Thermal decomposition of cellulose has been widely studied for several years. It has been reported that the source of cellulose and its composition greatly affect its pyrolysis. Understanding cellulose decomposition could be helpful in a vast array of areas such as generation of energy from biomass and the improvement of flame retardants for cotton. One of the most widely used analytical tools for cellulose pyrolysis study is thermogravimetric analysis. Several model fitting methods have been employed to study cellulose pyrolysis kinetics. An alternative to the model fitting approach is the so-called “model-free” method developed by Vyazovkin. This isoconversional technique calculates the activation energy as a function of the degree of the conversion. In this work, our objective is to investigate the pyrolysis of cellulose in cotton fibers. We selected as a control for this study a sample of microcrystalline cellulose Avicel (PH 105). Thermograms were acquired as a function of the heating rates (4, 5, 8, 10 and 16°C/min). The data were analyzed using “model-free” method. For Avicel, the results showed that the activation energy is constant between 5% and 85% conversion level. This could mean that although the cellulose thermal decomposition is reported as a multi-step process, the pyrolysis kinetics are governed by the slowest step. A comparison of our results with data reported in the literature was made. Models for isothermal decomposition of cellulose are calculated at different temperatures. They are compared with experimental data at the same temperatures.
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