多尺度分子模拟法研究轮胎用SSBR的大分子结构与节能构效关系及实验

With the increasing severity of energy and environmental issues, the development of energy-saving tires with low fuel consumption and long service life will contribute significant social and economic benefits. Traditional development of solution-polymerized styrene butadiene rubber (SSBR) usually relies on experience and trial and error experiments, and the relationship between structure and energy-saving is mostly qualitative, lacking systematic research and quantitative conclusions, and the analysis of energy-saving mechanism is not deep. Molecular simulation technology has unique advantages in explaining phenomena, establishing theory, and prediction performance. Therefore, in this study, the combination of experimental and multiscale (atomistic and coarse-grained) molecular dynamics simulation is employed to bring insight into the relationship between macromolecular structure and energy-saving of silica/graphene filled SSBR composites. By creating effective atomistic and coarse-grained models, the energy-saving effect parameters including dynamic mechanical properties and intermolecular friction are obtained, and the synergistic mechanism of two-component fillers system as well as the dynamic evolution behavior of microstructures involving two-component fillers dispersion and morphology, molecular chain size and conformation during the dynamic stretching process is analyzed. The simulation results are validated through experimental studies, so as to summarize the energy-saving mechanism of materials, to construct a model and force field method that can accurately describe and predict the energy-saving performance of composites, to establish a new simulation method for SSBR molecular structure design, and to provide a molecular-level theoretical basis for the preparation of high-performance energy-saving tire materials.

随着能源和环保问题的日益严峻，开发低油耗、长使用寿命的节能轮胎将产生显著的社会和经济效益。传统溶聚丁苯橡胶SSBR的开发多依赖经验和试错法实验，结构与节能关系多为定性分析，缺乏系统的研究和定量的结论，且对节能机理剖析不深。分子模拟在解释现象、建立理论、预测性能方面有独特的优势。基于此，本课题拟采用实验和多尺度（全原子和粗粒度）分子动力学模拟相结合的方法，对白炭黑/石墨烯填充SSBR复合材料的大分子结构与节能关系进行研究，创建有效的全原子和粗粒度计算模型，模拟得到材料的动态力学行为、分子链间摩擦等表征节能效果的参数，同时分析双填料体系的协同机理以及双填料分散与形貌、分子链尺寸和构象等微观结构在动态过程中的演化规律，与实验结果进行对比，总结节能机理，构建能较准确描述和预测复合材料节能效果的模型和力场，形成一套SSBR分子结构设计的模拟计算新方法，为高节能轮胎材料的制备提供分子级别的理论基础。

SSBR分子结构与性能关系，已开展了大量实验工作，但对微观结构和节能机理剖析不深，目前的工作更偏重于应用，构效关系缺乏系统的研究和统一的结论，且结构与性能关系缺乏能达到量化程度的原子、分子级别水平的理论基础，难以形成对SSBR链结构及其复合材料进行分子设计的新理论和新方法。基于此，本项目采用多尺度分子模拟和实验相结合的方法，对白炭黑/石墨烯并用填充SSBR复合材料体系进行研究。对其分子结构与节能效果关系、节能机理展开深入探索，创建了有效的计算模型，分析分子结构与节能效果之间的定量关系以及复合材料受动态应变时的微观结构演化，得到能较准确描述SSBR结构与节能关系的模拟计算新方法，并用该方法预测特定SSBR结构的节能性能，指导实验开发，以期为SSBR分子结构设计提供原子、分子级别的理论基础，探索出一条高节能胎面材料设计的新途径。该工作的主要亮点如下：区别与传统将石墨烯和白炭黑与SSBR基体简单的共混，本项目中通过偶联剂和改性剂将石墨烯和白炭黑共价接枝后填充到SSBR中，有效降低了填料间的摩擦，制备了低滚阻的SSBR复合材料。对SSBR进行环氧化改性，通过环氧化基团开环与白炭黑和石墨烯上的羟基的反应，实现SSBR分子链和填料的共价接枝。不使用硅烷偶联剂就能实现白炭黑较好的分散。因此环氧化SSBR不仅可以有效降低滚动阻力，还可以大大降低硅烷偶联剂的使用，降低VOC的排放。通过实验和多尺度分子模拟的结合，建立了能较好预测填料和橡胶相容性的模型，定量给出了填料表面接枝基团对不同SSBR结构相容性和滚动阻力的影响，为实验的表面改性提供理论指导。