3D-printing of thermoplastic protein-based composites by fused deposition modelling

Proteins can be plasticised to create thermoplastic materials suitable for 3D printing using fused deposition modelling (FDM). This study explores the plasticisation of zein, calcium caseinate, and their blends with glycerol, focusing on their thermal and rheological properties, as well as their performance in 3D printing. Thermoplastics protein-based composites were prepared through a process of protein dissolution, plasticisation, film casting and pelletisation. Calcium caseinate (CaCas) showed good miscibility with glycerol, whereas phase separation was observed in zein-based composites at higher glycerol concentrations. Zein-based pellets were successfully 3D-printed by using a pellet extruder as the printhead. Stable 3D structures were printed without need for post-processing and an unsupported 45 degree overhang angle was achieved. Calcium caseinate-based pellets were not extrudable using the current setup due to their high viscosity. Furthermore, the thermal and rheological properties of protein composites correlated well with their printing performance. This study showed that protein-based composites are promising materials for FDM applications. • Concentrated thermoplastic proteins were 3D printed using pellet extrusion FDM • Zein and CaCas showed different miscibility with glycerol as the plasticiser • Rheological properties of protein composites affect their printing performance • Blending zein and CaCas yields materials with favourable printing properties