Study on the preparation and performance of the self-healing polyurethane modified asphalt from waste polyethylene terephthalate (PET)

This study designed an environment friendly dynamic covalent bond self-healing polyurethane modified asphalt (DPUMA) system that can achieve self-healing at room temperature. Employing waste polyethylene terephthalate (PET) polyols as raw materials, we synthesized polyurethane (PU) modified asphalt incorporating oxime-urethane, disulfide, and Diels-Alder bonds. The chemical structure, micromorphology, rheological properties, and fatigue resistance of DPUMA were characterized via Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), rheological tests, and linear amplitude sweep (LAS) testing. Multi-angle self-healing evaluations were conducted to comprehensively assess the self-healing performance of asphalt. Results demonstrate that the DPUMA system achieves self-healing at room temperature, exhibiting markedly superior healing efficiency compared to base asphalt. Hydrogen bonds in PU modifiers enhance asphalt's mechanical properties while facilitating interfacial contact between crack surfaces. Simultaneously, ruptured dynamic covalent bonds undergo spontaneous reformation upon contact, thereby enabling accelerated molecular reconstruction across crack interfaces and subsequent recovery of mechanical properties. Among the three DPUMAs, DPUMA containing Diels-Alder bonds manifests optimal high-temperature stability and self-healing capability, while DPUMA containing oxime-urethane bonds delivers superior low-temperature flexibility, and DPUMA containing disulfide bonds exhibits the best fatigue resistance. This study provides theoretical basis and practical foundation for research on eco-friendly self-healing PU modified asphalt. • Eco-friendly self-healing asphalt heals cracks at room temperature. • Dynamic covalent bonds enable efficient autonomous crack repair. • Hydrogen bonds enhance asphalt's mechanical strength and crack healing efficiency.