纳米粒子影响下橡胶裂纹生长多层次形态结构演变规律和机理

The understanding of rubber crack growth mechanism is of vital theoretical and application importance for the improvement of rubber safety. However, hierarchical morphological structure evolution rules and mechanisms during rubber crack growth influenced by nanoparticles are still unclear. In this proposal, nanoparticles filled rubber model system with different filler morphologies, dimensions, volume fractions and interfacial interactions will be constructed. Dynamic mechanical analyzer of crack growth detection function will be used to test the crack growth behavior. By the application of microscopic high speed video recording, small angle X-ray scattering, field emission scanning electron microscopy and other characterization methods, three aspects of research will be studied: 1) Investigate the nano-cavitation effect of rubbers under cyclic loading and study the mechanism of evolution process from nano-cavitation to damage structure in the vicinity of crack tip; 2) Characterize the damage structure evolution rules. The influence of nanoparticles on the damage structure will also be studied; 3) Analyze the crack tip morphology evolution based on real time morphology monitoring and reveal the generating mechanism of crack tip morphology, which originates from the damage structure. Based on the above systematic and correlated investigations, hierarchical morphology and structure evolution rules and mechanisms of rubber crack growth influenced by nanoparticles will be clarified. The research of the present proposal may provide new ideas and methods for the analysis of fundamental scientific problems of rubber crack growth. This research may also provide theoretical basis for the development of rubbers with high anti-cracking performance.

理解橡胶裂纹生长机理对提高橡胶安全使用性能具有重要的理论与应用价值。然而，纳米粒子影响下橡胶裂纹生长的多层次形态结构演变规律与机理仍未清楚。本项目拟构筑填料形态、尺寸、体积分数及填料与基体界面作用强度不同的纳米填充橡胶模型体系，采用具有裂纹扩展功能的动态力学分析仪进行裂纹生长测试，并结合显微型高速摄像、小角X射线散射、配备拉伸附件的场发射扫描电镜成像等技术手段开展以下三方面研究：考察周期性载荷作用下的橡胶纳米空洞化效应，分析纳米空洞发展为裂纹尖端损伤结构的机理；表征损伤结构演化规律，探讨纳米粒子对损伤结构演化的影响机制；在线考察裂纹尖端开裂形态演变，阐明损伤结构发展为开裂形态的机理。基于以上三方面的系统性、关联性研究，揭示出纳米粒子影响下，橡胶裂纹生长的多层次形态结构演变规律与机理。本研究旨在以新的思路、新的方法分析橡胶裂纹生长过程中的基本科学问题，为发展高性能抗开裂橡胶提供理论基础。

裂纹生长导致的橡胶失效是爆胎事故发生的主要原因之一。有关橡胶裂纹生长机理的研究关乎千家万户的生命安全。掌握橡胶裂纹生长过程的多层次形态结构演变是从本质上理解橡胶裂纹生长机理，开发出更高性能抗开裂橡胶材料的关键。本团队根据研究计划，选择丁苯橡胶、天然橡胶等为代表的二烯类橡胶材料及其填充复合材料为开展裂纹生长多层次形态结构演变及机理研究的对象，建立了裂纹扩展在线检测平台，实现了裂纹生长速率等开裂数据及裂纹尖端开裂形态的在线追踪。发现并总结出了“剥离态”、“韧带断裂态”、次级裂纹的生成等典型的开裂形态与形成机理，揭示了其与裂纹生长率的关系，提出通过开裂形态控制实现裂纹生长行为的调控；从亚微观到宏观的角度详细探讨了炭黑、白炭黑、碳纳米管及石墨烯填料粒子对橡胶裂纹生长、开裂形态的影响机制，揭示了开裂形态的产生机理及填料调控规律，实现了开裂形态分布区间及裂纹生长速率、能量耗散等的调控。详细研究了裂纹生长从纳米空穴化到损伤结构演变，再到裂纹尖端开裂形态的发展过程，阐明了纳米粒子尺寸、与基体界面作用强度、纳米粒子聚集态结构分布等对纳米空穴化及宏观裂纹生长的影响规律。相比唯象性的研究而言，本研究结果以更清晰的物理图景展现了橡胶裂纹生长从纳米级的微观到毫米级的宏观发展机理，指导了高性能抗开裂橡胶的开发。