Avrami equation

Avrami equation

The Avrami equation is a mathematical formula used to predict the fraction of a material that has undergone a phase change, such as crystallization, based on a given transformation rate. It was originally developed for systems approaching equilibrium at a constant temperature and is represented by the equation (1 - xc) = exp(-kt^n).From: Introduction to the Physics and Chemistry of Materials [2019], Model for batch-to-glass conversion: coupling the heat transfer with conversion kinetics [2021], Alkylene Oxides and Their Polymers [2020]

P

View Chapter

Purchase Book

Published in Joseph C. Salamone, Polymeric Materials Encyclopedia, 2020

David R. Fagerburg

The crystallization of polymers proceeds through a series of stages: melt, nucleation, lamellar growth, spherulite growth, and aggregation growth. The crystallization kinetics of polymers is complex and multifarious. According to thermal history, the crystallization can be isothermal or non-isothermal, and each process involves nucleation, spherulite growth, and bulk or overall crystallization kinetics. Most of the research for polymer crystallization has been concerned with the kinetics of the combined nucleation and spherulite growth. The crystallization processing can be isothermal, non-isothermal with a constant cooling rate, or non-isothermal with varying cooling rates. The Avrami equation is often used to describe the isothermal polymer crystallization kinetics. Frequently, however, the equation accurately fits the experimental data only during the early stage of the crystallization process and unsuccessfully describes the entire process because it does not account for the secondary crystallization.

Model for batch-to-glass conversion: coupling the heat transfer with conversion kinetics

View Article

Journal Information

Published in Journal of Asian Ceramic Societies, 2021

Pavel Ferkl, Pavel Hrma, Jaroslav Kloužek, Miroslava Vernerová, Albert Kruger, Richard Pokorný

The original Avrami equation [44–46] was derived for the kinetics of a phase change, such as crystallization, in a system approaching equilibrium at a constant temperature. The DA model [47,48] can be applied to nonisothermal processes, including phase disappearance, such as crystal dissolution [49]. Using the dissolved silica fraction as a measure of the phase change degree, the DA equation can be written as

Explore chapters and articles related to this topic

P

Model for batch-to-glass conversion: coupling the heat transfer with conversion kinetics