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.

当前实体商品经济体系通过开采有限珍贵资源生产材料，却未考量其全生命周期末端影响与环境代价。菌丝体基材料则提供了一种全新的制造范式：依托材料自身生长而非资源开采来制备产品。农业残余纤维经真菌菌丝体接种后，会形成交织的三维丝状网络，将原料结合为轻质材料。菌丝体基材料在生长完成后需经热灭活处理。
本研究针对采用不同种类木质纤维素增强纤维，结合白腐真菌彩绒革盖菌（Trametes versicolor）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系统探究。本研究为首项借助公开完整的实验方案，针对彩绒革盖菌与五种纤维（大麻、亚麻、亚麻废料、软木、秸秆）及五种纤维加工方式（松散、切碎、粉尘、预压缩及丝束）制备的菌丝体基复合材料，报道其干密度、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）分析结果的研究。
相较于岩棉、玻璃棉、挤塑聚苯乙烯等传统绝热材料，采用亚麻、大麻及秸秆制备的菌丝体复合材料，其导热系数与吸水率整体表现出优异的绝热综合性能。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加工方式（松散、切碎、预压缩及丝束）与纤维尺寸，而非纤维的化学成分。本实验结果证实，菌丝体复合材料可满足绝热材料的性能要求。