A combined kinetic analysis for thermal characteristics and reaction mechanism based on non-isothermal experiments: The case of poly(vinyl alcohol) pyrolysis

Kinetics Study of PVA Polymer by Model-Free and Model-Fitting Methods Using TGA

“…Wang et al (2018) [ 18 ] also highlighted that the PVA pyrolysis can be considered as two steps; one between 230 and 320 °C for elimination reactions, followed between 320 and 500 °C for chain scission and cyclization reactions. For instance, Zhao et al (2023) [ 16 ] elucidated that the TG and DTG curves have very similar behavior with two peak reactions, (550–660 K) and (700–800 K), if they are compared with our curves for the common heating rate 20 K min −1 . The difference in the characteristic temperatures between the published papers could be attributed to the experimental conditions, sample source and size, operating pressure, and carrier gas flow rate.…”

“…By checking Figure 2 a–e, it has been noticed that while moving from 0.1 conversion to 0.7, the slope which is a function of the activation energy, are increasing, and this observation has been confirmed by changing the average activation energy values from 89 kJ mol −1 at conversion 0.1 to 280 kJ mol −1 at conversion 0.7 with average 145 kJ mol −1 . This high value of activation energy value at high conversion is attributed to the beginning of the second reaction which has not been included in this calculation (Zhao et al (2023) [ 16 ]). Table 6 presents activation energy from three published papers.…”

“…This increase in E a value has been attributed to the formation of thermally stable char at a conversion greater than 0.6. The third paper considered two reactions, the first one with an average activation energy value of 136.50 kJ mol −1 , while the second reaction has an average of 261.30 kJ mol −1 [ 16 ].…”

“…Figure 5 shows the linear relationship with a (R 2 = 1.0), and this shows the suitability of the suggested model for PVA pyrolysis. This relationship between A 0 and E a is called the kinetic compensation effect [ 16 ].…”

“…Zhao et al (2023) [ 16 ] aimed to determine the kinetics paramters and the reaction mechanism for PVA pyrolysis using TGA under inert nitrogen at different heating rates. They identified two reactions within the whole pyrolysis, and calcualted the activations for these reactions using different model free methods.…”