Extrudability and Mechanical Properties of Wood–Sodium Silicate Composites with Hemp Fiber Reinforcement for Additive Manufacturing

This study investigates the potential of hemp fiber reinforcement in wood-sodium silicate composites for additive manufacturing. It focuses on the impact of hemp fiber length and content on the rheological, flexural, compression properties, and extrudability of the composite. Composites contained varying amounts of sodium silicate (45, 50, 55 wt%) and hemp fibers of varying lengths (1, 3, 5 mm) and amounts (2.5, 5, 10 wt%) along with wood fibers sifted through a 40-mesh sieve. The study shows that higher sodium silicate content significantly increases viscosity while reducing the motor power needed to extrude the composite. Hemp fiber amount positively affects flexural and compression strength, increasing by 31.2% and 35.6%, respectively, with 5 wt% hemp fiber. This improvement in mechanical properties significantly increases the thermoset-based composite's potential for various applications. This study also demonstrates for the first time, the feasibility of using the hemp fiber-reinforced wood-sodium silicate composite for additive manufacturing by successfully depositing a multi-layer sample print and determining its bending strength.