分子模拟在SBS改性沥青中的应用

Application of molecular simulation for study of SBS modified asphalt

利用分子模拟技术对SBS改性剂与沥青之间的相溶机理进行了研究. 选用一种有代表性的基质沥青构建了其三维无定形单元平均结构, 然后采用分子力学(MM) 和分子动力学(MD) 方法在不同温度下进行模拟, 得到能量最低也即最稳定的构象. 经过对分子运动轨迹数据的分析, 计算出不同温度下的无定形模型的内聚能密度(CED), 进而计算出溶解度参数. 研究发现, 从模拟数据来看: 在110 ℃低温共熔态, 线形SBS在沥青中的溶解性很差, 然而在加了少量的硫以后, 情况大为改善; 而星形SBS在沥青中的溶解性较好, 加入少量硫以后效果不明显. 在150 ℃高温共熔态, 线形和星形SBS与沥青均能很好地互溶, 此结论验证了实验结果, 同时数据也很接近.

The dissolution mechanism between SBS modifier and asphalt was studied with the Computer Aided Molecular Design (CAMD) method. One type of the base asphalt models was defined for 3D amorphous cell construction. Molecular Mechanics (MM) and Molecular Dynamics (MD) computations were carried out on these amorphous cell structures at customized temperatures to determine the lowest energy structures and hence the most stable configurations. The solubility parameters derived from the cohesive energy density (CED) of each amorphous cell system at different co-melting temperatures were calculated with the molecule modeling analysis module. Comparison of experimental and simulation data showed that the solubility of SBS line-shaped modifier in base asphalt was improved and reached that of star-shaped by adding a small amount of sulfur at co-melting temperature of 110°C. However, the solubility of both line-shaped and star-shaped modifiers is satisfactory at a higher temperature of 150°C even without sulfur addition. The CAMD method could be useful in preparing SBS modified asphalt.