Sandwich Mycelium-Based Composite Panels Fabricated with a Lightweight Core from Forest Waste Using Ganoderma lucidum and Pleurotus ostreatus

The present study aims to determine the properties of sandwich mycelium-based composite panels (sandwich-MBC-panel) fabricated with a lightweight core of mycelium-based composites (MBCs) of Ganoderma lucidum and Pleurotus ostreatus and veneers of Gmelina arborea and Vochysia guatemalensis wood. Physical and mechanical properties, acoustic capacity, chemical composition (determined by FT-IR), thermal degradation, and inorganic components were evaluated. The results showed that the sandwich-MBC-panel presented a density of 0.27–0.40 g/cm3, an MC between 14.56 and 24.71%, and a water absorption between 43.64 and 61.32%. Regarding mechanical characteristics, the sandwich-MBC-panel with the highest MOR, MOE, and internal bond was that composed of G. lucidum and G. arborea. The treatment with the best tensile force value was the mixture of G. lucidum with O. pyramidale. The sandwich-MBC-panel constructed with balsawood showed the lowest noise reduction coefficient, while the panel composed of G. lucidum and P. ostreatus showed good substrate properties and appropriate carbon and nitrogen content. FT-IR spectroscopy revealed substrate degradation by fungal mycelium formation, and TGA curves showed that the MBC containing G. lucidum presented higher thermal degradation than the panel without G. lucidum, without fungal attack. The main results of this study showed that sandwich MBC panels, in which the MBC is used as a lightweight core and wood veneers are used on the faces, have the potential for use as acoustic panels and could represent a sustainable alternative to panels that are generally fabricated from synthetic materials and of low densities.