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CEF Frequently Asked Questions

We are aware that acquiring a lab instrument is an important decision, furthermore if Polyolefins’ research is related with your core business.

Although you can ask directly to our consultants whenever you want, you may prefer to know first the answers to the most typical questions about our instruments. Here are packed the most relevant questions about CEF.


Questions


Answers

Which is the purpose of CEF instrument?
CEF (Crystallization Elution Fractionation) instrument is a simple and reliable high-throughput analyzer performing a new approach to measure the Chemical Composition Distribution (CCD) in polyolefins by combining CRYSTAF and TREF separation mechanisms. CEF is of special interest for high speed analysis.

May I perform TREF and / or TGIC techniques in my CEF instrument?
CEF instrument can perform TREF method directly, without any change in the configuration of the instrument. CEF instrument can also perform TGIC method by acquiring the corresponding license from Polymer Char (TGIC is a patented technique by The Dow Chemical Company).

Does CEF provide the physical fractions in temperature?
CEF is an analytical instrument intended to obtain the chemical composition distribution curve, but it doesn’t provide any physical fraction. For this purpose, please read about PREP mc2.

How many samples can be run at a time and how long will it take?
Up to 42 vials can be handled by the CEF autosampler, and they can be dissolved and analyzed with no supervision required. Each sample can be analyzed with different conditions, so the total time will depend on the analysis method selected for each sample. Analysis method time may vary between 30 min up to several hours, obtaining a fair resolution when analyzing 50 samples per day.

How many grams of sample do I need for a CEF analysis?
The standard amount used in CEF analysis is 32mg per sample in 8 mL, therefore the instrument can be used both for research and also for quality control.

Which solvents can be used?
1.2.4-Trichlorobenzene (TCB) and Orto-Dichlorobenzene (oDCB) are the most used solvents. Perchloroethylene could be used too. To use other solvents please consult Polymer Char first.

What kind of sample preparation is required by the user? How is the sample prepared?
No samples preparation is required by the user but weighing the dry samples and putting them inside of the disposable glass vials. The rest of the steps are performed by the instrument automatically: vials filling, dissolution, filtration, injection, elution, etc.

May I use different analysis conditions for each vial within the same run?
Different analysis conditions can be selected from the CEF software for each vial within the same run, therefore, different samples can be analyzed unattended and with the appropriate dissolution time, crystallization ramp, elution ramp, pump flow, etc.

Do I need to handle solvents?
Solvents don’t need to be handled at any time; the whole process is fully automated, the instrument is in charge of all the needed steps: vials filling, dissolution, filtration, injection, elution, etc.

Do I need to prefilter the samples out of the instrument?
No prefiltration step is required by using CEF instrument thanks to an in-line filter, which is integrated in the instrument as an option, connected before the CEF column. Additionally, after each injection, this filter is automatically cleaned in backflush to become ready and clean again for the next injection.

How long will last my CEF column? Are temperature or flow changes affecting my CEF column?
CEF column is not a consumable part of the instrument and it is not affected by temperature or flow changes. It has been designed in Polymer Char especially for CEF instrument to achieve good resolution and high throughput.

Which kind of samples can be analyzed?
LLDPE, LDPE, HDPE, PP, E-P copolymers, multicatalyst reactor resins, and any semicrystalline polymer soluble in TCB or oDCB, giving response to C-H absorption.

Which detector is used for the concentration measurement?
CEF incorporates an infrared detector to measure the concentration of the solution which is being eluted and going out of the column. This detector can be Polymer Char's IR4 or IR5 in their integrated versions.

May I couple additional detectors to CEF?
A capillary viscometer detector can be connected to the CEF instrument, to obtain information on composition-molar mass interdependence.

How can I access and review my results?
After each injection, data can already be accessed and calculated through the CEF software database. Polymer Char CEF Calculations software integrates all detectors signals in the same package. A reporting tool is available to generate reports in Excel adapted to each user needs.

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