To correlate the importance of thermal stability, using TGA, we further analyze the thermodynamic kinetics between VE_Neat and the optimal result from PCFC, VE_5% MEPECO. Here, the first, Figure , and second, Figure , degradations were determined as the temperature according to the intersection points: the tangent line to the decomposition start and the tangent line to the maximum weight loss rate. It can be obviously seen that the MEPECO additive caused a shift of the TGA graph toward the right. This finding indicates a higher temperature was needed to initiate devolatilization of the samples for additives when compared with the pure vinyl ester resin. Here, a possible chemical reaction between two polymeric components during mechanical blending happened. As a result of the process, the chemical reaction takes place within the interphase; hence, the interfacial agent is produced in situ, increasing its thermal stability . Furthermore, by considering three phase transformations as 1 st order reactions, activation energy and other thermodynamic parameters were analyzed by using the 1 st order reaction equation as given in equations ( ) to . Following the straight line for each individual phase, which confirmed that transformations were first-order reactions, the below equations determined the slope of each line, which equals the value of the rate constant (k) :