Thermal characterization of natural and synthetic spider silks by both the 3ω and transient electrothermal methods

Publication date: 5 April 2017
Source:Materials & Design, Volume 119
Author(s): Changhu Xing, Troy Munro, Colby Jensen, Heng Ban, Cameron G. Copeland, Randolph V. Lewis
Thermal conductivity, thermal diffusivity, and volumetric heat capacity of three spider silks are measured in this paper as a benchmark for further studies. These silks include the major and minor ampullate silks of the Nephila clavipes spider, and a synthetic spider silk fiber made from recombinant dragline silk proteins purified from transgenic goats' milk. Two complementary measurement techniques are employed in the thermal characterization of these microscale single fibers for self-verification. One is the transient electrothermal technique (TET) and the other is the 3ω method. Experimental measurements indicate that thermal properties of the dragline silk are very close to those of the minor ampullate silk, whereas the ones for the synthetic silk are much lower due in part to its low crystallinity. The directly measured thermal conductivity, thermal diffusivity, and volumetric heat capacity of the major and minor ampullate silks are 1.2–1.26Wm⁻¹K⁻¹, 5.7–6×10⁻⁷m²s⁻¹, and 2–2.17 MJm⁻³K⁻¹, respectively. The thermal conductivity and thermal diffusivity of the as-spun synthetic silk are 0.24Wm⁻¹K⁻¹ and 1.6×10⁻⁷m²s⁻¹ respectively. As part of this study, a detailed comparison of the TET and 3ω methods is provided showing the complementary nature of the techniques and illustrating the strengths and weaknesses of each.

Graphical abstract

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