Study on CNT/TPU Cubic under the 3D Printing Conditions of Infill Patterns and Density

Abstract

Soft sensors applicable to wearable robots can be manufactured using stretchable polymers and conductive fillers. In this study, 3.25 wt% carbon nanotubes/thermoplastic polyurethane composites were used to manufacture filaments with shore 94 A. Three infill densities (20%, 50%, and 80%) and patterns (zigzag (ZG), triangle (TR), honeycomb (HN)) were applied to print a cubic via fused filament fabrication 3D printing. Most suitable infill conditions were confirmed based on the slicing images, morphologies, compressive properties, electrical properties, and electrical heating properties. For each fill pattern, ZG and TR divided the layers into lines and figures, and the layers were stacked by rotation. For HN, the same layers were stacked in a hexagonal pattern. Consequently, TR, in which the layer was divided in various directions, showed the strongest compressive properties. For each infill density, 20%, 50%, and 80% measured 0.18 J, 0.84 J, and 1.99 J, respectively. The HN pattern became tougher with increased infill density. The HN laminated with the same layer showed excellent electrical properties, with results greater than 14.7 mA. The electrical heating properties confirmed that ZG had the highest layer density, which exhibited excellent heating characteristics.