Peidayesh Hamed, Špitalský Zdenko, Chodák Ivan
Polymer Institute of the Slovak Academy of Sciences, Dúbravská Cesta 9, 845 41 Bratislava, Slovakia.
Polymers (Basel). 2022 Sep 2;14(17):3640. doi: 10.3390/polym14173640.
Studies addressing electroconductive composites based on rubber have attracted great interest for many engineering applications. To contribute to obtaining useful materials with reproducible behavior, this study focused on understanding the mechanism of conductivity changes during mechanical deformation for rubber composites based on styrene-butadiene rubber (SBR) or ethylene-propylene-diene terpolymer (EPDM) vulcanized for various times. The composites were characterized by static electrical conductivity, tensile testing, dynamic mechanical thermal analysis (DMTA), and crosslink density measurements. The tensile strength and Young's modulus were found to increase significantly with rising vulcanization time. Higher static conductivity values of the composites were observed with the increase in vulcanization time. The most important aspect of this investigation consisted in the electrical current measurement online with recording the stress-strain curves, revealing the details of the uniaxial cyclic deformation effect on changes in the structure of conductive pathways indirectly. The electrical conductivity during five runs of repeated cyclic mechanical deformations for SBR composites increased permanently, although not linearly, whereas EPDM composites showed a slight increase or at least a nearly constant current, indicating healing of minor defects in the conductive pathways or the formation of new conductive pathways.
针对基于橡胶的导电复合材料的研究，在许多工程应用中引起了极大的兴趣。为了有助于获得具有可重复行为的有用材料，本研究着重于理解基于苯乙烯-丁二烯橡胶（SBR）或乙烯-丙烯-二烯三元共聚物（EPDM）且硫化不同时间的橡胶复合材料在机械变形过程中电导率变化的机制。通过静态电导率、拉伸试验、动态力学热分析（DMTA）和交联密度测量对复合材料进行了表征。发现拉伸强度和杨氏模量随硫化时间的增加而显著提高。随着硫化时间的增加，观察到复合材料的静态电导率值更高。本研究最重要的方面在于在线测量电流并记录应力-应变曲线，间接揭示单轴循环变形对导电路径结构变化的影响细节。SBR复合材料在五次重复循环机械变形过程中电导率持续增加，尽管不是线性增加，而EPDM复合材料显示出轻微增加或至少电流几乎恒定，这表明导电路径中的微小缺陷得到修复或形成了新的导电路径。
