Mycelium-Based Laminated Composites: Investigating the Effect of Fungal Filament Growth Conditions on the Layer Adhesion

Mycelium-based composites are self-grown biodegradable materials, made using agricultural residue fibers that are inoculated with fungi mycelium. The mycelium forms an interwoven three-dimensional filamentous network, binding every fiber particle together to create a rigid, lightweight composite material. Although having potential in packaging and in the construction industry, mycelium composites encounter molding limitations due to fiber size and oxygen access which hinder design capabilities and market engagement. To cope with these limitations, this study reports an alternative way to form mycelium composite using cut precultivated mycelium composite panels, laminated to biologically fuse into a unique assembly. By controlling the growth conditions of the mycelium network, it is possible to adjust physical properties such as flexural strength and strain energy density. These mycelium composite panels were fabricated from hemp fibers and Ganoderma lucidum mushroom. Seven different growth conditions were tested to increase layer adhesion and create the strongest assembly. Three-point flexural tests were conducted on ten samples extracted from each assembled panel triplicate set. The data collected in this study suggested that cultivating an opaque layer of mycelium on the surface of the panel before stacking can enhance total strain energy density by approximately 60%, compared to a single-layer mycelium composite of identical size. In addition, this eliminates abrupt material failure by dividing failure behavior into multiple distinct stages. Finally, by layering multiple thinner layers, the resulting mycelium composite could contain even higher mycelium proportions exhibiting augmented mechanical properties and higher design precisions opening market possibilities.