Study On Stabilization Mechanism And Preparation Process Of SBS Copolymer Modified Asphalt

Study on Stabilization Mechanism and Preparation Processof SBS Copolymer Modified AsphaltABSTRACTThe compatibility and stabilization mechanism of SBS copolymer modified asphalt were discussed in this paper. Major problems of SBS copolymer modified asphalt were compatibility of SBS with asphalt and storage stability of the polymer modified asphalt (PMA). The phase separation between the SBS phase and the asphalt phase would take place and the PMA could not be stored for long periods at elevated temperatures, because the two components of PMA had different chemical structures, and very different molecular masses, viscosities and densities. In this study, the problem of storage stability of PMA was solved by adding a compatilizer and a stabilizer. The compatilizer acted as a plasticizer and could swell SBS remarkably, which made SBS dispersed more homogeneously in asphalt. The stabilizer could initiate the crosslinking reaction of the swollen SBS and formed a stable three-dimensional network, therefore, asphalt was wrapped in the network and could prevent separation from SBS. On the other hand, the stabilizer could initiate the grafting reaction between SBS and asphalt to produce the SBS-grafted-asphalt. The Gibbs free energy of the PMA system and the surface tension between the SBS phase and the asphalt phase were decreased in the condition that the SBS-grafted-asphalt acted as an effective emulsifier at the interface of SBS and asphalt. The SBS modified asphalt with good storage stability could be obtained provided that the phase separation between SBS and asphalt could be prevented in the case that the SBS was finely dispersed in asphalt and formed a stable blending system. The different grades of SBS modified asphalt could be prepared by adjusting the process parameters.