Thermogravimetric kinetics of polymer degradation: Science or fiction?

Weight changes in thermogravimetry are dependent on the volatility of the degradation products. Thus, molecular weight determinations (or related studies) must fist be undertaken to prove whether or not nonvolatile chain fragments will be removed only at high temperatures. In this case both thermal stability and kinetic studies by thermogravimetry are senseless. But even if volatile products are formed, the kinetic parameters will depend on the conversion degrees because of the kinetic chain character of the polymer degradation. Changes in reaction mechanism aggravate the situation; it is thus problematic to define in such conditions reliable kinetic parameters. Values calculated from a single TG curve are valid for specific conditions only, but of no sense from the general kinetic view.