thermal-insulation tiles to withstand temperatures up to 1,000 C, silica aerogel/fused-quartz-fiber composite materials containing La0.7Sr0.3MnO3 particles as opacifiers have been investigated as potentially offering thermal conductivities lower than those of the otherwise equivalent silica-aerogel composite materials not containing La(0.7)Sr(0.3)MnO3 particles. The basic idea of incorporating opacifying particles into silica-aerogels composite to reduce infrared radiative contributions to thermal conductivities at high temperatures is not new: it has been reported in a number of previous NASA Tech Briefs articles. What is new here is the selection of La(0.7)Sr(0.3)MnO3 particles as candidate opacifiers that, in comparison with some prior opacifiers (carbon black and metal nanoparticles), are more thermally stable. The preparation of a composite material of the present type includes synthesis of the silica-aerogel component in a sol-gel process. The La(0.7)Sr(0.3)MnO3 particles, made previously in a separate process, are mixed into the sol, which is then cast onto fused-quartz-fiber batting. Then the aerogel-casting solution is poured into the mold, where it permeates the silica fiber felt. After the sol has gelled, the casting is aged and then subjected to supercritical drying to convert the gel to the final aerogel form. The separate process for making the La(0.7)Sr(0.3)MnO3 particles begins with the slow addition of corresponding proportions of La(CH3COOH)3, Mn(CH3COOH)3, and Sr(NO3)2 to a solution of H2O2 in H2O. The solution is then peptized by drop-wise addition of NH4OH to obtain a sol. Next, the sol is dried in an oven at a temperature of 120 C to obtain a glassy solid. The solid is calcined at 700 C to convert it to La(0.7)Sr(0.3)MnO3. Then La(0.7)Sr(0.3)MnO3 particles are made by ball-milling the calcined solid. The effectiveness of La(0.7)Sr(0.3)MnO3 particles as opacifiers and thermal

Low dielectric constant and moisture-resistant polyimide aerogels containing trifluoromethyl pendent groups

NASA Astrophysics Data System (ADS)

Wu, Tingting; Dong, Jie; Gan, Feng; Fang, Yuting; Zhao, Xin; Zhang, Qinghua

2018-05-01

Conventional polyimide aerogels made from biphenyl-3,3‧,4,4‧-tetracarboxylic dianydride (BPDA) and 4,4‧-oxidianiline (ODA) exhibit poor resistance to moisture and mechanical properties. In this work, a versatile diamine, 2,2‧-bis-(trifluoromethyl)-4,4‧-diaminobiphenyl (TFMB), is introduced to BPDA/ODA backbone to modify the comprehensive performance of this aerogel. Among all formulations, the resulted polyimide aerogels exhibit the lowest shrinkage and density as well as highest porosity, at the ODA/TFMB molar ratio of 5/5. Dielectric constants and loss tangents of the aerogels fall in the range of 1.29-1.33 and 0.001-0.004, respectively, and more TFMB fractions results in a slightly decrease of dielectric constant and loss tangent. In addition, moisture-resistance of the aerogels are dramatically enhanced as the water absorption decreasing from 415% for BPDA/ODA to 13% for the polyimide aerogel at the ODA/TFMB molar ratio of 7/3, and even to 4% for the homo-BPDA/TFMB polyimide aerogel, showing a superhydrophobic characteristic, which is a great advantage for polyimide aerogels used as low dielectric materials. Meanwhile, all of formulations of aerogels exhibit high absorption capacities for oils and common organic solvents, indicating that these fluorinated polyimide aerogels are good candidates for the separation of oils/organic solvents and water. Mechanical properties and thermal stability of the polyimide aerogels are also raised to varying degrees due to the rigid-rod biphenyl structure introduced by TFMB.

Preparation of sponge-reinforced silica aerogels from tetraethoxysilane and methyltrimethoxysilane for oil/water separation

NASA Astrophysics Data System (ADS)

Li, Ming; Jiang, Hongyi; Xu, Dong

2018-04-01

Polyurethane sponge-reinforced silica aerogels based on tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) were fabricated by a facile method through sol-gel reaction followed by ambient pressure drying. In sponge-reinforced silica aerogels, nanoporous aerogel aggregates fill in the pores of polyurethane sponge. The sponge-reinforced aerogels are hydrophobic and oleophilic and show extremely high absorption for machine oil (10.6 g g‑1 for TEOS-based aerogel and 9.2 g g‑1 for MTMS-based aerogel). In addition, the sponge-reinforced aerogel composites exhibit notable improvements with regards to mechanical properties. The compressive strength was enhanced obviously up to about 349 KPa for TEOS-based aerogel and 60 KPa for MTMS-based aerogel. Specially, sponge-reinforced silica aerogels based on MTMS drastically shrank upon loading and then recovered to the original size when unloaded. The property differences of the sponge-reinforced silica aerogels caused by the two precursors were discussed in terms of morphologies, pore size distributions and chemical structure.

Method to produce alumina aerogels having porosities greater than 80 percent

DOEpatents

Poco, John F.; Hrubesh, Lawrence W.

2003-09-16

A two-step method for producing monolithic alumina aerogels having porosities of greater than 80 percent. Very strong, very low density alumina aerogel monoliths are prepared using the two-step sol-gel process. The method of preparing pure alumina aerogel modifies the prior known sol method by combining the use of substoichiometric water for hydrolysis, the use of acetic acid to control hydrolysis/condensation, and high temperature supercritical drying, all of which contribute to the formation of a polycrystalline aerogel microstructure. This structure provides exceptional mechanical properties of the alumina aerogel, as well as enhanced thermal resistance and high temperature stability.

Robust superhydrophobic bridged silsesquioxane aerogels with tunable performances and their applications.

PubMed

Wang, Zhen; Wang, Dong; Qian, Zhenchao; Guo, Jing; Dong, Haixia; Zhao, Ning; Xu, Jian

2015-01-28

Aerogels are a family of highly porous materials whose applications are commonly restricted by poor mechanical properties. Herein, thiol-ene chemistry is employed to synthesize a series of novel bridged silsesquioxane (BSQ) precursors with various alkoxy groups. On the basis of the different hydrolyzing rates of the methoxy and ethoxy groups, robust superhydrophobic BSQ aerogels with tailorable morphology and mechanical performances have been prepared. The flexible thioether bridge contributes to the robustness of the as-formed aerogels, and the property can be tuned on the basis of the distinct combinations of alkoxy groups with the density of the aerogels almost unchanged. To the best of our knowledge, the lowest density among the ambient pressure dried aerogels is obtained. Further, potential application of the aerogels for oil/water separation and acoustic materials has also been presented.

Carbon aerogel electrodes for direct energy conversion

DOEpatents

Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

1997-01-01

A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

Robust, Flexible and Lightweight Dielectric Barrier Discharge Actuators Using Nanofoams/Aerogels

NASA Technical Reports Server (NTRS)

Siochi, Emilie J. (Inventor); Sauti, Godfrey (Inventor); Wilkinson, Stephen P. (Inventor); Guo, Haiquan N. (Inventor); Xu, Tian-Bing (Inventor); Meador, Mary Ann B. (Inventor)

2015-01-01

Robust, flexible, lightweight, low profile enhanced performance dielectric barrier discharge actuators (plasma actuators) based on aerogels/nanofoams with controlled pore size and size distribution as well as pore shape. The plasma actuators offer high body force as well as high force to weight ratios (thrust density). The flexibility and mechanical robustness of the actuators allows them to be shaped to conform to the surface to which they are applied. Carbon nanotube (CNT) based electrodes serve to further decrease the weight and profile of the actuators while maintaining flexibility while insulating nano-inclusions in the matrix enable tailoring of the mechanical properties. Such actuators are required for flow control in aeronautics and moving machinery such as wind turbines, noise abatement in landing gear and rotary wing aircraft and other applications.

Characterization of pure and composite resorcinol formaldehyde aerogels doped with silver

NASA Astrophysics Data System (ADS)

Attia, S. M.; Abdelfatah, M. S.; Mossad, M. M.

2017-07-01

A series of Resorcinol Formaldehyde (RF) aerogels composites with nanoparticles of sliver were prepared by the sol-gel method at different concentrations doped silver. FTIR spectra of pure and composite RF aerogels show six absorption bands attributed to -OH groups bonded to the benzene ring, stretching of -CH2- bonds and aromatic ring stretching. FTIR results ensured that sliver particles do not interact with aerogel network. UV-visible spectrum of pure silver show an absorbance peak at 420 nm attributed to the surface plasmon excitation of sliver Nano spheres. UV-visible spectral of pure and composite RF aerogels shows a steep decrease of absorption with wavelength after 500 nm, making sample’s color reddish brown. TEM and SEM images of pure and composite RF aerogels revealed that the textural arrangement of RF aerogels can be described as densely packed small nodules.

Highly porous and mechanically strong ceramic oxide aerogels

NASA Technical Reports Server (NTRS)

Johnston, James C. (Inventor); Leventis, Nicholas (Inventor); Ilhan, Ulvi F. (Inventor); Meador, Mary Ann B. (Inventor); Fabrizio, Eve F. (Inventor)

2012-01-01

Structurally stable and mechanically strong ceramic oxide aerogels are provided. The aerogels are cross-linked via organic polymer chains that are attached to and extend from surface-bound functional groups provided or present over the internal surfaces of a mesoporous ceramic oxide particle network via appropriate chemical reactions. The functional groups can be hydroxyl groups, which are native to ceramic oxides, or they can be non-hydroxyl functional groups that can be decorated over the internal surfaces of the ceramic oxide network. Methods of preparing such mechanically strong ceramic oxide aerogels also are provided.

Highly porous and mechanically strong ceramic oxide aerogels

NASA Technical Reports Server (NTRS)

Fabrizio, Eve F. (Inventor); Leventis, Nicholas (Inventor); Ilhan, Ulvi F. (Inventor); Meador, Mary Ann B. (Inventor); Johnston, James C. (Inventor)

2010-01-01

Structurally stable and mechanically strong ceramic oxide aerogels are provided. The aerogels are cross-linked via organic polymer chains that are attached to and extend from surface-bound functional groups provided or present over the internal surfaces of a mesoporous ceramic oxide particle network via appropriate chemical reactions. The functional groups can be hydroxyl groups, which are native to ceramic oxides, or they can be non-hydroxyl functional groups that can be decorated over the internal surfaces of the ceramic oxide network. Methods of preparing such mechanically strong ceramic oxide aerogels also are provided.

Cylindrical cryogenic calorimeter testing of six types of multilayer insulation systems

NASA Astrophysics Data System (ADS)

Fesmire, J. E.; Johnson, W. L.

2018-01-01

Extensive cryogenic thermal testing of more than 100 different multilayer insulation (MLI) specimens was performed over the last 20 years for the research and development of evacuated reflective thermal insulation systems. From this data library, 26 MLI systems plus several vacuum-only systems are selected for analysis and comparison. The test apparatus, methods, and results enabled the adoption of two new technical consensus standards under ASTM International. Materials tested include reflectors of aluminum foil or double-aluminized Mylar and spacers of fiberglass paper, polyester netting, silk netting, polyester fabric, or discrete polymer standoffs. The six types of MLI systems tested are listed as follows: Mylar/Paper, Foil/Paper, Mylar/Net, Mylar/Blanket, Mylar/Fabric, Mylar/Discrete. Also tested are vacuum-only systems with different cold surface materials/finishes including stainless steel, black, copper, and aluminum. Testing was performed between the boundary temperatures of 78 K and 293 K (and up to 350 K) using a thermally guarded one-meter-long cylindrical calorimeter (Cryostat-100) for absolute heat flow measurement. Cold vacuum pressures include the full range from 1 × 10-6 torr to 760 torr with nitrogen as the residual gas. System variations include number of layers from one to 80 layers, layer densities from 0.5 to 5 layers per millimeter, and installation techniques such layer-by-layer, blankets (multi-layer assemblies), sub-blankets, seaming, butt-joining, spiral wrapping, and roll-wrapping. Experimental thermal performance data for the different MLI systems are presented in terms of heat flux and effective thermal conductivity. Benchmark cryogenic-vacuum thermal performance curves for MLI are given for comparison with different insulation approaches for storage and transfer equipment, cryostats, launch vehicles, spacecraft, or science instruments.

STS-40 Columbia, OV-102, payload bay aft firewall and thermal insulation

NASA Image and Video Library

1991-06-14

STS040-31-029 (5-14 June 1991) --- This close-up 35mm scene of the aft firewall in the Space Shuttle Columbia's cargo bay reveals a piece of thermal insulation that had loosened. The crew discovered the loose blanket soon after opening the cargo bay doors on June 5, 1991.

Carbon aerogel electrodes for direct energy conversion

DOEpatents

Mayer, S.T.; Kaschmitter, J.L.; Pekala, R.W.

1997-02-11

A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes is described, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome. 1 fig.

Parametric Weight Comparison of Advanced Metallic, Ceramic Tile, and Ceramic Blanket Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Myers, David E.; Martin, Carl J.; Blosser, Max L.

2000-01-01

A parametric weight assessment of advanced metallic panel, ceramic blanket, and ceramic tile thermal protection systems (TPS) was conducted using an implicit, one-dimensional (I-D) finite element sizing code. This sizing code contained models to account for coatings fasteners, adhesives, and strain isolation pads. Atmospheric entry heating profiles for two vehicles, the Access to Space (ATS) vehicle and a proposed Reusable Launch Vehicle (RLV), were used to ensure that the trends were not unique to a certain trajectory. Ten TPS concepts were compared for a range of applied heat loads and substructural heat capacities to identify general trends. This study found the blanket TPS concepts have the lightest weights over the majority of their applicable ranges, and current technology ceramic tiles and metallic TPS concepts have similar weights. A proposed, state-of-the-art metallic system which uses a higher temperature alloy and efficient multilayer insulation was predicted to be significantly lighter than the ceramic tile stems and approaches blanket TPS weights for higher integrated heat loads.

Micro-mechanical modelling of cellulose aerogels from molten salt hydrates.

PubMed

Rege, Ameya; Schestakow, Maria; Karadagli, Ilknur; Ratke, Lorenz; Itskov, Mikhail

2016-09-14

In this paper, a generalised micro-mechanical model capable of capturing the mechanical behaviour of polysaccharidic aerogels, in particular cellulose aerogels, is proposed. To this end, first the mechanical structure and properties of these highly nanoporous cellulose aerogels prepared from aqueous salt hydrate melts (calcium thiocyanate, Ca(SCN)2·6H2O and zinc chloride, ZnCl2·4H2O) are studied. The cellulose content within these aerogels is found to have a direct relation to the microstructural quantities such as the fibril length and diameter. This, along with porosity, appears to influence the resulting mechanical properties. Furthermore, experimental characterisation of cellulose aerogels was done using scanning electron microscopy (SEM), pore-size data analysis, and compression tests. Cellulose aerogels are of a characteristic cellular microstructures and accordingly a network formed by square shaped cells is considered in the micro-mechanical model proposed in this paper. This model is based on the non-linear bending and collapse of such cells of varying pore sizes. The extended Euler-Bernoulli beam theory for large deflections is used to describe the bending in the cell walls. The proposed model is physically motivated and demonstrates a good agreement with our experimental data of both ZnCl2 and Ca(SCN)2 based cellulose aerogels with different cellulose contents.

Optical shock waves in silica aerogel.

PubMed

Gentilini, S; Ghajeri, F; Ghofraniha, N; Di Falco, A; Conti, C

2014-01-27

Silica aerogels are materials well suited for high power nonlinear optical applications. In such regime, the non-trivial thermal properties may give rise to the generation of optical shock waves, which are also affected by the structural disorder due to the porous solid-state gel. Here we report on an experimental investigation in terms of beam waist and input power, and identify various regimes of the generation of wave-breaking phenomena in silica aerogels.

Engineering Polymer Nanocomoposite Aerogels for Energy Storage and Harvesting

NASA Astrophysics Data System (ADS)

Zheng, Qifeng

Various porous polymer nanocomposite aerogels were synthesized using an environmentally friendly freeze-drying process. These polymer nanocomposite aerogels exhibit ultralow densities, high porosities, high specific surface areas and high flexibility. The advantages of these polymer nanocomposites aerogels for energy storage and energy harvesting applications have been demonstrated. Flexible supercapacitors (SCs) are particularly attractive for energy storage applications due to their high power densities and long life cycles. A novel type of highly flexible and all-solid-state SCs using cellulose nanofibril (CNF)-reduced graphene oxide (RGO)-carbon nanotube (CNT) aerogels as electrodes was developed. Due to the porous structure of the CNF/RGO/CNT aerogel electrodes, and the excellent electrolyte absorption properties of the CNFs present in the electrodes, the resulting all-solid-state SCs exhibited excellent electrochemical performance, superior flexibility and cycle stability. To further increase the capacitances and energy densities, pseudocapacitive materials (i.e., MoO3) were incorporated to prepare the free-standing and highly flexible CNF-RGO-molybdenum oxynitride (MoOxNy) aerogel film electrode. Supercapacitors made with the CNF/RGO/MoOxNy aerogel electrodes exhibited outstanding specific capacitances and remarkable energy densities in different electrolytes while maintaining the high power densities and superior cycle stability. Flexible nanogenerators (NGs) that can harvest ubiquitous mechanical energy from ambient environments have attracted significant attention during the past decade. A novel, simple, cost-effective, and scalable technique was developed to fabricate high-performance flexible compact NGs using porous CNF-poly(dimethylsiloxane) (PDMS) aerogel film. Under external stress, the resulting NGs exhibited very stable and high output signals. We hypothesized that the remarkable electric outputs would not only be attributable to the intrinsic

Thermal performance of gaseous-helium-purged tank-mounted multilayer insulation system during ground-hold and space-hold thermal cycling and exposure to water vapor

NASA Technical Reports Server (NTRS)

Sumner, I. E.

1978-01-01

An experimental investigation was conducted to determine (1) the ground-hold and space-hold thermal performance of a multilayer insulation (MLI) system mounted on a spherical, liquid-hydrogen propellant tank and (2) the degradation to the space-hold thermal performance of the insulation system that resulted from both thermal cycling and exposure to moisture. The propellant tank had a diameter of 1.39 meters (4.57ft). The MLI consisted of two blankets of insulation; each blanket contained 15 double-aluminized Mylar radiation shields separated by double silk net spacers. Nineteen tests simulating basic cryogenic spacecraft thermal (environmental) conditions were conducted. These tests typically included initial helium purge, liquid-hydrogen fill and ground-hold, ascent, space-hold, and repressurization. No significant degradation of the space-hold thermal performance due to thermal cycling was noted.

Metal Nanoparticle Aerogel Composites

NASA Technical Reports Server (NTRS)

Smith, David D.; Sibille, Laurent; Ignont, Erica; Snow, Lanee; Rose, M. Franklin (Technical Monitor)

2000-01-01

We have fabricated sol-gels containing gold and silver nanoparticles. Formation of an aerogel produces a blue shift in the surface plasmon resonance as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping this blue shift does not obey effective medium theories. Annealing the samples in a reducing atmosphere at 400 C eliminates this discrepancy and results in narrowing and further blue shifting of the plasmon resonance. Metal particle aggregation also results in a deviation from the predictions of effective medium theories, but can be controlled through careful handling and by avoiding the use of alcohol. By applying effective medium theories to the heterogeneous interlayer surrounding each metal particle, we extend the technique of immersion spectroscopy to inhomogeneous materials characterized by spatially dependent dielectric constants, such as aerogels. We demonstrate that the shift in the surface plasmon wavelength provides the average fractional composition of each component (air and silica) in this inhomogeneous layer, i.e. the porosity of the aerogel or equivalently, for these materials, the catalytic dispersion. Additionally, the kinetics suggest that collective particle interactions in coagulated metal clusters are perturbed during silica gelation resulting in a change in the aggregate geometry.

Alginate-based hybrid aerogel microparticles for mucosal drug delivery.

PubMed

Gonçalves, V S S; Gurikov, P; Poejo, J; Matias, A A; Heinrich, S; Duarte, C M M; Smirnova, I

2016-10-01

The application of biopolymer aerogels as drug delivery systems (DDS) has gained increased interest during the last decade since these structures have large surface area and accessible pores allowing for high drug loadings. Being biocompatible, biodegradable and presenting low toxicity, polysaccharide-based aerogels are an attractive carrier to be applied in pharmaceutical industry. Moreover, some polysaccharides (e.g. alginate and chitosan) present mucoadhesive properties, an important feature for mucosal drug delivery. This feature allows to extend the contact of DDS with biological membranes, thereby increasing the absorption of drugs through the mucosa. Alginate-based hybrid aerogels in the form of microparticles (<50μm) were investigated in this work as carriers for mucosal administration of drugs. Low methoxyl pectin and κ-carrageenan were co-gelled with alginate and further dried with supercritical CO2 (sc-CO2). Spherical mesoporous aerogel microparticles were obtained for alginate, hybrid alginate/pectin and alginate/κ-carrageenan aerogels, presenting high specific surface area (370-548m(2)g(-1)) and mucoadhesive properties. The microparticles were loaded with ketoprofen via adsorption from its solution in sc-CO2, and with quercetin via supercritical anti-solvent precipitation. Loading of ketoprofen was in the range between 17 and 22wt% whereas quercetin demonstrated loadings of 3.1-5.4wt%. Both the drugs were present in amorphous state. Loading procedure allowed the preservation of antioxidant activity of quercetin. Release of both drugs from alginate/κ-carrageenan aerogel was slightly faster compared to alginate/pectin. The results indicate that alginate-based aerogel microparticles can be viewed as promising matrices for mucosal drug delivery applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Process for preparing polymer reinforced silica aerogels

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B. (Inventor); Capadona, Lynn A. (Inventor)

2011-01-01

Process for preparing polymer-reinforced silica aerogels which comprises a one-pot reaction of at least one alkoxy silane in the presence of effective amounts of a polymer precursor to obtain a silica reaction product, the reaction product is gelled and subsequently subjected to conditions that promotes polymerization of the precursor and then supercritically dried to obtain the polymer-reinforced monolithic silica aerogels.

Three insulation methods to minimize intravenous fluid administration set heat loss.

PubMed

Piek, Richardt; Stein, Christopher

2013-01-01

To assess the effect of three methods for insulating an intravenous (IV) fluid administration set on the temperature of warmed fluid delivered rapidly in a cold environment. The three chosen techniques for insulation of the IV fluid administration set involved enclosing the tubing of the set in 1) a cotton conforming bandage, 2) a reflective emergency blanket, and 3) a combination of technique 2 followed by technique 1. Intravenous fluid warmed to 44°C was infused through a 20-drop/mL 180-cm-long fluid administration set in a controlled environmental temperature of 5°C. Temperatures in the IV fluid bag, the distal end of the fluid administration set, and the environment were continuously measured with resistance thermosensors. Twenty repetitions were performed in four conditions, namely, a control condition (with no insulation) and the three different insulation methods described above. One-way analysis of variance was used to assess the mean difference in temperature between the IV fluid bag and the distal fluid administration set under the four conditions. In the control condition, a mean of 5.28°C was lost between the IV fluid bag and the distal end of the fluid administration set. There was a significant difference found between the four conditions (p < 0.001). A mean of 3.53°C was lost between the IV fluid bag and the distal end of the fluid administration set for both the bandage and reflective emergency blanket, and a mean of 3.06°C was lost when the two methods were combined. Using inexpensive and readily available materials to insulate a fluid administration set can result in a reduction of heat loss in rapidly infused, warmed IV fluid in a cold environment.

Reinforcement of bacterial cellulose aerogels with biocompatible polymers

PubMed Central

Pircher, N.; Veigel, S.; Aigner, N.; Nedelec, J.M.; Rosenau, T.; Liebner, F.

2014-01-01

Bacterial cellulose (BC) aerogels, which are fragile, ultra-lightweight, open-porous and transversally isotropic materials, have been reinforced with the biocompatible polymers polylactic acid (PLA), polycaprolactone (PCL), cellulose acetate (CA), and poly(methyl methacrylate) (PMMA), respectively, at varying BC/polymer ratios. Supercritical carbon dioxide anti-solvent precipitation and simultaneous extraction of the anti-solvent using scCO2 have been used as core techniques for incorporating the secondary polymer into the BC matrix and to convert the formed composite organogels into aerogels. Uniaxial compression tests revealed a considerable enhancement of the mechanical properties as compared to BC aerogels. Nitrogen sorption experiments at 77 K and scanning electron micrographs confirmed the preservation (or even enhancement) of the surface-area-to-volume ratio for most of the samples. The formation of an open-porous, interpenetrating network of the second polymer has been demonstrated by treatment of BC/PMMA hybrid aerogels with EMIM acetate, which exclusively extracted cellulose, leaving behind self-supporting organogels. PMID:25037381

Aerogel Antennas Communications Study Using Error Vector Magnitude Measurements

NASA Technical Reports Server (NTRS)

Miranda, Felix A.; Mueller, Carl H.; Meador, Mary Ann B.

2014-01-01

This presentation discusses an aerogel antennas communication study using error vector magnitude (EVM) measurements. The study was performed using 2x4 element polyimide (PI) aerogel-based phased arrays designed for operation at 5 GHz as transmit (Tx) and receive (Rx) antennas separated by a line of sight (LOS) distance of 8.5 meters. The results of the EVM measurements demonstrate that polyimide aerogel antennas work appropriately to support digital communication links with typically used modulation schemes such as QPSK and 4 DQPSK. As such, PI aerogel antennas with higher gain, larger bandwidth and lower mass than typically used microwave laminates could be suitable to enable aerospace-to- ground communication links with enough channel capacity to support voice, data and video links from CubeSats, unmanned air vehicles (UAV), and commercial aircraft.

Aerogel Antennas Communications Study Using Error Vector Magnitude Measurements

NASA Technical Reports Server (NTRS)

Miranda, Felix A.; Mueller, Carl H.; Meador, Mary Ann B.

2014-01-01

This paper discusses an aerogel antennas communication study using error vector magnitude (EVM) measurements. The study was performed using 4x2 element polyimide (PI) aerogel-based phased arrays designed for operation at 5 GHz as transmit (Tx) and receive (Rx) antennas separated by a line of sight (LOS) distance of 8.5 meters. The results of the EVM measurements demonstrate that polyimide aerogel antennas work appropriately to support digital communication links with typically used modulation schemes such as QPSK and pi/4 DQPSK. As such, PI aerogel antennas with higher gain, larger bandwidth and lower mass than typically used microwave laminates could be suitable to enable aerospace-to-ground communication links with enough channel capacity to support voice, data and video links from cubesats, unmanned air vehicles (UAV), and commercial aircraft.

Flame Retardant Effect of Aerogel and Nanosilica on Engineered Polymers

NASA Technical Reports Server (NTRS)

Williams, Martha K.; Smith, Trent M.; Roberson, Luke B.; Yang, Feng; Nelson, Gordon L.

2010-01-01

Aerogels are typically manufactured vIa high temperature and pressure-critical-point drying of a colloidal metal oxide gel filled with solvents. Aerogel materials derived from silica materials represent a structural morphology (amorphous, open-celled nanofoams) rather than a particular chemical constituency. Aerogel is not like conventional foams in that it is a porous material with extreme microporosity and composed of individual features only a few nanometers in length with a highly porous dendriticlike structure. This unique substance has unusual properties such as low thermal conductivity, refractive index and sound suppression; in addition to its exceptional ability to capture fast moving dust. The highly porous nature of the aerogel's structure provides large amounts of surface area per unit weight. For instance, a silica aerogel material with a density of 100 kilograms per cubic meters can have surface areas of around 800 to 1500 square meters per gram depending on the precursors and process utilized to produce it. To take advantage of the unique properties of silica aerogels, especially the ultra light weight and low thermal conductivity, their composites with various engineering polymers were prepared and their flammability was investigated by Cone Calorimetry. The flammability of various polystyrene/silica aerogel nanocomposites were measured. The combination of these nanocomposites with a NASA patented flame retardant SINK were also studied. The results were compared with the base polymer to show the differences between composites with different forms of silica.

Property control of graphene aerogels by in situ growth of silicone polymer

NASA Astrophysics Data System (ADS)

Zhou, Shuai; Zhou, Xiang; Hao, Gazi; Jiang, Wei; Wang, Tianhe

2018-05-01

Modulation of the density (from 3.5 to 64 mg cm-3), hydrophobicity and oil-uptake capability of graphene aerogels in extensive ranges were achieved by reacting (3-Mercaptopropyl)trimethoxysilane (MPS) with graphene oxide solutions under heating. The reaction allowed a characteristic silicone substructure to be formed on graphene and joint the graphene layers firmly together. With the increase of MPS concentrations (≤ca. 0.2 vol%), the nano silicone polymer grown on graphene functioned as a "linker" and "spacer", leading to a substantial decrease of the aerogel density. Because of the formation of silicone polymer and the characteristic nano-micro substructures on the backbones of graphene aerogels, the graphene aerogels exhibited a high hydrophobicity with the water contact angle consistently exceeding 142 degrees. Functionalized graphene aerogels with a density of 3.5 mg cm-3 were conveniently fabricated that displayed an extraordinary oil absorption capacity, 182 times for lubricating oil and 143 times for n-hexane of its own weight. Furthermore, the aerogels maintained their ultra-high absorption capability even after 20 absorption-distillation cycles, due to structural integrity held by the strong interfacial adhesion between graphene sheets and polymer chains of aerogels. This study offers a promising graphene aerogels and also provides a strategy for fabricating extra low dense functional materials.

Novel Polymer Aerogel toward High Dimensional Stability, Mechanical Property, and Fire Safety.

PubMed

Shang, Ke; Yang, Jun-Chi; Cao, Zhi-Jie; Liao, Wang; Wang, Yu-Zhong; Schiraldi, David A

2017-07-12

Inorganc silica-based aerogels, the earliest and widely used aerogels, have poorer mechanical properties than their organic substitutes, which are flammable. In this study, a novel polymeric aerogel with high strength, inherent flame retardancy, and cost-effectiveness, which is based on poly(vinyl alcohol) (PVA) cross-linked with melamine-formaldehyde (MF), was prepared under aqueous condition with an ecofriendly freeze-drying and postcuring process. Combined with the additional rigid MF network and benifited from the resulting unique infrastructure of inter-cross-linked flexible PVA segments and rigid MF segments, PVA-based aerogels exibited a significantly decreased degradation rate and sharply decreased peak heat release rate (PHRR) in cone calorimeter tests (by as much as 83%) compared with neat PVA. The polymer aerogels have a limiting oxygen index (LOI) as high as 36.5% and V-0 rating in UL-94 test. Furthermore, the aerogel samples exposured to harsh temperatures maintain their dimensions (<10% change), original mechanical strength and fire safety. Therefore, this work provides a novel stragegy for preparing pure organic polymeric aerogel materials with high mechanical strength, dimensional stability, and fire safety.

Recent Advances in Research on the Synthetic Fiber Based Silica Aerogel Nanocomposites

PubMed Central

Ślosarczyk, Agnieszka

2017-01-01

The presented paper contains a brief review on the synthesis and characterization of silica aerogels and its nanocomposites with nanofibers and fibers based on a literature study over the past twenty years and my own research. Particular attention is focused on carbon fiber-based silica aerogel nanocomposites. Silica aerogel is brittle in nature, therefore, it is necessary to improve this drawback, e.g., by polymer modification or fiber additives. Nevertheless, there are very few articles in the literature devoted to the synthesis of silica aerogel/fiber nanocomposites, especially those focusing on carbon fibers and nanofibers. Carbon fibers are very interesting materials, namely due to their special properties: high conductivity, high mechanical properties in relation to very low bulk densities, high thermal stability, and chemical resistance in the silica aerogel matrix, which can help enhance silica aerogel applications in the future. PMID:28336876

Recent Advances in Research on the Synthetic Fiber Based Silica Aerogel Nanocomposites.

PubMed

Ślosarczyk, Agnieszka

2017-02-16

The presented paper contains a brief review on the synthesis and characterization of silica aerogels and its nanocomposites with nanofibers and fibers based on a literature study over the past twenty years and my own research. Particular attention is focused on carbon fiber-based silica aerogel nanocomposites. Silica aerogel is brittle in nature, therefore, it is necessary to improve this drawback, e.g., by polymer modification or fiber additives. Nevertheless, there are very few articles in the literature devoted to the synthesis of silica aerogel/fiber nanocomposites, especially those focusing on carbon fibers and nanofibers. Carbon fibers are very interesting materials, namely due to their special properties: high conductivity, high mechanical properties in relation to very low bulk densities, high thermal stability, and chemical resistance in the silica aerogel matrix, which can help enhance silica aerogel applications in the future.

Method for preparing a solid phase microextraction device using aerogel

DOEpatents

Miller, Fred S [Bethel Island, CA; Andresen, Brian D [Livermore, CA

2006-10-24

A sample collection substrate of aerogel and/or xerogel materials bound to a support structure is used as a solid phase microextraction (SPME) device. The xerogels and aerogels may be organic or inorganic and doped with metals or other compounds to target specific chemical analytes. The support structure is typically formed of a glass fiber or a metal wire (stainless steel or kovar). The devices are made by applying gel solution to the support structures and drying the solution to form aerogel or xerogel. Aerogel particles may be attached to the wet layer before drying to increase sample collection surface area. These devices are robust, stable in fields of high radiation, and highly effective at collecting gas and liquid samples while maintaining superior mechanical and thermal stability during routine use. Aerogel SPME devices are advantageous for use in GC/MS analyses due to their lack of interfering background and tolerance of GC thermal cycling.

Blanket design and optimization demonstrations of the first wall/blanket/shield design and optimization system (BSDOS).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gohar, Y.; Nuclear Engineering Division

2005-05-01

In fusion reactors, the blanket design and its characteristics have a major impact on the reactor performance, size, and economics. The selection and arrangement of the blanket materials, dimensions of the different blanket zones, and different requirements of the selected materials for a satisfactory performance are the main parameters, which define the blanket performance. These parameters translate to a large number of variables and design constraints, which need to be simultaneously considered in the blanket design process. This represents a major design challenge because of the lack of a comprehensive design tool capable of considering all these variables to definemore » the optimum blanket design and satisfying all the design constraints for the adopted figure of merit and the blanket design criteria. The blanket design capabilities of the First Wall/Blanket/Shield Design and Optimization System (BSDOS) have been developed to overcome this difficulty and to provide the state-of-the-art research and design tool for performing blanket design analyses. This paper describes some of the BSDOS capabilities and demonstrates its use. In addition, the use of the optimization capability of the BSDOS can result in a significant blanket performance enhancement and cost saving for the reactor design under consideration. In this paper, examples are presented, which utilize an earlier version of the ITER solid breeder blanket design and a high power density self-cooled lithium blanket design for demonstrating some of the BSDOS blanket design capabilities.« less

Blanket Design and Optimization Demonstrations of the First Wall/Blanket/Shield Design and Optimization System (BSDOS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gohar, Yousry

2005-05-15

In fusion reactors, the blanket design and its characteristics have a major impact on the reactor performance, size, and economics. The selection and arrangement of the blanket materials, dimensions of the different blanket zones, and different requirements of the selected materials for a satisfactory performance are the main parameters, which define the blanket performance. These parameters translate to a large number of variables and design constraints, which need to be simultaneously considered in the blanket design process. This represents a major design challenge because of the lack of a comprehensive design tool capable of considering all these variables to definemore » the optimum blanket design and satisfying all the design constraints for the adopted figure of merit and the blanket design criteria. The blanket design capabilities of the First Wall/Blanket/Shield Design and Optimization System (BSDOS) have been developed to overcome this difficulty and to provide the state-of-the-art research and design tool for performing blanket design analyses. This paper describes some of the BSDOS capabilities and demonstrates its use. In addition, the use of the optimization capability of the BSDOS can result in a significant blanket performance enhancement and cost saving for the reactor design under consideration. In this paper, examples are presented, which utilize an earlier version of the ITER solid breeder blanket design and a high power density self-cooled lithium blanket design for demonstrating some of the BSDOS blanket design capabilities.« less

Silica Aerogel Captures Cosmic Dust Intact

NASA Technical Reports Server (NTRS)

Tsou, P.

1994-01-01

The mesostructure of silica aerogel resembles stings of grapes, ranging in size from 10 to 100 angstrom. This fine mesostructure transmits nearly 90 percent of incident light in the visible, while providing sufficiently gentle dissipation of the kinetric energy of hypervelocity cosmic dust particles to permit their intact capture. We introduced silica aerogel in 1987 as capture medium to take advantage of its low density, fine mesostruicture and most importantly, its transparency, allowing optical location of captured micron sized particles.

Incorporation of noble metals into aerogels

DOEpatents

Hair, Lucy M.; Sanner, Robert D.; Coronado, Paul R.

1998-01-01

Aerogels or xerogels containing atomically dispersed noble metals for applications such environmental remediation. New noble metal precursors, such as Pt--Si or Pd(Si--P).sub.2, have been created to bridge the incompatibility between noble metals and oxygen, followed by their incorporation into the aerogel or xerogel through sol-gel chemistry and processing. Applications include oxidation of hydrocarbons and reduction of nitrogen oxide species, complete oxidation of volatile organic carbon species, oxidative membranes for photocatalysis and partial oxidation for synthetic applications.

Low dielectric polyimide aerogels as substrates for lightweight patch antennas.

PubMed

Meador, Mary Ann B; Wright, Sarah; Sandberg, Anna; Nguyen, Baochau N; Van Keuls, Frederick W; Mueller, Carl H; Rodríguez-Solís, Rafael; Miranda, Félix A

2012-11-01

The dielectric properties and loss tangents of low-density polyimide aerogels have been characterized at various frequencies. Relative dielectric constants as low as 1.16 were measured for polyimide aerogels made from 2,2'-dimethylbenzidine (DMBZ) and biphenyl 3,3',4,4'-tetracarbozylic dianhydride (BPDA) cross-linked with 1,3,5-triaminophenoxybenzene (TAB). This formulation was used as the substrate to fabricate and test prototype microstrip patch antennas and benchmark against state of practice commercial antenna substrates. The polyimide aerogel antennas exhibited broader bandwidth, higher gain, and lower mass than the antennas made using commercial substrates. These are very encouraging results, which support the potential advantages of the polyimide aerogel-based antennas for aerospace applications.

Preparation of lignin-based carbon aerogels as biomaterials for nano-supercapacitor

NASA Astrophysics Data System (ADS)

Yang, Bong Suk; Kang, Kyu-Young; Jeong, Myung-Joon

2017-10-01

Kraft and organosolv lignins, generally produced in chemical pulping and bio-refinery processes of lignocellulosic biomass, were used to prepare lignin-based carbon aerogels for supercapacitors as raw materials. The difference between lignins and lignin-based aerogels were compared by analyzing physical and chemical properties, including molecular weight, polydispersity, and reactivity with formaldehyde. Also, density, shrinkage, Brunauer-Emmett-Teller (BET) surface area and scanning electron microscope (SEM) images of the lignin-based aerogel were investigated. Kraft lignin consisting of coniferyl alcohol (G) and p-coumaryl alcohol (H) increased the reactivity of formaldehyde, formed a hydrogel well (porosity > 0.45), and specific surface area higher than organosolv lignin. In the case of kraft lignin, there were irregular changes such as oxidation and condensation in the pulping process. However, reaction sites with aromatic rings in lignin impacted the production of aerogel and required a long gelation period. The molecular weight of lignin influences the gelation time in producing lignin-based aerogel, and lignin composition affects the BET surface area and pore structures of the lignin-based carbon aerogels.

Van der Waal Interactions in Ultrafine Nanocellulose Aerogels

NASA Astrophysics Data System (ADS)

Fritch, Byron; Bradley, Derek; Kidd, Tim

Nanocellulose aerogels have shown an ability to be used in many different applications ranging from oil sponges to conductive materials to possibly a low calorie food substitute. Not much is known about the structural and physical property changes that occur when the composition of the aerogel changes. We studied what properties change when the aerogel amounts change, as well as how sticky the aerogels are and how strong they are. The higher concentrations appeared to have more plate-like structures while the lower concentrations had a more fibrous material. These fibers in the low concentrations had a smaller diameter than a human hair. Only the low concentration aerogels were able to stick to a glass surface in the adhesion test, but were able to support a mass much larger than their own. These low concentrations also would stick to your finger when lightly touched. Preliminary tests show that a concentration that is not too low, but not too high, is best for tensile strength. All concentrations were able to hold many times their own mass. Cellulose should be studied more because it is a renewable material and is easily accessed. Nanocellulose is also not environmentally dangerous allowing it to be used in applications involving humans and the environment like noted above. National Science Foundation Grant DMR-1410496.

Regeneration of mesoporous silica aerogel for hydrocarbon adsorption and recovery.

PubMed

Zhang, Chengzhao; Dai, Chong; Zhang, Huaqin; Peng, Shitao; Wei, Xin; Hu, Yandi

2017-09-15

Silica aerogel, with mesoporous structure and high hydrophobicity, is a promising adsorbent for oil spill clean-up. To make it economic and environmental-friendly, hydrocarbon desorption and silica aerogel regeneration were investigated. After hydrocarbon desorption at 80°C, silica aerogel maintained its hydrophobicity. After toluene, petrol, and diesel desorption, shrinkage of mesopores (from 19.9 to 16.8, 13.5, and 13.4nm) of silica aerogels occurred, causing decreased adsorption capacities (from 12.4, 11.2, and 13.6 to 12.0, 6.5, and 2.3g/g). Low surface tension of petrol caused high stress on mesopores during its desorption, resulting in significant pore shrinkage. For diesel, its incomplete desorption and oxidation further hindered the regeneration. Therefore, diesel desorption was also conducted at 200°C. Severe diesel oxidation occurred under aerobic condition and destroyed the mesopores. Under anaerobic condition, no diesel oxidation occurred and the decreases in pore size (to 13.2nm) and adsorption efficiency (to 10.0g/g) of regenerated silica aerogels were much less, compared with under aerobic condition. This study provided new insights on silica aerogel regeneration for oil spill clean-up. Copyright © 2017 Elsevier Ltd. All rights reserved.

Structural and Acidic Properties of Niobia-Silica and Niobia-Alumina Aerogels

DTIC Science & Technology

1991-05-06

some weak Bronsted acidity. The silica aerogel supported niobia samples also had strong Lewis acidity as well as strong iv Bronsted acidity which was...NS25w or the silica aerogel supported niobia because of the formation of a distorted octahedral niobia-rigid silica interface. Isomerization of 1...67 2.1.2 Silica Aerogel .......................................................... 70 2.1.3 Alumina

Anisotropic phases of superfluid ^{3}he in compressed aerogel.

PubMed

Li, J I A; Zimmerman, A M; Pollanen, J; Collett, C A; Halperin, W P

2015-03-13

It has been shown that the relative stabilities of various superfluid states of ^{3}He can be influenced by anisotropy in a silica aerogel framework. We prepared a suite of aerogel samples compressed up to 30% for which we performed pulsed NMR on ^{3}He imbibed within the aerogel. We identified A and B phases and determined their magnetic field-temperature phase diagrams as a function of strain. From these results, we infer that the B phase is distorted by negative strain forming an anisotropic superfluid state more stable than the A phase.

Highly porous ceramic oxide aerogels having improved flexibility

NASA Technical Reports Server (NTRS)

Guo, Haiquan (Inventor); Meador, Mary Ann B. (Inventor); Nguyen, Baochau N. (Inventor)

2012-01-01

Ceramic oxide aerogels having improved flexibility are disclosed. Preferred embodiments exhibit high modulus and other strength properties despite their improved flexibility. The gels may be polymer cross-linked via organic polymer chains to further improve strength properties, without substantially detracting from the improved flexibility. Methods of making such aerogels are also disclosed.

Transmissivity testing of multilayer insulation at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Van Dresar, N. T.; Chato, D. J.; Demers, J. R.

2017-09-01

The problem of degraded emissivity of thin films at low temperatures has been a long observed phenomena. Previous efforts at measuring properties have suggested that transmission of energy through the films may play a key role in the thermal performance of multilayer insulation systems at low temperatures. Similarly, recent testing on tank applied systems has suggested a radiative degradation at low temperatures. Two different approaches were used to attempt to measure the transmission of energy through MLI at low temperatures. A laser based measurement system was set up to directly measure transmittance and a calorimetric based measurement system was used to measure relative emittance of a single layer between aluminum foil and double aluminized Mylar. Minimal transmission at long wavelengths were observed through standard MLI blanket materials at deposition thicknesses of even 35 nm. Where transmission was measured, it was too low to effect the performance of a multilayers system. Similarly, the calorimeter showed similar increases of emissivity for both standard blanket materials and aluminum foils. Multiple different methodologies of measurement have all yielded the same result: that there is no transmission through standard MLI blanket materials at wavelengths associated with temperatures as low as 2 K.

Simulation and Analysis of Mechanical Properties of Silica Aerogels: From Rationalization to Prediction

PubMed Central

Ma, Hao; Zheng, Xiaoyang; Luo, Xuan; Yang, Fan

2018-01-01

Silica aerogels are highly porous 3D nanostructures and have exhibited excellent physio-chemical properties. Although silica aerogels have broad potential in many fields, the poor mechanical properties greatly limit further applications. In this study, we have applied the finite volume method (FVM) method to calculate the mechanical properties of silica aerogels with different geometric properties such as particle size, pore size, ligament diameter, etc. The FVM simulation results show that a power law correlation existing between relative density and mechanical properties (elastic modulus and yield stress) of silica aerogels, which are consistent with experimental and literature studies. In addition, depending on the relative densities, different strategies are proposed in order to synthesize silica aerogels with better mechanical performance by adjusting the distribution of pore size and ligament diameter of aerogels. Finally, the results suggest that it is possible to synthesize silica aerogels with ultra-low density as well as high strength and stiffness as long as the textural features are well controlled. It is believed that the FVM simulation methodology could be a valuable tool to study mechanical performance of silica aerogel based materials in the future. PMID:29385745

Simulation and Analysis of Mechanical Properties of Silica Aerogels: From Rationalization to Prediction.

PubMed

Ma, Hao; Zheng, Xiaoyang; Luo, Xuan; Yi, Yong; Yang, Fan

2018-01-30

Silica aerogels are highly porous 3D nanostructures and have exhibited excellent physio-chemical properties. Although silica aerogels have broad potential in many fields, the poor mechanical properties greatly limit further applications. In this study, we have applied the finite volume method (FVM) method to calculate the mechanical properties of silica aerogels with different geometric properties such as particle size, pore size, ligament diameter, etc. The FVM simulation results show that a power law correlation existing between relative density and mechanical properties (elastic modulus and yield stress) of silica aerogels, which are consistent with experimental and literature studies. In addition, depending on the relative densities, different strategies are proposed in order to synthesize silica aerogels with better mechanical performance by adjusting the distribution of pore size and ligament diameter of aerogels. Finally, the results suggest that it is possible to synthesize silica aerogels with ultra-low density as well as high strength and stiffness as long as the textural features are well controlled. It is believed that the FVM simulation methodology could be a valuable tool to study mechanical performance of silica aerogel based materials in the future.

Incorporation of noble metals into aerogels

DOEpatents

Hair, L.M.; Sanner, R.D.; Coronado, P.R.

1998-12-22

Aerogels or xerogels containing atomically dispersed noble metals for applications such as environmental remediation are disclosed. New noble metal precursors, such as Pt--Si or Pd(Si--P){sub 2}, have been created to bridge the incompatibility between noble metals and oxygen, followed by their incorporation into the aerogel or xerogel through sol-gel chemistry and processing. Applications include oxidation of hydrocarbons and reduction of nitrogen oxide species, complete oxidation of volatile organic carbon species, oxidative membranes for photocatalysis and partial oxidation for synthetic applications.

Ambient pressure dried tetrapropoxysilane-based silica aerogels with high specific surface area

NASA Astrophysics Data System (ADS)

Parale, Vinayak G.; Han, Wooje; Jung, Hae-Noo-Ree; Lee, Kyu-Yeon; Park, Hyung-Ho

2018-01-01

In the present paper, we report the synthesis of tetrapropoxysilane (TPOS)-based silica aerogels with high surface area and large pore volume. The silica aerogels were prepared by a two-step sol-gel process followed by surface modification via a simple ambient pressure drying approach. In order to minimize drying shrinkage and obtain hydrophobic aerogels, the surface of the alcogels was modified using trichloromethylsilane as a silylating agent. The effect of the sol-gel compositional parameters on the polymerization of aerogels prepared by TPOS, one of the precursors belonging to the Si(OR)4 family, was reported for the first time. The oxalic acid and NH4OH concentrations were adjusted to achieve good-quality aerogels with high surface area, low density, and high transparency. Controlling the hydrolysis and condensation reactions of the TPOS precursor turned out to be the most important factor to determine the pore characteristics of the aerogel. Highly transparent aerogels with high specific surface area (938 m2/g) and low density (0.047 g/cm3) could be obtained using an optimized TPOS/MeOH molar ratio with appropriate concentrations of oxalic acid and NH4OH.

Ultrafast Sol-Gel Synthesis of Graphene Aerogel Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Mathew; Hu, Matthew; Manandhar, Sandeep

2015-12-01

Graphene aerogels derived from graphene-oxide (GO) starting materials recently have been shown to exhibit a combination of high electrical conductivity, chemical stability, and low cost that has enabled a range of electrochemical applications. Standard synthesis protocols for manufacturing graphene aerogels require the use of sol-gel chemical reactions that are maintained at high temperatures for long periods of time ranging from 12 hours to several days. Here we report an ultrafast, acid-catalyzed sol-gel formation process in acetonitrile in which wet GO-loaded gels are realized within 2 hours at temperatures below 45°C. Spectroscopic and electrochemical analysis following supercritical drying and pyrolysis confirmsmore » the reduction of the GO in the aerogels to sp2 carbon crystallites with no residual carbon–nitrogen bonds from the acetonitrile or its derivatives. This rapid synthesis enhances the prospects for large-scale manufacturing of graphene aerogels for use in numerous applications including sorbents for environmental toxins, support materials for electrocatalysis, and high-performance electrodes for electrochemical capacitors and solar cells.« less

Reinforcement of bacterial cellulose aerogels with biocompatible polymers.

PubMed

Pircher, N; Veigel, S; Aigner, N; Nedelec, J M; Rosenau, T; Liebner, F

2014-10-13

Bacterial cellulose (BC) aerogels, which are fragile, ultra-lightweight, open-porous and transversally isotropic materials, have been reinforced with the biocompatible polymers polylactic acid (PLA), polycaprolactone (PCL), cellulose acetate (CA), and poly(methyl methacrylate) (PMMA), respectively, at varying BC/polymer ratios. Supercritical carbon dioxide anti-solvent precipitation and simultaneous extraction of the anti-solvent using scCO2 have been used as core techniques for incorporating the secondary polymer into the BC matrix and to convert the formed composite organogels into aerogels. Uniaxial compression tests revealed a considerable enhancement of the mechanical properties as compared to BC aerogels. Nitrogen sorption experiments at 77K and scanning electron micrographs confirmed the preservation (or even enhancement) of the surface-area-to-volume ratio for most of the samples. The formation of an open-porous, interpenetrating network of the second polymer has been demonstrated by treatment of BC/PMMA hybrid aerogels with EMIM acetate, which exclusively extracted cellulose, leaving behind self-supporting organogels. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Locating Stardust-like Particles in Aerogel Using X-Ray Techniques

NASA Technical Reports Server (NTRS)

Jurewicz, A. J. G.; Jones, S. M.; Tsapin, A.; Mih, D. T.; Connolly, H. C., Jr.; Graham, G. A.

2003-01-01

Silica aerogel is the material that the spacecraft STARDUST is using to collect interstellar and cometary silicates. Anticipating the return of the samples to earth in January of 2006, MANY individual investigators and, especially, the investigators in NASA's SRLIDAP program are studying means of both in situ analysis of particles, as well as particle extraction. To help individual PI's with extraction of particles from aerogel in their own laboratories, we are exploring the use of standard laboratory x-ray equipment and commercial techniques for precisely locating specific particles in aerogel. We approached the evaluation of commercial x-ray techniques as follows. First, we determined the most appropriate detector for use with aerogel and particulates. Then, we compared and contrasted techniques useful for university laboratories.

[Ambient pressure synthesis and characterization of silica aerogel as adsorbent for dieldrin].

PubMed

Sha, Wei; Liu, Rui-ping; Liu, Hui-juan; Qu, Jiu-hui

2008-12-01

Hydrophobic silica aerogels were prepared from cheap waterglass precursors via surface modification of wet gels and ambient pressure drying route. Its adsorption capacity of Dieldrin, a typical of persistent organic pollutants (POPs), was examined. It is characterized via BET, FTIR, and DSC-TGA. The silica aerogels were highly hydrophobic with contact angles of 135 degrees-142 degrees, and the hydrophobicity of the aerogels could be maintained up to the temperature of 380 degrees C. The silica aerogels were porous with, pore size distribution of 17.5-23.4 nm, porosity of 94.8%-95.6%, and surface area of 444-560 m2 x g(-1). The results of adsorption experiments indicated that the hydrophobic aerogels could remove 84% of dieldrin from aqueous solution within 4 h; the adsorption process followed the pseudo-second-order kinetics process. Based on the adsorption equilibrium results, the adsorption capacity of silica aerogel was 11 times bigger than by active carbon.

Ultralight Graphene/Carbon Nanotubes Aerogels with Compressibility and Oil Absorption Properties

PubMed Central

Zhao, Da; Yu, Li; Liu, Dongxu

2018-01-01

Graphene aerogels have many advantages, such as low density, high elasticity and strong adsorption. They are considered to be widely applicable in many fields. At present, the most valuable research area aims to find a convenient and effective way to prepare graphene aerogels with excellent properties. In this work graphene/carbon nanotube aerogels are prepared through hydrothermal reduction, freeze-drying and high temperature heat treatment with the blending of graphene oxide and carbon nanotubes. A new reducing agent-ascorbic acid is selected to explore the best preparation process. The prepared aerogels have compression and resilience and oil absorption properties due to the addition of carbon nanotubes as designed. PMID:29690559

Ultralight Graphene/Carbon Nanotubes Aerogels with Compressibility and Oil Absorption Properties.

PubMed

Zhao, Da; Yu, Li; Liu, Dongxu

2018-04-22

Graphene aerogels have many advantages, such as low density, high elasticity and strong adsorption. They are considered to be widely applicable in many fields. At present, the most valuable research area aims to find a convenient and effective way to prepare graphene aerogels with excellent properties. In this work graphene/carbon nanotube aerogels are prepared through hydrothermal reduction, freeze-drying and high temperature heat treatment with the blending of graphene oxide and carbon nanotubes. A new reducing agent-ascorbic acid is selected to explore the best preparation process. The prepared aerogels have compression and resilience and oil absorption properties due to the addition of carbon nanotubes as designed.

Synthesis and Properties of Cross-Linked Polyamide Aerogels

NASA Technical Reports Server (NTRS)

Williams, Jarrod; Meador, Mary Ann; McCorkle, Linda

2014-01-01

We report our ongoing research on polyamide aerogels made by step growth polymerization using a combination of terephthaloyl chloride, isophthaloyl chloride and m-phenylenediamine. Crosslinking of the amine capped polymer chains with 1,3,5-benzenetricarbonyl trichloride causes gelation in as little as two to five minutes. Removing the reaction solvent is accomplished through solvent exchange, followed by drying using supercritical CO2 extraction to give colorless aerogels with densities ranging from 0.07 to 0.33 grams per cubic centimeter and surface areas as high as 440 square meters per gram. Statistical experimental design methodology has been utilized to investigate dependence of properties of these aerogels, such as density, compressive modulus, and surface area, on changes in fabrication parameters including formulated number of amide oligomer repeat units (n-value), acid chloride (meta, para or combination), and solids concentration of solution used for gelation. For example, the density of these materials was found to be dependent on the acid chloride type and the solids concentration, but n was not a significant variable. However, surface area was significantly influenced by all three parameters. The polyamide aerogels represent a potential cost savings over previously reported polyimide aerogels, since monomers are all inexpensive and commercially available. Surface area and density were both highest when 100 terephthaloyl chloride was used but a combination of 5 solid concentration, 100 terephthaloyl chloride and n of 20 gave the best combination of properties.

Repeatability of Cryogenic Multilayer Insulation

NASA Technical Reports Server (NTRS)

Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

2017-01-01

Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between multiple identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five GRC provided coupons with 25 layers was shown to be +/- 8.4 whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0. A second group of 10 coupons have been fabricated by Yetispace and tested by Florida State University, through the first 4 tests, the repeatability has been shown to be +/- 16. Based on detailed statistical analysis, the data has been shown to be statistically significant.

Repeatability of Cryogenic Multilayer Insulation

NASA Technical Reports Server (NTRS)

Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

2017-01-01

Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between multiple identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five GRC provided coupons with 25 layers was shown to be +/- 8.4% whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0%. A second group of 10 coupons have been fabricated by Yetispace and tested by Florida State University, through the first 4 tests, the repeatability has been shown to be +/- 15-25%. Based on detailed statistical analysis, the data has been shown to be statistically significant.

Repeatability of Cryogenic Multilayer Insulation

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

2017-12-01

Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation (MLI) has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five Glenn Research Center (GRC) provided coupons with 25 layers was shown to be +/- 8.4% whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0%. A second group of 10 coupons has been fabricated by Yetispace and tested by Florida State University, the repeatability between coupons has been shown to be +/- 15-25%. Based on detailed statistical analysis, the data has been shown to be statistically significant.

Efficiently dense hierarchical graphene based aerogel electrode for supercapacitors

NASA Astrophysics Data System (ADS)

Wang, Xin; Lu, Chengxing; Peng, Huifen; Zhang, Xin; Wang, Zhenkun; Wang, Gongkai

2016-08-01

Boosting gravimetric and volumetric capacitances simultaneously at a high rate is still a discrepancy in development of graphene based supercapacitors. We report the preparation of dense hierarchical graphene/activated carbon composite aerogels via a reduction induced self-assembly process coupled with a drying post treatment. The compact and porous structures of composite aerogels could be maintained. The drying post treatment has significant effects on increasing the packing density of aerogels. The introduced activated carbons play the key roles of spacers and bridges, mitigating the restacking of adjacent graphene nanosheets and connecting lateral and vertical graphene nanosheets, respectively. The optimized aerogel with a packing density of 0.67 g cm-3 could deliver maximum gravimetric and volumetric capacitances of 128.2 F g-1 and 85.9 F cm-3, respectively, at a current density of 1 A g-1 in aqueous electrolyte, showing no apparent degradation to the specific capacitance at a current density of 10 A g-1 after 20000 cycles. The corresponding gravimetric and volumetric capacitances of 116.6 F g-1 and 78.1 cm-3 with an acceptable cyclic stability are also achieved in ionic liquid electrolyte. The results show a feasible strategy of designing dense hierarchical graphene based aerogels for supercapacitors.

Forced-air patient warming blankets disrupt unidirectional airflow.

PubMed

Legg, A J; Hamer, A J

2013-03-01

We have recently shown that waste heat from forced-air warming blankets can increase the temperature and concentration of airborne particles over the surgical site. The mechanism for the increased concentration of particles and their site of origin remained unclear. We therefore attempted to visualise the airflow in theatre over a simulated total knee replacement using neutral-buoyancy helium bubbles. Particles were created using a Rocket PS23 smoke machine positioned below the operating table, a potential area of contamination. The same theatre set-up, warming devices and controls were used as in our previous study. This demonstrated that waste heat from the poorly insulated forced-air warming blanket increased the air temperature on the surgical side of the drape by > 5°C. This created convection currents that rose against the downward unidirectional airflow, causing turbulence over the patient. The convection currents increased the particle concentration 1000-fold (2 174 000 particles/m(3) for forced-air warming vs 1000 particles/m(3) for radiant warming and 2000 particles/m(3) for the control) by drawing potentially contaminated particles from below the operating table into the surgical site. Cite this article: Bone Joint J 2013;95-B:407-10.

Adsorption and desorption of cationic malachite green dye on cellulose nanofibril aerogels.

PubMed

Jiang, Feng; Dinh, Darren M; Hsieh, You-Lo

2017-10-01

Ultra-light aerogels have been assembled from cellulose nanofibrils into hierarchically macroporous (several hundred μm) honeycomb cellular structure surrounded with mesoporous (8-60nm) thin walls. The high specific surface (193m 2 /g) and surface carboxyl content (1.29mmol/g) of these aerogels were demonstrated to be highly capable of removing cationic malachite green (MG) dye from aqueous media. The rapid MG adsorption was driven by electrostatic interactions and followed a pseudo-second-order adsorption kinetic and monolayer Langmuir adsorption isotherm. At a low 1:5mg/mL aerogel/MG ratio, both initial MG adsorption rate (2.3-59.8mgg -1 min -1 ) and equilibrium adsorption capacity (53.0-203.7mgg -1 ) increased with increasing initial MG concentrations from 10 to 200mg/L, reaching a maximum adsorption of 212.7mgg -1 . The excellent dye removal efficiency was demonstrated by complete MG removal through four repetitive adsorptions at a low 1:5mg/mL aerogel/MG ratio and 10mg/L dye concentration as well as 92% MG adsorption in a single batch at one order of magnitude higher10:5mg/mL aerogel/MG ratio and 100mg/L dye concentration. The adsorbed MG in aerogels could be desorbed in aqueous media by increasing ionic strength, demonstrating facile recovery of both dye and aerogel as well as the robust capability of this aerogel for repetitive applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Strong, low-density nanocomposites by chemical vapor deposition and polymerization of cyanoacrylates on aminated silica aerogels.

PubMed

Boday, Dylan J; Stover, Robert J; Muriithi, Beatrice; Keller, Michael W; Wertz, Jason T; Defriend Obrey, Kimberly A; Loy, Douglas A

2009-07-01

Strong polymer-silica aerogel composites were prepared by chemical vapor deposition of cyanoacrylate monomers onto amine-modified aerogels. Amine-modified silica aerogels were prepared by copolymerizing small amounts of (aminopropyl)triethoxysilane with tetraethoxysilane. After silation of the aminated gels with hexamethyldisilazane, they were dried as aerogels using supercritical carbon dioxide processing. The resulting aerogels had only the amine groups as initiators for the cyanoacrylate polymerizations, resulting in cyanoacrylate macromolecules that were higher in molecular weight than those observed with unmodified silica and that were covalently attached to the silica surface. Starting with aminated silica aerogels that were 0.075 g/cm(3) density, composite aerogels were made with densities up to 0.220 g/cm(3) and up to 31 times stronger (flexural strength) than the precursor aerogel and about 2.3 times stronger than an unmodified silica aerogel of the same density.

From Green Aerogels to Porous Graphite by Emulsion Gelation of Acrylonitrile

DTIC Science & Technology

2012-01-01

interesting uses of PAN aerogels is not dealing with monoliths at all but rather with films made by grafting PAN on carbon nanotubes that in turn are...REPORT From ‘Green’ Aerogels to Porous Graphite by Emulsion Gelation of Acrylonitrile 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Porous carbons ...including carbon (C) aerogels, are technologically important materials, while polyacrylonitriile (PAN) is the main industrial source of graphite fiber

Investigation of Aerogel/Xerogel Catalysts for Autothermal Reforming of JP-8

DTIC Science & Technology

2013-12-19

Investigation of Aerogel /Xerogel Catalysts for Autothermal Reforming of JP-8 The views, opinions and/or findings contained in this report are those of the...VA 23668 -0108 ABSTRACT Number of Papers published in peer-reviewed journals: Investigation of Aerogel /Xerogel Catalysts for Autothermal Reforming...Conference held in Houston, TX, April 19-22, 2011 Synthesis and Characterization of Nickel-Silica Aerogels Using a Sub-Critical Drying Approach

Whey protein aerogel as blended with cellulose crystalline particles or loaded with fish oil.

PubMed

Ahmadi, Maede; Madadlou, Ashkan; Saboury, Ali Akbar

2016-04-01

Whey protein hydrogels blended with nanocrystalline and microcrystalline cellulose particles (NCC and MCC, respectively) were prepared, followed by freeze-drying, to produce aerogels. NCC blending increased the Young's modulus, and elastic character, of the protein aerogel. Aerogels were microporous and mesoporous materials, as characterized by the pores sizing 1.2 nm and 12.2 nm, respectively. Blending with NCC decreased the count of both microporous and mesoporous-classified pores at the sub-100 nm pore size range investigated. In contrast, MCC blending augmented the specific surface area and pores volume of the aerogel. It also increased moisture sorption affinity of aerogel. The feasibility of conveying hydrophobic nutraceuticals by aerogels was evaluated through loading fish oil into the non-blended aerogel. Oil loading altered its microstructure, corresponding to a peak displacement in Fourier-transform infra-red spectra, which was ascribed to increased hydrophobic interactions. Surface coating of aerogel with zein decreased the oxidation susceptibility of the loaded oil during subsequent storage. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bioinspired Ultralight Inorganic Aerogel for Highly Efficient Air Filtration and Oil-Water Separation.

PubMed

Zhang, Yong-Gang; Zhu, Ying-Jie; Xiong, Zhi-Chao; Wu, Jin; Chen, Feng

2018-04-18

Inorganic aerogels have been attracting great interest owing to their distinctive structures and properties. However, the practical applications of inorganic aerogels are greatly restricted by their high brittleness and high fabrication cost. Herein, inspired by the cancellous bone, we have developed a novel kind of hydroxyapatite (HAP) nanowire-based inorganic aerogel with excellent elasticity, which is highly porous (porosity ≈ 99.7%), ultralight (density 8.54 mg/cm 3 , which is about 0.854% of water density), and highly adiabatic (thermal conductivity 0.0387 W/m·K). Significantly, the as-prepared HAP nanowire aerogel can be used as the highly efficient air filter with high PM 2.5 filtration efficiency. In addition, the HAP nanowire aerogel is also an ideal candidate for continuous oil-water separation, which can be used as a smart switch to separate oil from water continuously. Compared with organic aerogels, the as-prepared HAP nanowire aerogel is biocompatible, environmentally friendly, and low-cost. Moreover, the synthetic method reported in this work can be scaled up for large-scale production of HAP nanowires, free from the use of organic solvents. Therefore, the as-prepared new kind of HAP nanowire aerogel is promising for the applications in various fields.

Neutronics Evaluation of Lithium-Based Ternary Alloys in IFE Blankets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jolodosky, A.; Fratoni, M.

Lithium is often the preferred choice as breeder and coolant in fusion blankets as it offers excellent heat transfer and corrosion properties, and most importantly, it has a very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and exacerbates plant safety concerns. For this reason, over the years numerous blanket concepts have been proposed with the scope of reducing concerns associated with lithium. The European helium cooled pebble bed breeding blanket (HCPB) physically confines lithium within ceramic pebbles. The pebbles reside within amore » low activation martensitic ferritic steel structure and are cooled by helium. The blanket is composed of the tritium breeding lithium ceramic pebbles and neutron multiplying beryllium pebbles. Other blanket designs utilize lead to lower chemical reactivity; LiPb alone can serve as a breeder, coolant, neutron multiplier, and tritium carrier. Blankets employing LiPb coolants alongside silicon carbide structural components can achieve high plant efficiency, low afterheat, and low operation pressures. This alloy can also be used alongside of helium such as in the dual-coolant lead-lithium concept (DCLL); helium is utilized to cool the first wall and structural components made up of low-activation ferritic steel, whereas lithium-lead (LiPb) acts as a self-cooled breeder in the inner channels of the blanket. The helium-cooled steel and lead-lithium alloy are separated by flow channel inserts (usually made out of silicon carbide) which thermally insulate the self-cooled breeder region from the helium cooled steel walls. This creates a LiPb breeder with a much higher exit temperature than the steel which increases the power cycle efficiency and also lowers the magnetohydrodynamic (MHD) pressure drop [6]. Molten salt blankets with a mixture of lithium, beryllium, and fluorides (FLiBe) offer good tritium

Synchrotron Microtomography Reveals the Fine Three-Dimensional Porosity of Composite Polysaccharide Aerogels

PubMed Central

Ghafar, Abdul; Parikka, Kirsti; Tenkanen, Maija; Suuronen, Jussi-Petteri

2017-01-01

This study investigates the impact of ice-templating conditions on the morphological features of composite polysaccharide aerogels in relation to their mechanical behavior and aims to get a better insight into the parameters governing these properties. We have prepared polysaccharide aerogels of guar galactomannan (GM) and tamarind seed xyloglucan (XG) by enzymatic oxidation with galactose oxidase (GaO) to form hydrogels, followed by conventional and unidirectional ice-templating (freezing) methods and lyophilization to form aerogels. Composite polysaccharide aerogels were prepared by incorporating nanofibrillated cellulose (NFC) into polysaccharide solutions prior to enzymatic oxidation and gel formation; such a cross linking technique enabled the homogeneous distribution of the NFC reinforcement into the gel matrix. We conducted phase-enhanced synchrotron X-ray microtomography (XMT) scans and visualized the internal microstructure of the aerogels in three-dimensional (3D) space. Volume-weighted pore-size and pore-wall thickness distributions were quantitatively measured and correlated to the aerogels’ mechanical properties regarding ice-templating conditions. Pore-size distribution and orientation depended on the ice-templating methods and the NFC reinforcement that significantly determined the mechanical and shape-recovery behavior of the aerogels. The results obtained will guide the design of the microporous structure of polysaccharide aerogels with optimal morphology and mechanical behavior for life-sciences applications. PMID:28773235

Aerogel as a Sample Collector and Sample Mount for Transmission XRD Analysis

NASA Technical Reports Server (NTRS)

Bish, D. L.; Vaniman, D. T.; Chipera, S. J.; Yen, A. S.; Jones, S. M.

2001-01-01

Silica aerogel can be used for dust collection and in situ X-ray analysis. Aerogels can be less absorbing than Be, and it is feasible to obtain X-ray transmission factors >50% using typical aerogels together with a 100-micrometer Be backing foil. Additional information is contained in the original extended abstract.

Insulation Testing Using Cryostat Apparatus with Sleeve

NASA Technical Reports Server (NTRS)

Fesmire, J. E.; Augustynowicz, S. D.

1999-01-01

The method and equipment of testing continuously rolled insulation materials is presented in this paper. Testing of blanket and molded products is also facilitated. Materials are installed around a cylindrical copper sleeve using a wrapping machine. The sleeve is slid onto the vertical cold mass of the cryostat. The gap between the cold mass and the sleeve measures less than 1 mm. The cryostat apparatus is a liquid nitrogen boiloff calorimeter system that enables direct measurement of the apparent thermal conductivity (k-value) of the insulation system at any vacuum level between 5 x 10(exp -5) and 760 torr. Sensors are placed between layers of the insulation to provide complete temperature-thickness profiles. The temperatures of the cold mass (maintained at 77.8 kelvin (K)), the sleeve (cold boundary temperature (CBT)), the insulation outer surface (warm boundary temperature (WBT)), and the vacuum can (maintained at 313 K by a thermal shroud) are measured. Plots of CBT, WBT, and layer temperature profiles as functions of vacuum level show the transitions between the three dominant heat transfer modes. For this cryostat apparatus, the measureable heat gain is from 0.2 to 20 watts. The steady-state measurement of k-value is made when all temperatures and the boiloff rate are stable.

Flexible, Mechanically Durable Aerogel Composites for Oil Capture and Recovery.

PubMed

Karatum, Osman; Steiner, Stephen A; Griffin, Justin S; Shi, Wenbo; Plata, Desiree L

2016-01-13

More than 30 years separate the two largest oil spills in North American history (the Ixtoc I and Macondo well blowouts), yet the responses to both disasters were nearly identical in spite of advanced material innovation during the same time period. Novel, mechanically durable sorbents could enable (a) sorbent use in the open ocean, (b) automated deployment to minimize workforce exposure to toxic chemicals, and (c) mechanical recovery of spilled oils. Here, we explore the use of two mechanically durable, low-density (0.1-0.2 g cm(-3)), highly porous (85-99% porosity), hydrophobic (water contact angles >120°), flexible aerogel composite blankets as sorbent materials for automated oil capture and recovery: Cabot Thermal Wrap (TW) and Aspen Aerogels Spaceloft (SL). Uptake of crude oils (Iraq and Sweet Bryan Mound oils) was 8.0 ± 0.1 and 6.5 ± 0.3 g g(-1) for SL and 14.0 ± 0.1 and 12.2 ± 0.1 g g(-1) for TW, respectively, nearly twice as high as similar polyurethane- and polypropylene-based devices. Compound-specific uptake experiments and discrimination against water uptake suggested an adsorption-influenced sorption mechanism. Consistent with that mechanism, chemical extraction oil recoveries were 95 ± 2 (SL) and 90 ± 2% (TW), but this is an undesirable extraction route in decentralized oil cleanup efforts. In contrast, mechanical extraction routes are favorable, and a modest compression force (38 N) yielded 44.7 ± 0.5% initially to 42.0 ± 0.4% over 10 reuse cycles for SL and initially 55.0 ± 0.1% for TW, degrading to 30.0 ± 0.2% by the end of 10 cycles. The mechanical integrity of SL deteriorated substantially (800 ± 200 to 80 ± 30 kPa), whereas TW was more robust (380 ± 80 to 700 ± 100 kPa) over 10 uptake-and-compression extraction cycles.

Effects of Fiber Reinforcement on Clay Aerogel Composites

PubMed Central

Finlay, Katherine A.; Gawryla, Matthew D.; Schiraldi, David A.

2015-01-01

Novel, low density structures which combine biologically-based fibers with clay aerogels are produced in an environmentally benign manner using water as solvent, and no additional processing chemicals. Three different reinforcing fibers, silk, soy silk, and hemp, are evaluated in combination with poly(vinyl alcohol) matrix polymer combined with montmorillonite clay. The mechanical properties of the aerogels are demonstrated to increase with reinforcing fiber length, in each case limited by a critical fiber length, beyond which mechanical properties decline due to maldistribution of filler, and disruption of the aerogel structure. Rather than the classical model for reinforced composite properties, the chemical compatibility of reinforcing fibers with the polymer/clay matrix dominated mechanical performance, along with the tendencies of the fibers to kink under compression. PMID:28793515

Analysis Techniques, Materials, and Methods for Treatment of Thermal Bridges in Building Envelopes

DTIC Science & Technology

2013-08-01

effects of the R-value for given increment of time ............................................. 89 64 Crystals on a post-conditioned Aspen Aerogel ... aerogel on specific sites compared to conventional polyurethane foam insulation. Figures 55 and 56 show two examples of preliminary parametric... Aerogel , and (4) Honeywell’s polyurethane. Table 14 lists the four tested insulation ma- terials, their experimental thermal properties (derived

Aerogel and xerogel composites for use as carbon anodes

DOEpatents

Cooper, John F [Oakland, CA; Tillotson, Thomas M [Tracy, CA; Hrubesh, Lawrence W [Pleasanton, CA

2008-08-12

Disclosed herein are aerogel and xerogel composite materials suitable for use as anodes in fuel cells and batteries. Precursors to the aerogel and xerogel compounds are infused with inorganic polymeric materials or carbon particles and then gelled. The gels are then pyrolyzed to form composites with internal structural support.

Method for making monolithic metal oxide aerogels

DOEpatents

Droege, M.W.; Coronado, P.R.; Hair, L.M.

1995-03-07

Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The present invention is especially advantageous for making metal oxides other than silica that are prone to forming opaque, cracked aerogels. 6 figs.

Method for making monolithic metal oxide aerogels

DOEpatents

Droege, Michael W.; Coronado, Paul R.; Hair, Lucy M.

1995-01-01

Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The present invention is especially advantageous for making metal oxides other than silica that are prone to forming opaque, cracked aerogels.

Functionalized silica aerogels for gas-phase purification, sensing, and catalysis: A review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amonette, James E.; Matyáš, Josef

Silica aerogels have a rich history and offer an unusual assembly of gas- and solid-phase properties that has lent them to many diverse applications. This review starts with a brief discussion of the fundamental issues driving the movement of gases in silica aerogels and then proceeds to provide an overview of the work that has been done with respect to the purification of gases, sensing of individual gases, and uses of silica aerogels as catalysts for gas-phase reactions. We present salient features of the research behind these different applications, and, where appropriate, critical aspects that affect the practical use ofmore » the aerogels are noted. Specific sections under the gas-purification category focus on the removal of airborne nanoparticles, carbon dioxide, volatile organic compounds, sulfur gases and radioactive iodine from gas streams. The use of silica aerogels as sensors for humidity, oxygen, hydrocarbons, volatile acids and bases, various non-ammoniacal nitrogen gases, and viral particles is discussed. With respect to catalysis, the demonstrated use of silica aerogels as supports for oxidation, Fischer-Tropsch, alkane isomerization, and hydrogenation reactions is reviewed, along with a section on untested catalytic formulations involving silica aerogels. A short section focuses on recent developments in thermomolecular Knudsen compressor pumps using silica aerogel membranes. Finally, the review continues with an overview of the production methods, locations of manufacturing facilities globally, and a brief discussion of the economics before concluding with a few remarks about the present and future trends revealed by the work presented.« less

Functionalized silica aerogels for gas-phase purification, sensing, and catalysis: A review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amonette, James E.; Matyáš, Josef

Silica aerogels have a rich history and a unique, fascinating gas-phase chemistry that has lent them to many diverse applications. This review starts with a brief discussion of the fundamental issues driving the movement of gases in silica aerogels and then proceeds to provide an overview of the work that has been done with respect to the purification of gases, sensing of individual gases, and uses of silica aerogels as catalysts for gas-phase reactions. Salient features of the research behind these different applications are presented, and, where appropriate, critical aspects that affect the practical use of the aerogels are noted.more » Specific sections under the gas-purification category focus on the removal of airborne nanoparticles, carbon dioxide, volatile organic compounds, sulfur gases and radioactive iodine from gas streams. The use of silica aerogels as sensors for humidity, oxygen, hydrocarbons, volatile acids and bases, various non-ammoniacal nitrogen gases, and viral particles is discussed. With respect to catalysis, the demonstrated use of silica aerogels as supports for oxidation, Fischer-Tropsch, alkane isomerization, and hydrogenation reactions is reviewed, along with a section on untested catalytic formulations involving silica aerogels. A short section focuses on recent developments in thermomolecular Knudsen compressor pumps using silica aerogel membranes. The review continues with an overview of the production methods, locations of manufacturing facilities globally, and a brief discussion of the economics before concluding with a few remarks about the present and future trends revealed by the work presented.« less

Functionalized silica aerogels for gas-phase purification, sensing, and catalysis: A review

DOE PAGES

Amonette, James E.; Matyáš, Josef

2017-09-01

Silica aerogels have a rich history and offer an unusual assembly of gas- and solid-phase properties that has lent them to many diverse applications. This review starts with a brief discussion of the fundamental issues driving the movement of gases in silica aerogels and then proceeds to provide an overview of the work that has been done with respect to the purification of gases, sensing of individual gases, and uses of silica aerogels as catalysts for gas-phase reactions. We present salient features of the research behind these different applications, and, where appropriate, critical aspects that affect the practical use ofmore » the aerogels are noted. Specific sections under the gas-purification category focus on the removal of airborne nanoparticles, carbon dioxide, volatile organic compounds, sulfur gases and radioactive iodine from gas streams. The use of silica aerogels as sensors for humidity, oxygen, hydrocarbons, volatile acids and bases, various non-ammoniacal nitrogen gases, and viral particles is discussed. With respect to catalysis, the demonstrated use of silica aerogels as supports for oxidation, Fischer-Tropsch, alkane isomerization, and hydrogenation reactions is reviewed, along with a section on untested catalytic formulations involving silica aerogels. A short section focuses on recent developments in thermomolecular Knudsen compressor pumps using silica aerogel membranes. Finally, the review continues with an overview of the production methods, locations of manufacturing facilities globally, and a brief discussion of the economics before concluding with a few remarks about the present and future trends revealed by the work presented.« less

Around Marshall

NASA Image and Video Library

1996-06-18

Scientists at MSFC have been studying the properties of Aerogel for several years. Aerogel, the lightest solid known to man, has displayed a high quality for insulation. Because of its smoky countenance it has yet to be used as an insulation on windows, but has been used to insulate the walls of houses and engine compartments in cars. It was also used in the space program as insulating material on the rover Sojourner, aboard the Mars Pathfinder. MSFC is one of the many research facilities conducting experiments to unlock the smoky properties of aerogel and make it a clear substance. MSFC researchers believe that by taking this research to space, they can resolve the problem of making aerogel transparent enough to see through. So far, recent space experiments have been encouraging. The samples produced in microgravity indicate a change in the microstructure of the material as compared to ground samples. MSFC scientists continue to study the effects of microgravity on Aerogel as their research is space continues.

The Morphology of Titanium Dioxide Aerogels

NASA Astrophysics Data System (ADS)

Zhu, Zhu

The morphology of titanium dioxide TiO _2 aerogels has been characterized by four major techniques. This work will discuss these complementary techniques such as nitrogen adsorption, X-ray powder diffraction (XRD), electron microscopies (EM- TEM, SEM), and small angle neutron scattering (SANS). The results of these characterizations have shown that the morphology of titanium dioxide TiO_2 aerogels can be characterized in terms of two length scales: 5 nm diameter, crystalline nanoparticles of anatase closely packed into mesoaggregates about 50 nm in size. The mesoaggregates are, in turn, packed into a loosely linked structure with an overall porosity of 80%.

Using Silica Sol as a Nanoglue to Prepare Nanoscale Mesoporous Composite Gel and Aerogels

DTIC Science & Technology

2000-03-31

solution-phase reactants remain unaltered. Furthermore, the composite constitutes a rigid solid architecture, such that the silica aerogel structure...nm) was immobilized in a silica aerogel structure according to the method of the present invention. The optical properties of 9 these materials...Aerogel Preparation. Acid- and base-catalyzed silica aerogels were prepared by procedures similarto those previously published in Russo et al.J.Non

Synthesis of silica aerogel monoliths with controlled specific surface areas and pore sizes

NASA Astrophysics Data System (ADS)

Gao, Bingying; Lu, Shaoxiang; Kalulu, Mulenga; Oderinde, Olayinka; Ren, Lili

2017-07-01

To replace traditional preparation methods of silica aerogels, a small-molecule 1,2-epoxypropane (PO) has been introduced into the preparation process instead of using ammonia as the cross-linking agent, thus generating a lightweight, high porosity, and large surface area silica aerogel monolithic. We put forward a simple solution route for the chemical synthesis of silica aerogels, which was characterized by scanning electron microscopy (SEM), TEM, XRD, FTIR, thermogravimetric analysis (TGA) and the Brunauer-Emmett-Teller (BET) method In this paper, the effect of the amount of PO on the microstructure of silica aerogels is discussed. The BET surface areas and pore sizes of the resulting silica aerogels can be freely adjusted by changing the amount of PO, which will be helpful in promoting the development of silica aerogels to fabricate other porous materials with similar requirements. We also adopted a new organic solvent sublimation drying (OSSD) method to replace traditional expensive and dangerous drying methods such as critical point drying and freeze drying. This simple approach is easy to operate and has good repeatability, which will further facilitate actual applications of silica aerogels.

Aerogel Fingerprint Media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Fred S.; Andresen, Brian D.

1999-09-21

A fingerprint medium which is made of an aerogel having a predetermined density. The fingerprint medium may have a midrange density for forming plates or may be crushed forming a powder. The fingerprint medium may further include at least one of a metal and metal oxide to enhance characteristics desirable in a fingerprint medium.

Improved oxidation resistance of organic/inorganic composite atomic layer deposition coated cellulose nanocrystal aerogels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Sean W.; Matthews, David J.; Conley, John F., E-mail: jconley@eecs.oregonstate.edu

2014-07-01

Cellulose nanocrystal (CNC) aerogels are coated with thin conformal layers of Al{sub 2}O{sub 3} using atomic layer deposition to form hybrid organic/inorganic nanocomposites. Electron probe microanalysis and scanning electron microscopy analysis indicated the Al{sub 2}O{sub 3} penetrated more than 1500 μm into the aerogel for extended precursor pulse and exposure/purge times. The measured profile of coated fiber radius versus depth from the aerogel surface agrees well with simulations of precursor penetration depth in modeled aerogel structures. Thermogravimetric analysis shows that Al{sub 2}O{sub 3} coated CNC aerogel nanocomposites do not show significant thermal degradation below 295 °C as compared with 175 °C for uncoatedmore » CNC aerogels, an improvement of over 100 °C.« less

Process for Preparing Epoxy-Reinforced Silica Aerogels

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B (Inventor)

2016-01-01

One-pot reaction process for preparing epoxy-reinforced monolithic silica aerogels comprising the reaction of at least one silicon compound selected from the group consisting of alkoxysilanes, orthosilicates and combination thereof in any ratio with effective amounts of an epoxy monomer and an aminoalkoxy silane to obtain an epoxy monomer-silica sol in solution, subsequently preparing an epoxy-monomer silica gel from said silica sol solution followed by initiating polymerization of the epoxy monomer to obtain the epoxy-reinforced monolithic silica aerogel.

Methods for controlling pore morphology in aerogels using electric fields and products thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Worsley, Marcus A.; Baumann, Theodore F.; Satcher, Jr., Joe H.

In one embodiment, an aerogel or xerogel includes column structures of a material having minor pores therein and major pores devoid of the material positioned between the column structures, where longitudinal axes of the major pores are substantially parallel to one another. In another embodiment, a method includes heating a sol including aerogel or xerogel precursor materials to cause gelation thereof to form an aerogel or xerogel and exposing the heated sol to an electric field, wherein the electric field causes orientation of a microstructure of the sol during gelation, which is retained by the aerogel or xerogel. In onemore » approach, an aerogel has elongated pores extending between a material arranged in column structures having structural characteristics of being formed from a sol exposed to an electric field that causes orientation of a microstructure of the sol during gelation which is retained by the elongated pores of the aerogel.« less

A Special Material or a New State of Matter: A Review and Reconsideration of the Aerogel

PubMed Central

Du, Ai; Zhou, Bin; Zhang, Zhihua; Shen, Jun

2013-01-01

The ultrahighly nanoporous aerogel is recognized as a state of matter rather than as a functional material, because of its qualitative differences in bulk properties, transitional density and enthalpy between liquid and gas, and diverse chemical compositions. In this review, the characteristics, classification, history and preparation of the aerogel were introduced. More attention was paid to the sol-gel method for preparing different kinds of aerogels, given its important role on bridging the synthetic parameters with the properties. At last, preparation of a novel single-component aerogel, design of a composite aerogel and industrial application of the aerogel were regarded as the research tendency of the aerogel state in the near future. PMID:28809350

Liquid-solid phase transition of hydrogen and deuterium in silica aerogel

NASA Astrophysics Data System (ADS)

Van Cleve, E.; Worsley, M. A.; Kucheyev, S. O.

2014-10-01

Behavior of hydrogen isotopes confined in disordered low-density nanoporous solids remains essentially unknown. Here, we use relaxation calorimetry to study freezing and melting of H2 and D2 in an ˜85%-porous base-catalyzed silica aerogel. We find that liquid-solid transition temperatures of both isotopes inside the aerogel are depressed. The phase transition takes place over a wide temperature range of ˜4 K and non-trivially depends on the liquid filling fraction, reflecting the broad pore size distribution in the aerogel. Undercooling is observed for both H2 and D2 confined inside the aerogel monolith. Results for H2 and D2 are extrapolated to tritium-containing hydrogens with the quantum law of corresponding states.

Biodegradable Pectin/clay Aerogels

USDA-ARS?s Scientific Manuscript database

Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. Addition of multivalent cations (Ca2+ and Al3+) resulted in apparent crosslinking of the polymer, and enhancement of aerogel p...

Fusion reactor blanket/shield design study

NASA Astrophysics Data System (ADS)

Smith, D. L.; Clemmer, R. G.; Harkness, S. D.; Jung, J.; Krazinski, J. L.; Mattas, R. F.; Stevens, H. C.; Youngdahl, C. K.; Trachsel, C.; Bowers, D.

1979-07-01

A joint study of Tokamak reactor first wall/blanket/shield technology was conducted to identify key technological limitations for various tritium breeding blanket design concepts, establishment of a basis for assessment and comparison of the design features of each concept, and development of optimized blanket designs. The approach used involved a review of previously proposed blanket designs, analysis of critical technological problems and design features associated with each of the blanket concepts, and a detailed evaluation of the most tractable design concepts. Tritium breeding blanket concepts were evaluated according to the proposed coolant. The effort concentrated on evaluation of lithium and water cooled blanket designs and helium and molten salt cooled designs. Generalized nuclear analysis of the tritium breeding performance, an analysis of tritium breeding requirements, and a first wall stress analysis were conducted as part of the study. The impact of coolant selection on the mechanical design of a Tokamak reactor was evaluated. Reference blanket designs utilizing the four candidate coolants are presented.

Transparent, Superflexible Doubly Cross-Linked Polyvinylpolymethylsiloxane Aerogel Superinsulators via Ambient Pressure Drying.

PubMed

Zu, Guoqing; Shimizu, Taiyo; Kanamori, Kazuyoshi; Zhu, Yang; Maeno, Ayaka; Kaji, Hironori; Shen, Jun; Nakanishi, Kazuki

2018-01-23

Aerogels have many attractive properties but are usually costly and mechanically brittle, which always limit their practical applications. While many efforts have been made to reinforce the aerogels, most of the reinforcement efforts sacrifice the transparency or superinsulating properties. Here we report superflexible polyvinylpolymethylsiloxane, (CH 2 CH(Si(CH 3 )O 2/2 )) n , aerogels that are facilely prepared from a single precursor vinylmethyldimethoxysilane or vinylmethyldiethoxysilane without organic cross-linkers. The method is based on consecutive processes involving radical polymerization and hydrolytic polycondensation, followed by ultralow-cost, highly scalable, ambient-pressure drying directly from alcohol as a drying medium without any modification or additional solvent exchange. The resulting aerogels and xerogels show a homogeneous, tunable, highly porous, doubly cross-linked nanostructure with the elastic polymethylsiloxane network cross-linked with flexible hydrocarbon chains. An outstanding combination of ultralow cost, high scalability, uniform pore size, high surface area, high transparency, high hydrophobicity, excellent machinability, superflexibility in compression, superflexibility in bending, and superinsulating properties has been achieved in a single aerogel or xerogel. This study represents a significant progress of porous materials and makes the practical applications of transparent flexible aerogel-based superinsulators realistic.

Crosslinking Amine-Modified Silica Aerogels with Epoxies: Mechanically Strong Lightweight Porous Materials

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B.; Fabrizio, Eve F.; Ilhan, Faysal; Dass, Amala; Zhang, Guo-Hui; Vassilaras, Plousia; Johnston, J. Chris; Leventis, Nicholas

2005-01-01