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. 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.

[1]  F. Asdrubali,et al.  A review of unconventional sustainable building insulation materials , 2015 .

[2]  R. C. Picu,et al.  Morphology and mechanics of fungal mycelium , 2017, Scientific Reports.

[3]  Petri Widsten,et al.  Adhesion improvement of lignocellulosic products by enzymatic pre-treatment. , 2008, Biotechnology advances.

[4]  Maya Jacob John,et al.  Biofibres and Biocomposites , 2008 .

[5]  B. Mohebby Attenuated total reflection infrared spectroscopy of white-rot decayed beech wood , 2005 .

[6]  Barbara Imhof,et al.  Built to Grow - Blending architecture and biology , 2016 .

[7]  Mitchell Jones,et al.  Mycelium composites: A review of engineering characteristics and growth kinetics , 2017 .

[8]  R. C. Picu,et al.  Mechanical behavior of mycelium-based particulate composites , 2018, Journal of Materials Science.

[9]  Elvin Karana,et al.  Fabrication factors influencing mechanical, moisture- and water-related properties of mycelium-based composites , 2019, Materials & Design.

[10]  F. Zhang,et al.  Physical and Mechanical Properties of Fungal Mycelium-Based Biofoam , 2017 .

[11]  Agis M. Papadopoulos,et al.  State of the art in thermal insulation materials and aims for future developments , 2005 .

[12]  Test Method for Determination of Thermal Conductivity of Soil and Soft Rock by Thermal Needle Probe Procedure , 2022 .

[13]  Krishpersad Manohar,et al.  Measurement of apparent thermal conductivity by the thermal probe method , 2000 .

[14]  Greg A. Holt,et al.  Evaluation of Physico-Mechanical Properties of Mycelium Reinforced Green Biocomposites Made from Cellulosic Fibers , 2016 .

[15]  Ilker S. Bayer,et al.  Advanced Materials From Fungal Mycelium: Fabrication and Tuning of Physical Properties , 2017, Scientific Reports.

[16]  A. Pitman,et al.  FTIR studies of the changes in wood chemistry following decay by brown-rot and white-rot fungi , 2003 .

[17]  K. Boulding The Economics of the Coming Spaceship Earth , 2013 .

[18]  Helena Pereira,et al.  Effects of short-time vibratory ball milling on the shape of FT-IR spectra of wood and cellulose , 2004 .

[19]  C. J. Hurst,et al.  Use of Fungi Biodegradation , 2002 .

[20]  R. ten Have,et al.  Oxidative mechanisms involved in lignin degradation by white-rot fungi. , 2001, Chemical reviews.

[21]  Matthew Brewer,et al.  Growing and testing mycelium bricks as building insulation materials , 2018 .

[22]  Hiromi Tanaka,et al.  Degradation of Lignin-Related Compounds, Pure Cellulose, and Wood Components by White-Rot and Brown-Rot Fungi , 1988 .

[23]  Ronald B. Bucinell,et al.  A New Approach to Manufacturing Biocomposite Sandwich Structures: Mycelium-Based Cores , 2016 .