Synthesis Of End Functionalized SBS And Its Application In Modified Asphalt

Recently, with the development of architecture and traffic, SBS is widely used in modified asphalt. However, the chemical properties, polarity and compositions between SBS and asphalt are different, which makes it difficult to form stable blends. It is meanful to explore SBS with functionalized groups and properties. According to the principle of anioic polymerization and controllable structure, functionalized group is attachend to the end of SBS by in-situ technology, which is more efficient to improve the compalibility and stablility of SBS and asphalt blends.In this studies, cyclohexane is used as solvent, THF is used as polar modifier, polymerization rate of polystyrene initiated by hexamethyleneimine lithium (LHMI) and hexamethyleneimine alkenyl lithium (N～Li) is investigated by the use of dilatometers. It is found that the activity of N~Li is ten times larger than LHMI. The infulences of THF, temperature on the polymerization of styrene are studied and the false first-order apparent rate constant and activation energy are calculated as well. The polymerizing condition of SBS is determined by studing the influence of polymerizing temperature and time on the content of free polystyrene. The molecular weight and its distribution, microstructure and conformation of SBS are characterized by GPC, IR, TEM and DMA. Amino group can be attached to the end of SBS and its molelular weight and microstructure are controllable, while the molecular weight distribution and the vinyl content of N-SBS is greater slightly than the corresponding SBS.Carbon dioxide, l,5-diazabicyclo[3.1.0]hexane, epoxy ethane are used as functionalized initiator and terminators to prepareω-carbixyl,amino and hydroxygen functionalized SBS. The conformation and dynamical mechanical properties ofω-functionalized SBS are studied by TEM and DMA. Results suggest that the attachment of end groups make the core of polystyrene random, the Tg of PS and PB increase, and the mechanic properties change slightly. Dynamic light scattering shows N-SBS-COOLi possesss a bimodal distribution of the hydrodynamic radius in CCU, and this intermolecular association depend on the concerntrarion.The end groups on the improvement of stability of SBS modified asphalt are studied. The high temperature segaration, DSC analysis, flurescence miceoscopy suggeste that carboxyl and amino group can improve the compability of SBS modified asphalt effectively.