Constitutive and Fracture Behavior of Double-Network Elastomers

The double-network (DN) concept, initially applied to hydrogels, has been adapted to elastomers, resulting in materials that combine exceptional toughness with tunable elasticity. This article delves into the constitutive and fracture behaviors of DN elastomers, elucidating the pivotal role of prestretch and composition in tailoring their properties. An incompressible hyperelastic model is employed to predict the stress–strain behavior and energy release rate of a DN elastomer, focusing on how the interactions between the two networks influence its overall material properties. The influence of prestretch and composition on increasing the stiffness and energy release rate of a DN elastomer is analytically determined. The analytical predictions are validated experimentally through comprehensive mechanical and fracture testing using a DN elastomer fabricated by a two-step crosslinking process to decouple the prestretch and composition. The results show that manipulating these processing parameters can finely tune the mechanical responses of DN elastomers, optimizing them for specific applications. The findings provide new insights into the mechanics of DN elastomers.