Material model proposal for biodegradable materials

Abstract A large range of biodegradable polymers are used in many products with short life cycle. Important applications of these are found in the biomedical field, where biodegradable materials are used to produce scaffolds that temporarily replace the biomechanical functions of a biologic tissue, while it progressively regenerates its capacities. However, the mechanical behavior of biodegradable materials along its degradation time, which is an important aspect of the project, is still an unexplored subject. In this work, hyper elastic constitutive models, such as the Neo-Hookean, the Mooney-Rivlin modified and the second reduced order are discussed. These can be used to predict the mechanical behavior of a blend composed of polylatic acid (PLA) and polycaprolactone (PCL). A numerical approach using ABAQUS® is presented, where the material properties of the model proposal are automatically updated in correspondence to the degradation time, by means of a User Material subroutine (UMAT). The parameterization of the material model proposal for different degradation times were achieved by fitting the theoretical curves with the experimental data of tensile tests. The material model proposal implemented in a subroutine could be used as a design toll for generic biodegradable devices.