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arXiv · 0808.2734

Elasticity of Spider dragline Silks Viewed as Nematics: Yielding Induced by Isotropic-Nematic Phase Transition

Lin-ying Cui·Fei Liu·Zhong-can Ou-Yang
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Abstract

Spider dragline silk shows well-known outstanding mechanical properties. However, its sigmoidal shape of the measured stress-strain curves (i.e. the yield) can not be described by classical polymer theories and recent hierarchical chain model. To solve the long lasting problem, we generalized the Maier-Saupe theory of nematics to construct an elastic model for the polypeptide chain network of the dragline silk. The comprehensive agreement between theory and experiments on the stress-strain curve strongly indicates the dragline silks to belong to liquid crystal elastomers. Especially, the remarkable yielding elasticity of the silk is understood for the first time as the force-induced isotropic-nematic phase transition of the chain network. Our theory also predicts a drop of the stress in supercontracted dragline silk, an early found effect of humidity on the mechanical property in many silks.

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Lin-ying Cui, Fei Liu, Zhong-can Ou-Yang. 2008-12-21. Elasticity of Spider dragline Silks Viewed as Nematics: Yielding Induced by Isotropic-Nematic Phase Transition. https://arxiv.org/abs/0808.2734

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