Thermo-hygro-mechanical behavior of spider dragline silk:: Glassy and rubbery states

Spider silk is considered as the basis of a new family of high performance fibers that would reproduce the excellent mechanical properties of the silk, in particular its extreme toughness. However, it has been observed that the mechanical properties of spider silk are severely influenced by humid environments that give rise to significant decreases in its length and elastic modulus. The change from stiff to compliant tensile properties is associated with the glass transition from a glassy to a rubbery state; here, we have found that it depends on both temperature and relative humidity. The glass transition was identified at different temperatures and relative humidities by monitoring the variation of the elastic modulus and observing the emergence of supercontraction. (c) 2006 Wiley Periodicals, Inc.