Sustainable synthesis of polyurethane using epoxidized soybean oil for enhanced performance of modified asphalt

With the increasing demand for sustainable and environmentally friendly materials, bio-based alternatives to petroleum-derived asphalt modifiers have gained significant attention in pavement engineering. This study explores the use of renewable epoxidized soybean oil (ESO) to develop a novel polyurethane-based asphalt modifier. ESO was first modified through a ring-opening reaction to produce Plant oil polyols (PESO). PESO was then reacted with isocyanate monomers in a stepwise process to synthesize bio-based polyurethane prepolymer (ESPU). ESPU was combined with asphalt to create bio-based polyurethane-modified asphalt materials (ESPUA). The structure and properties of the PESO, ESPU and ESPUA were analyzed using FT-IR NMR, TG, and DSR. The results demonstrated that ESPU exhibited excellent thermal stability. The ESPU reacts chemically with hydroxyl, ether, carboxylic acid, and aromatic ring groups in asphalt when utilized for asphalt modification, leading to the formation of new chemical bonds and promoting the development of high molecular weight polymers. At an optimal dosage of 9 %, ESPU significantly enhanced the asphalt’s performance, including its high- and low-temperature resilience, composite shear modulus, and stiffness. This research provides valuable insights into the sustainable application of plant oils in road construction.