Investigation of combustion kinetics of treated and untreated waste wood samples with thermogravimetric analysis

In the present study, combustion mechanisms, thermal kinetics, and phases of combustion were investigated for waste wood samples (untreated pine and treated MDF, plywood and particleboard). Waste wood samples were combusted in air at 10, 20 and 30 °C/min heating rates in TGA. The results of TG analysis have shown that thermal decomposition of treated samples takes place at lower temperatures as compared to the untreated pine sample because of the catalyzing effects of the chemicals in the samples. Therefore, there were less flammable products, lower weight losses in the main oxidation region, and decrease in the maximum weight loss temperatures and formation of more char for treated samples as compared to untreated pine sample. Thermal kinetic constants for the samples were calculated by using Coats Redfern Method. In order to find out the mechanisms responsible for the oxidation of the waste wood samples, six solid-state mechanisms of Coats Redfern Method were tested. The results of the Coats Redfern Method have shown that diffusion mechanism is the effective mechanism for all regions of the pine samples. For the main oxidation region, D4 mechanism (Ginstling–Brounshtein equation) was found to be the main diffusion mechanism for pine samples. For the treated samples such as MDF, plywood and particleboard, first-order reaction (F1) was found as an effective mechanism. Treatment of wood with different additives and glues seemed to alter the thermal oxidation process and change the effective oxidation mechanisms.