Spider silk conducts heat better than copper07 March 12
In addition to being extremely strong and stretchy, spider silk conducts heat better than most materials, including silicon, aluminium and pure iron, mechanical engineers at Iowa State University have discovered.
Spider silk has long been the subject of scientific scrutiny, but mostly for its impressive strength. Xinwei Wang, lead researcher on the study, was keen to put speculation that spider silk would be a good thermal conductor to the test as part of a search for organic materials that can effectively transfer heat; most materials from living things are very bad at conducting heat. Wang enlisted the help of eight golden silk orbweaver spiders. They were given lodgings in an Iowa State University greenhouse and fed crickets to fuel their web-spinning.
Wang, along with colleagues Xiaopeng Huang and Guoging Liu, found that spider silk conducts heat 1,000 times better than woven silkworm silk and 800 times better than other organic tissues. Spider silk conducts heat at a rate of 416 watts per metre Kelvin, compared with copper at 401 and skin at 0.6 watts per metre Kelvin.
Wang said: "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."
The thermal conductivity of the spider silk also increased by 20 percent when it was stretched to its 20 percent limit. Most materials lose thermal conductivity when stretched.
These unusual properties are down to the defect-free molecular structure of spider silk, including proteins that contain nanocrystals and the spring-shaped structures connecting the proteins. However, more research is needed to fully understand why spider silk is so good at conducting heat.
This discovery could open a door to using spider silk to create flexible, heat-dissipating parts for electronics, better clothes for hot weather and bandages that don't trap heat.
The research is detailed in a paper in Advanced Materials called New Secrets of Spider Silk: Exceptionally High Thermal Conductivity and its Abnormal Change under Stretching.
Wednesday, 7 March 2012
Spider silk conducts heat better than copper (Wired UK)