Welcome, please login:
  |  [Join]  |     |   [Contact Us]


Business




Aerogel-based insulation continuing to make progress with commercialization

Published on April 5th, 2013 | Edited By: Eileen De Guire

Official video (in German) of STO In Aevero aerogel insulation boards. Credit: STO.

One of the promises of your basic silica-based aerogel is that it would make a fantastic component in insulation systems—but there have always been a lot of manufacturing and processing “ifs” involved. Nevertheless, several companies are starting to make headway with emerging commercial products.

Before I get into the details, I always try to point out that in the big picture the importance—in terms of energy consumption—of improved building insulation varies among regions of the globe. While it is a second-tier concern in North America, the energy-consumption pattern in many European nations is dominated by heating. Germany is one of the best examples, where well over 25 percent of the nation’s energy consumption goes into residential and commercial space heating. Much of the problem is related to the age of the building stock. Besides the heat leakage problems that come from very old buildings, remediation is also a challenge because of sheer space limitations.

Thus, while the availability of aerogel-containing insulation panels and systems may not be front-page news in the United States, it is a fairly big deal in Europe (where the EU is already funding a major research and commercialization initiative). It’s worth keeping this in mind as you read about the developments below, and illustrated in the video above.

The first is that an internal insulation and finishing system developed by STO AG—”STO in Aevero”—recently received the “Award for Product Innovation” at the BAU 2013 trade fair. At least in terms of product recognition, this is a nice accomplishment because BAU, as far as I know, is the world’s largest expo for architecture, materials, and systems. STO’s system uses aerogel develop by Cabot.

Sixty companies were part of the competition, vying for three prizes and six awards. The STO/Cabot system won the events “Investing in the Future” award, which apt. A Cabot news release describes the product as a “super slim system is comprised of a composite board that combines Cabot’s aerogel particles for superior energy-savings performance with STO’s binder and composite technology. This results in an insulation board that offers greater energy efficiency than traditional materials. Cabot’s aerogel enables an ultra-low thermal conductivity of 0.016 W/mK applied in very thin insulation thicknesses from 10 to 40 millimeters (R3.5 – R14).”

Here is a summary of STO In Aevero’s properties:

  • Thermal conductivity: 0.016 W / (mK)
  • Compressive strength: ≥ 100 kPa
  • Water vapor diffusion resistance factor μ: 10
  • Tensile strength perpendicular to faces: ≥ 20 kPa
  • Density: ≥ 150 kg / m³
  • Panel thicknesses: 10, 15, 20, 30, 40 mm
  • Sheet size: 580 x 390 mm
  • Material class B2 according to DIN 4102 (B1 in the system)

STO’s contribution is significant in that it had to design and manufacture a composite board that, besides incorporating the aerogel, also addresses permeability and vapor control and delivers a product in a thin form factor. STO also has developed some important installation methodologies, and leveraged its experience with installing high-quality facade, plasters, paints and rain screen-cladding systems.

In the Cabot release, Raj Chary, vice president and general manager for Cabot Aerogel says, ”[STO's] modern, intelligent solutions in reconstruction, renovation and renewal work are helping architects and builders meet the highest regional and industry standards for energy conservation, [and to] help deliver energy efficient renovation solutions for historical buildings as well as new construction.”

One frustrating thing that unfortunately is lacking in these announcements is pricing/installation cost information relative to traditional insulation.

While STO and Cabot seem to be staking out the building sector, Aspen Aerogels continues to refine its products for industrial application. Aspen was one of the first companies that demonstrated a flexible insulation system that could, for example, be used as a wrapable barrier around pipes. Aspen and others saw a business opportunity with insulating pipes that pass through cold regions, such as the petroleum pipelines that cross Alaska.

Apparently the company was also keeping an eye on high-temperature applications, too. Recently Aspen, announced a new high-temperature insulation, Pyrogel XT-E. A news release from the company indicates that the new product is a variation of if the existing XT product, and that it is being aimed at uses refining, petrochemical, power and other facilities. Given the recent boom in the drilling and refining industries, a product aimed at this sector makes a lot of sense.

In the Aspen release, Don Young, president and CEO, says Pyrogel XT-E is “the most effective high-temperature insulation material in the industrial market and improves our customers’ ability to use our product in the most demanding environments.”

A document (pdf) on the Aspen websites says that it is available in rolls of sizes of 850 and 1,500 square feet, is available in 5 and 10-millimeter thicknesses, and has a density of about 12.5 pounds per cubic foot.

Like Aspen’s other products, the Pyrogel XT-E comes in rolls that makes it a “labor saver.” Aspen also says it has been able to significantly reduce the dust that comes from installation. It says its flexible blanket form is up to five-times thinner than competing insulation products and can serve in applications that range from -270 °C to 650°C.

No pricing was mentioned for the Aspen product, either.


Business




Aerogel-based insulation continuing to make progress with commercialization

Published on April 5th, 2013 | Edited By: Eileen De Guire

Official video (in German) of STO In Aevero aerogel insulation boards. Credit: STO.

One of the promises of your basic silica-based aerogel is that it would make a fantastic component in insulation systems—but there have always been a lot of manufacturing and processing “ifs” involved. Nevertheless, several companies are starting to make headway with emerging commercial products.

 

Before I get into the details, I always try to point out that in the big picture the importance—in terms of energy consumption—of improved building insulation varies among regions of the globe. While it is a second-tier concern in North America, the energy-consumption pattern in many European nations is dominated by heating. Germany is one of the best examples, where well over 25 percent of the nation’s energy consumption goes into residential and commercial space heating. Much of the problem is related to the age of the building stock. Besides the heat leakage problems that come from very old buildings, remediation is also a challenge because of sheer space limitations.

 

Thus, while the availability of aerogel-containing insulation panels and systems may not be front-page news in the United States, it is a fairly big deal in Europe (where the EU is already funding a major research and commercialization initiative). It’s worth keeping this in mind as you read about the developments below, and illustrated in the video above.

The first is that an internal insulation and finishing system developed by STO AG—”STO in Aevero”—recently received the “Award for Product Innovation” at the BAU 2013 trade fair. At least in terms of product recognition, this is a nice accomplishment because BAU, as far as I know, is the world’s largest expo for architecture, materials, and systems. STO’s system uses aerogel developed by Cabot.

 

Sixty companies were part of the competition, vying for three prizes and six awards. The STO/Cabot system won the event’s “Investing in the Future” award, which is apt. A Cabot news release describes the product as a “super slim system is comprised of a composite board that combines Cabot’s aerogel particles for superior energy-savings performance with STO’s binder and composite technology. This results in an insulation board that offers greater energy efficiency than traditional materials. Cabot’s aerogel enables an ultra-low thermal conductivity of 0.016 W/mK applied in very thin insulation thicknesses from 10 to 40 millimeters (R3.5 – R14).”

 

Here is a summary of STO In Aevero’s properties:

  • Thermal conductivity: 0.016 W / (mK)
  • Compressive strength: ≥ 100 kPa
  • Water vapor diffusion resistance factor μ: 10
  • Tensile strength perpendicular to faces: ≥ 20 kPa
  • Density: ≥ 150 kg / m³
  • Panel thicknesses: 10, 15, 20, 30, 40 mm
  • Sheet size: 580 x 390 mm
  • Material class B2 according to DIN 4102 (B1 in the system)

STO’s contribution is significant in that it had to design and manufacture a composite board that, besides incorporating the aerogel, also addresses permeability and vapor control and delivers a product in a thin form factor. STO also has developed some important installation methodologies, and leveraged its experience with installing high-quality facade, plasters, paints and rain screen-cladding systems.

 

In the Cabot release, Raj Chary, vice president and general manager for Cabot Aerogel says, ”[STO's] modern, intelligent solutions in reconstruction, renovation and renewal work are helping architects and builders meet the highest regional and industry standards for energy conservation, [and to] help deliver energy efficient renovation solutions for historical buildings as well as new construction.”

 

One frustrating thing that unfortunately is lacking in these announcements is pricing/installation cost information relative to traditional insulation.

While STO and Cabot seem to be staking out the building sector, Aspen Aerogels continues to refine its products for industrial application. Aspen was one of the first companies that demonstrated a flexible insulation system that could, for example, be used as a wrapable barrier around pipes. Aspen and others saw a business opportunity with insulating pipes that pass through cold regions, such as the petroleum pipelines that cross Alaska.

 

Apparently the company was also keeping an eye on high-temperature applications, too. Recently Aspen, announced a new high-temperature insulation, Pyrogel XT-E. A news release from the company indicates that the new product is a variation of if the existing XT product, and that it is being aimed at uses refining, petrochemical, power and other facilities. Given the recent boom in the drilling and refining industries, a product aimed at this sector makes a lot of sense.

 

In the Aspen release, Don Young, president and CEO, says Pyrogel XT-E is “the most effective high-temperature insulation material in the industrial market and improves our customers’ ability to use our product in the most demanding environments.”

 

A document (pdf) on the Aspen websites says that it is available in rolls of sizes of 850 and 1,500 square feet, is available in 5 and 10-millimeter thicknesses, and has a density of about 12.5 pounds per cubic foot.

 

Like Aspen’s other products, the Pyrogel XT-E comes in rolls that makes it a “labor saver.” Aspen also says it has been able to significantly reduce the dust that comes from installation. It says its flexible blanket form is up to five-times thinner than competing insulation products and can serve in applications that range from -270 °C to 650°C.

No pricing was mentioned for the Aspen product, either.


Business




Aerogel-based insulation continuing to make progress with commercialization

Published on April 5th, 2013 | Edited By: Eileen De Guire

Official video (in German) of STO In Aevero aerogel insulation boards. Credit: STO.

One of the promises of your basic silica-based aerogel is that it would make a fantastic component in insulation systems—but there have always been a lot of manufacturing and processing “ifs” involved. Nevertheless, several companies are starting to make headway with emerging commercial products.

Before I get into the details, I always try to point out that in the big picture the importance—in terms of energy consumption—of improved building insulation varies among regions of the globe. While it is a second-tier concern in North America, the energy-consumption pattern in many European nations is dominated by heating. Germany is one of the best examples, where well over 25 percent of the nation’s energy consumption goes into residential and commercial space heating. Much of the problem is related to the age of the building stock. Besides the heat leakage problems that come from very old buildings, remediation is also a challenge because of sheer space limitations.

Thus, while the availability of aerogel-containing insulation panels and systems may not be front-page news in the United States, it is a fairly big deal in Europe (where the EU is already funding a major research and commercialization initiative). It’s worth keeping this in mind as you read about the developments below, and illustrated in the video above.

The first is that an internal insulation and finishing system developed by STO AG—”STO in Aevero”—recently received the “Award for Product Innovation” at the BAU 2013 trade fair. At least in terms of product recognition, this is a nice accomplishment because BAU, as far as I know, is the world’s largest expo for architecture, materials, and systems. STO’s system uses aerogel develop by Cabot.

Sixty companies were part of the competition, vying for three prizes and six awards. The STO/Cabot system won the events “Investing in the Future” award, which apt. A Cabot news release describes the product as a “super slim system is comprised of a composite board that combines Cabot’s aerogel particles for superior energy-savings performance with STO’s binder and composite technology. This results in an insulation board that offers greater energy efficiency than traditional materials. Cabot’s aerogel enables an ultra-low thermal conductivity of 0.016 W/mK applied in very thin insulation thicknesses from 10 to 40 millimeters (R3.5 – R14).”

Here is a summary of STO In Aevero’s properties:

  • Thermal conductivity: 0.016 W / (mK)
  • Compressive strength: ≥ 100 kPa
  • Water vapor diffusion resistance factor μ: 10
  • Tensile strength perpendicular to faces: ≥ 20 kPa
  • Density: ≥ 150 kg / m³
  • Panel thicknesses: 10, 15, 20, 30, 40 mm
  • Sheet size: 580 x 390 mm
  • Material class B2 according to DIN 4102 (B1 in the system)

STO’s contribution is significant in that it had to design and manufacture a composite board that, besides incorporating the aerogel, also addresses permeability and vapor control and delivers a product in a thin form factor. STO also has developed some important installation methodologies, and leveraged its experience with installing high-quality facade, plasters, paints and rain screen-cladding systems.

In the Cabot release, Raj Chary, vice president and general manager for Cabot Aerogel says, ”[STO's] modern, intelligent solutions in reconstruction, renovation and renewal work are helping architects and builders meet the highest regional and industry standards for energy conservation, [and to] help deliver energy efficient renovation solutions for historical buildings as well as new construction.”

One frustrating thing that unfortunately is lacking in these announcements is pricing/installation cost information relative to traditional insulation.

While STO and Cabot seem to be staking out the building sector, Aspen Aerogels continues to refine its products for industrial application. Aspen was one of the first companies that demonstrated a flexible insulation system that could, for example, be used as a wrapable barrier around pipes. Aspen and others saw a business opportunity with insulating pipes that pass through cold regions, such as the petroleum pipelines that cross Alaska.

Apparently the company was also keeping an eye on high-temperature applications, too. Recently Aspen, announced a new high-temperature insulation, Pyrogel XT-E. A news release from the company indicates that the new product is a variation of if the existing XT product, and that it is being aimed at uses refining, petrochemical, power and other facilities. Given the recent boom in the drilling and refining industries, a product aimed at this sector makes a lot of sense.

In the Aspen release, Don Young, president and CEO, says Pyrogel XT-E is “the most effective high-temperature insulation material in the industrial market and improves our customers’ ability to use our product in the most demanding environments.”

A document (pdf) on the Aspen websites says that it is available in rolls of sizes of 850 and 1,500 square feet, is available in 5 and 10-millimeter thicknesses, and has a density of about 12.5 pounds per cubic foot.

Like Aspen’s other products, the Pyrogel XT-E comes in rolls that makes it a “labor saver.” Aspen also says it has been able to significantly reduce the dust that comes from installation. It says its flexible blanket form is up to five-times thinner than competing insulation products and can serve in applications that range from -270 °C to 650°C.

No pricing was mentioned for the Aspen product, either.


Basic science




There’s more to multifunctional ultra-flyweight aerogel produced at a Zhejiang U. lab than just ‘world’s lightest material’ record

Published on March 28th, 2013 | Edited By: Eileen De Guire

(a) Photograph of new UFAs with diverse shapes; (b) a 100 cm3 cylinder standing on a flower like “dog’s tail”; (c) a ~1000 cm3 pie pan-shaped cylinder (21 cm in diameter and 3 cm in thickness). Credit: Gao et al.; Advanced Materials.

I suspect this story may seem a little like old news to some readers, but a lot of the pop-sci reporting in the last few days about a new ultralight aerogel (actually, a UFA or ultra-flyweight aerogel, i.e., less than 1 mg cm−3) has missed the point by a wide margin. The big takeaway from this story, as documented in a new Advanced Materials paper, is that the graphene–carbon nanotube (CNT) aerogel is relatively easy to make, appears to be easily scalable, and is moldable into any shape. Moreover, the new UFA, besides having ultralow density, also is extremely flexible and elastic—with the elasticity independent of temperature—and is thermally stable, a good electrical conductor, hydrophobic, and capable of absorbing extremely high capacities for organic liquids and phase change materials.

Now, certainly, there is a significant gee-whiz factor for gaining the “world’s lightest material” title, an achievement based on a density of 0.16 mg cm−3, accomplished by the research team at Zhejiang University headed by Gao Chao.

The group’s material is not the first UFA. Within the past 18 months, other researchers have constructed nickel foams with density of 0.9 mg cm−3 (via electroless plating and subsequently etching away a polymer template), and another group constructed an aerographite with a density of 0.18 mg cm−3 (via a ZnO template-based chemical vapor deposition approach). But, both groups’ dependency on a template also creates enormous limitations to scalability. Sol-gel-derived, low-density aerogels can be made on fairly large scales, but with sol-gel processes it is difficult to control the dimensions of the structures.

Gao’s group, instead, uses a process that involves freeze-drying aqueous solutions of CNTs and giant graphene oxide (GGO) sheets, followed by chemical reduction of graphene oxide into graphene using hydrazine vapor. The researchers named their method a “sol-cryo” approach and note in their paper that it is easy to make large samples:

Because of the simplicity of assembly process in our template-free “sol-cryo” methodology and the large-scale availability of GGO and CNTs, the integrated all-carbon aerogels with desired densities and shapes such as rods, cylinders, papers and cubes were readily accessible. More significantly, UFAs can be easily manufactured in a large-scale. For example, a UFA cylinder up to 1000 cm3 was made with a mold of 1-liter plate.

A story on the university’s website reports quotes Gao saying, ”With no need for templates, its size only depends on that of the container. [A] bigger container can help produce the aerogel in bigger size, even to thousands of cubic centimeters or larger.” The story also reports that Gao believes ”the value of this achievement lies not in the record but in its simple way in developing the material and the superior performance exhibited.”

Briefly speaking, the microstructure of the material is a 3D porous framework constructed with cell walls of randomly oriented, crinkly graphene sheets and CNT “ribs.” The macropores ranged from hundreds of nanometers to tens of micrometers. The authors of the paper say the properties of the UFA derive from the graphene-CNT synergy: “Giant graphene flakes build a framework with macro-pores, making the aerogel ultralight; the coating of CNTs reinforces the relatively flexible graphene substrate and endows their intrinsic elasticity to the coorganized aerogel.”

One of the UFA’s interesting properties is its elasticity that allows it to be repeatedly compressed and returned to its nearly original size. This sponginess comes in handy in combination with another property: It can rapidly absorb up to 900 times its own weight in oil or other organic liquids. For example, one gram can absorb 68.8 grams of organics per second. The elasticity remained the same in tests that ranged from −190 to 300°C. The elasticity also remained after researchers annealed the UFA at 900°C for five hours.

There are probably many ways the elasticity and absorbability can be useful, not the least of which is that, because of its hydrophobicity, it could be a reusable medium to soak up oil spills on lakes and oceans. Gao says in the university story, “Maybe one day when oil spill occurs, we can scatter them on the sea and absorb the oil quickly. Due to its elasticity, both the oil absorbed and the aerogel can be recycled.” (Another Chinese research group working at Tsinghua and Peking Universities published a paper in 2010 about the use of CNTs for oil spills, and I suspect that there is some overlap between the work of the two groups.)

Another property of the UFA is that it has elasticity-dependent electrical conductivity. For example, they report connecting an LED lamp top the UFA bulk, and “its brightness fluctuates upon compressing and releasing the aerogel. This phenomenon promises the application of UFAs as pressure-responsive sensors.”

They also say that by loading the UFA with tiny amounts of certain liquids (say, CCl4 or 1-hexadecanol), they can make conductive composites with very high electrical conductivity compared to just CNT- or graphene-based composites.

[flash http://ceramictechweekly.org/wp-content/video/ufa_aerogel_led.flv mode=1 f={image=http://ceramictechweekly.org/wp-content/video/ufa_aerogel_led.jpg}]

Video of variable conductivity of UFA demonstrating current change to LED when aerogel is compressed and released. Credit: Gao et al.; Advanced Materials.

Gao and the other authors also suggest the UFA could find use as supercapacitors and catalyst beds, but another intriguing application they only hint at is its use as a medium that enhances phase-change energy storage materials. For example, unlike other composites, a UFA-paraffin combination delivers higher phase-change enthalpy (ΔH) than ordinary paraffin.

These applications may only be the beginning. When it comes to learning how to leverage the properties of their fluffy stuff, the researchers say their new UFA is “just like a new-born baby.” A baby that was, perhaps, born with a silver spoon in its mouth.


Aeronautics & Space




New flexible and stronger aerogel expected to open new applications for super-insulator

Published on August 19th, 2012 | Edited By: Peter Wray

Newly developed flexible aerogels are 500 times stronger than earlier versions and can be used in everything from clothing insulation to building insulation. Credit: NASA.

A NASA scientist has just reported that the agency has devised major improvements in aerogel, a development that should speed its use in super-insulated clothing and shoes, higher capacity and efficiency refrigerators, building envelope insulation, heat shields and other products. The report was presented by Mary Ann B. Meador at a meeting of American Chemical Society.

Meador is part of a group working on aerogel at the NASA Glenn Research Center in Cleveland, Ohio.

Although “ordinary” silica aerogel is brittle, is is also very strong, as measured by high compressive strength in comparison to its mass. That is, it resists denting or crushing under load. Thus, it is eyeopening when Meador says, “The new aerogels are up to 500 times stronger than their silica counterparts. A thick piece actually can support the weight of a car.”

According to an ACS news release, the NASA group has devised two new types of aerogel.

One involves making changes in the internal structure of traditional silica aerogels. They used a polymer, to reinforce the networks of silica that extend throughout an aerogel’s structure. Another involved making aerogels from polyimide, an incredibly strong and heat-resistant polymer, or plastic-like material, and then inserting brace-like cross-links to add further strength to the structure.

Heretofore, there have been several practical headaches for aerogel manufacturers, including the above-mentioned brittleness plus difficulties with forming shapes and finding suitable processing and installation methods. The holy grail quest has been to find a low-cost, easy-to-manufacture form of aerogel. Meador makes the remarkable observation that the new aerogels “can be produced in a thin form, a film so flexible that a wide variety of commercial and industrial uses are possible.”

We’ve written in the past how some aerogel has found its way into very limited lines of apparel, such as high-performance (and expensive) jackets atop Mt. Everest. Although I doubt today’s news means that Eddie Bauer or Patagonia will be offering a new aerogel line in time for the holidays, the descriptions of NASA aerogel do make it seem like it should be more conducive to garment assembly lines. Outdoor enthusiasts have other reasons to be happy: Meador also suggests that a new generation of insulated tents and sleeping bags should be attainable.

Building envelope applications are a natural for aerogel, and companies such as Thermoblok, Aspen and Cabot already have been working in these markets. Despite the production, handling and installation problems of silica aerogel, there has been some evidence that just using small strips of the material to prevent thermal bridging at target areas—such as wall studs—can be cost effective. So, cheaper and flexible aerogel strips would go a long way toward making the savings calculation easier. The housing stock in Europe, particularly Northern Europe, is particularly in need of improved insulation (no word yet on the results of the EU’s first Aerocoins aerogel workshop that was to be held this past June). Meador says that the new aerogel is five to 10 times more efficient than existing insulation, with a quarter-inch-thick sheet providing as much insulation as three inches of fiberglass. These insulation values are generally in line with ordinary silica aerogel, so the ease of use is the main thing here.

Meador doesn’t specifically mention it, but the ease of use factor would also be a big plus for the petroleum industry for pipeline insulation. She told me in an telephone interview that NASA has indeed been looking at several private sectors to license the new materials.

But, all of these are spin-off applications. NASA, of course, has a core interest in space, and Meador says the new aerogel may be suitable for improved spacesuit insulation and as a thermal barrier for advanced reentry systems. While the spacesuit application would seem to be relatively straightforward, the thermal barrier use is very novel. When it comes to efforts such as the International Space Station missions and Mars missions, rather than waste space with a thick and fixed heat shield, she says one concept is to store on the reentry vehicle something like a aerogel bag that can be inflated and deployed when needed.

Recently NASA posted a video (below) showing how such an inflated 10-foot-diameter shield could be packed into a 22-inch diameter nose cone, as part of the Inflatable Reentry Vehicle Experiment (IRVE-3) series of tests.

The inflation system was successfully tested July 21, 2012, while being deployed at 7,600 mph, and although the aerogel composition is not specifically mentioned in the news release about the test, Meador tells me that the outer layer of the shield was composed of pyrogel. She says new polyimide aerogel would be a desirable substitute for pyrogel because the latter creates significant dust release problems during the prelaunch handling and folding of the shield.

NASA has provided a brief description in a press release about the success of the test.

An inflation system pumped nitrogen into the IRVE-3 aeroshell until it expanded to a mushroom shape almost 10 feet in diameter. Then the aeroshell plummeted at hypersonic speeds through Earth’s atmosphere. Engineers in the Wallops control room watched as four onboard cameras confirmed the inflatable shield held its shape despite the force and high heat of reentry. Onboard instruments provided temperature and pressure data. Researchers will study that information to help develop future inflatable heat shield designs.

Check out NASA’s video of the launch and deployment here.


Ceramic Tech Today




Toughened, flexible silica aerogel? Joint Japanese–Chinese group shows how to do it

Published on January 31st, 2012 | Edited By: Peter Wray

Demonstration of the flexibility of cellulose–silica composite aerogel. Credit: J. Cai et al.; Angewandte Chemie.

This sounds like the type of breakthrough aerogel fans have yearning for.

A newly published paper in Angewandte Chemie reports on an Asian group’s success at using cellulose fibers as a scaffold/template for a resultant silica aerogel that delivers a product that has great mechanical strength and flexibility, while retaining a large surface area and semitransparency.

Aerogel has been something of a tease for many years. It has incredible insulating abilities, but the one enormous problem for silica aerogel is that it is frustratingly brittle and difficult to work into practical applications. Some developers have found limited success via hybridization techniques with support materials such as polyurethane, polystyrene or even nanofibrillar bacterial cellulose and microfibrillated cellulose gel.

However, with support from the Japan Society for the Promotion of Science‘s Foreign Researcher Fund of Japan and the National Basic Research Program of China, researchers at Wuhan University, China, and University of Tokyo, took a different cellulose-based route. They already knew that they could exploit “cellulose II” crystallinity  (dissolution and then regeneration/reassembly of fibrils) to form aerogels with good mechanical strength, light transmittance and high porosity — characteristics that they suspected would make it an effective substrate for silica aerogel.

In brief, the group, led by Lina Zhang, impregnated a sample of nanoporous cellulose gel (with its interconnected nanofibrillar network) with a silica precursor, tetraethyl orthosilicate. According to the paper, “The resulting composite gels were dried with supercritical CO2 to give cellulose–silica aerogels with low density, moderate light transmittance, a large surface area, high mechanical integrity and excellent heat insulation.”

They then went one step farther and used calcination to remove the cellulose matrix, leaving a silica-only aerogel. The key point here is that this silica aerogel’s structure is much different than pure silica aerogel. In the latter, primary silica nanoparticles form and then randomly coagulate resulting in an isotropic 3D network. “In contrast,” again quoting from the paper, the authors say, “the formation of silica nanoparticles in the cellulose gel seems to cause their deposition onto the cellulose fibrils. As a result, removal of cellulose by calcination results in the nanofibrillar silica network.”

The group compared a variety of aerogels, including silica-only and cellulose-only aerogels; cellulose-silica composites, with varying levels of silica; and cellulose-templated silica aerogel.

What they found at the macroscopic level is that the composite aerogels didn’t inherit the fragility of the silica, but instead seem to inherit the flexibility and strength of the cellulose network (see knotted sample of one of the composites, above).

While the tensile modulus and strength of the cellulose–silica aerogel were less than pure cellulose aerogel, “the compression modulus of the composite (7.9MPa) is more than two orders of magnitude higher than that of silica aerogel, and about 50 times higher than that of the aerogel prepared from bacterial cellulose.”

Because of the cellulose content, the composite aerogels break down when used above 300°C. However, below that temperature, the cellulose-silica aerogel retained strong heat insulating properties. Thermal conductivity of the prepared samples ranged from 0.025 W m-1 K-1 to 0.045 W m-1 K-1.

These numbers compare favorably with polystyrene foam (0.030 W m-1 K-1), however, the researchers note that the ability of the cellulose–silica aerogels to perform up to 300°C give it a leg up on insulation materials made of polymer that soften and breakdown at similar temperatures.

“Thus,” according to the authors,”the cellulose–silica composite is potentially useful as heat insulating material with high mechanical stability, together with processability to form sheets, fibers, or beads. … [They] retained the mechanical strength and flexibility, large surface area, semitransparency, and low thermal conductivity of the cellulose aerogels. The ease of preparation and wide tuneability of composition/properties with this method are expected to form the basis for the development of various advanced nano-porous materials.”

The paper, ”Cellulose-silica nanocomposite aerogels by in situ formation of silica in cellulose gel,” (doi:10.1002/ange.201105730) is written by Jie Cai, Shilin Liu, Jiao Feng, Satoshi Kimura, Masahisa Wada, Shigenori Kuga, and Lina Zhang.


Business




Europe Union launches aerogel insulation research and commercialization project

Published on September 27th, 2011 | Edited By: Peter Wray

Credit: ARMINES/MINES ParisTech/CEP.

A push like this in Europe was bound to happen sooner or later, and part of me thinks it would have been smart for the US, via the DOE, to put about $25 million of ARRA money (ah, the good old days) into something like this.  Yesterday, CORDIS, the European Community Research and Development Information Service, announced that a consortium of research centers and two companies will be getting €4.3 million (about $5.8 million) for a four-year effort to find a real-world silica aeroegel that can be a “superinsulating material” and a widespread commercial success.

The announcement specifically mentions that the “AEROCOINs” effort will address the two major roadblocks currently preventing widespread use of classic silica aerogel: poor mechanical properties (e.g., it is highly fragile) and production costs. (I believe AEROCOINs is something of an abbreviation for aerogel construction insulation.)

CORDIS says

The AEROCOINs project proposes a clever combination of sol-gel chemistry and nanotechnology, which will rapidly advance the development of novel superinsulating aerogel materials.

The actual project is being conducted under the aegis of the EU’s R&D 2007-2013 Seventh Framework Program, and the FP7 project description provides a little more detail.

The AEROCOINs project proposes to create a new class of mechanically strong super-insulating aerogel composite/hybrid materials by overcoming the two major obstacles which have endured for so long and have prevented a more widespread use of silica-based aerogel insulation components in the building industry:

i) strengthening of silica aerogels by cross-linking with cellulosic polymers or the incorporation of cellulose-based nanofibers; and

ii) lowering the production cost of monolithic plates or boards of composite/hybrid aerogel materials via ambient drying and continuous production technology.

The European Union is providing €3.0 million of the project budget. The research centers include Tecnalia (Spain), ARMINES/MINES ParisTech (France), EMPA (Switzerland), VTT (Finland), ZAE Bayern (Germany) and Technical University of Lodz (Poland). The private companies involved in the effort are PCAS (France), Acciona Infraestructuras (Spain) and SEPAREX (France). Tecnalia will coordinate the project.

Tecnalia has already been involved in projects related to energy efficiency and new construction and the development of polymeric nanocomposites for curtain walls. EMPA has done work on aerogel plasters and the Swiss lab’s Matthias Koebel’s research group has been working in translucent aerogels for some time (pdf), so I suspect he will be involved. ZAE Bayern has also been working in sol-gel nanoporous materials.

FP7 projects are supposed to be vetted for a strong impact on the EU region, and the focus on a superinsulator sounds right. Last year, Lux Research issued a report about the appropriate emphasis of energy R&D in various developed regions of the world, and its report asserted that the energy-consumption pattern in many European nations is “dominated by heating” and that, for example, well over 25 percent of Germany’s energy consumption went into residential and commercial space heating.

I would be remiss if I didn’t mention that Cabot and Aspen are also active in developing aerogel applications for the European market.


Ceramic Tech Today




Transformed aerogels: From amorphous carbon to nanocrystalline diamond

Published on June 1st, 2011 | Edited By: Eileen De Guire

Laser-heated diamond anvil cell allows very large hydrostatic pressure to be applied to amorphous carbon aerogels. Credit: LLNL

Laser-heated diamond anvil cell allows very large hydrostatic pressure to be applied to amorphous carbon aerogels. Cavity dimensions are approximately 100–170 μm wide by 35 μm thick. Credit: LLNL.

While there has been considerable interest in capturing the properties of diamond in a low-density form, converting an amorphous carbon aerogel to a crystalline phase without collapsing the porous network has proven tricky — but not impossible.

In a paper published in the May 9 online edition of the Proceedings of the National Academy of Sciences, a team of Lawrence Livermore researchers describe the successful synthesis of a diamond aerogel from an amorphous carbon aerogel precursor (“Synthesis and characterization of a nanocrystalline diamond aerogel,” doi: 10.1073/pnas.1010600108). The density of the amorphous precursor aerogel in this study is 0.04 g/cm3, which according to a LLNL press release, is about the density of the nanocrystalline diamond aerogel (pure diamond has a density of 3.52 g/cm3).

The team, led by former LLNL fellow, Peter Pauzauskie (now at the University of Washington, Department of Materials Science & Engineering), created an amorphous carbon precursor material using sol-gel processing (see pdf describing details, here) and used a diamond anvil to subject the aerogel to pressures where diamond is the stable phase of carbon. Laser heating was used to overcome the kinetic barriers of the phase transformation to nanocrystalline diamond.

A key goal of the experiment was to maintain the porous structure of the sample. The precursor aerogel is self-supporting, but the researchers note that it is still delicate – finger pressure is enough to crush it. Supercritical neon was used to apply hydrostatic pressures of 21.0 GPa, 22.5 GPa and 25.5 GPa (that’s about 3,000-3,700 ksi), and the samples were laser heated to approximately 1850 oC. The study made no attempt to optimize the pressure and temperature parameters.

Using Raman spectroscopy, the researchers concluded that there was not a superhard graphite phase helping to prevent pore collapse, which had been suggested as a possible mechanism for mesoporous carbon. TEM showed that diamond aerogel is a network of nanocrystals (2.5-100 nm) that appear to be connected by thin surface coatings of graphitic carbon and that the porous morphology seems to have been preserved.

It’s likely a long road from diamond anvil synthesis to a bulk processing method, but the study shows that the phase transformation from amorphous carbon to diamond can be achieved nondestructively while maintaining the porous morphology. Materials of this type are expected to have applications as tunable and optically effficient antireflective coatings, optical quantum bits, and cellular biomarkers. The unique optical, thermal, and chemical properties of a nanocrystalline diamond, porous material will lead quickly to other applications, some novel and some fairly pedestrian (but important), such as  water desalination.

As a proof-of-concept, the study showed that nondestructive phase transformation from amorphous to nanocrystalline morphologies is possible from sol-gel precursor materials, which, the authors note, opens the possibility of producing other highly porous, nanocrystalline materials such as SiO2.


Business




Another step towards practical superinsulation? Cabot launches new aerogel additives for coatings

Published on March 29th, 2011 | Edited By: Peter Wray

Cabot’s Enova 3110 aerogel particles. Credit: Cabot.

In my mind, the holy grail for thermal insulation is a practical (i.e, inexpensive and easy to use) product that incorporates silica-based aerogel, and, at first glance, Cabot’s new Enova line of aerogel particles appears to be a step in the right direction.

Bulk silica aerogel is a hydrophobic superinsulator, but it is extremely brittle and therefore not so easy to manufacture in quantity, transport, use in large sizes, etc. Some niche applications have been found where the size of the products are small and buyers are willing to pay a premium for the extra performance.

Other companies, such as Cabot, ThermoBlok and Aspen also have been trying to find a useful middle ground, where some thickness and performance characteristics are being traded off for ease-of-use considerations. And, so far, even these are being aimed at high-payoff types of applications, such as pipelines and storage tanks where added temperature control can yield major energy savings, and to create thermal barriers in isolated construction elements, such as steel stud facings.

Cabot’s innovation in aerogel seems to be developing a product aimed specifically at the coatings market. While the reliance on particles rather than sheets of aerogel decreases the potential for insulation, this disadvantage could be offset by the advantage of being easily sprayed on using standard manufacturing and constructon equipment.

An announcement from the company, timed to coincide with the opening of the European Coatings Show, says that, “applying a 1mm coating containing Enova aerogel to a 200°C metal surface meets U.S. and European testing protocols for safe touch temperature, preventing the first-degree burns one would normally expect within five seconds of skin contact. A thicker application such as a 2mm coating results in a reduction in energy use of 30 percent for uninsulated metal vessels maintained at 70°C. This can easily translate to potential applications as wide ranging as home and commercial appliances, process piping, building and tank storage.”

Cabot says the thermal conductivity of the particles is 12 mW/mK. Although this is theoretically better than polyurethane foam (30 mW/mK), the company admits that the thermal conductivity of Enova can exceed polyurathane (30 mW/mK to 50 mW/mK) when the particles are used as an additive in a water-borne formulation. Cabot points out that this is still seven to 10 times more insulative than standard paint — and I suspect that the company will be looking to develop some partnerships with paint manufacturers and construction material suppliers.

It should be noted that the Enova brand actually encompasses three types of aerogel products, which are mainly differentiated by particle size. 0.1–0.7 mm, 0.1–1.2 mm and 2–40 µm.

So far, I have been unsuccessful in speaking with James Pidhurney, Cabot’s manager for the Enova products, (he is apparently tied up at the show), but he predicted in the company’s announcement that big changes may be in store. He says the, “Enova aerogel [additive] creates a paradigm shift in how the industry thinks about insulation and coatings, two products which were once mutually exclusive. In the past, if you wanted flexibility in a coating, you had to compromise on insulation performance. Enova additives enable a new class of coatings that deliver the performance of traditional insulation and the flexibility of a coating in a single product.”


Business




‘Promising’ lightweight, multiwalled carbon nanotube aerogel debuts

Published on January 14th, 2011 | Edited By: Peter Wray

SEM images showing the morphology and structure of MWCNT aerogels. (a) & (d)  Surface morphology indicating a “honeycomb”  structure, (b) & (e) porous honeycomb wall of aerogel, (c) vertical section image of MWCNT aerogel showing straight and parallel channels. (Credit: ACS Nano.)

A new development has been announced in the world of aerogel. ACS Nano published a paper on the process of developing and characterization of multi-walled carbon nanotube aerogel. The full text can be read for free here.

MWCNT aerogels have been hard to develop, largely due to the miniscule size of carbon nanotubes. Aerogels have typically been developed using silicon dioxide.

According to the paper, this new aerogel is fabricated from a wet gel of well-dispersed pristine MWCNTs. The researchers employed poly(3-(trimethoxysilyl) propyl methacrylate) as a dispersant and stabilizer, and also to encourage permanent chemical bonding the MWCNTs (chemical cross-linking was assisted with an ammonia aqueous solution). After removing the liquid component from the wet gel, researchers are left with MWCN aerogel.

To optimize the final structure, the group sought something close to a honeycomb structure. They accomplished this during the wet-gel stage by using the controlled growth of ice rods via unidirectional freezing (the ice rods formed parallel to the freezing direction).

The resulting “honeycomb” structure separated by less than 100 nm-thick walls and a density of 4 mg/cm3. As the authors note, this “represents the lowest density ever for free-standing monolithic CNT aerogel, and is only slightly larger than the lowest recorded aerogel density in literature (3 mg/cm3)”.

The University of Central Florida researchers at the NanoScience Technology Center, including Jianhua Zou, Jianhua Liu, Ajay Singh Karakoti, Amit Kumar, Daeha Joung, Qiang Li, Saiful I. Khondaker, Sudipta Seal and Lei Zhai, also discovered that the honeycomb walls of entangled MWCNTs had a with a surface area of 580 m2/g.

Fabrication procedure of MWCNT aerogel. (Credit: ACS Nano.)

Fabrication procedure of MWCNT aerogel. (Credit: ACS Nano.)

So what can this material do? For starters, despite its ultralow density, the group says the MWCNT aerogel has an excellent compression recoverable property, as well as an electrical conductivity of 3.2 × 10−2 S/cm (which can be permanently increased to 0.67 S/cm by a high-current pulse).

This video recorded at Zai’s laboratory at the NanoScience Technology Center (University of Central Florida) demonstrates the compression strength and recoverability of the aerogel. It can be repeatedly compressed down to 5 percent of its original volume and the recover most of its original volume, due to the anisotropic structure of the material and the cross-linking between MWCNTs. When the compressing stress is applied to the aerogel, the MWCNTs tend to be bent instead of slipping past each other. Consequently, the strain energy is stored within the MWCNT aerogel; volume recovery is driven by the release of the strain energy.

The resistance change of (a) MWCNT aerogel and (b) MWCNT thin film upon exposure to chloroform vapor. The bias voltage is fixed at 0.1 V. (Credit: ACS Nano.)

Compare the resistance change of (a) MWCNT aerogel upon exposure to chloroform vapor to the control material (b), a MWCNT thin film on glass. (Credit: ACS Nano.)

This compression and conductivity of the aerogel gives it valuable pressure-response properties: electrical resistance varies with pressure. They measured is a linear drop in resistance from as low as 5 Pa to 180 Pa. (Above 180 Pa, little change occurs.) This effect is reproducible with resistance changes occurring .2-.4 seconds after pressuring loading/unloading. As the authors note, this makes the MWCNT aerogel a “promising” candidate for pressure sensing.

Vapor sensing is another potential application for the material. For example, in the lab, the response of the MWCNT aerogels response to chloroform vapor was investigated. With just a .5 second exposure to chloroform, the resistance of the MWCNT aerogel spiked, and within .5 second of exposure to air, the resistance returned to its prior level. This response occurred with vapor concentration levels as low as 1 ppb. This is attributed to the material’s unique hierarchical porous structure.

Assembling the MWCNT aerogel into bulk materials will open new doors in material developments and applications. Besides uses in sensors to detect pollutants and toxic substances, chemical reactors and electronics components, the authors foresee it being a good candidate for catalyst supports and novel electrodes.

 


Back to Top ↑