分子模拟技术在乳化沥青研究中的应用

利用分子模拟技术对乳化沥青的乳化和稳定机制进行研究。选用结构不同的基质沥青,基于改进的B-L法,构建三维无定型平均结构;利用分子模拟软件构建水/乳化剂/沥青体系进行分子动力学模拟;通过界面形成能、界面层厚度、扩散系数等参数研究沥青与乳化剂相互作用对油水界面性质的影响。结果表明:分子模拟技术能够有效表征乳化沥青乳化和稳定机制;随着乳化剂用量的增加,界面形成能增大、界面层厚度增加、分子扩散系数变小,乳化剂单层膜的稳定性增加,降低油水界面张力的能力增强;对于不同的沥青体系,具有高芳碳率、高环烷碳率、高芳香环缩合度、低烷基碳率的沥青与乳化剂的相互作用越强,界面形成能绝对值越大、界面层厚度越大、扩散系数越小,乳化剂降低沥青/水界面能量的能力越强。

Application of molecular simulation technology to emulsified asphalt study

The emulsion and stabilization mechanism of emulsified asphalt were studied using the molecular simulation technique. Four types of typical base asphalts with different structures were defined for 3D amorphous cell construction on the basis of the improved B-L method. Molecular dynamics (MD) computations were carried out on the water/emulsifier/asphalt system constructed via materials studio (MS). The effect of interactions between asphalt and emulsifier on oil-water interfacial property was characterized through interfacial formation energy, interfacial thickness and diffusion coefficient. The results show that molecular simulation is an effective method to studying the emulsion and stabilization mechanism. With the dosage of emulsifiers increasing, the interfacial formation energy and the interfacial thickness increase, meanwhile the molecular diffusion coefficient decreases. Hence, the stability of emulsifier monolayer increases, which improves the ability to reduce the interfacial tension. Also, it is found that asphalt, which has more aromaticity carbon, naphthenic carbon, as well as stronger condensation index of the aromatic ring and less alkyl carbon, has stronger interaction with emulsifier. This result in the higher interfacial formation energy, thicker interfacial thickness and smaller diffusion coefficient. And the oil-water interfacial tension is more reduced as well.