Development of Biodegradable Fungal Mycelium Based Foams from Corn Husk Waste

Sustainable substitutes for foams can be made from fungal mycelium as an environmentally friendly alternative to synthetic materials. In this study, biodegradable biocomposite foams were developed using corn husk waste and three different fungal strains: Lentinus sp., Trametes sp., and Ganoderma sp., Only a few fungal species have previously been used to fabricate biocomposites, and many other strains have not been explored yet. These experimental strains of fungi could have the potential to rival traditional synthetic materials that are non-biodegradable. To the best of our knowledge, this is the first report of biocomposite foam production with corn husk and a locally isolated fungal species in Sri Lanka. This study investigated the physical and mechanical properties of biocomposite samples, including the density, tensile strength, flexural strength, Young’s modulus, water absorption, thermal stability, biodegradability, and flame retardancy. All the biocomposites exhibited a soft and foamy appearance, whereas the Lentinus sp., based composite had a milky appearance with the lowest density (97.68 kg/m3). Ganoderma sp., based composite recorded the lowest shrinkage and the highest density, 5.86% and 187.88 kg/m3, respectively. The highest tensile strength (0.24 MPa) and Young's modulus (3.12 N/mm2) were recorded for the Trametes sp. based composite. The most significant effects were observed in the Trametes sp., based composite with the highest flexural strength, and flexural modulus, at 0.41 MPa and 3.04 MPa, respectively. None of the three biocomposites exceeded the burning rate of 37 mm/min during the flame retardancy test. Notably, all three biocomposites exhibited better flame retardancy properties than expanded polystyrene (EPS). Biodegradability tests using a soil burial method exhibited high biodegradability within 30 days of exposure to compost, and they are competitive with non-biodegradable synthetic foam materials. Therefore, these new biocomposites have the potential to replace conventional synthetic foam materials.