A critical review: recent developments of natural fiber/rubber reinforced polymer composites

Recent advancements in the development of low-emission materials have become a global imperative to achieve net-zero emissions in efforts to limit the effects of climate change. The materials transition agenda not only aims to substitute emission-intensive materials but also incorporates emission reduction efforts into goods and applications. Natural fiber composites have received attention from both commercial and research communities because of their inherent eco-friendliness, lower cost, and lower energy consumption during processing than their synthetic counterparts. Additionally, rubber-reinforced polymer composites have generally shown promising results, particularly in resisting sudden deformation. Although studies combining waste rubber with natural fibers in polymer composites are nascent, with limited existing literature, this area demonstrates remarkable potential for the substitution of traditional synthetic composites. Therefore, this review outlines the recent developments in polymer composites incorporating the use of natural fibers and rubber in various forms. The use of rubber as a filler has been shown to enhance tensile strength and impact performance while enhancing the surface finish, however, conflicting studies were identified. Hybridizing waste rubber and natural fibers presents a promising path to further enhance the mechanical performance of composite materials. Emphasis has been placed on the use of fillers in various forms and on their inclusion in thermoset matrices. The future outlook and research opportunities are also presented in this review.