| High-performance modified asphalt,possessing excellent physical and rheological performance at both high and low temperatures,can be applied in many fields including high load roads or special applications.From the view point of technology and cost,high SBS content modified asphalt is one of the most promising methods to prepare high-performance modified asphalt.In the modification process of preparing high SBS content modified asphalt(HSmA),modification effect can’t be exerted as the result of poor dispersion of SBS in asphalt,which is caused by the huge difference of molecular weight,density and polarity between SBS and asphalt.Besides,the deterioration of asphalt quality also aggravates the poor compatibility between SBS and asphalt.Therefore,it is meaningful to develop a green and sustainable method for improving the compatibility between SBS and based asphalt.Effects of molecular structure,molecular weight and S/B ratio of SBS on dispersion process of SBS in asphalt are investigated with optical microscope(OM).Meanwhile,effects of contents,properties of SBS on physical and rheological performance of modified asphalt are also discussed.Based on research results,swollen mechanism and polymer blending theory,for the condition of high asphaltene and SBS content,the mechanism of improvement on compatibility is proposed,which is by incorporation of aromatics to swollen process of SBS or adding interface materials to reduce interfacial tension.For researching mechanism of improvement on compatibility,waste bio-oil(WO)and aromatic oil(AO)are used as the the first compatibilizer in the preparation process of HSmA.Results show that the waste bio-oil contains unsaturated fatty acid esters with relative higher polarity than the aromatic oil,which can result in a smaller dispersion diameter of SBS in asphalt.There is existing compatibilization and plastification effect for WO in the preparation process of HSmA.Furthermore,compared with aromiatic oil,the HSmA containing WO shows excellent performance on dutility,elascity recovery at low-temperature and anti-aging capacity.C9 petroleusm resin(PR)is chosen as the secondary compatibilizer to improve the high-temperature performance that is degraded by incorporation of oils as the first compatibilizer.The effect of PR content on micromorphology,physical and rheological properties of HSmA is studied.Furthermore,the interaction mechanism of PR,SBS and based asphalt is revealed by using methods of solubility parameters calculation,DSR,DSC and FM.Results show that the interface energy between maltene in asphalt and PS phase in SBS can be decreased by incorporation of PR as interface.Therefore,the adding of PR as compatibilizer contributes to decaresing dispersion diameter of SBS and improving on the network structure formed by SBS.The softening point,60℃ zero shear viscosity and 5℃ ductiliy of HSmA prepared by using both WO and PR as co-compatibilizer reach 94.5℃,67391 Pa-s and 54.7cm respectively,which means the performance at both high and low temperature is much higher than specification of high-viscosity modified asphalt.The preparation process parameters of HSmA containing WO and PR as composite compatibilizer are investigated based on polymer blending theory.Results show that the composite compatibilizer can shorten the disperison time of SBS in asphalt from 3h to less than 1h,and can effectively improve the physical and rheological properties of modified asphalt.A novel pre-vulcanization process,adding crosslinking sulfur before the dispersion process of SBS,is proposed to fabricate HSmA for solving the problem of the gel formation caused by excessive crosslinking reaction.Results show that the HSmA prepared with pre-vulcanization process has almost no phase separation during thermal storage,and has excellent physical and rheological performance. |
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