No really – it isn’t like learning about the War of Jenkins Ear, where you have to imagine being alive in the 1700’s and fighting with a large group of Spanish and British soldiers and it’s a bit of a stretch. You know what compression when you attempt to balance a pile of textbooks about colonial military campaigns on your head and your neck shortens, and you understand tension because you actually feel it when you pull on a locked doorknob.

Image courtesy wikimedia commons

So far I haven’t worked on any projects like the Denver Airport, where tension and its expression are major elements of the design. But I am working on a competition entry that will incorporate wind-resistant architectural fabric, and research for that project caused me to dig through my lovely ARCHITERIALS submissions inbox where I found product information from Tensotherm with Nanogel®, developed by Birdair, Cabot Corporation and Geiger Engineers.

Tensotherm is a tensile fabric material that insulates like standard roofing, although it can be made translucent if you’re interested in letting light shine in.  According to the product literature, “Tensotherm is comprised of two layers of PTFE fabric membrane with a layer of Nanogel aerogel sandwiched between the two layers. PTFE, or polytetrafluoroethylene, is a Teflon®-coated woven fiberglass membrane that is extremely durable and water resistant; it is capable of withstanding temperatures from -100°F to +450°F, immune to UV rays, and waterproof.” The aerogel layer is as light as a feather and as an insulator it makes whale blubber look pathetic (please do read this post for more on the awesome characteristics of aerogels).

Image courtesy birdair.com

The product is manufactured in Tijuana, Mexico, but unlike strong narcotics arriving daily from South and Central America, Tensotherm is suitable for use as roofing in stadiums, arenas, schools, convention centers, transportation facilities, retail facilities and more. Don’t use it for open-air structures, as it’s not suited for the application.

Image courtesy birdair.com

While it’s hard to know what goes in to the manufacturing process, translucent Tensotherm could contribute to a green building strategy that incorporates daylighting, and if it’s indeed an effective insulator it could reduce heating and cooling loads in buildings.  Another benefit of a lightweight, tensile roof is the fact that support structure can be smaller in size; this reduces expenditures on shipping and installation.  The system produces very little job site waste and the fabric can contribute to the acoustic environment.

Have you used Tensotherm or similar products in your work? Let us know what’s what in the comments!

WU XING:

I have filed Tensotherm under Wood because it’s great in tension.

Image courtesy www.aqua-velvet.com

Foam does more than cushion the inelegant landings of would-be circus performers; we use it to pad furniture, for insulation, packaging, and miscellaneous other products, such as foam-coated wire hair curlers that resemble play-doh spaghetti.  While we love foam because it’s light-weight, absorptive, insulating, and so on, the manufacturing process is energy-intensive and an awful lot of it winds up accumulating in landfill. 

In response to the problem, scientists have developed an “ultra-light biodegradable foam plastic material made from two unlikely ingredients: The protein in milk and ordinary clay” (Physorg.com).  Before you go out and throw some pottery shards in your 2%, let me explain how this works.  Nearly all of the protein in cow milk is casein, and we already use it in an industrial setting to make adhesives and paper coatings.  The substance is not particularly strong and it’s water-soluble, so to “beef up” the casein and increase its water resistance the researchers “blended in a small amount of clay and a reactive molecule called glyceraldehyde, which links casein’s protein molecules together” (Physorg.com).

Powdered casein courtesy www.spectrafix.com

The resulting mixture was promptly freeze-dried, producing a “spongy aerogel, one of a family of substances so light and airy that they have been termed ‘solid smoke.’  To make the gossamer foam stronger, they cured it in an oven, then tested its sturdiness. They concluded that it is strong enough for commercial uses, and biodegradable, with almost a third of the material breaking down within 30 days” (Physorg.com).  You can read more about aerogel here.

Images courtesy Biomacromolecules

The biodegradable foam could find a use as a packing material or as a protective coating that degrades after a period of time to reveal a different material underneath.  I suppose you could also shoot it out of a circus cannon but I’m not sure the Ringling Brothers would be keen about it.

WU XING:

I’ve filed biodegradable foam under earth because it’s made with clay!

Cited:

“Development of Biodegradable Foamlike Materials Based on Casein and Sodium Montmorillonite Clay.” Tassawuth Pojanavaraphan, Rathanawan Magaraphan, Bor-Sen Chiou, David A. Schiraldi. Biomacromolecules 2010 11 (10), 2640-2646.

“Biodegradable Foam Plastic Substitute Made from Milk Protein and Clay.” Physorg.com 10/20/10. Accessed 11/16/10. URL

Image courtesy madsilence.wordpress.com

Three score and ten years ago, a bunch of scientists invented aerogel, a material so air-entrained that it makes angel food cake seem as dense as a lead ingot.  As an insulator, aerogel is “four times more efficient than fiberglass or foam … according to Dr. Peter Tsou of NASA’s Jet Propulsion Laboratory, ‘you could take a two- or three-bedroom house, insulate it with aerogel, and you could heat the house with a candle. But eventually the house would become too hot'” (Fox).  Aerogel is lightweight, efficient, flameproof, vapor-permeable, and more plastic than fiberglass or foam insulation.  And, until recently it has been prohibitively expensive.

Image courtesy Aspen Aerogel

You make aerogel by first constructing a conventional gel, and then replacing the entrained liquid though supercritical drying.  If you’re thinking supercritical drying involves some pretty harsh language and a lot of gelatinous tears, think again.  The process is “accomplished by increasing the temperature and pressure of the solvent phase inside of the gel structure beyond its critical point. This ‘supercritical’ extraction condition lowers the surface tension between the liquid and the solid pore surfaces so that depressurization of the system at temperatures above the critical temperature leaves the pore structure filled with gas. The resultant material is 90 percent air, but retains the structure and rigidity of the non-liquid gel components” (Source: Aspen Aerogel). 

Image courtesy Aspen Aerogel

I’m thinking of this kind of like a salad dressing where you mix oil and vinegar together vigorously, so that tiny droplets of vinegar are suspended in the oil.  The supercritical part is that you basically zap the vinegar out and suddenly the oil has tiny pores in it where the acid used to be … only the salad dressing is more solid than oil, really it’s kind of like swiss cheese…. Hmmm maybe the culinary metaphor was the wrong way to go. 

Anyway, you might want to grab a chair at this point because you’re not going to believe this next part and you might fall down if you’re standing up because I mean really, who comes up with this stuff???

Researchers (I know not where) decided to soak some cellulose, which is the structural component of plant cells from which we make paper and cardboard, in a solution of metallic nanoparticles (like ya do).  In case you’re taking notes, the solution was comprised of iron sulfate and cobalt chloride, so the cellulose fibers took on the properties of metal and became magnetic.  Next, in order to turn this crazy wood-metal cocktail into an aerogel the researchers freeze-dried the nanoparticle-infused cellulose, leaving behind a lightweight, moisture-free, porous mesh of solid fibers.  This resulted in “a flexible, lightweight, super-absorbent sponge that can also be crushed down into a flat piece of magnetic “nanopaper” capable of supporting 400,000 pounds per square inch” (Dillow).  Or to put it another way, it can support the weight of approximately 33 adult male elephants per square inch.

Image courtesy www.popsci.com (The Aerogel is supporting a brick).

The resulting material can be flexed and folded, and it’s highly absorbent.  If you hammer the air out of it, you are essentially left with a piece of magnetic paper that can support the weight of the aforementioned elephants.  Applications for a “super-strong, flexible, absorbent, magnetic sponge” abound in materials science: for example, it could easily find a home in “microfluidic devices like fuel cells or used to make small actuators” (Dillow).  I could also see how it might be incorporated as a filter or used to insulate submarines.

WU XING:

Filing under wood and metal – this was a no-brainer.

Cited:

Dillow, Clay. “New Flexible Cellulose Aerogel is both a Magnetic Sponge and a Flexible Nanopaper” Popsci.com 08/09/10.  Accessed 10/26/10.  URL.

Fox, Stuart. “Superinsulating Aerogels Arrive on Home Insulation Market at Last” Popsci.com 02/04/10. Acessed 10/26/10. URL.