Modification of the Avrami model for application to the kinetics of the melt crystallization of lipids |
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Authors: | Suresh S Narine Kerry L Humphrey Laziz Bouzidi |
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Affiliation: | (1) Alberta Lipid Utilization Program, Department of Agricultural, Food and Nutritional Science, University of Alberta, T6G 2P5 Edmonton, Alberta, Canada;(2) 4-10 Agricultural/Forestry Centre, University of Alberta, T6G 2P5 Edmonton, Alberta, Canadal |
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Abstract: | The Avrami model was developed to model the kinetics of crystallization and growth of a simple metal system. The original
assumptions of the model do not apply for high-volume-fraction crystallizing lipids, although it is incorrectly and frequently
applied. A modified form of the Avrami model, wellsuited to complex lipid crystallization kinetics, is developed. It produces
excellent fits to experimental data and allows the prediction of physically meaningful parameters, such as changes in nucleation
rate and type, growth rate, morphology, and dimensionality. Morphological changes highlighted by time-resolved temperature-controlled
polarized light microscopy support its application to crystallizing lipids. The kinetics of crystallization for six separate
lipid samples were monitored by pulsed NMR, and fits were performed using the classical and modified Avrami model. In all
cases, the modified model provided superior fits to the data compared with that of the classical model. The modified model
supports the theory that lipids crystallize and grow into networks via very specific growth modes. Furthermore, the case is made that it is useful for interpreting crystallization kinetics of
other systems such as polymer melts, which have nonconstant growth rates, dimensionalities, and nucleation conditions, and
whose growth become diffusion-limited within specific regimes. |
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Keywords: | Avrami model crystallization kinetics lipids |
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