The effect of the combined chemical treatment of sisal fibres through the subsequent processes of mercerisation (alkali treatment), then silane treatment and eventually acid hydrolysis, on sisal fibre was investigated. The effect of the treated fibres on the impact toughness and hardness of their composites with epoxy resin was also studied. Scanning electron microscopy of the surfaces of the treated and untreated fibres showed that the chemical treatment processes enhanced the removal of surface impurities and therefore increased the roughness of the surfaces of the fibres. This avails an increased surface area for interlocking with matrix and is, therefore, expected to enhance adhesion of the two. The treated fibre reinforced composites were observed to have higher values of impact toughness and hardness than the untreated fibre reinforced composites. These higher values were attributed to better interfacial bonding due to better mechanical interlocking between the treated fibres and epoxy resin arising from the increased roughness of the treated fibres.

This study examines the mechanical and thermal properties of a sustainable composite material made from recycled high‐density polyethylene (HDPE), denim fibers, and maleic anhydride polypropylene (MAPP). The influence of denim filler volume fractions (0%–20%) on tensile strength, stiffness, and thermal stability is evaluated. Tensile strength and stiffness increase significantly with higher filler content, reaching 30 MPa and 1,000,000 N/m, respectively, at a 20% filler volume fraction. However, elongation at fracture declines sharply, indicating reduced ductility. Thermogravimetric analysis shows decreased thermal stability with increasing denim content, while differential scanning calorimetry reveals reductions in melting and crystallization temperatures. Fourier‐transform infrared spectroscopy confirms MAPP's role in enhancing fiber–matrix adhesion. While this study maintains a fixed MAPP content of 5%, its influence on composite properties highlights the need for future studies exploring variable concentrations. These findings underline the composite's potential for structural applications requiring strength and rigidity but limited thermal stability.Highlights: Recycled HDPE and denim fibers are used to create a sustainable composite. MAPP enhances fiber–matrix adhesion, improving mechanical properties. Increased denim content raises stiffness and tensile strength but reduces ductility. Denim fibers reduce thermal stability and crystallinity of the composite. The composite is ideal for structural applications prioritizing rigidity.

The growing demand for sustainable and lightweight materials in the aerospace industry has prompted significant research into bio‐based composites for interior applications. This study investigates the flammability behaviour of epoxy‐reinforced flax fibre composites intended for use as interior lining panels in aircraft. Two different flame retardant (FR) treatments—designated FR A and FR B—were applied to the flax fibre composites, and their flammability studies, including vertical burn tests (AITM2‐0002), smoke density measurements (FAR‐25 Airworthiness Standards), toxicity analysis (AITM2‐0005), and heat release assessment (AITM2‐0006), were conducted. The results showed that all test specimens met the burn length requirements, with flame‐retardant‐treated samples exhibiting slightly reduced flammability. However, both treated and untreated composites exceeded the allowable smoke density limits, and all specimens produced peak heat release rates higher than the 65 kW/m ² threshold defined by FAR 25.853. Toxic gas analysis indicated reduced emissions of carbon monoxide (CO), nitrous gases (NOx), and sulphur dioxide (SO₂), with HCN, HF and HCl remaining at minimal levels across all samples. These values were benchmarked against established safety standards such as BSS 7239 and ISO 19700, confirming their compliance with acceptable toxicity thresholds. These findings suggest that while flax fibre composites demonstrate potential as a sustainable alternative for non‐structural aircraft interior components, further optimisation of flame‐retardant formulations is necessary to mitigate smoke generation and heat release. Addressing these challenges could enhance the viability of natural fibre composites in aerospace applications, contributing to the industry's sustainability efforts.

Due to a technical error, this article was incorrectly made available as an accepted manuscript and has been temporarily removed. IOP Publishing apologise for the mistake.

Finite element analysis was used to formulate novel models of both mono and hybrid nanocomposites, and, also to predict their flexural properties. This study also formulated the optimal combination mix ratio of fibres and matrix of the flexural properties for use in different applications. The predicted properties were verified using the experimental method. This study found that the flexural properties of all the composites depicted an increase with fibre additions up to a certain optimum point, beyond which they began to fall gradually with further fibre additions. There was also evidence of transverse matrix fracture in rice husk nanoparticle-reinforced epoxy resin composites’ flexural stiffness graphs. Moreover, it was found that the increases in flexural properties of mono composites were about two times lower in magnitude than hybrid composites. With regards to the formulation of optimal combination mix ratio of fibres and matrices for different applications, it was noted that the optimal combination mix ratio of fibres to the matrix for applications where all the flexural properties were maximized was 4:1. Moreover, the optimal combination mix ratio of fibres to the matrix for applications where the flexural properties were minimized was 1:2. Furthermore, the optimal combination mix ratio of fibres to the matrix for applications with a target of 10 MPa flexural strength properties and 10 GPa for flexural stiffness properties was 2:3.