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. 2021 Apr 8;11:7800. doi: 10.1038/s41598-021-87044-x

Figure 7.

Figure 7

1H (left) and 13C (right) MAS NMR spectra of 20 μl propylene glycol in 75 psig O2 heated to various temperatures prior to cooling to monitor the thermal degradation processes taking place. 1H: the spectrum at 133 °C completed after 3.4 h of heating, 175 °C completed after 3.4 h of heating at 175 °C. 13C: the spectrum at 175 °C completed after 19.8 h of heating at 175 °C. The total heating time including temperature ramping was ~ 24 h.