Modelling the fractionation process in TREF systems: Thermodynamic simple approach

Abstract

A simple thermodynamic model, based on an extension of Flory-Huggins theory, is applied to temperature rising elution fractionation (TREF). Dependence of the fractionation process on melting temperature, melting enthalpy, average crystallinity, average crystallizable sequence length, and polymer-solvent interaction parameter is predicted. Results from the model fit experimental TREF data, and correctly predict number-average branch points for TREF fractions. 0 1995 John Wiley & Sons, Inc.

Study on molecular chain heterogeneity of linear low‐density polyethylene by cross‐fractionation of temperature rising elution fractionation and successive self‐nucleation/annealing thermal fractionation

“…In this article, LLDPE is a copolymer of ethylene and 1‐butene, and the content and distribution of SCB are the key factors to its melting temperature and crystallizability. Thus the content of SCB plays an important role in the crystallization behaviors from dilute solution and subsequent elution of polymer according to the elution thermodynamic mode of TREF 22. This further proves that TREF separates LLDPE according to the crystallizability or the content of SCB.…”

SSA study of early polyethylenes degradation stages. Effects of attack rate, of average branch length, and of backbone polymethylene sequences length distributions

“…A Linear Low Density Polyethylene (LLDPE, ethylenee butene copolymer) is used as an example for linear polyethylene with short branches not randomly distributed along the main chains, associated with non-homogeneous intermolecular chemical composition distributions. For these LLDPE, the short branches concentration for all molecules is not uniform, and this is sometimes referred to as intermolecular branching distribution [14,15].…”

Effects of low molecular weight compounds with hydroxyl groups on properties of poly(L‐lactic acid)

“…The first approach describes TREF profiles based on the Stockmayer bivariate distribution assuming that all polymer molecules with a specific comonomer content are fractionated at the same elution temperature 9–11. The second approach assumes that the solid–liquid equilibrium between crystallized polymers and polymers in a dilute solution at each elution temperature governs the TREF fractionation process 21–25. Both modeling approaches intrinsically assume that fractionation takes place at thermodynamic equilibrium and cannot describe the important crystallization and dissolution kinetics effects (cooling, heating, and solvent flow rates) that have been observed experimentally in TREF 18…”