Improving Anisotropic Properties of Objects Printed via Stereolithography

Brian Green, University of Iowa

Abstract:In this research, we examine the effect of incorporating a small amount of reversible addition-fragmentation chain transfer (RAFT) agent into a standard acrylate system to control the network formation. It was found that including a trithiocarbonate RAFT agent in the 3D printed formulation lead to a 45% increase in elongation and toughness with a corresponding 20% decrease in Young’s modulus when compared to a 3D printed dogbone with no RAFT. To measure the anisotropic properties of SL, “horizontal” dogbones were printed with the long axis in the x-direction and “vertical” dogbones were printed with the long axis in the z-direction. For the model acrylate formulation, it was found that printing in the vertical direction decreased the modulus by approximately 33% after a UV post cure. However, this effect was diminished when the RAFT agent was included in the formulation, leading to a 10% increase in modulus upon UV post cure. This indicates that the inclusion of a RAFT agent in our model acrylate formulation facilitated improved interlayer adhesions and diminished anisotropic properties based on print orientation.