天然橡胶在真实服役条件下结构和动力学非均匀性与宏观服役性能的关系

天然橡胶诸多优异特性主要归功于在形变过程中应变诱导结晶现象。尽管已有诸多理论和模型尝试解释应变诱导结晶的本质，但是理论预测与实验结果间仍存在较大的差异。一主要原因即忽略形变过程中橡胶网络的非均匀性变化。同时大多数理论和实验处理的是天然橡胶单轴拉伸的情况，而在真实服役过程中，橡胶进行的是多维拉伸。为获取天然橡胶在多维外场作用下的网络非均匀性演变规律，本项目结合多量子固体核磁和中子散射技术，并研发配套的在线多维拉伸装置，获取其在形变过程中网络非均匀性演变规律。针对模拟天然橡胶在低温区域真实服役行为，我们拟利用同步辐射X射线技术，并结合宽温域辊拉，双轴拉伸以及可变压变温的多维拉伸装置，研究其在宽温域多维外场作用下的应变诱导结晶。以此计算体系在形变过程中自由能变化，并重构其力学响应行为。以期为优化天然橡胶在真实服役条件下的服役性能提供基础理论指导，并为多维外场作用下的流动场诱导结晶提供参考。

The excellent properties of natural rubber are mainly due to strain-induced crystallization during deformation. Although numerous theories and models have tried to explain the origin of strain-induced crystallization, there is still a large gap between theoretical expectations and experimental results. One of the main reasons is the ignorance of network inhomogeneity during the deformation process. Meanwhile, most of the current theories and experiments mainly focus on the uniaxial deformation of natural rubber. However, in the actual service process, the rubber is more subjected to multi-dimensional deformation. In order to obtain the evolution of network inhomogeneity under the multi-dimensional external field, we plan to use multi-quantum solid-state nuclear magnetic and neutron scattering techniques to obtain the evolution of the network inhomogeneity during deformation, in combination with the home-made device. With respect to the strain-induced crystallization under multidimensional deformation, we plan to use synchrotron radiation X-ray scattering technology, together with in-situ devices, i.e. a roller pulling device capable of the wide temperature range, a biaxial stretching and a multi-dimensional stretching device with variable pressure and variable temperature. Afterward, the free energy of natural rubber during deformation is calculated and can be used to reproduce the macroscopically mechanical performance. The obtained results will help us to explore the roots of the excellent performance of natural rubber and to provide a basis for optimizing the macroscopic performance of natural rubber in real service conditions. Finally, the current project expects to provide theoretical guidance and experimental results for the flow field induced crystallization under the multi-dimensional external field.