PREP mc2

Preparative instrument to fractionate polymers by Molar Mass or Composition (TREF or CRYSTAF).

PREP mc2 Overview


Preparative (PREP) fractionation of a resin obtaining the physical fractions is a powerful approach in Polyolefin characterization research. Resulting fractions can be analyzed afterward by other techniques such as GPC, TREF, CRYSTAF, NMR, FTIR or DSC. Therefore, results can be used to study the interdependence among different microstructure parameters. The most common and useful approach is the bivariate distribution study, as it combines chemical composition distribution results with molar mass results.

PREP mc2 is an instrument intended for the semipreparative fractionation of polymers by molar mass or by composition Temperature Rising Elution Fractionation (TREF) and Crystallization Analysis (CRYSTAF) approaches. Samples are put into the vessels and the fractionation is performed automatically according to the selected method conditions in less than 24 hours.

Molar Mass fractionation is based on the solvent interaction with the polymer chains through a solvent/non-solvent separation approach. Polydispersity of resulting fractions can be very narrow.

Composition fractionation is based on differences in the crystallizability of the copolymer resins and can be performed by dissolution (TREF) or by precipitation (CRYSTAF) approaches. A single solvent is used to separate fractions according to their composition by dissolution or crystallization at different temperatures.

Up to 16 fractions can be obtained from a single sample fractionation as per the sample collector capacity. Two different samples can be fractionated at the same time, in which case up to 8 fractions per sample can be collected per run.

This instrument facilitates cross-fractionation studies, which have been shown to be a powerful tool to fully characterize resins.

PREP mc2 Features

The same hardware is used in order to fractionate by molar mass or by composition in the TREF mode. The instrument offers the possibility of changing to composition in the CRYSTAF mode by adding just one extra line.

The flexible software allows the user to always use the same methods with no need of modifying many parameters, or, to develop his own methods for research purposes.

The fractionation can be performed in different modes depending on the user's needs

The fractionation process is fully-automated. Therefore, there is no manual handling of hot solvents at any moment. Once the dry sample is placed in the vessel, the instrument takes care of the rest of the steps involved in the fractionation.

Liquid Nitrogen is necessary for this operation.

Virtual Instrumentation software with full control of the instrument hardware and process.

The remote control connection allows a fast diagnosis of troubleshooting or other tasks from the Polymer Char Service Center.

Prep mc2 is designed to easily access to each component and facilitate the maintenance tasks when needed

PREP mc2 Software

The PREP mc2 Software automates the fractionation process by composition TREF, CRYSTAF or by Molar Mass solvent-non solvent approaches. The corresponding separation method is selected from the PREP mc2 Software before starting the process, as well as a set of parameters involved in the fractionation, which can be configured by the user to get the desired separation conditions: such as the number of fractions obtained, volume, temperature steps (when fractionating by composition), solvent-non solvent percentages (when fractionating by molar mass) or cleaning cycles.

The PREP mc2 Software has been designed as a powerful Virtual Instrumentation interface to the instrument hardware, collecting all the sensors signals during the whole fractionation process as well as monitoring them in real time, watching at the expected behaviors and warning the user about any abnormal issues during the fractionation.

A manual mode is also available in the PREP mc2 Software, like in all Polymer Char’s instruments, without handling manually hot solvents and very useful as a fast diagnosis tool. As a result, every part of the instrument can be operated remotely. This manual mode is especially useful in the PREP mc2 instrument when fractionating unknown or difficult samples, allowing to perform step by step fractionations, which provides the user all the flexibility to adapt the fractionation conditions to the sample requirements.


PREP mc2 is a preparative instrument intended to fractionate polymers by Molar Mass or by Composition (TREF or CRYSTAF modes) with no hot solvents handling.

Yes, it will provide the different fractions corresponding to the temperature steps selected if the fractionation method is by composition; or will provide fractions with different molar mass cuts, if the fractionation method by molar mass is chosen before the run has started.

No, it doesn’t. PREP mc2 is a preparative instrument and no detector is incorporated in it. Thus, no analytical result is provided as its purpose is to fractionate polymers and to obtain physical fractions.

Two different samples can be fractionated at a time in Molar Mass mode and in TREF mode. One sample at a time can be fractionated in CRYSTAF mode.

In Molecular Weight fractionation, up to 2 grams can be put into each vessel and in composition around 1.5g per vessel.
The PREP mc2 instrument has two vessels available; therefore, if a larger sample needs to be fractionated, both vessels can be run at the same time with the same sample.

The maximum number of fractions that can be obtained by PREP mc2 is 16 fractions as per the PREP’s sample collector specifications.

For 6 to 8 fractions, polidispersity obtained in a molar mass fractionation is around 2.

No samples preparation is required by the user but weighing the dry samples and putting them inside of the vessels. The rest of the steps are performed by the instrument automatically: vessels filling, dissolution, filtration to the samples collector, final cleaning, etc.

After the automated fractionation process, fractions will be found in the sample collector separated in different glass vessels and mixed with solvent. By using any standard filtration system, fractions can be separated from the solvent and dried, to become ready to be weighted and analyzed by GPC, TREF, CRYSTAF, DSC, NMR, etc.

Solvents just need to be handled after the fractionation process, which is completely performed by the instrument.
After the automated fractionation process, fractions will be found in the sample collector separated in different glass vessels and mixed with solvent. By using any simple filtration system, fractions can be separated from the solvent and dried, to become ready to be weighted and analyzed by GPC, TREF, CRYSTAF, DSC, NMR, etc.

Any solvent compatible with viton o’rings and sealings can be used. To fractionate polyolefin samples, the solvents mostly used are TCB, oDCB and DEGMBE.

PREP mc2 has been used to fractionate polyolefin mainly, but any polymeric sample might be fractionated by using any compatible solvent. Please refer to the question above, ‘Which solvents can be used?’ for more on solvents used.

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