Kinetic analysis of derivative curves in thermal analysis

Abstract

Two methods of obtaining kinetic parameiers from derivative thermoanalytical curves are proposed. The methods are based on the general form of kinetic formulae and are applicable to general types of reactions governed by a single activation energy. One method utilizes the linear relation between peak temperature and heating rate in order to estimate the activation energy, and only the information of the rate of conversion versus the temperature is necessary. The other method needs the information of both the conversion and the rate of conversion versus the temperature, and the Arrhenius plot is made for an assumed kinetic mecha!aism, Various types of thermal analysis have been applied in almost all fields of material research. The thermoanalytical method, in which the properties of a sample heated at a constant rate of heating are observed continuously, is an effective method when the thermal response time is large compared with the rate of the process and considerable change occurs during the period of heating the sample up ~o ~the desired temperature in an isothermal measurement. For kinetic investigation of the pyrolysis of a substance, thermogravimetry has been utilized mainly, and many methods of obtaining kinetic parameters from thermogravimetric data have been proposed. These have been thoroughly reviewed by Flynn and Wall [1].Recently mass-spectrometric thermal analysis (MTA) was proposed [2] and has been applied to the thermal degradation of polymeric materials [3][4][5][6]. This technique has some advantages over thermogravimetry since the volatilized products can be identified by mass-spectroscopy and the rate of the volatilization of eael~ 'product is also recorded simultaneously. Thus, we can obtain kinetic information as well as a knowledge of the products, and if the reaction proceeds in parallel reactions, these can be distinguished by identification of the products; this is not possible with thermogravimetry.However, a method of kinetic analysis of such derivative types of thermoanalytical curves as are obtained by MTA and differential scanning calorimetry (DSC) has not yet been proposed. Methods of kinetic analysis using data of both the conversion and the rate of conversion are reported for thermogravimetry, but these are only applicable to reactions of the n-th order, and hence can-,L Thermal Anal. 2, 2970

Thermochemical behaviour of Algal Waste: Kinetics and Mechanism of the Pyrolysis

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Statistical Copolymers Of Benzyl Methacrylate And Diethylaminoethyl Methacrylate: Monomer Reactivity Ratios And Thermal Properties

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Pyrolysis Characterization of a Lineal Low Density Polyethylene

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