Sustainable Reinforcement of Rubber Compound Using Recycled PET (Polyethylene Terephthalate): A Review

Increasing environmental concerns over plastic waste and the depletion of non-renewable resources have intensified the search for sustainable alternatives in rubber reinforcement. This review comprehensively investigates the use of recycled polyethylene terephthalate (r-PET) as a green reinforcing agent in rubber compounds, replacing traditional fillers such as carbon black and silica. Experimental studies reveal that incorporating r-PET can improve tensile strength by up to 45%, enhance thermal stability by 20–30°C, and lead to energy savings of approximately 50 MJ.kg-1 compared to virgin PET. Notably, this review is the first to integrate mechanical performance analysis with life cycle assessment (LCA), providing a dual perspective on technical feasibility and environmental impacts. Processing methods, such as mechanical blending, chemical grafting, and surface modification, have been discussed to enhance r-PET compatibility with rubber matrices. Challenges such as poor dispersion, interfacial adhesion, and thermal degradation are critically analyzed, along with mitigation strategies. The findings demonstrate that r-PET not only offers performance and cost advantages but also supports circular economy initiatives by repurposing postconsumer PET waste into high-performance rubber composite. Future research directions are proposed, focusing on hybrid reinforcement systems, compatibility enhancement, and carbon-footprint reduction.