Effects of aging degradation and reactive reconstruction on the structure and properties of styrene–butadiene–styrene block copolymer.

• The behavior of aging degradation and reactive reconstruction for SBS were studied. • The molecular weight of SBS decreased and its rheological properties deteriorated seriously after simulated aging. • The creep recovery ability and medium–high temperature rheological properties of aged SBS can be well restored by reactive reconstruction. • Isocyanate pre-polymer showed the better performance for restoring the molecular weight and the glass transition temperature of aged SBS. Achieving high-performance recycling of aged SBS modified asphalt will help promote the sustainable development of transportation infrastructure. The destruction of the SBS cross-linking network is an important reason for the deterioration of the performance of aged SBS modified asphalt. Scientific reconstruction of aged SBS cross-linked network is the key to achieving the performance recovery of aged modified asphalt. In this research, the evolution of chemical structure, molecular weight, thermodynamic properties, multiple stress creep recovery capability and rheological property of SBS during the process of aging degradation and reactive reconstruction were systematically investigated. The results showed that the molecular weight and creep recovery capability of SBS decreased sharply, and its complex modulus and phase angle exhibited a strong temperature and frequency dependence after aging. While the number average molecular weight of aged SBS increased by over 70% after reactive reconstruction, and its thermal-oxygen stability shown better performance as compared with that of fresh SBS. Meanwhile, the glass transition temperature of aged SBS was restored to −43.8℃ and −54.9℃ after reactive reconstructed by toluene diisocyanate (TDI) and isocyanate pre-polymer. Therefore, isocyanate pre-polymer with flexible long chain structure was more benefit for improving the low-temperature performance of reactive reconstructed aged SBS. Furthermore, the creep recovery ability and complex modulus of aged SBS were all significantly improved, and exhibited dramatically high-elastic properties after reactive reconstruction. And as compared with isocyanate pre-polymer, TDI with benzene ring rigid structure was more conducive to restoring the medium–high temperature rheological properties of aged SBS. Therefore, effective restoration of molecular weight and performance of aged SBS can be achieved by using reaction reconstruction method. This study would provide inspiration and ideas for the high-value recycling of waste polymer modified asphalt. [ABSTRACT FROM AUTHOR]