https://doi.org/10.3390/polym15010224
“Thermogravimetric analyses coupled to Fourier transform infrared spectroscopy (TG-IR) curves were obtained by the Mettler Toledo TGA2 coupled with an iS50 FTIR spectrophotometer (Thermo Fisher Scientific, New York, NY, USA), heated from room temperature to 800 °C with a linear heating rate of 20 °C/min under a nitrogen flow of 100 mL/min with a resolution of 32 cm−1.”
Further, TG-IR in the air atmosphere could be a more visual means of illustrating the thermal oxide decomposition product. The 3D spectra and its vertical view could intuitively describe the thermal degradation process, and the results are displayed in Figure 12 and Figure S6. This further confirmed that PET and its composites had two thermal degradation steps and a shorter degradation progress was observed in MIL-PET (Figure 12a–d). The Gram-Schmidt curves in Figure 12e well disclosed the concentration changes of the gas-phase. This suggested that the first step of degradation would be violent, resulting in noticeable mass loss and heat release, but lower gas-phase concentration. The second peaks in the Gram-Schmidt curves of MIL-PET were advanced, meaning that ferric ions were mainly catalyzing the gas generation instead of smoke in the first step.
Figure 12. 3D spectra and its vertical view of TG-FTIR in air atmosphere of (a1,a2) PET, (b1,b2) MIL-PET, (c1,c2) P-PET, and (d1,d2) MIL–P-PET. The (e) Gram-Schmidt curves and (f,g) FTIR in the second highest and highest peaks of Gram-Schmidt curves of PET, MIL-PET, P-PET, and MIL-P-PET.