Comparative study of the degradation kinetics of three powder thermoset coatings

This paper deals with the thermal stability and thermal degradation kinetics of three powder thermoset coatings that are representative of the most common product families on the market at present: polyester, epoxy and hybrid. The study was carried out in a thermobalance at different rates of heating and using different atmospheres: nitrogen, air and oxygen. The procedure applied for characterising the most significant kinetic processes consisted in separating the peaks of the DTG signal and associating each peak with a kinetic system by means of an isoconversional procedure or the familiar Kissinger method. The results showed that, although all three coatings have high thermal stability, they do not all behave in the same way, particularly in an oxidising atmosphere. The decomposition kinetics of the three systems, although similar in a nitrogen atmosphere, are different in the presence of oxygen or air, allowing each to be characterised individually.