Innovative Sustainable Composites: Enhancing Recycled <scp>HDPE</scp> Properties With Waste Aluminum and Carbon Fiber Additives

ABSTRACT Sustainable polymer composites were developed using recycled HDPE (rHP) reinforced with waste aluminum foil (AF) powder from food packaging and carbon fibers (CF). Two primary composite systems were designed: AF‐reinforced rHP (rHP/AF) and a hybrid AF‐to‐CF (4:1) (ACF) reinforced rHP (rHP/ACF) by incorporating at weight fractions of 5%, 10%, 20%, and 30%, and were fabricated through a hot‐pressing technique. This study aims to explore the AF and CF reinforcements on the mechanical and thermal properties of rHP composites, to upcycle waste materials. The testing plan includes tensile and flexural tests for mechanical behavior characterization, TGA and DSC for thermal behavior assessment, and XRD, XPS, FTIR, Raman, and FESEM for structural and chemical characterization of synthesized composites. The rHP/ACF20 composite shows higher tensile strength and tensile modulus in comparison with the other rHP composites, and it is improved to 87.6% and 104.67%, respectively, compared to the neat rHP. The maximum degradation temperature ( T max ) and melting temperature ( T m ) of the rHP/ACF20 were improved to 502.3°C and 135.4°C respectively, proving the higher thermal stability of the rHP/ACF20. These outcomes reveal a synergistic effect of both AF and CF that led to improved mechanical and thermal properties of the composites.