Spider Silks Mechanics: Predicting Humidity and Temperature Effects

We deduce a microstructure inspired model for humidity and temperature effects on the mechanical response of spider silks, modeled as a composite material with a hard crystalline and a soft amorphous region. Water molecules decrease the percentage of crosslinks in the softer region inducing a variation of natural length of the macromolecules. The resulting kinematic incompatibility between the regions crucially influences the final mechanical response. We demonstrate the predictivity of the model by quantitatively reproducing the experimentally observed behavior.