Development of Bio-Based Composite Materials for Additive Manufacturing Using PLA and Mycelium

The increasing demand for sustainable materials in additive manufacturing has accelerated the development of bio-based composites as alternatives to conventional petroleum-based polymers. This study investigates the feasibility of integrating Pleurotus ostreatus mycelium as a natural reinforcing phase into FDM-printed PLA composite structures for sustainable engineering applications. The developed composites are intended for lightweight bio-based structures, including sustainable packaging and other applications requiring biodegradable reinforcement materials.

PLA shell structures were fabricated by fused deposition modeling (FDM) and filled with different bio-based core materials, including wood–PLA composite, wood–PLA colonized by Pleurotus ostreatus, and hemp substrate colonized by P. ostreatus. The mycelium was cultivated within the printed PLA shells for seven days under controlled environmental conditions and subsequently dried in a two-step process (60 °C for 2 h followed by 80 °C for 2 h) to inactivate the mycelium, reduce moisture, and obtain dimensionally stable composite specimens for tensile testing. The dried mycelium served as a natural bio-based reinforcing core within the printed structures.

Tensile tests were performed to evaluate the influence of the different filler materials on the mechanical properties of the composites. Wood–PLA-filled specimens achieved the highest average yield stress of 8.83 MPa, whereas composites containing wood–PLA and mycelium reached 7.33 MPa, compared with 5.61 MPa for hollow PLA shells. These findings indicate that the mechanical performance strongly depends on the filler composition and that mycelium can contribute to the reinforcement of FDM-printed bio-based composite structures.

Overall, the study demonstrates the feasibility of integrating mycelium into FDM-printed PLA composites as a sustainable reinforcing material. The developed composite structures show potential for lightweight bio-based applications, including sustainable packaging and other biodegradable composite products. Further optimization of cultivation and processing conditions is expected to improve their mechanical performance.