Facilitating Improved Isotropy in Fused Deposition Modeling Utilizing UV Initiated Reactive Processing

Minimizing anisotropy in parts prepared by fused deposition modeling (FDM) remains a key area of research in the development of robust and mechanically useful 3D printed objects. Due to the bulky nature of polymer chains and the complex thermal environment experienced by adjacent filaments, interaction of polymer chains in between layers is minimized. Weak interfaces and poor layer adhesion results. In recent years, our group has addressed these issues through the introduction of low molecular weight surface segregating additives (LMW-SuSAs). LMW-SuSAs are smaller than the polymer chains of the neat material and can more readily diffuse and entangle in adjacent layers. In the current research, we report, bimodal blends containing linear and 3-arm PLA LMW-SuSAs terminated with methacrylate groups and crosslinked by UV irradiation. In situ irradiation of the printed layers results in drastic increases in the transverse tensile stresses of the printed layers up to ~140% and ~200% for the linear and 3-arm LMW-SuSAs respectively. Additional experiments examine the effect of UV power on the process. By controlling the UV power, printed parts can be prepared with minimal interfilamentous voids and substantially robust interfaces.