March 6, 2012
The Amazing Properties Of Spider Silk
New research has revealed that spider silk carries amazing physical properties, according to a new paper published in the journal Advanced Materials.
Xinwei Wang, who wanted to take a closer look at spider webs, ordered eight Nephila clavipes, commonly known as golden silk orbweavers. He put them to work eating crickets and spinning webs so their materials and habits could be studied.
Wang, who is an associate profess of mechanical engineering at Iowa State University studies thermal conductivity, or the ability of materials to conduct heat. Wang has been searching for organic materials that could conduct heat, something diamonds, copper, and aluminum do extremely well. Typically organic materials are poor conductors of heat.
Wang's research indicated that spider silks are very good conductors of heat. The draglines that anchor parts of the web in place conducted heat better than most materials, including silicon, aluminum and pure iron. According to his research, spider silk conducts heat 1,000 times better than woven silkworm silk and 800 times better than organic tissues.
Wang wrote, “Our discoveries will revolutionize the conventional thought on the low thermal conductivity of biological materials.”
Using laboratory techniques developed by Wang, the researchers found the spider silk conducted heat at the rate of 416 watts per meter Kelvin, compared to copper that conducts at 401 watts per meter Kelvin. Skin tissues measure 0.6 watts per meter Kelvin.
“This is very surprising because spider silk is organic material. For organic material, this is the highest ever. There are only a few materials higher - silver and diamond,” Wang said.
One of the surprising properties Wang found about spider silk is that when it is stretched, the thermal conductivity increases. Stretching spider silk by 20 percent increases its conductivity by 20 percent.
Some of the new applications for spider silk include better clothes for hot weather, creating flexible, heat-dissipating parts for electronics and bandages that don´t trap heat.
These amazing properties are caused by the spider-webs defect-free molecular structure. This structure contains proteins that have nanocrystals and sprint=shaped structures connecting the proteins. He wants to do more research studying the thermal conductivity of the webs.
While studying the webs, Wang became fascinated by the creatures that created the webs. He is amazed about everything from spider care to web unraveling techniques to the different silks within a single web. One colleague is calling him Iowa State´s Spiderman
“I´ve been doing thermal transport for many years. This is the most exciting thing, what I´m doing right now”, Wang said.
Image Caption: This is one of the golden silk orbweavers spinning webs for Xinwei Wang's research project. Photo courtesy of the Xinwei Wang research group.
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