Degradation kinetics of PET/PEN blend nanocomposites using differential isoconversional and differential master plot approaches

Thermal degradation of PET/PEN/75/25 blend and PET/PEN/Cu-Re-modified, PET/PEN/Si-Re-modified, and PET/PEN/Cloisite 30B composites was investigated by thermogravimetric analysis under nonisothermal conditions. Values of the apparent activation energies ( E a ) were estimated using Friedman’s isoconversional methods. A strong dependence of the E a value on conversion ( α ) was observed. It seems that the apparent mechanism of overall reaction cannot be expressed in terms of one simple reaction model. Direct differential method was used to determine the reaction models which best describe the degradation process in the convergence range where the apparent activation energy is nearly constant. To confirm the predetermined reaction models, differential master plot analysis was used. It was established that the degradation of PET/PEN blend and PET/PEN/clay composite can be described by the reaction-order (F type) kinetic models. The order of the average value of the apparent activation energy in the range of α = 0.10–0.45 is found to be as: PET/PEN/Si-Re-modified > PET/PEN/Cloisite 30B > PET/PEN > PET/PEN/Cu-Re-modified.