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
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
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
New Secrets of Spider Silk: Exceptionally High Thermal Conductivity
and its Abnormal Change under Stretching.
/ Hunter Desportes /