A predictive model for protein materials: from macromolecules to macroscopic fibers

We propose a model for the mechanical behavior of protein materials. Based on a limited number of experimental macromolecular parameters (persistence and contour lengths, rate of unfolding dissipation) we obtain the macroscopic behavior of keratin fibers (human, cow, and rabbit hair), taking into account the damage and residual stretches effects which are fundamental in many functions of life. We support our theoretical results by showing that our model is robust and able to reproduce with high quantitive accuracy the cyclic experimental behavior of different keratinous protein materials we tested. We also show the capability of describing, even if with lower precision, the dissipation and permanent strain effects in spider silks.