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

Abstract

The current physical goods economy produces materials by extracting finite valuable resources without taking their end of the life and environmental impact into account. Mycelium-based materials offer an alternative fabrication paradigm, based on the growth of materials rather than on extraction. Agricultural residue fibres are inoculated with fungal mycelium, which 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. In this paper, we investigate the production process, the mechanical, physical and chemical properties of mycelium-based composites made with different types of lignocellulosic reinforcement fibres combined with a white rot fungus, Trametes versicolor. 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 FTIR analyse of mycelium-based composites by making use of a fully disclosed protocol with T. versicolor and five different type of fibres (hemp, flax, flax waste, softwood, straw) and fibre processings (loose, chopped, dust, pre-compressed and tow). 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 materials such as rock wool, glass wool and extruded polystyrene. The conducted tests reveal that the mechanical performance of the mycelium-based composites depends more on the fibre processing (loose, chopped, pre-compressed, and tow), and size than on the chemical composition of the fibres. These experimental results show that mycelium-composites can fulfil the requirements of thermal insulation and have the potential to replace fosile-based composites. The methology used to evaluate the suitability and selection of organic waste-streams proved to be effective for the mycelium-material manufacturing applications.

Fungal Based Biopolymer Composites for Construction Materials

“…A test conducted with Trametes versicolor revealed that the mechanical performances of the mycelium based composites depend more on the fiber condition, size, processing, than on the chemical composition. The study evaluated many lignocellulosic substrates (hemp, flax, flax waste, soft wood, straw), processed in different ways (loose, chopped, dust, pre-compressed and tow) [ 28 ].…”

“…The fungus grew differently depending on the micro-neighborhood of the inoculation points with Ganoderma that is important and can act differently, in a stimulating sense, if it is predominantly lignocellulosic substrate, and relatively restrictive if it is polymer. Also, inside the board, there is an absence of air and an accumulation of heat produced by mycelium growth [ 28 ].…”

Fabricate 2020

“…Fungal-lignocellulosic materials inherit properties from both wood and mycelium, resulting in lightweight and strong bio-composites. Generally, they exhibit good insulative performance for both heat and sound, are hydrophobic, and have good tension and compression resistance (Yang et al, 2017;Elsacker, 2019). In addition, the raw materials for such composites are low in cost, locally sourced, renewable, and able to capture and store carbon dioxide.…”

Gypsum, Geopolymers, and Starch—Alternative Binders for Bio-Based Building Materials: A Review and Life-Cycle Assessment

“…However, adding flame retardants or other additives to bio-composites to improve their performance may render them less environmentally friendly [11]. Bio-based fillers have different physical properties and chemical compositions, and they influence various properties of bio-composites [13][14][15]. As fillers have been widely researched, this paper focuses on the binder aspect of bio-composites.…”