Characterization of the auto-curing behavior of rapid prototyping materials for three-dimensional printing using dielectric analysis

Three-dimensional printing technology applies the high efficiency of the ink jet printer technology to manufacture functional prototypes. To optimize the printing process of PMMA powder containing an initiator and a liquid binder consisting of polymerizable monomers with activator molecules, the knowledge of the curing kinetics is required. Therefore, a methodology was developed to apply dielectric analysis measuring changes of the ion and dipole mobility in terms of a quantity called ion viscosity. Connecting time-dependent changes of ion viscosity and reaction heat determined by DSC leads to detailed insight into the curing process. The results show that the styrene concentration of the binder determines the curing kinetics - reduces thermal stresses and provides time for stress relaxation. The curing process differs significantly with respect not only to composition of the binder, but also to its aging state. The proposed approach can be implemented directly to a printer to detect dielectric changes of the materials during the manufacturing process. © 2015 Society of Plastics Engineers