Preparation of polyol from waste polyethylene terephthalate (PET) and its application to polyurethane (PU) modified asphalt

In this study, to reduce the accumulation of waste polyethylene terephthalate (PET) and decrease the dependence of polyurethane (PU) modified asphalt on petrochemicals, the waste PET-based PU modified asphalt was investigated. Three different molecular weight polyols were used to depolymerize waste PET for obtaining three types of waste PET polyol. Then, the three types of waste PET polyol were used to prepare PU modified asphalt. The feasibility of applying waste PET to PU modified asphalt was investigated through basic physical properties tests, rheological tests and microscopic tests, and the impacts of depolymerizers with different molecular weight on the properties of waste PET-based PU modified asphalt were discussed. The results showed that polyols can depolymerize waste PET through transesterification, and the depolymerization products can be used to prepare waste PET-based PU modified asphalt to improve the pavement performance of the base asphalt. The hightemperature stability and permanent deformation resistance of waste PET-based PU modified asphalt are positively correlated with the molecular weight of the depolymerizer, while the low-temperature performance is the opposite. WPDMA has the best high-temperature stability and permanent deformation resistance, and WP6MA has the best low-temperature performance. In addition, due to the increase of ester group content, the waste PET polyol is more conducive to improving the storage stability and high-temperature stability of PU modified asphalt than the original polyol. This study suggests a novel way to recycle waste PET in PU modified asphalt.