Fabrication of composite polymers with micron size copper and graphite additives in masked stereolithography

Masked stereolithography makes the fabrication of complex parts more effortless and less expensive and enables high surface quality. We fabricated pure resin, flexible resin, resin-6.1-wt% graphite, and resin with Cu concentrations spanning from 5.5 to 15.5 wt% at different printing conditions. The structure was investigated with electron and light microscopes, and tensile testing of the printed sample was carried out. Resin temperature, post-curing temperature, and time are the dominating factors determining the strength of printed samples. Resin-Cu composite depicted a strengthening effect at 10 °C degrees resin and post-curing temperatures, but no strengthening effect was found for flexible resin-Cu composite at 20 °C degrees. Cu particles agglomerated, forming a density-graded composite; however, graphite particles distributed more homogenously in the parts. Increasing the graphite gradually reduces the composite strength. As a result, the mechanical properties of the composites are dominated by the interaction between the fillers and the matrix.