Okano Makoto, Watanabe Shinichi
Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan.
Polymers (Basel). 2018 Dec 21;11(1):9. doi: 10.3390/polym11010009.
We discuss the internal status of rubber composites consisting of an insulating rubber matrix and conductive carbon black (CB) fillers ("black rubber") using polarization-sensitive terahertz time-domain spectroscopy (THz-TDS). The black rubber composites under stretched conditions exhibit a large optical anisotropy or birefringence in the terahertz regime. From systematic studies, it is revealed that the large birefringence of black rubbers is due to the orientation distribution of anisotropically shaped CB aggregates in the rubber matrix and the orientation distribution is strongly linked to the mechanical deformation of the black rubber. A model simulation based on this relation between deformation and reorientation allows conversion of the birefringence () information into strain () information. In addition, the spectroscopic information obtained using the THz-TDS technique is useful to evaluate the changes in the internal conductive filler network caused by the mechanical deformation. Our findings demonstrate that the terahertz polarization spectroscopy is a promising nondestructive inspection method for contactless investigation of the internal condition of black rubber composites.
我们使用偏振敏感太赫兹时域光谱（THz-TDS）来讨论由绝缘橡胶基体和导电炭黑（CB）填料组成的橡胶复合材料（“黑色橡胶”）的内部状态。拉伸条件下的黑色橡胶复合材料在太赫兹波段表现出很大的光学各向异性或双折射。通过系统研究发现，黑色橡胶的大双折射是由于橡胶基体中各向异性形状的炭黑聚集体的取向分布，且该取向分布与黑色橡胶的机械变形密切相关。基于这种变形与重新取向之间关系的模型模拟，可将双折射（）信息转换为应变（）信息。此外，使用THz-TDS技术获得的光谱信息有助于评估由机械变形引起的内部导电填料网络的变化。我们的研究结果表明，太赫兹偏振光谱是一种很有前景的非破坏性检测方法，可用于非接触式研究黑色橡胶复合材料的内部状况。
