橡胶复合材料结合胶结构和性能的分子动力学模拟研究

发布时间：2018-12-15 18:23

【摘要】：近年来,随着科学技术、纳米材料和纳米技术的快速发展,聚合物基(或者弹性体基)纳米复合材料在人们生活中广泛运用,同时也是科学研究的一大热点。而结合胶的形成也是聚合物基(或弹性体基)纳米复合材料的一个典型特征。采用分子动力学模拟探究结合胶的形成机理对实验具有很重要的指导意义。基于以上,本论文主要包括以下工作：桥链形成的原因和形成条件：(一) 桥链形成的原因和形成条件：通过模拟在纳米颗粒和聚合物分子链体系中加入溶剂的粗粒度模型,我们研究了结合胶的形成机理,以及同时吸附在两个纳米颗粒聚合物分子链的桥链数目和桥链的形成与纳米颗粒表面间距的关系。我们从中可以看出,桥链形成的条件是：当两个相邻纳米颗粒之间表面间距小于或者等于该聚合物分子链均方回转半径的2倍时,桥链可以形成。我们可以看出,两个相邻纳米颗粒的表面距离是决定桥链形成与否的最为关键的因素。但是,聚合物分子链桥链的形成,与纳米颗粒和聚合物分子链的相互吸引作用力并无直接的关系。换而言之,桥链的形成主要是取决于相邻纳米颗粒最近的表面距离。(二) 结合胶形成原因探索：通过计算均方位移,径向分布函数,聚合物分子与纳米颗粒、聚合物分子链与溶剂小分子以及纳米颗粒和溶剂小分子之间的总能量,桥链数目等参数来表征结合胶的形成过程。通过三个方法,一步步推进,最终模拟出结合胶的形成过程和机理,即溶剂小分子萃取混炼胶时,有一部分自由聚合物分子链会析出,而有一部分分子链会依然和纳米颗粒结合在一起形成稳定的网络结构。同时我们发现,结合胶的形成与纳米颗粒的含量或者体积分数有很重要的关系。当纳米颗粒含量达到一定值后,才能形成结合胶,才能在溶剂小分子加入萃取后仍然能形成纳米颗粒与聚合物分子链的网络结构。在纳米颗粒含量达到一定值后,加强聚合物分子链与纳米颗粒的吸引力,体系被溶剂小分子萃取出来自由聚合物分子链链会降低,导致所形成的结合胶含量会随之增加。(三) 聚合物-纳米颗粒-溶剂小分子三组分体系力学性能我们探索了三组分体系纳米颗粒-聚合物分子链-溶剂小分子三组分体系的力学性能与加入溶剂小分子数目之间的关系。随着溶剂小分子的加入,体系的力学性能会随之降低。总而言之,本论文对纳米颗粒-聚合物分子链-溶剂小分子三组分体系的结构和性能关系提供了更好的理论研究支持。
[Abstract]:In recent years, with the rapid development of science and technology, nano-materials and nanotechnology, polymer-based (or elastomeric) nanocomposites are widely used in people's lives, but also a hot spot of scientific research. The formation of adhesive is also a typical feature of polymer-based (or elastomer-based) nanocomposites. It is very important for the experiment to explore the formation mechanism of binder by molecular dynamics simulation. Based on the above, this paper mainly includes the following work: (1) the reasons and conditions for the formation of the bridge chain: (1) the coarse-grained model of adding solvent into the system of nano-particles and polymer chains by simulating the reasons and conditions of the formation of the bridge-chain. The formation mechanism of binding adhesive and the relationship between the number of bridged chains and the formation of bridging chains and the surface spacing of nanocrystalline polymers were studied. It can be seen that the bridge chain can be formed when the surface spacing between two adjacent nanoparticles is less than or equal to 2 times of the mean square radius of rotation of the polymer molecular chain. It can be seen that the surface distance of the two adjacent nanoparticles is the most important factor to determine the formation of the bridge chain. However, the formation of polymer molecular chain bridge chain is not directly related to the attraction force between nanoparticles and polymer chain. In other words, the formation of the bridge chain mainly depends on the nearest surface distance of the adjacent nanoparticles. (2) exploring the reasons for the formation of adhesive: by calculating the mean square displacement, radial distribution function, polymer molecule and nanoparticles, polymer molecular chain and solvent small molecule, and the total energy between nanoparticles and solvent small molecules, The number of bridge chains was used to characterize the formation process of binder. Through three methods, step by step, the formation process and mechanism of the binder were simulated, that is, when the solvent was small molecule extraction, some free polymer molecular chains would precipitate. Some molecular chains will still bind to nanoparticles to form a stable network structure. At the same time, we found that the formation of binder has a very important relationship with the content or volume fraction of nanoparticles. When the content of nano-particles reaches a certain value, the binding adhesive can be formed, and the network structure of nano-particle and polymer molecular chain can still be formed after the solvent small molecule is added into the extraction. When the content of nanoparticles reaches a certain value, the attraction of polymer chains and nanoparticles will be enhanced, and the free polymer chains extracted by small solvent molecules will decrease, resulting in an increase in the content of binder. (III) Mechanical Properties of three component Systems of Polymer-Nano-particles and small molecules in solvent We have explored the mechanical properties of the three-component system of nano-particle polymer molecular chain solvent small molecule and small solvent. The relationship between the number of molecules. With the addition of small solvent, the mechanical properties of the system will decrease. All in all, this paper provides a better theoretical support for the relationship between structure and properties of nano-particle, polymer molecular chain and solvent small molecule three-component system.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ330.1;TB33

【相似文献】