硫化橡胶抗裂纹扩展能力与氢键强度和含量之间的关系

橡胶的疲劳破坏与其抗裂纹增长能力密切相关。目前，提高橡胶疲劳性能的研究仅限于橡胶复合体系的优化，鲜有从橡胶网络结构调控抗裂纹增长性能的研究。理论上，在共价交联橡胶网络中引入额外的氢键交联，氢键优先于共价键断裂的特性将提高裂纹扩展时的尖端能量耗散，从而有效阻止裂纹生长。但人们对氢键强度和含量与橡胶抗裂纹增长能力之间的关系不甚了了。本项目拟采用可逆加成-断裂链转移低温乳液聚合制备功能化丁苯橡胶，通过在分子链中引入种类、含量及分布可调的氢键功能基团，进一步制备含共价键/氢键两重交联的橡胶网络。在共价交联密度不变的前提下，建立氢键网络结构参数与裂纹增长速率和撕裂能等关键性能之间的关系，实现橡胶网络结构的优化，并探明氢键种类和含量对裂纹增长过程的影响，从而揭示抑制裂纹增长的新机理。本项目研究不仅为提高橡胶抗裂纹增长能力提供全新思路，而且将丰富橡胶疲劳断裂的机理，具有重要的理论意义和现实意义。

The fatigue failure of rubber is closely related to its crack growth resistance. Currently, the state-of-the-art research on improving the fatigue performance of rubber is limited to the optimization of rubber composite system, and there is little research on the control of crack growth resistance by manipulating the rubber network structure. In theory, if additional crosslinks based on hydrogen bonds (H-bonds) are introduced into a covalently crosslinked rubber network, the tip energy dissipation during crack propagation may be increased as the H-bonds will be ruptured prior to the covalent crosslinks, thereby effectively preventing crack growth. However, the effect of H-bond strength and content on the crack growth resistance of rubber is not well understood. In this project, the functional styrene-butadiene rubbers with H-bond moieties will be prepared by reversible addition-fragmentation chain transfer emulsion polymerization at low temperature. The type and content of the functional groups of molecular chain will be tuned. Subsequently, the rubbers with covalent/hydrogen bonding dual-crosslink will be prepared. On the premise of constant covalent crosslinking density, the relationship between the network structure parameters of H-bonds and the crack growth rate, tear energy and other key properties will be established to optimize the rubber network structure. The influence of the type and content of H-bonds on the crack growth process will be explored, and the new mechanism of inhibiting crack growth will be revealed. The research of this project will not only provide a new avenue to improve the crack growth resistance of rubber, but also enrich the fatigue mechanism of rubber, which is of theoretical and practical significance.