Sustainable solutions: recent developments in recycled plastic composites and hybrid materials

The improper management of plastic waste remains a critical global environmental issue, posing severe risks to marine ecosystems, wildlife, and human health. Plastic, due to its long decomposition period spanning hundreds of years, causes persistent ecological damage. Despite growing awareness, inadequate handling of plastic waste is still prevalent, particularly in developing regions such as Southeast Asia, where rapid urbanization, industrial growth, and population increase exacerbate the problem. This review highlights the potential of recycled plastic composites in advancing sustainable solutions. Incorporating recycled plastic into composites offers multiple advantages, including reduced environmental impact, economic viability, and enhanced material performance. The article comprehensively explores the manufacturing of recycled plastic composites reinforced with fibers, nanoparticles, and their hybrids, emphasizing recent advances and challenges. From this review, (i) Mechanical and chemical recycling remain the most technically mature and industrially established strategies for converting waste plastics into functional composite matrices. (ii) Natural fiber and nanoparticle reinforcements significantly enhance the mechanical, thermal, and barrier properties of recycled plastics, enabling their use in structural and functional applications. (iii) Hybrid reinforcement systems, combining fibers and nanoparticles, offer synergistic improvements in stability, conductivity, and long-term durability compared to single-filler composites. (iv) Emerging surface modification, compatibilization, and green processing techniques are key to improving interfacial adhesion and recyclability. (v) Future research trends focus on developing circular design strategies, integrating life cycle assessment (LCA), and engineering next-generation high-value composites for sustainable manufacturing.