Preparation and performance of self-healing SBS modified bitumen based on dynamic disulfide bonds

In this study, self-healing SBS (S-SBS) was first synthesized by introducing dynamic disulfide bonds into the molecular structure of SBS. Subsequently, a self-healing SBS modified bitumen (S-SMB) was prepared by blending of S-SBS and bitumen. The chemical structure of S-SBS and S-SMB was charactered by Fourier   transform infrared spectrometer (FTIR) and Raman spectrometer. The physical properties, low-temperature rheological properties and self-healing performance of S-SMB were investigated. The results of FTIR and Raman showed that dynamic disulfide bonds were successfully introduced into the molecular structure of SBS. With the increase of dynamic disulfide bonds content in SBS molecular structure, the softening point and ductility of S-SMB enhanced, and the penetration was decreased. Fluorescence microscope showed that the S-SBS in S-SMB formed a complete crosslinking network structure compared to SMB. The bending beam rheometer illustrated that the low-temperature rheological properties and the cracking resistance of SMB were improved by introducing dynamic disulfide bonds. The fluorescence microscopy observation indicated that the crack in S-SBS can self heal. The fracture healing test and fatigue healing test demonstrated that dynamic disulfide bonds endow S-SMB with great self-healing performance. The fracture healing rate of S-SMB reached 58.7% after 4 h of healing, and the fatigue healing index reached 0.93 after 1 h of healing.