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

This article focuses on the development and evaluation of sustainable polymer composites made from recycled polyethylene terephthalate (PET) and ground tire rubber (GTR) to address environmental challenges associated with plastic and rubber waste. Using an entropy-weighted Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) multi-criteria decision-making (MCDM) framework, the study identifies the 70:30 PET-GTR ratio as optimal, balancing physical, mechanical, and thermal properties for lightweight, durable, and eco-friendly applications. Characterization techniques including Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Fourier Transform Infrared Spectroscopy (FTIR) confirm good compatibility and bonding between PET and GTR. The composites show increased tensile strength and flexural modulus with higher GTR content but decreased density, impact strength, hardness, and melting temperature, indicating trade-offs depending on application needs. The research highlights potential uses in automotive, construction, and prosthetic industries while emphasizing the importance of policy support and further studies on long-term durability and expanded material formulations.