Advances in Crystallization Elution Fractionation

Abstract

Crystallization Elution Fractionation has been optimized to improve resolution power and reduce co-crystallization. Most important step to be optimized is the first separation cycle of Dynamic Crystallization which can be investigated with the help of Crystallization Analysis Fractionation experiments. A new approach to reduce co-crystallization and improve resolution is presented by applying successive cooling and heating cycles in a long column. The new process known as Multiple Crystallization Elution Fractionation adds extended separation at each cooling and heating cycles.

Effect of Operating Conditions on Dynamic Crystallization of Ethylene/1‐Octene Copolymers

“…The fractionation mechanism in CEF during the crystallization step is similar to that of DC; however, during the elution step in CEF, the column temperature is increased at a constant heating rate under constant solvent fl ow, similarly to the elution step in TREF, instead of the rapid heating in DC. [7][8][9] CEF was recently introduced as a commercial technique that can investigate the CCD of polymers with better resolution than other CCD analysis techniques and much shorter analysis time, allowing high throughput CCD characterization. Understanding of fractionation mechanism in DC is crucial for quantifying CEF.…”

“…The characterization techniques for measuring the CCD of semicrystalline copolymers have been continuously developed, especially crystallization-based techniques that fractionate polymers according to chain crystallizabilities in a dilute solution, such as temp erature-rising elution fractionation (TREF), crystallization analysis fractionation (CRYSTAF), and crystallization elution fractionation (CEF). [ 1,[3][4][5][6][7][8] Dynamic crystallization (DC) was recently introduced as a new CCD analysis tool using fractionation concepts similar to TREF and CRYSTAF, but with the fractionation step occurring under a constant solvent fl ow to enhance the physical separation of the polymer chains during the crystallization step. [ 7,8 ] DC consists of two consecutive steps: crystallization and elution steps.…”

“…[ 1,[3][4][5][6][7][8] Dynamic crystallization (DC) was recently introduced as a new CCD analysis tool using fractionation concepts similar to TREF and CRYSTAF, but with the fractionation step occurring under a constant solvent fl ow to enhance the physical separation of the polymer chains during the crystallization step. [ 7,8 ] DC consists of two consecutive steps: crystallization and elution steps. In the crystallization step, the dilute polymer solution is loaded into a column packed with inert particles.…”

An Overview of Important Microstructural Distributions for Polyolefin Analysis

“…In this case, the following generic expression applies, Figure 7 illustrates two bivariate distributions for LLDPE resins. The experimental distribution on the left side was measured using Polymer Char CFC 300, a cross fractionation instrument that combines fractionation by temperature rising elution fractionation (TREF) and GPC, [8] while the distribution on the right side of the figure is a model representation using Equation (16) for a three site-type catalyst.…”

Recent Advances in High-Temperature Fractionation of Polyolefins

“…CEF can be performed in a typical column based TREF instrument and can easily adapt viscometry, light scattering, composition or other molar mass sensitive detectors. In another paper, Monrabal et al [77] demonstrated that dynamic crystallization analysis can be optimized by knowing the crystallization range of the sample and adapt the experimental conditions accordingly. CRYSTAF and dynamic crystallization (DC) results obtained using the same cooling rates provided comparable results.…”