3.5. Production of Force-Degradation Identification by Raman
The Raman spectra of samples after 48 h of heat treatment are presented in Figure 1a. They exhibited clear differences and were clearly distinguishable by visual inspection alone. However, the spectra before 24 h of heat treatment appeared similar. In addition, in Figure 4c, the Raman spectra of samples after different durations of light treatment appeared similar. Therefore, PCA of the multivariate algorithms was used to construct the Raman spectral models.