Improving the adhesion and properties in the material extrusion of polypropylene by blending with a polyolefin elastomer

We examine the effect of the thermorheological properties of polypropylene (PP) on its material extrusion characteristics using a 3D printer. Rheological characterization showed that PP with higher viscosity exhibited low extrusion rates during printing and suffered significant pressure drop. All PP grades tested suffered from warpage in the built structures, and debonding of individual strands under tensile deformation. Blending 20–40 wt% of an elastomeric ethylene-octene copolymer (EOC) with PP improved the flow properties and the interfacial fusion. Investigation into the morphology and thermal properties of the blends showed that owing to its amorphous structure and low melting point, the EOC dispersed phase facilitated the material extrusion process, reduced warpage, and promoted fusion between the printed strands, improving the mechanical properties.