Fully Automated Column-based Preparative Fractionation Equipment for Polymers

Fractionation of polyolefins has always been a difficult and physically demanding task due to the manual handling of large volumes of hot solvent. In addition, new complex polymers have shown to require a support to achieve a proper fractionation.

As a response, Polymer Char has developed PREP C20, a fully-automated column-based fractionation equipment capable of fractionating up to 20 grams of polymer, according to its chemical composition.

By adding a column as a support for the solution to crystallise in, the separation for each of the fractions is more appropriate, especially for recently developed products such as the multiple-reactor catalyst resins, in which a support for the solution to adhere to is critical.

PREP C20 works as a pilot plant in a completely automated manner. The main steps of fractionation are performed automatically: dissolution, loading of the column, crystallisation, elution, and collection of the fractions, avoiding the need of handling hot and large amounts of solvent.

The software allows the analysts to create their own methods adjusted to their samples. Up to 9 fractions can be obtained automatically, and it is possible to check the fractionation process thanks to an interactive software. Once the fractionation is finished, the equipment is clean and ready to start a new fractionation right away. The obtained fractions can be further analysed by other techniques and/or can be used for micromechanical testing as well.

Fractionation takes place in a Temperature Rising Elution Fractionation (TREF) mode, although other techniques of fractionation, such as Thermal Gradient Interaction Chromatography (TGIC), Molar Mass, and Solvent Gradient Interaction Chromatography (SGIC) might be possible as well.

Although this instrument was initially developed for polyolefins, PREP C20 can also be used for other polymers depending on the solvents required for dissolution.

Also available, is PREP mc2, an instrument intended for semipreparative fractionating polymers by molar mass or by composition (TREF and CRYSTAF approaches). With PREP mc2 samples are put into the vessels and the fractionation is performed automatically according to the selected method conditions in less than 24 hours.

This instrument facilitates the cross-fractionation studies, which have been shown to be a needed tool to fully characterise resins. Fractions collected can be analysed by other techniques such as NMR, FTIR and DSC.