Preparation of reactive chain extension rejuvenators and its application in the aged SBS modified bitumen sustainable recycling

In order to better restore the properties of aged SBS modified bitumen (ASMB) and promote its sustainable recycling, in this paper, the reactive chain extension rejuvenators (RCERs) were prepared from polyethylene glycol (PEG-400/PEG-1000) and diisocyanate (2,4-toluylene diisocyanate (TDI)/hexamethylene diisocyanate (HDI)) and the effect of RCERs on the rejuvenation of aged SBS was studied. Different rejuvenation systems composed by TDI, HDI, RCERs and aromatic hydrocarbon oil (AHO) were constructed, and the influence of rejuvenation systems ((TDI + AHO), (HDI + AHO) and (RCERs + AHO)) on the physical properties of ASMB were investigated. Fourier transform infrared spectra demonstrated that the RCERs were successfully synthesized. Gel permeation chromatography indicated that the number average molecular weight range of RCERs was 550–1150 and the molecular weight of SBS rejuvenated by RCERs was larger than that of SBS rejuvenated by TDI and HDI. Thermogravimetry-differential thermal analysis manifested that the thermal stability of SBS rejuvenated by RCERs were enhanced evidently compared with that of TDI and HDI. The physical properties of ASMB could be fully recovered by the rejuvenation systems, and the ‘RCERs +AHO’ had better rejuvenation effect on ASMB than that of ‘TDI + AHO’ and ‘HDI + AHO’.