介电谱技术是一种利用宏观介电参数分析微观结构变化的技术。相比于微波频段,太赫兹介电谱含有丰富的指纹谱信息,能反映物质内部多种运动模式。在太赫兹频段研究了天然橡胶制品热氧老化后的介电谱,进而分析了分子结构的变化。研究结果表明,经过不同老化时间后,样本的太赫兹介电常数的实部和虚部均具有明确的变化规律,且与材料在老化中的微观结构变化相对应。对测试得到的太赫兹介电谱数据进行拟合,获得了相应的零频介电常数、光频介电常数和介电强度,从分子整体结构的角度分析了橡胶老化过程中材料的极性结构和分子间的网络化结构与分子链分解和交联的关系。研究结论表明,太赫兹介电谱在材料老化无损检测方面具有潜在的应用价值。

Dielectric spectral technique is the technique to analyze microstructural changes by means of macroscopic dielectric parameters. Compared with microwave ones, terahertz dielectric spectra contain rich fingerprint information and can reflect multiple motion modes within materials. In this paper, the dielectric spectra in the terahertz spectral band of natural rubber after thermal aging are investigated and the corresponding changes in the molecular structures are further analyzed. The research results show that both the real and imaginary parts of terahertz dielectric constants of samples possess definite change laws, which is corresponding to the microstructural changes during aging of materials. In addition, the acquired terahertz dielectric spectral data is fitted to obtain the corresponding dielectric constant at zero frequency, dielectric constant at optical frequency and dielectric strength. From the standpoint of overall structures of molecules, the relationship of the polar structures and intermolecular network structures during aging with the decomposition and crosslink of molecule chains is analyzed. The research conclusion indicates that terahertz dielectric spectra have potential application value in non-destructive detection of aging materials.