Agricultural waste to aircraft interiors: mechanical, dynamic mechanical and durability characteristics of rice husk-reinforced composites based on waste polyethylene terephthalate

Purpose The growing need for lightweight and eco-friendly materials has led to interest in bio-based polymer composites for non-structural engineering applications. This study aims to examine the effect of sodium bicarbonate-treated rice husk (RH) on the mechanical, thermomechanical and durability properties of recycled polyethene terephthalate (rPET)-based composites, with a special focus on their application in future non-structural aircraft interior components. Design/methodology/approach Green composites were prepared by reinforcing unsaturated polyester resin (UPR) chemically derived from waste polyethylene terephthalate (PET) with RH. The RH surface was modified by using sodium bicarbonate (NaHCO3) treatment. Mechanical performance was evaluated using tensile and flexural tests, and durability was assessed through a six-week water-immersion exposure. The dynamic mechanical and thermal behaviour of the developed composites was also studied. Findings Composites with treated RH fibre exhibited improved mechanical properties, with the tensile strength increasing from 8.36 ± 0.39–11.99 ± 0.25 MPa (+43.4%) and flexural strength from 18.98 ± 0.77 to 25.7 ± 1.52 MPa (+35.4%) after NaHCO3 treatment. The glass transition temperature increased from 66.1 to 84.0 °C, as determined by dynamic mechanical analysis (DMA), consistent with reduced chain mobility in the strengthened interphase. The trends in thermal degradation (thermogravimetric analysis) are consistent with the thermo-mechanical and mechanical properties of the composites. Practical implications The combination of these attributes (increased stiffness, improved vibration-damping capacity and environmental durability) indicates the potential of developed composites for future non-structural components of the aircraft interior, such as interior panels, acoustic backing layers, vibration-damped elements and lightweight housings, where moderate mechanical performance, environmental sustainability and waste valorisation are desired. Originality/value This work combines agricultural and plastic waste to produce sustainable composite materials using an environmentally friendly chemical treatment. It is a systematic evaluation of RH-reinforced UPR composites for use in aircraft interiors. It establishes a critical linkage between interface modification, dynamic mechanical behaviour and durability performance, in comparison with aerospace-relevant functional requirements.