Comparing Mechanical and Tribological Properties of PETg-PTFE-EG/h-BN Composites Produced by Injection Moulding and Additive Manufacturing

Key processing technologies for polymers include traditional injection moulding (IM) and emerging 3D printing or additive manufacturing (AM). The meso-scale structuring and the degree of degradation during processing are likely different for IM and AM, affecting the material properties of the produced parts. Here, studies that examine both mechanical and tribological behaviour remain rare, specifically for less studied materials such as polyesters. In this work, we selected polyethylene terephthalate-glycol (PETg) as the matrix, incorporating polytetrafluoroethylene (PTFE) and solid lubricants such as hexagonal boron nitride (h-BN) or expanded graphite (EG), to compare IM and AM mechanical and tribological performance under similar degradation conditions, as verified by gel permeation chromatography. The thermal properties were not altered by the addition of fillers, while the mechanical properties, i.e., tensile modulus and impact strength, could be tuned through the addition of specific levels of additives. Once the specific load of the additives was reached, we observed a reduction in the specific wear rate. The findings suggest that well-optimised filler combinations and robust processing control can significantly enhance the performance of PETg composites.