Effects of Heat and Radiation on the Terahertz Absorption in Silicone Rubber

The effects of heat and radiation on the terahertz (THz) absorption spectra in silicone rubber (SiR) was examined. By conducting peak fitting, the THz absorption was found to be composed of several components at 1.2, 2.0, 4.1, 4.6, and 5.5 THz. By analyzing the changes of these components as a function of the ageing time, the 1.2-THz absorption seems to have a certain close relation with Si-CH$_{\mathbf {3}}$textbf, while the 2.0-THz absorption is related with the formation of carbonyls. Furthermore, SiR seems to form mainly cross-linked structures if it is annealed thermally, whereas decomposition becomes dominant if it is gammairradiated at room temperature.