Entropy-TOPSIS-based material selection for sustainable polymer composite: An MCDM framework promoting circular economy

The increasing environmental challenges posed by plastic and rubber waste have necessitated the development of sustainable materials aligned with the principles of the circular economy. This study explores the fabrication and evaluation of sustainable polymer composites derived from recycled polyethylene terephthalate (PET) and ground tire rubber (GTR). Using an entropy-TOPSIS-based multi-criteria decision-making (MCDM) framework, optimal material compositions were identified to balance physical, mechanical, and thermal properties. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Fourier Transform Infrared Spectroscopy (FTIR) analyses provided insights into the microstructure, elemental composition, and chemical bonding, confirming the compatibility of PET and GTR. Mechanical and thermal characterizations revealed that increased GTR ratios reduce density (1.306–1.208 gm/cm 3 ) and melting temperature (220.25–192.57°C) while enhancing tensile strength (52.78–73.58 MPa) and flexural modulus (66.23–106.32 MPa). The study identifies the 70:30 PET-GTR ratio as the best composition for lightweight, durable, and ecofriendly applications. These composites demonstrate potential for use in industries such as automotive, construction, and prosthetics. By utilizing recycled materials, the research addresses environmental concerns while promoting innovative applications of waste-derived resources. This framework provides a robust approach for advancing sustainable material selection, contributing to a circular economy, and supporting eco-friendly manufacturing practices.