UC Berkeley

Mycelium materials are made of fungi. By digesting waste to create a bio-composite of mycelium and the feedstock, they are becoming a sustainable material option. Fungi are nature’s recyclers, with millions of species that can digest everything from cellulose to polymers. By selecting specific species to digest industrial waste such as sawdust, bio-composites can be grown that can be disposed of after use by composting. Composting reduces their environmental impact in comparison to synthetic composites. As part of an academic-industry collaboration, bio-composites were explored made of Ganoderma lucidum fungi. The findings provide researchers and commercial developers with information on the properties, performance and suitable applications of these novel materials. The material was characterized from a physical, mechanical, thermal, and manufacturing standpoint using American Society of Testing and Materials standards.

The ultimate tensile strength was 176 kPa, with a tensile modulus of 1.3 MPa, and an ultimate compressive strength of 490 kPa. These properties are comparable to brittle, cellular materials such as expanded polymer foams. The values for the thermal resistance and thermal conductivity ranged from 0.0014 to 0.0019 m2 K/W and 0.053 to 0.077 W/m K respectively, which are comparable to current natural insulator materials such as balsa wood and natural cork. The average maximum use temperature was found to be 390 ºC (734ºF). These properties are comparable to polymer foams such as expanded polystyrene foam, suiting the material to non-structural applications such as packaging and insulation. Combining a mycelium material core with carbon fiber and bamboo laminate skins improved the flexural strength. The core shear ultimate stress was 36.2 kPa for the mycelium material alone, rising to 63.3 kPa with bamboo skins and 76.6 kPa with carbon fiber skins. The large improvement in strength suggests that with development mycelium materials could be suited to higher-performance applications such as interior wall panels and construction bricks. Methods were tested to manufacture mycelium materials, finding the material could be shaped with drilling, milling, sanding, and that laser cutting can form features of ~3mm.

Finally, current and future applications were considered using three use case studies: as packaging, as fabrics, and as a sanitation solution to digest human waste to create useful products. Overall, mycelium materials show great promise for further development as a bio-composite that can digest waste to create useful materials.