3D printing by photopolymerisation of biobased monomers with conductive fillers and characterisation of the resulting specimens

The study focuses on the utilization of biobased photopolymerizable monomers, particularly acrylate polyglycerol, which are derived from renewable resources like vegetable oils. The main objective is to create 3D-printed objects via DLP technology that possess not only the environmental benefits of bio-derived materials but also additional functionalities, such as electrical conductivity and the capacity to be heated by the Joule effect. To achieve this, conductive fillers, including silver, copper, nickel powders, and recycled carbon fibers (RCF), were incorporated into the photopolymerizable resin, which consisted of the liquid monomer and the photoinitiator, at varying concentrations. Subsequently, the DLP printing process was optimized to align with the characteristics of these formulations, addressing challenges associated with viscosity, UV absorption, and filler dispersion. The results of the characterization tests, including FT-IR spectroscopy, photo-DSC, rheology, DMTA, tensile tests, and electrical conductivity analysis, demonstrate that while increasing the filler content generally results in a decrease in the polymerization rate and an increase in viscosity, it markedly enhances the electrical conductivity of the printed objects, and, in some instances, their mechanical properties. It should be emphasized that RCF was identified as a particularly effective filler due to its sustainability, cost-effectiveness, and the relatively low amount required to achieve electrical percolation. Moreover, it was demonstrated that a significant Joule effect can be achieved, particularly with the use of Ag and RCF fillers, resulting in a uniform heating of the printed samples. The study concludes that it is feasible to produce electrically conductive 3D-printed objects using biobased acrylate polyglycerol monomers combined with various conductive fillers. The research demonstrates the potential for these materials in various applications, including custom-designed medical devices for thermotherapy and intricated conductive pathways in electronics. Overall, the thesis contributes to the field of sustainable materials by offering a promising approach to creating functional 3D-printed objects that align with the principles of a circular economy. Additionally, the integration of conductive fillers opens new doors for the use of biobased polymers in advanced manufacturing technologies.