Influence of glass fibers on the processability and mechanical properties of PP homopolymer for fused filament fabrication (FFF) Open Access

Polypropylene (PP) has been used very little as additive manufacturing material so far. Commercial filaments often consist of copolymers or blends and thus do not achieve the mechanical stability of PP homopolymers. Therefore, the topic of this work is the investigation of PP homopolymers and their glass fiber (GF) reinforced compounds regarding the processability in the fused filament fabrication (FFF) process and the mechanical properties of printed parts. A PP homopolymer was used as neat material and as compounds with 10 or 20 wt% of short or long GF. All materials were extruded into filaments and printed using FFF. The mechanical properties of the printed samples were compared to injection-molded ones. The study showed that filaments with a suitable mean diameter could be produced from all compounds. Good printability was demonstrated for neat PP and the short GF reinforced compounds. Concerning mechanical properties, an excellent welding quality of the neat material led to strength and stiffness in the range of the injection-molded reference. A slightly lower welding quality and the presence of pores in the GF reinforced parts resulted in lower mechanical values. Overall, the work showed a high potential of PP homopolymer compounds regarding processability and mechanical properties.