Chemical and Physical Insights of Efficient Conversion of Lignin-Rich <i>Camellia oleifera</i> Shell to Thermal and Fire Resistant Mycelium-Based Composite

Mycelium-based composite (MBC) shows great potential for replacing petroleum-based plastic products in various engineering applications, but its inefficient biomanufacturing has long been a significant challenge for upscale production and industrialization. This paper presents a novel and efficient preparation of MBC from the ingenious mixture of lignin-rich Camellia oleifera Abel. shell (COS) and the lignin-first fungus Ganoderma sessile (G. sessile). The preparation process has been reduced from 2–6 weeks to 8 days by combining liquid and solid-state fermentations. The chemical and physical pathways of COS and mycelium during solid-state fermentation were specifically explored to elucidate the transformation mechanism of the composite. The adhesive-free, layered, porous structure with different particle sizes of COS provided the developed MBC with a superb compressive strength of up to 0.73 MPa and a low thermal conductivity of up to 0.041 (±0.001) W m–1 K–1. The protein-rich mycelium network within and on the surface grants the developed MBC (peak heat release rate of 121.7 kW m–2) with superior fire resistance over the widely used expanded polystyrene (peak heat release rate of 177.3 kW m–2). This work not only offers an effective solution of valorizing COS agroforestry waste but also establishes an efficient, feasible process of MBC manufacturing.