High-throughput extraction of cellulose nanofibers from Imperata cylindrica grass for advanced bio composites

Extracting high-quality cellulose nanofibers (CNFs) with superior yield and purity particularly due to the cost and efficiency limitations inherent in current extraction methods. In this study, we present a novel and cost-effective approach for extracting cellulose nanofibers (ECNFs) from naturally available Imperata cylindrica grass using an optimized chemical process. This process involves tailoring adjusting acid-base ratios and bleaching conditions to successfully extract CNFs with a uniform diameter (90 nm), length (11 μm), high crystallinity (71.64 %), and a small average crystal size (2.06 nm). These characteristics were confirmed using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses. To evaluate the potential of ECNFs in enhancing polymer mechanical properties, ECNFs-reinforced chitosan (CS) composite films were fabricated via a simple solution casting process. The addition of 2 wt% ECNFs significantly improved the Young's modulus by 402 % (reaching 1.37 GPa) and the tensile strength by 748 % (reaching 16.77 MPa) compared to pristine CS films (0.27 GPa and 1.98 MPa), underscoring their effectiveness as reinforcement agents. Furthermore, to expand the functionality of the CS composites, cost-effective graphene nanoplatelets (GNPs) were incorporated. These hybrid ECNFs/CS/GNP composites exhibited remarkable improvements in thermal stability, flame retardancy, and electromagnetic interference (EMI) shielding compared to pure CS films. In conclusion, this study presents a facile and cost-effective method for extracting high-quality CNFs. The ECNFs-reinforced CS composites demonstrate superior mechanical properties, while the incorporation of GNPs further enhances their functionality by improving thermal stability, reducing flammability, and providing effective EMI shielding. These findings could facilitate the development of high-performance green composites with diverse applications across various industries.