Characterization of CFRP Thermal Degradation by the Polarization-Frequency Reflectometry Method in Subterahertz Frequency Range

We investigate the carbon fiber reinforced plastics (CFRP) thermal degradation using the polarization-frequency reflectometry (PFR) method in subterahertz frequency range. The setup that realizes the PFR method is developed and includes the sample scanning by a quasi-optical wave beam with various polarizations and frequencies. The CFRP thermal degradation can be detected in the 260 ^°C-300 ^°C temperature range using the PFR method confidently enough. Applying full-wave simulation of a plane wave scattering from a CFRP sample with the aid of the integral functional technique, we show that the temperature dependence of the reflection coefficient is due to the change of the CFRP filler permittivity.