The formulation combines a melt-stable lignin with a low-melting nylon, and carbon fiber to create a composite right for extrusion with weld strength between layers and excellent mechanical properties.
Prolonged exposure of Lignin to heat increases its viscosity, making it difficult to extrude.
When lignin was combined with nylon, the composite’s room temperature stiffness increased while its melt viscosity decreased.
The lignin-nylon composite demonstrated tensile strength similar to nylon alone and lower viscosity than conventional ABS or HIPS (high-impact polystyrene).
The combination of lignin and nylon had almost a lubrication or plasticizing effect on the composite.
The ORNL scientists were able to mix in a higher percentage of lignin, 40 to 50 percent by weight.
They added 4 to 16 percent carbon fiber into the mix.
The new composite heats up more easily, flows faster for speedier printing, and results in a stronger product.
The new composite is patent-pending and work is underway to refine the material and find other ways to process it.