(221g) Additive Manufacturing with Soft Tpu: Thermal Properties for Printability and Adhesion Strength in Multimaterial Flexible Joints

Characterizing 3D-printing filament allows for the quantification and fine-tuning of printing parameters to optimize printing capabilities with respect to the type of 3D printer that is being used. A rather simple yet new method of “line printing” measures the mass flowrate of a semi-crystalline thermoplastic polyurethane blend (NinjaTek Cheetah TPU) over a range of extrusion temperatures via fused filament fabrication (FFF). Melt temperatures and crystallization temperatures that are based on heating and cooling rates via differential scanning calorimetry (DSC) confirmed complicated characteristics of melting behavior of TPU. Despite recommendations from manufacturers, the results obtained from line printing and DSC, coupled with related measurements of temperature-dependent dynamic oscillatory shear using 3D-printed disks, confirmed a wider range of printing capabilities that still provide high quality parts. This work uses a combination of both thermal and rheological characterization to observe intricate melt behavior of a variety of 3D-printing filaments (e.g., TPU, ABS, ASA, PLA) that are based on fundamental fluid mechanics.