Abstract:
Kinetic analysis was made applying TG/DTG/HF data in nitrogen and air atmosphere for thermal decomposition of hydrogel of polymethylvinyl maleic acid ester, linked with polypropy- lene glycol, at different heating rates. TG/DTG/HF data were processed according to the following kinetic models: Friedman, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Coates-Redfern and non- parametric kinetic method (NPK) was used, to obtain the following kinetic parameters: activation energy and pre-exponential factor.
According to the attained values of activation energy, the mechanism of degradation of the hydro- gel was suggested. Values of kinetic parameters attained by different methods, are compliant to each other. Isoconversion method is one of the methods for definition of activation energy; this method does not require knowledge on analytical form of conversion function, and gives the possibility to define the activation energy against conversion degree as well.
To obtain full kinetic analysis it is necessary to process the data using non-parametric kinetic method. Non-parametric kinetics method (NPK) of Serra, Nomen and Sempere is based upon the suggestion that reaction velocity may be expressed as multiplication of two independent functions, f (α) and k (T) . Reaction model f (α) considers the dependence of conversion degree, and k (T) considers the temperature dependence.
