Thermal Degradation Kinetics of Chemically Modified Wood Sawdust Using Thermogravimetric Analysis (TGA)

Abstract

The kinetic study of the thermal degradation of NaOH modified Gmelina arborea sawdust was investigated by thermogravimetric analysis (TGA). Samples were treated with 4% NaOH solution for a period of 30 and 90 minutes. Thermogravimetric analysis was carried out at five different heating rates of 10, 20, 30 and 50°C min-1 from a temperature range of 50 to 650C° at a constant nitrogen flow rate of 20 ml min-1 . The activation energy and other kinetic parameters of the decomposition process were calculated by model free Kissinger and Ozawa methods. TG and DTG analysis revealed that sample treated for 90 minutes presented the highest onset and peak degradation temperature of 274.04°C and 372.11°C respectively. The activation energy (Ea) obtained by Kissinger and Ozawa methods were 183.32 and 184.69 KJ/mol, while the pre-exponential factor (lnA) was 6.97 x 104 and 7.00 x 104 min-1 respectively. Therefore, alkali treatment with 4% NaOH solution for 90 minutes imparted a significant improvement on the thermal stability of Gmelina arborea sawdust. This implies that this sample will withstand higher temperature without appreciable degradation when compounded with a thermoplastic polymer in polymer matrix composites.