Simple Determination of the Melt Flow Index of Composite Polymer Filaments Used in Material Extrusion Additive Manufacturing

Abstract

The mechanical properties improving filler introduction into polymer filaments often lead to the formation of defects in 3D-printed products. Studying the bulk modification of polyethylene terephthalate glycol (PETG) filaments with 0.5–1.5 wt% of natural shungite and molybdenum disulfide, we found the melt flow index (MFI) value reduced by 18%–30%. We investigate the effect of bulk modification on the filaments’ rheological properties, develop a technique that eliminates typical additive prototyping defects by regulation of the extrusion parameters in Cura slicing software, and propose an effective method for the MFI-measurement of the 3D-printed filaments that does not require special laboratory equipment (plastometers).