Number: 2005-009-3-400
Title: Efficiency and reproducibility
of temperature rising elution fractionation (TREF)
Task Group
Chairman: Robert
Brüll
Members: Petra
Eiselt, Eric Gelade,
Jerrie Vermeulen,
Peter Mallon, Valerie
Grumel, Dieter Lilge,
Volker Dolle, Vincent
Mathot, Georg Michler,
Benjamin Monrabal,
Harald Pasch, and
Colin Li Pi Shan
Objective:
The aims of this project are (1) to fractionate a given number of
Polyethylene (PE) test samples with regard to their composition
using a given experimental procedure, (2) to compare the quantity
and chemical composition of the obtained fractions in the partner
laboratories, (3) to compare the results with regard to influence
of the instrumental setup and reproducibility and (4) to establish
suitable conditions for the compositional fractionation of polyethylene.
Finally conclusions shall be drawn with regard to the comparability
of the results and the robustness of TREF procedures in daily routine.
Description:
TREF is a technique which fractionates semicrystalline polyolefins
from solution according to composition and microstructure. The technique
has been invented in the late 1970s. In TREF the polymer is dissolved
in a suitable solvent at elevated temperatures. Subsequently the
solution is slowly cooled down to crystallize the sample. In the
third step the sample is eluted by fresh solvent at successively
rising temperatures. The fractions are collected and analyzed after
workup. The instrumental setup and experimental parameters which
are used vary between the different laboratories. Crystallization
and elution can be carried out either in a column which is packed
with a porous support or in a reactor without packing. As there
was no commercial instrumentation available until the late 90s the
equipment which is used is in most cases in-house constructed. The
steps of crystallization and elution are influenced by the concentration
of the polymer, the dimensions of the reactor, the type of support
used and the cooling rate. However there are no guidelines about
these parameters and little information is available in the literature.
Therefore the results from different laboratories are difficult
to compare. Due to the pivotal importance of TREF for the compositional
fractionation of polyethylene it is highly important to compare
the results between different laboratories. TREF is used in various
countries, ranging from industrialized nations to developing countries.
Progress: