Characterization\nof Mycelium Biocomposites under Simulated\nWeathering Conditions

Expanded polystyrene\n(EPS) remains a popular packaging\nmaterial\ndespite environmental concerns such as pollution, difficulty to recycle,\nand toxicity to wildlife. The goal of this study is to evaluate the\npotential of an ecofriendly alternative to traditional EPS composed\nof a mycelium biocomposite grown from agricultural waste. In this\nmaterial, the mycelium spores are incorporated into cellulosic waste,\nresulting in a structurally sound biocomposite completely enveloped\nby mycelium fibers. One of the main criteria for shipping applications\nis the ability of a material to withstand extreme weather conditions.\nAccordingly, this study focused on evaluating a commercially available\nmycelium material before and after exposure to various weathering\nconditions, including high and low temperatures at different humidity\nlevels. Fourier transform infrared spectroscopy (FTIR) was performed\nto examine any transformations in the mycelium structure and composition,\nwhereas scanning electron microscopy (SEM) was used to reveal any\nchanges in the morphology. Similarly, thermogravimetric analysis (TGA)\nand differential scanning calorimetry (DSC) analyses were conducted\nto evaluate the thermal behavior, whereas mechanical properties were\nmeasured by using shore hardness and Izod Impact testing. Although\nsome irreversible changes were observed due to the exposure to high\ntemperatures, the material exhibited good thermal stability and impact\nresistance. FTIR analysis demonstrated small changes in the biocomposite\nstructure and protein rearrangement as a result of weathering, whereas\nSEM revealed some cracking in the cellulose substrate. A combination\nof low temperatures and humidity resulted in significant moisture\nabsorption, as indicated by TGA and DSC. This in turn decreased the\nhardness of the fibers by nearly 2-fold; however, the impact strength\nof the entire biocomposite remained unchanged. Overall, these results\nprovide important insight into the structure–property relationships\nof mycelium-based materials.