Revising the exceptionally high thermal diffusivity of spider silk

The outstanding mechanical properties of spider silk have been widely studied, but measuring its thermal transport properties is actually a challenge, since the silk fibers are very thin (few micrometers in diameter). Recently, an exceptionally high thermal diffusivity value for the dragline silk has been reported, 70 mm(2) s(-1), similar to the best thermal conducting metals. In this work, by means of a lock-in thermography setup specially designed to measure thermal diffusivity of very thin filaments, we have measured the thermal diffusivity of spider dragline silk. The value we have obtained, 0.20 +/- 0.01 mm(2) s(-1), is 400 times lower than the previously reported result and falls within the typical diffusivity range of biomaterials (0.1-0.3 mm(2) s(-1)). (C) 2013 Elsevier B.V. All rights reserved.