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. 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.当前实体商品经济在生产材料时，仅通过开采有限的宝贵自然资源，却未考虑材料的生命周期末端影响与环境代价。基于菌丝体（mycelium）的材料则提供了一种全新的制造范式，其核心在于材料的生长培育，而非资源开采。农业残余纤维经接种真菌菌丝体后，菌丝体可形成交织的三维丝状网络，将原料黏合为轻质复合材料。待生长过程完成后，菌丝体基材料会通过热灭活工艺定型。本研究针对以白腐真菌杂色云芝（Trametes versicolor）搭配不同木质纤维素增强纤维所制备的菌丝体基复合材料，对其生产工艺、力学、物理及化学性能展开探究。本研究为首项采用完全公开的实验方案，使用杂色云芝与五种纤维（大麻、亚麻、亚麻废料、软木、秸秆）及五种纤维加工方式（松散状、切碎状、粉尘状、预压缩状及束状），系统报道菌丝体基复合材料干密度、杨氏模量（Young’s modulus）、压缩刚度、应力-应变曲线、导热系数、吸水率以及傅里叶变换红外光谱（FTIR）分析的相关研究。相较于岩棉（rock wool）、玻璃棉（glass wool）、挤塑聚苯乙烯（extruded polystyrene）等传统隔热材料，添加亚麻、大麻及秸秆的菌丝体复合材料在导热系数与吸水率两项指标上，整体均展现出更优异的综合隔热性能。本次实验结果表明，菌丝体基复合材料的力学性能更多取决于纤维的加工方式（松散、切碎、粉尘、预压缩及束状）与纤维尺寸，而非纤维的化学成分。上述实验证实，菌丝体复合材料能够满足隔热保温材料的性能要求。