基于分子动力学的相变微胶囊与沥青相容性及增强机理研究

微胶囊法是相变材料（PCM）封装的一种重要手段，为了改善加入相变微胶囊后沥青路面的低温性能，采用分子动力学方法，对相变微胶囊的相变机制、与沥青共混后的相容性和抗拉强度等进行模拟分析。对沥青四组分（As，R，S，Ar）、三聚氰胺甲醛树脂（MF）、沥青四组分与MF共混体系、沥青四组分与石墨烯（CG）共混体系、MF与CG共混体系、沥青体系、沥青与MF共混体系、沥青与CG共混体系等17个分子体系分别进行了溶度参数和内聚能密度计算，分析了MF，CG与沥青四组分之间的相容性变化规律，评价了MF，CG对沥青四组分抗拉强度的影响。对以MF为壁材、正十四烷为芯材的3种不同微观结构PCM分子模型和以石墨烯复合三聚氰胺甲醛树脂（CGMF）为壁材、正十四烷为芯材的2种不同微观结构PCM分子模型进行了升温过程相变性能模拟研究，分析了壁材厚度、芯材体积大小对PCM相变性能的影响，并比较了不同种类壁材PCM的热效率。通过对CGMF为壁材的PCM降温过程的相变性能模拟研究，进一步分析了CG对PCM热效率的影响。研究结果表明：采用CGMF为壁材制备PCM，可以提升PCM的热效率，CGMFPCM2031的能量效率比MFPCM2026平均增加141.15%，在沥青体系中加入CGMF为壁材的PCM，可以提高沥青组分之间的相容性和抗拉强度，有利于增强沥青体系的低温抗裂性能。

Compatibility and Enhancement Mechanism of Phase-change Microcapsules Modified Asphalt Based on Molecular Dynamics

The microcapsule method is an important means of encapsulation of phase change materials (PCM). Molecular dynamics methods were used to investigate the phase change mechanism of phase change microcapsules modified asphalt to improve the low-temperature performance of asphalt pavement after adding phase change microcapsules. The compatibility and tensile strength after mixing were simulated and analyzed for the four-component asphalt (As, R, S, Ar), melamine formaldehyde resin (MF), four-component asphalt and MF blend, four-component asphalt and graphene (CG) blend, and MF and CG systems. The solubility parameters and cohesive energy densities were calculated for 17 molecular systems, such as the mixing, asphalt, asphalt and MF blending, and asphalt and CG blending systems, respectively. The four components of MF, CG, and asphalt were analyzed. The influence of MF and CG on the tensile strength of the four-component asphalt was evaluated according to the law of compatibility change. The PCM molecular model with three different microstructures using MF as the wall material and n-tetradecane as the core material, and that with two different microstructures using the graphene composite melamine formaldehyde resin (CGMF) as the wall material and n-tetradecane as the core material ware used to simulate the phase-transition performance during the heating process. The effects of wall thickness and core volume on the PCM phase-transition performance were analyzed, and the thermal efficiency of different types of wall material PCM was compared. The effect of CG on the thermal efficiency of PCM was further analyzed by simulating the phase change performance of PCM with CGMF as the wall material during the cooling process. The results show that the use of CGMF as a wall material to prepare PCM can improve the thermal efficiency of PCM. The energy efficiency of CGMFPCM2031 increases by an average of 141.15% compared with MFPCM2026. Adding PCM as a wall material to the asphalt system can increase the compatibility and tensile strength between the components of asphalt, and enhance the low-temperature crack resistance of asphalt systems.