In the present paper, we report on a detailed study regarding the thermal degradation behaviours of some bio-sourced substrates. These were previously identified as the base materials in the formulations for fireproofing wood plaques through our investigations. The substrates included: β-cyclodextrin, dextran, potato starch, agar-agar, tamarind kernel powder and chitosan. For deducing the Arrhenius parameters from thermograms obtained through routine thermogravimetric analyses (TGA), we used the standard Flynn-Wall-Ozawa (FWO) method and employed an in-house developed proprietary software. In the former case, five different heating rates were used, whereas in the latter case, the data from one dynamic heating regime were utilized. Given that the FWO method is essentially based on a model-free approach that also makes use of multiple heating rates, it can be considered in the present context as superior to the one that is dependent on a single heating rate. It is also relevant to note here that the values of energy of activation (Ea) obtained in each case should only be considered as apparent values at best. Furthermore, some useful, but limited, correlations were identified between the Ea values and the relevant parameters obtained earlier by us from pyrolysis combustion flow calorimetry (PCFC).
Keywords: bio-based substrates; correlations; energy of activation; kinetic analysis; thermogravimetry tests.