Extraction of Cellulose from Soybean Hulls for the Development of Polymer Matrix Composites with Fishtail Palm Fibers

Abstract This study aims to extract and characterize cellulose nanocrystals (CNCs) from soybean hulls, and investigate their application as reinforcement in fishtail palm leaf stalk fiber (FPLSF) composites. CNCs were extracted through a multistep process involving alkalization, bleaching, acid hydrolysis and mechanical fibrillation. Analysis confirmed the transformation of cellulose I to cellulose II, yielding nanocrystals with 70.58% crystallinity index and thermal degradation peak at 371 °C. FTIR analysis verified removal of lignin and hemicellulose after extraction. The extracted CNCs were incorporated into FPLSF-epoxy composites at 2.5-10 wt% loading. Results showed 7.5 wt% CNCs (FT/SH4) provided optimal mechanical properties, with 51.4 MPa tensile strength, 46.09 MPa flexural strength and 36.47 kJ mm −2 impact strength. Lower CNC percentages showed significantly inferior properties due to poor fiber-matrix interfacial bonding. Overall, extracted soybean hull CNCs demonstrated good reinforcement capabilities for natural fiber composites. This provides a sustainable application route for agricultural residues and contributes to the development of high-performance biocomposites.