Upcycling Discarded Polyethylene Terephthalate Plastic into Highly Valuable Flexible Materials with Good Tensile Strength, Weather, and Corrosion Resistance via Molecular Structure Reconstruction

Abstract

The chemical conversion of discarded poly(ethylene terephthalate) (dPET) into functional materials presents a promising approach to waste disposal. However, the loss of flexibility and tensile strength significantly limits the practical application of these fabricated materials. This work aims to develop a simple and effective approach to convert dPET into functional materials with flexible properties through molecular structure reconstruction. Molecular structures─C₁₀H₁₁ClO₃, (C₇H₄O₂)_n, and C₁₅H₁₄O₃─were formed through the introduction of styrene butadiene styrene block polymer to react with dPET. These three products were embedded into a viscous fluid in rodlike or sheet-like shapes, and homogeneous and stable cross-linked structures were formed by physical and chemical bonds rather than a simple physical mixture, which is responsible for the good tensile strength, corrosion resistance, and weather resistance properties of the flexible material. The resulting flexible material had a tensile strength of up to 4.2 MPa. Even after 50 cycles of stretching at 80% elongation without a dwell time, the sample retained its resilience. The material also exhibited good corrosion and weather resistance, with no deformation or dissolution observed even after 30 h of exposure to harsh environments, including strong acids, alkalis, and salt solutions. When exposed to simulated sunlight for 6 h, the sample exhibited a strong resistance in the 200–340 nm range. Overall, the successful fabrication of dPET into flexible materials presents a simple and effective approach to the high-value disposal of waste plastic. The resulting samples show potential applications in various areas such as soft joints, shock absorbers, and pipe shock absorbers.