Selective laser sintering of polyhydroxybutyrate: Influence of processing parameters and biocarbon reinforcement

Poly(3-hydroxybutyrate) (PHB) has generated noteworthy attention in the materials science community as a biodegradable polymer with desirable mechanical properties, presenting a possible alternative to petroleum-based plastics. However, the method of manufacturing PHB parts has been a significant limitation for its potential applications, particularly in the biomedical field, a sector where PHB shows great promise. Due to the nature of the biomedical field, complex shapes and use-specific geometries are required. To allow PHB to meet this criteria, additive manufacturing (AM), otherwise known as 3D printing, has been proposed. The most common form of 3D printing, fused deposition modelling (FDM), has proven unsuccessful with neat PHB due to the challenges in filament extrusion. As such, selective laser sintering (SLS) has been suggested as a solution. This AM method uses a laser to sinter polymer powders. In this study, experiments are carried out to determine the optimal conditions for the highest printability and greatest mechanical performance of SLS printed PHB. Subsequently, printer parameters were varied to optimize mechanical properties. Layer height was tested at 0.1 mm, 0.15 mm, and 0.2 mm; laser power was varied between 22 W, 25 W, and 28 W; and hatching distance was tested at 0.1 mm, 0.15 mm, and 0.2 mm. Lower layer height and hatching distance generated the strongest parts, with layer height having the greatest influence. Laser power exhibited a strengthening effect as it increased. Subsequently, PHB composites containing 2 and 5 wt.% wood biocarbon were fabricated and printed under the optimized conditions to assess the influence of biocarbon addition on part performance.