title: An incremental isoconversional method for kinetic analysis based on the orthogonal distance regression.
abstract: The parameters obtained from a kinetic analysis of thermoanalytical data often exhibit a conversion-dependent behavior. A novel incremental isoconversional method able to deal with this phenomenon is proposed. The kinetic model is directly fitted to the experimental data using nonlinear orthogonal least squares procedure. The data are processed without transformations, so their error distribution is preserved. As the objective function is based on a maximum likelihood approach, reliable uncertainties of the parameters can be estimated. In contrast to other methods, the activation energy and the pre-exponential factor are treated as equally important kinetic parameters and are estimated simultaneously. Validity of the method is verified on simulated data, including a dataset with local nonlinearity in the temperature variation. A practical application on the nonisothermal cold crystallization of polyethylene terephthalate is presented.
authors.affiliation: Department of Physical Chemistry, Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37, Bratislava, Slovakia.
authors.forename: Tibor
authors.initials: T
authors.lastname: Dubaj
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Cibulková
authors.forename: Peter
authors.initials: P
authors.lastname: Šimon
keywords: Arrhenius equation; activation energy; general rate equation; model-free kinetics