Chitin nanofiber from fungal source for fabrication of nanopaper and reinforcing element in pla-based composite

Abstract

Fungal chitin nanofiber from mushrooms is covalently associated with glucan which can contribute to higher mechanical properties compared to conventional animal-based chitin. However, recent studies had limited discovery on fungal chitin sources, which restricted the availability in some regions. Therefore, this study explored the possible fungal chitin sources from different species of mushrooms. Further in this study, the mechanical performance of chitin nanofiber from mycelium as chitin nanopaper and reinforcement element in PLA filament composites for 3D printing application were explored. The fungal chitin nanofiber was extracted using a mild extraction process and further fabricated into nanopaper using the solvent casting method. For PLA filament composites, the samples were prepared using a filament extruder and proceeded with 3D printed for mechanical performance tests. This study suggested that nanopaper from enoki was more crystalline than other samples. This translated to slightly higher modulus and tensile strength (Eenoki = 2.83 GPa, σenoki = 51 MPa). However, oyster nanopaper exhibited higher toughness (1.92 MJ/m3) and was selected for mycelium study. Chitin nanopaper from oyster mycelium had a superior tensile strength (σenoki = 93 MPa) and toughness (4.18 MJ/m3) compared to that of from oyster mushrooms. For the mechanical properties of 3D printed specimens from oyster chitin/PLA composites, the 7% chitin loading showed a threshold effect on the toughness (2.00 MJ/m3). The samples from 3% chitin mycelium/PLA had higher performance compared to that of 3% chitin oyster mushroom/PLA. Overall, this study suggested that fungal chitin nanofiber has the potential to be used as a reinforcement element in PLA for 3D filament.