Optimising Thermoplastic Polyurethane for Desktop Laser Sintering

Laser Sintering (LS) is an industrially relevant Additive Manufacturing method that has become more accessible since the introduction of commercially available desktop-LS systems. However, useable materials are currently limited to several grades of nylon, and so the aim of this study was to optimise an unknown, novel material for use in desktop-LS. A grade of thermoplastic polyurethane (UNEXTPU) was analysed to determine thermal properties, particle characteristics and bulk powder flow efficiency. To facilitate laser absorption at 445nm, a carbon additive (graphite) was added to UNEXTPU; the addition of graphite also significantly improved flow efficiency. UNEXTPU was successfully processed on a desktop-LS system, and mechanical testing found that it possesses properties comparable to industrial grade thermoplastic polyurethanes (Elongation at Break: 139%, Tensile Modulus: 48.7Mpa, Ultimate Tensile Strength: 7.9Mpa, Shore Hardness: 75). Bulk powder flow efficiency and mechanical properties were retained in twice recycled powder. This research has established a new viable elastomeric material for use in desktop-LS.