Impact of Fomes fomentarius growth on the mechanical properties of material extrusion additively manufactured PLA and PLA/Hemp biopolymers

Fungal-based biomaterials are emerging as sustainable alternatives to synthetic polymers, offering biodegradability and low environmental impact. However, the interaction between mycelium and 3D-printed biopolymers, particularly regarding mechanical performance, remains underexplored. This research investigates the tensile behavior of biopolymer specimens produced by Material Extrusion Additive Manufacturing (MEX AM), focusing on the effects of Fomes fomentarius mycelium colonization. The study examines how pre- and post-processing steps, as well as different 3D-printing infill patterns, influence mycelial growth and its mechanical impact. Both pure PLA and PLA_Hemp biopolymers were studied to assess the role of natural particles in fungal interaction and structural performance. The results indicate that mycelial colonization has a minor impact on the mechanical properties of PLA, while PLA_Hemp shows more pronounced, time-dependent effects. Environmental conditions such as humidity and incubation also affect mechanical performance, whereas certain pretreatments, like autoclaving, can significantly weaken the material. Overall, this work provides insight into the integration of mycelium within 3D-printing biopolymers, demonstrating the feasibility of hybrid biocomposites and highlighting both opportunities and challenges, thereby paving the way for more sustainable materials design and construction practices.