Enhancing mechanical, thermo-mechanical and low velocity impact properties of epoxy methyl ricinoleate toughened epoxy composites by integrating microcrystalline cellulose

Flax fibre-reinforced bio-composites are developed using both unmodified petroleum-based epoxy and Epoxy Methyl Ricinoleate (EMR) toughened epoxy modified with microcrystalline cellulose (MCC) as the base matrix. Base-catalyzed transesterification is employed for the synthesis of EMR as a low-viscosity reactive green monomer for the modification of petroleum-based epoxy. MCC is incorporated into the EMR-modified epoxy through mechanical stirring and subsequent sonication at loading rates of 1%, 3%, and 5% by weight. The compression molding technique was employed to prepare the composites. The results show an enhancement in tensile strength, modulus, impact strength, and inter-laminar shear strength values up to 19%, 34%, 34.2%, and 22.7%, respectively for MCC filled EMR toughened epoxy composite compared to neat epoxy composite. The storage and loss moduli, as revealed by the dynamic mechanical analysis (DMA), also demonstrate improvement for the 3% MCC-C composite signifying the improved fibre/matrix bonding. The low-velocity impact test at 10 J and 20 J for non-perforation and perforation conditions was also performed on the composites. The MCC-incorporated EMR-modified composite demonstrated the highest low velocity impact resistance among all other bio-composites, highlighting its potential for use in semi-structural applications due to the enhanced interfacial adhesion. The SEM analysis revealed that the fibre surface of MCC-modified EPEMR20 composites exhibited surface damage, and adherence of MCC fillers and matrix fragments, indicating superior adhesion to the matrix system.