Physical and thermal properties of mycelium-composite materials made from cattail biomass for the manufacture of compostable coffee cups

An investigation was carried out to develop compostable, thermally stable, and water-resistant mycelium-based biocomposite materials for beverage cups using cattail biomass. Calcium-rich cattail biomass promoted hyphal tip extension and proliferation, resulting in the successful production of Ganoderma lucidum-cattail paper sheets that can be used to manufacture beverage cups. This was evidenced by the formation of a dense hyphal network, as shown by scanning electron microscopy (SEM); the complete degradation of hemicellulose; the partial degradation of cellulose, and lignin in the biomass; and the weakened X-ray diffraction peak at a 2θ angle of 22.5°. The thermal degradation, thermal conductivity, and critical temperatures of the mycelium–cattail composites were comparable to those of pure cattail biomass and pure mycelium. Furthermore, the contact angle of the mycelium–cattail composites (ranging from 104° to 109°) was significantly higher than that of cattail or mycelium alone, indicating water-resistant properties. These findings were further supported by qualitative real-life usage observations, which indicated that the produced mycelium–cattail biocomposites outperformed commercial coffee cup paper sheets in both thermal resistance and water resistance properties. However, despite their hydrophobicity and thermal stability, the compressive strength of the composites was lower than that of commercially used coffee cup paper. Further research and development are required to enhance the compressive strength of the mycelium-biomass paper sheets so that they meet commercial performance standards. The outcomes of this research are significant, as they reduce dependency on wood-based paper, promote the use of agricultural waste, and improve human health by eliminating microplastics exposure from polyethylene coatings. The development of mycelium-cattail biocomposite materials may result in compostable beverage cups, which will mitigate the need the disposal of Paper Plastic Laminate (PPL) disposable cups in landfill sites.