Kinetical thermal degradation study of maize straw and soybean hull celluloses by simultaneous DSC–TGA and MDSC techniques

Abstract

The kinetics of thermal decomposition process of two celluloses extracted from maize straw and soybean hull and commercial microcrystalline cellulose was investigated using simultaneous DSC–TGA technique obtaining data from TGA module. The modulated differential scanning calorimetry (MDSC) was used to understand thermal events as volatilization of absorbed water and thermal decomposition. TGA data were used to the half-width and isoconversional FWO (Flynn–Wall–Osawa) methods and indicated that kinetic degradation behavior of soybean hull cellulose is more similar to commercial microcrystalline cellulose than maize straw cellulose behavior. However, the activation energy values of maize straw cellulose and commercial microcrystalline cellulose are higher than soybean hull cellulose; this is to be expected, once the crystallinity index of maize straw cellulose is similar to that of commercial microcrystalline cellulose. Kinetics studies on thermal degradation process of those two celluloses in comparison with commercial microcrystalline cellulose were satisfactory. In this work, it was confirmed the applicability of the software TA Instruments (TA Specialty Library Software Version 2.2), where kinetic parameters can be readily calculated, through comparison to results obtained by FWO method calculations. The values of activation energy are comparable showing that both procedures are suitable for the determination of kinetic parameters.