Multiphysics modelling of the mechanical properties in polymers obtained via photo-induced polymerization

Photopolymerization is an advanced technology to trigger free radical polymerization in a liquid monomer solution through light-induced curing, during which mechanical properties of the material are significantly transformed. Widely used in additive manufacturing, parts fabricated with this technique display precisions up to the nanoscale; however, the performance of final components is not only affected by the raw material but also by the specific setup employed during the printing process. In this paper, we develop a multiphysics model to predict the mechanical properties of the photo-cured components, by taking into account the process parameters involved in the considered additive manufacturing technology. In the approach proposed, the main chemical, physical, and mechanical aspects of photopolymerization are modelled and implemented in a finite element framework. Specifically, the kinetics of light diffusion from a moving source and chain formation in the liquid monomer is coupled to a statistical approach to describe the mechanical properties as a function of the degree of cure. Several parametric examples are provided, in order to quantify the effects of the printing settings on the spatial distribution of the final properties in the component. The proposed approach provides a tool to predict the mechanical features of additively manufactured parts, which designers can adopt to optimize the desired characteristics of the products.