Numerical and Physical Modeling of Polymer Crystallization

Abstract

Crystallization of thin polypropylene films was performed in isothermal, constant cooling-rate and mixed conditions. The experiments were first analyzed using the classical procedures based on simplified forms (Avrami, Ozawa) of the general Kolmogoroff-Avrami-Evans (KAE) theory. These analyses, which can be applied over an unusually wide transformation range, show that the crystallizations are actually 2 D. Then, a procedure has been established for the determination of the nucleation and growth parameters involved in the theoretical model presented in the first paper of this series. These parameters have been introduced into the model in order to predict the crystallization behavior in isothermal, constant-cooling-rate and mixed-conditions: transformed fraction, number of activated nuclei, final size distribution of semi-crystalline entities. A very good agreement is generally found between predictions and experimental results.

A Monte Carlo Simulation of Homogeneous Crystallization in Confined Spaces: Effect of Crystallization Kinetics on the Avrami Exponent

“…Further numerical work revealed the feasibility of using a computer simulation for nucleation rate determination [17] and modeling of nonisothermal crystallization. [18] Raabe [19] and Raabe and Godara [20] performed a Monte Carlo simulation of small volumes of crystallizing isotactic poly(propylene) and achieved simulation results consistent with the crystallization parameters obtained by thermal analysis. Recently Jabbarzadeh and Tanner [21] have demonstrated applicability of simulations of molecular dynamics for modeling of crystallization kinetics of short-chain alkanes under quiescent and high shear rate conditions.…”

Effect of cooling on crystallization and microstructure of polypropylene

“…This resulted in an equation for what they called the real distribution of the mean radii. Unfortunately, the equation predicted spherulite size distributions, which deviated systematically from the experimentally observed distributions [15]. The reason is the assumption about the equivalence of the rates.…”

Structure Development in Injection Molding: A 3D Simulation with a Differential Formulation of the Kinetic Equations

“…To ensure the quality of our experiments, we first checked that the crystallizations were actually 2D [33]. The experiments were analyzed with an image analysis software.…”

“…More complete information can be found in [33]. Although our objective is to perform 3D calculations, we found after some trials that the best conditions for such a preliminary validation were in fact met in pure 2D crystallizations.…”

“…The determination of N 0 and q is done in two steps: first a crude approximation of these parameters and then an accurate one using the model with a trial and error method, in order to fit the experimental evolutions of α and N a [33]. This measurement can be done in isothermal conditions and during the isothermal period of mixed-condition experiments.…”