基于橡胶大分子链段反应动力学机制的高温磨耗机理研究

Based on the key problem of temperature effect on rubber abrasion performance in complex area, we carried out theoretical and experimental research on the evolution of micro molecular structure. By constructing the temperature control system to simulate the internal heat buildup of rubber materials, the wear performance of rubber under temperature influence was characterized. The relationship between the wear characteristics , wear performance and the temperature, pressure, speed, abrasive characteristics and physical properties of the rubber filler network, molecular structure, etc was studied by microstructure characterization methods. The dynamics models describing the rubber chain segment movement and the interaction between rubber molecules and grinding surface molecules were developed. The rubber morphology, molecular structure, molecular chain extension, rubber molecular aggregation morphology, chain segment movement and the movement of molecular chain were studied under different temperature. The change rule of key physical parameters was studied such as the average chain length, number average molecular weight, etc. The change of micro physical and chemical structure of rubber composites during wear under high temperature was described. It will be great significance to reveal the mechanism of high temperature wear of rubber materials, and the results will provide scientific basis for the development of rubber materials with excellent high temperature wear resistance performance. This project combined thermology and materials science which contributes to the development and cross of the related disciplines.

本项目立足于复杂区域内温度对橡胶磨耗性能影响的关键问题，基于微观分子结构演变开展理论和实验研究。通过构建模拟橡胶材料内部生热后温度升高的温控体系，实现橡胶温度影响下的磨耗性能表征；借助材料微观表征手段研究磨耗特征及性能与温度、压力、速度、磨料特性及橡胶的物理机械性能、分子结构、填料网络等的内在联系；发展适用于橡胶大分子链段运动和橡胶分子与磨面分子之间相互作用的动力学模型，研究不同温度下橡胶形貌、分子结构、橡胶分子伸展、分子链聚集形态、链段运动及整个分子链运动等微观结构，探明网链的平均链长、数均分子量等关键物理参数的变化规律，科学描述高温磨耗中橡胶复合材料微观物理化学结构的变化规律。本项目的开展对于揭示橡胶材料的高温磨耗机理具有重要意义，研究结果为开发具有优良高温磨耗性能的橡胶材料提供科学依据。本项目将热学和材料科学结合起来，有助于促进相关学科的交叉与发展。

构建的试验台可实现高温达110℃的精确测试,磨耗胶样的加热方式接近橡胶实际生热模式。研究发现,磨耗角度、负荷和温度均会对胶料磨耗性能及表面形貌产生很大影响，其中磨耗角度和负荷与磨耗量呈一次函数关系，而温度的影响最大且复杂，呈三次幂关系。磨耗表面形貌随着磨耗工况的不同而变化，主要与不同工况下橡胶磨耗表面分子链受力及其抗撕裂能力有关。而温度的影响还与表层分子链段动能和碳碳等键能对抗有关，高温下磨耗表面活性自由基的氧化与磨屑脱落对磨耗表面形貌及磨耗量有重要影响。红外光谱研究表明，磨耗使得橡胶表面产生分子链断裂和氧化降解两种表面力化学效应。室温时以分子链断裂为主，氧化降解次之，高温时则相反。随磨耗行程、角度和负荷增加，分子链断裂增加，导致磨耗量增加。氧化降解后，更易从表面脱离形成磨屑。温度影响磨耗性能剧烈，是由于温度升高，橡胶分子热效应和体积膨胀效应叠加，分子间物理交联点作用降低，分子间内聚能下降，磨耗表面区域抗剪切和拉伸强度下降，故磨耗性能降低，磨耗量明显增大。高温时磨耗表面发生热降解和力化学降解，导致生成胶粘层，向油性磨粒磨损转变，磨屑粘附能力增强，磨耗量增大趋势减弱。进行共混胶测试，发现胶料共混可抑制天然胶磨耗表面的热氧化行为。构建了锥形探头、纳米粗糙表面结构两种碳原子团簇与橡胶接触的分子动力学模型，考察了界面接触行为、摩擦过程和摩擦性能，探明了摩擦力、摩擦系数和橡胶基体温升随环境温度、运动速度的变化规律，发现并解释了橡胶分子链段在接触界面蠕动行为与机理。研究发现，当橡胶处于玻璃态时，摩擦力和摩擦系数随温度升高而变大。当橡胶处于高弹态时则相反。接触区域温度变化率随温度升高而增大，与橡胶分子链玻璃化转变无关。橡胶分子链段在界面处的蠕动行为是由于橡胶分子局部链段所受范德华力与分子链内原子键合力的对抗。