Mechanical, physical and chemical characterisation of mycelium-based composites with different types of lignocellulosic substrates

The current physical goods economy produces materials by extracting finite valuable resources without taking their end of the life and environmental impact into account. Modernity leaves us with devasted landscapes of depleted resources, waste landfill, queries, oil platforms. At the time of the Anthropocene, the various effects the human role has on the constitution of the soils create an acceleration of material entropy. It is the terrestrial entanglement of fungal materials that we investigate in this paper by offering an alternative fabrication paradigm based on the growth of resources rather than on extraction. Unlike the latter, biologically augmented building materials can be grown by combining micro-organisms such as fungal mycelium with agricultural plant-based waste. In this study, we investigate the production process, the mechanical, hygrothermal and chemical properties of mycelium-based composites with different types of lignocellulosic reinforcement fibres combined with a white rot fungus, Trametes versicolor . Together, they form an interwoven three-dimensional filamentous network binding the feedstock into a lightweight material. The mycelium-based material is heat-killed after the growing process. This is the first study reporting the dry density, the Young’s modulus, the compressive stiffness, the stress-strain curves, the thermal conductivity, the water absorption rate and a complete FTIR analyse of mycelium-based composites by making use of a disclosed protocol with T. versicolor and five different type of fibres (hemp, flax, flax waste, softwood, straw) and fibre conditions (loose, chopped, dust, pre-compressed and tow). These experimental results show that mycelium-composites can fulfil the requirements of thermal insulation. The thermal conductivity and water absorption coefficient of the mycelium composites with flax, hemp, and straw have an overall good insulation behaviour in all the aspects compared to conventional unsustainable materials. The conducted tests reveal that the mechanical performances of the mycelium-based composites depend more on the fibre condition, size, and processing than on the chemical composition of the fibres. Abstract Figure Graphical abstract Highlights The type of fibre influences the colonisation of mycelium: samples containing flax, hemp, straw and flax-waste resulted in a well-developed composite The type of fibre has a smaller influence on the compressive stiffness than the fibre processing and size. Pre-compression and chopped fibres (particle size <5mm) improve the compressive mechanical properties of mycelium composites. The thermal conductivity and water absorption coefficient of the mycelium composites with flax, hemp, and straw have an overall good insulation behaviour in all the aspects compared to conventional unsustainable materials.