Basalt fiber reinforced polypropylene to manufacture 3D printed composites

Polypropylene (PP) is one of the most used polymeric materials worldwide, either as a neat material or as a matrix for composite manufacture employing a molding process. Fused deposition modeling (FDM) 3D printing is an alternative process that offers the potential for manufacturing value-added products from PP. However, using neat PP for FDM is challenging because 3D-printed PP warps and shrinks when cooled, and the mechanical properties of PP are poor. PP-based composites with different fillers (e.g., glass, carbon, and natural fibers) have shown improved properties using FDM processes. An alternative filler for 3D-printed PP-based composites is basalt fiber (BF). The objective of this work was to assess the potential and impacts of BF as a filler for BF-PP composites using FDM processes. PP was compounded with 15, 25, 35, and 45 wt% BF to produce filaments for 3D printing without adding any compatibilizer. Results of rheology studies, morphology, and mechanical and thermal properties of the 3D printed specimens showed that BF positively impacts Young's modulus (E), thermal stability, and dimensional stability of the composite. All composites, when processed at high shear rates (i.e., above 100 1/s), show approximately similar rheological behavior. E is almost doubled in the composite with 25 wt% BF and increased fourfold in the composite with 35 and 45 wt% BF, compared to neat PP. The Izod impact resistance of the formulations containing 35 and 45 wt% BF is similar to 70% that of neat PP. BF process easily and adequately reinforces PP composites manufactured via FDM.