(356a) Tough, High Impact Resistant 3D Printed Objects from Core-Shell Filaments

Fused deposition modeling (FDM), an extrusion-based 3D printing method, uses solid polymeric filaments. Typically, the polymers are formulated to provide desired characteristics and extruded into homogeneous filaments with well-defined diameter. However, an intrinsic weakness of FDM is the poor adhesion between printed layers with the bonding interfaces being poorly developed during printing. These poorly constructed interfaces lead to poor mechanical properties from FDM. Here, we propose a route to attack this intrinsic problem using core-shell structured filaments, where the shell has a solidification temperature much lower (> 100 C) than the core. The disparate solidification temperatures lead to the core solidifying first to act as fiber reinforcement for shape control, while the shell generates a strong shell-shell interface between adjacent filaments. Samples printed from core-shell filaments show enhanced mechanical strength with samples that do not fail and order of magnitude improvements in impact resistance. We discuss how the dimensional accuracy and mechanical properties of the 3D printed part are impacted by polymer selection and print processing parameters.