Valorisation of luffa cylindrica and corn husk waste into multifunctional bio composites for sustainable acoustic applications

Abstract A novel eco-friendly hybrid composite is developed using luffa and corn husk fibers in an epoxy matrix for improved strength and sound absorption. The work aims to valorize agro-residues by fabricating lightweight, porous and biodegradable sound-absorbing materials. Luffa’s fibrous network and orange peel’s cellular microstructure were chemically treated and homogenized at defined ratios to enhance interfacial bonding and sound dissipation capacity. Scanning electron microscopy (SEM) confirmed an interconnected hybrid matrix with hierarchical porosity, while FTIR analysis validated effective chemical treatment and retention of cellulose-rich domains.The composite samples were fabricated via compression molding and evaluated across 100–5000 Hz using impedance tube-based tests (ASTM E1050). The composite was made using a multi-stage technique that encompassed surface modification, fiber hybridization, and resin infusion, achieving remarkable sound, structural, and thermal properties. The acoustic behavior of the composite was calculated using the Johnson-Champoux-Allard (JCA) model, which was in excellent agreement with measurements from sound absorption impedance tubes. The hybrid composite reached a maximum sound absorption coefficient (SAC) of 0.96 at 3000Hz and a Noise Reduction Coefficient (NRC) of 0.49, thus classifying it as Class A under ISO 11654 standards. Structure and dynamic mechanical tests indicated an increase of fundamental porosity, interfacial adhesion, viscoelastic damping, and suffuse acoustic broadband attenuation. This study offers insight into the use of hybrid luffa-corn husk composites as eco-friendly and efficient materials for active noise control systems in buildings and vehicles.