Healable polymer blends: Computational analysis of damage and healing mechanisms

Healable polymer blends with phase-separated thermoset/thermoplastic (TS/TP) microstructures have gained significant interest for their high potential in sustainable structural applications. To better understand the damage and healing behavior of these materials, an isotropic continuum cohesive damage-healing model specific to the healable TS/TP blends is first presented within the framework of finite element method. Traction–separation laws of cohesive models are integrated into regular finite elements, where damage variables of each element can be achieved by explicit modeling of crack evolution. A parabolic damage evolution law is derived for elastoplastic polycaprolactone (PCL) based on its experimental stress–strain behavior. Temperature-dependent material properties and time-dependent loading are incorporated in the model. The phase change of PCL is characterized by linking its modulus to crystallinity. The proposed model is validated by applying the model prediction for epoxy/PCL blends consisting of epoxy particles and PCL matrix and comparing the results with experimental data in available literature. Representative volume element (RVE) models of epoxy/PCL blends are developed from realistic micrographs through image-based model generation to capture true microstructures. The proposed model provides a good starting basis for understanding the damage and healing mechanisms in healable TS/TP polymer blends.