聚氨酯前驱体/苯乙烯-丁二烯-苯乙烯嵌段共聚物复合改性沥青及其改性机理

Polyurethane-precursor/Styrene-Butadiene-Styrene Composite Modified Asphalt and Its Modification Mechanism

为有效解决当前聚合物改性沥青生产所面临的改性剂用量多、热储存稳定性差、热力学不稳定等难题,采用聚氨酯前驱体基反应型改性剂(polyurethane-precursor-based reactive modifier,PRM)和苯乙烯-丁二烯-苯乙烯嵌段共聚物(styrene-butadiene-styrene,SBS)制备了PRM/SBS复合改性沥青,并以基质沥青、PRM改性沥青和SBS改性沥青为参照,采用宏-微观相结合的方法对PRM/SBS复合改性沥青的性能和改性机理进行了研究.结果表明,复合改性过程兼具物理改性和化学改性,PRM不仅能够与沥青分子产生明显的化学交联,同时可以作为沥青质和SBS之间的相容剂,促使PRM/SBS复合改性沥青内部形成更为稳定的网络结构.基于上述作用机制,PRM的加入极大提升了SBS改性沥青的热储存稳定性.PRM/SBS复合改性沥青较同等改性剂掺量SBS改性沥青具有更优的抗高温永久变形能力且具备良好的低温性能.

To effectively solve the problems of large amount of modifier,poor thermal storage stability,and thermodynamic instability faced by the current production of polymer modified asphalt,the polyurethane-precursor-based reactive modifier(PRM)and styrene-butadiene-styrene(SBS)were employed to prepare the PRM/SBS composite modified asphalt in this study.Taking base asphalt,PRM modified asphalt and SBS modified asphalt as references,the performance and modification mechanism of PRM/SBS composite modified asphalt were studied by macro-micro methods.Results show that the composite modification process presents both physical and chemical characteristics.PRM can not only produce obvious chemical cross-linking with asphalt molecules,but also act as a compatibilizer between asphalt and SBS to promote the formation of a more stable network structure in PRM/SBS composite modified asphalt.Based on the above mechanism,the addition of PRM significantly improves the thermal storage stability of SBS modified asphalt.PRM/SBS composite modified asphalt has higher resistance to high-temperature permanent deformation than SBS modified asphalt with the same modifier content,and it presents a good low-temperature performance.