Cross-Fractionation Chromatography (CFC) (1)
Determination of Crystallinity Distribution of Copolymer by Use of the Temperature Rising Elution Fractionation Device (TREF Column)

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Summary

The temperature rising elution fractionation method is a type of column separation method intended to be used for analyzing olefin-based polymers. The separation is achieved by using a TREF column built in a cross-fractionation chromatography (CFC) device. The separation is realized on the basis of the difference in the crystallinity. This makes it possible to evaluate the crystallinity distribution of polymers by the use of the TREF method.

In the case of olefin-based copolymers which crystallinity has a correlation with the monomer content, an evaluation of the crystallinity distribution by use of the TREF method is the same as an evaluation of the composition distribution. The TREF method is used well to evaluate the composition distribution of linear low-density polyethylene (LLDPE).

Example of determination

Sample: Linear low-density polyethylene (LLDPE)

  1. Polymer dissolved in a solvent is injected into the TREF column.
  2. The temperature is lowered at a constant rate so that the polymer will be crystallized on the column carrier. At this time, the component that has a smaller number of branches showing a high crystallinity will be crystallized first, and then the component that has a larger number of branches showing a low crystallinity will be crystallized as the temperature lowers.
  3. After that, the temperature is raised conversely so that the components will be eluded, starting with the component showing a low crystallinity to the one showing a high crystallinity, and thus, separation is accomplished according to the degree of short-chain branching.

TREFF elution curve (showing crystallinity distribution)

Search Number 1029

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