Harbin, China – The wood product lignin is an abundant eco-friendly substance, and while there is interest as using it as a substrate for 3D printing, its inherent brittleness and lack of thermoplasticity make its large-scale use in additive manufacturing difficult.
A team of scientists in the Key Laboratory of Bio-Based Material Science and Technology at the Northeast Forestry University in north-east China has combined it with thermoplastic polyurethane to improve its rheological properties for 3D printing.
Materials printed using the lignin/TPU composite with a 50% lignin loading, they said, had a smooth surface, a warm wood, non-plasticky touch, and a natural colour.
Further mechanical improvements were achieved by adding carbon fibre to the composite, too. The resulting materials had tensile strength 1.7 times higher than the lignin/TPU composite, and 2.4 times higher elongation at break. Here, the filament had a smooth surface and dense inter-layer bonds in printed objects. They suggested that their finding might make 3D printing with lignin a more practical proposition.
The work has been published in the International Journal of Biological Micromolecules.