Mechanical and Sound Absorption Performance of Cashew Apple Bagasse and Mahogany Fruit-based Hybrid Composites

Abstract

Mechanical and acoustic properties were studied for hybrid composites developed from Cashew Apple Bagasse (CAB) fibers and Mahogany tree Fruit Filler (MFF) in an epoxy matrix. The effect of alkali treatment (5% and 10% NaOH solutions) on CAB fiber composites at different weight fractions of MFF (0 to 25 wt%) was studied. The composites including 15 to 20 wt% MFF and treated with 5% NaOH offered the highest performance. Tensile, flexural, and impact strengths were improved by 40%, 50%, and 45.7%, respectively, when compared to untreated ones; also, a 56.7% increase in noise reduction coefficient (NRC) was measured. These enhancements can be attributed to the removal of surface impurities on the fiber surface, improving fiber-matrix bonding, and achieving even dispersion of filler in the matrix. Using alkali treatment with NaOH concentration exceeding 10% and with a higher filler content (> 20 wt%) embrittled the fibers, at the same time allowing them to clump together, which decreased both mechanical and acoustic performance. The best approach was to combine CAB and MFF in appropriate quantities into a hybrid composite, striking a good balance between reinforcement and load transfer efficiency. These composites are intended to be used in car interiors, soundproof panels, and lightweight structural parts.