Analysis of the nonisothermal melt and cold crystallization kinetics of poly(aryl ether ether ketone ketone) (PEEKK) was performed by using differential scanning calorimetry (DSC). The Avrami equation modified by Jeziorny could describe only the primary stage of nonisothermal crystallization of PEEKK. And, the Ozawa analysis, when applied to this polymer system, failed to describe its nonisothermal crystallization behavior. A new and convenient approach for the nonisothermal crystallization was proposed by combining the Avrami equation with the Ozawa equation. By evaluating the kinetic parameters in this approach, the crystallization behavior of PEEKK was analyzed. According to the Kissinger method, the activation energies were determined to be 189 and 328 kJ/mol for nonisothermal melt and cold crystallization, respectively.

Nonisothermal melt and cold crystallization kinetics of poly(aryl ether ether ketone ketone)

Poly(e-caprolactone) (PCL)/layered double hydroxide (LDH) nanocomposites were prepared success- fully via simple solution intercalation. The nonisothermal melt crystallization kinetics of neat PCL and its LDH nano- composites was investigated with the Ozawa, Avrami, and combined Avrami-Ozawa methods. The Ozawa method failed to describe the crystallization kinetics of the studied systems. The Avrami method was found to be useful for describing the nonisothermal crystallization behavior, but the parameters in this method do not have explicit meaning for nonisothermal crystallization. The combined Avrami- Ozawa method explained the nonisothermal crystallization behavior of PCL and its LDH nanocomposites effectively. The kinetic results and polarized optical microscopy obser- vations indicated that the addition of LDH could affect the mechanism of nucleation and growth of the PCL matrix. The Takhor model was used to analyze the activation ener- gies of nonisothermal crystallization. V C 2010 Wiley Periodicals,

Crystallization behavior of poly(ε-caprolactone)/layered double hydroxide nanocomposites

A brief review is given of previously suggested methods for analysis of experimental data of non-isothermal crystallization kinetics based on the Johnson-Mehl-Avrami transformation rate equation. Conditions for applicability are outlined and an estimate of error is made. A method of non-isothermal analysis is presented which facilitates rapid data evaluation over large temperature ranges and which justifies the previous applications in the literature of Kissinger's method to the analysis of crystallizations kinetics. An extension of these methods is made to the case of growth rates which obey a Vogel-Further temperature relation.

Thermal analysis of non-isothermal crystallization kinetics in glass forming liquids

Crystallization behaviour of poly(ether-ether-ketone)

A critical review is presented of mathematical methods advanced over the last 20 years for the analysis of data obtained from non-isothermal thermoanalytical studies of crystallization of glass-forming liquids. Methods proposed by Ozawa, Piloyan and Borchardt, Coats, Redfern and Sestak, Ozawa and Chen, Takhor, Kissinger, and Augis and Bennett are examined in detail. All these methods are based on the Avrami treatment of transformation kinetics and define an effective crystallization rate coefficient having an Arrhenian temperature dependence. Several different ways of mathematically treating the data have been proposed. Most are shown to be based on an incorrect neglect of the temperature dependence of the rate coefficient. By taking proper account of the temperature dependence of the crystallization rate coefficient, all the methods are shown to lead to similar conclusions. In detail, it is shown that the effective activation energy of the overall crystallization process can be calculated from the slope of the line obtained by plotting 1n[ Q /( T P − T 0 )] versus 1/ T P is the temperature of maximum crystallization rate, T O is an initial temperature and Q is the heating rate employed in the experiment. It is further argued that in general the overall crystallization rate coefficient is not Arrhenian in character. Thus, in general, non-isothermal transformation cannot be treated analytically. A detailed description of nonisothermal transformation can, however, be obtained by numerical methods. Such a method is described and its uses in obtaining kinetic data from thermoanalytical studies are demonstrated.

T. Ozawa

Papers

Kinetics of non-isothermal crystallization