Mechanical behaviour of photopolymerized materials

Abstract The photopolymerization process used for the production of additively manufactured polymers employed in advanced applications, enables to obtain objects spanning a large dimensional scale thanks to the molecular size achievable by the solidification process. In fact, the photopolymerization is based on the physical-chemical network cross-linking mechanism taking place at the nanoscale. Since the starting raw material is a liquid resin that progressively becomes solid upon the irradiation by a suitable light source, the mechanical properties – and so the corresponding mechanical response of the final printed structural material – heavily depend on the degree and distribution of the polymerization induced in the material itself. In the present study, starting from the governing equations of the light-induced polymerization process, we determine the chain density formed within the solid domain. Then, the mechanical response of photopolymerized elements obtained with different photopolymerization parameters is investigated. Moreover, the microstructure optimization of polymeric elements in relation to the achievement of the desired mechanical response with the least energy spent in the polymer's formation, is studied. Finally, some interesting considerations related to the modelling of the photopolymerization process are outlined.