Processing Characteristics of High Molecular Weight Polyethylene in Laser Sintering: The Role of Carbon Black Concentration and Processing Strategy for Diode Laser Sintering Machines

ABSTRACT Until now, most results on processing high molecular weight polyethylene (HMWPE) in laser sintering (PBF‐LB/P) have been achieved using industrial machines with a CO₂ laser. The use of diode laser sintering machines could make new materials more accessible to a wider audience. In this study, the role of carbon black (CB) concentration and processing strategy in HMWPE processing using diode laser PBF‐LB/P machines is investigated. This work reveals that the carbon black concentration strongly influences processing, as it affects both absorption and specific heat capacity. Changes of specific heat capacity impact thermal balance during processing. Due to its narrow sintering window, HMWPE exhibits a high tendency for curling, which can be mitigated by reducing the scanning area and layer thickness. A suitable CB concentration ranges from 0.25 to 0.5 wt.%. In general, mechanical properties improve with volume energy density. This effect is caused by a more pronounced particle coalescence and interlayer bonding. However, the absorption properties of carbon black have a stronger impact on the mechanical properties than the energy input for the tested parameters. Mechanical tests on fabricated tensile bars reveal brittle fracture, which results from the high melt viscosity of HMWPE and the resulting delayed coalescence of particles.