Extrusion‐based 3D printing with high‐density polyethylene Birch‐fiber composites

High‐density polyethylene (HDPE) is one of the most widely used semi‐crystalline polyolefin thermoplastics. However, 3D printing with this material remains rare because of massive shrinkage and poor adhesion to common 3D printing build surfaces. In this study, shrinkage and warping were overcome by blending in short fibers of yellow birch at 10–30 wt% along with a coupling agent. Square tubes were printed to measure deformation and mechanical properties of this composite material. Deformation was reduced by 80% in material containing 30 wt% wood compared to neat HDPE. Young's modulus increased respectively by 25%, 30%, and 35% as the filler content increased to 10, 20, and 30 wt%. This is the first known successful 3D printing with wood‐fiber HDPE composite.