Zhao Xiuying, Fu Bozhi, Zhang Wenfeng, Li Haoxiang, Lu Yonglai, Gao Yangyang, Zhang Liqun
Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology 10029 China
State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology 100029 People's Republic of China.
RSC Adv. 2020 Jun 19;10(39):23394-23402. doi: 10.1039/d0ra04103c. eCollection 2020 Jun 16.
It is very important to improve the thermal conductivity of styrene butadiene rubber (SBR) which can widen its application. By employing reverse nonequilibrium molecular dynamics simulations in a full atomistic resolution, the effect of the composition ratio of styrene, temperature, and tensile strain on the thermal conductivity of SBR has been investigated in this work. The results indicate that the thermal conductivity of SBR gradually decreases with increasing composition ratio of styrene. This closely depends on the number of degrees of freedom and the diffusion coefficient of backbone atoms. Under the tensile field, the orientation of backbone bonds improves the thermal conductivity parallel to the tensile direction, but reduces the thermal conductivity perpendicular to it. Meanwhile, the thermal conductivity parallel to the tensile direction is enhanced with the strain rate while it is reduced with the composition ratio of styrene. Interestingly, there exists a linear relationship between the logarithm of anisotropy of the thermal conductivity and the orientation degree of bonds. Finally, the parallel thermal conductivity of the strained SBR first rises and then declines with temperature. This transition reflects a crossover from disorder to anharmonicity dominated phonon transport. Moreover, the transition temperature is gradually reduced with increasing strain which is attributed to the polymer orientation. In summary, this work provides some fundamental insights into the thermal transport processes in SBR with different composition ratios of styrene and temperature, especially under tensile strain.
提高丁苯橡胶（SBR）的热导率非常重要，这可以拓宽其应用范围。通过采用全原子分辨率的反向非平衡分子动力学模拟，本文研究了苯乙烯的组成比、温度和拉伸应变对SBR热导率的影响。结果表明，SBR的热导率随着苯乙烯组成比的增加而逐渐降低。这紧密依赖于主链原子的自由度数量和扩散系数。在拉伸场下，主链键的取向提高了平行于拉伸方向的热导率，但降低了垂直于拉伸方向的热导率。同时，平行于拉伸方向的热导率随应变率增加而增强，随苯乙烯组成比降低。有趣的是，热导率各向异性的对数与键的取向度之间存在线性关系。最后，应变SBR的平行热导率随温度先升高后下降。这种转变反映了从无序到非谐性主导的声子输运的转变。此外，转变温度随着应变增加而逐渐降低，这归因于聚合物的取向。总之，这项工作为不同苯乙烯组成比和温度的SBR中的热输运过程提供了一些基本见解，特别是在拉伸应变下。
