Chemistry Reference
In-Depth Information
Figure 12.
TREF profile and M
w
plot for a LLDPE sample. Two independent cross-fractionation analyses are overlaid to
demonstrate the good reproducibility of this technique.
Polyethylene Resins Made in
Multiple Reactors
Another commercial product that has a
broad and complex chemical composition
distribution, in this case produced presum-
ably by a multiple reactor process, was
analyzed using the cross-fractionation instru-
ment under the same conditions as in the
previous sections. The 3D plots in Figure 13
show a peculiar structure in which three
different populations can be identified.
One of the remarkable characteristics of
this product is the highly short chain
branched component eluting in the range
of 55 to 70
C showing a higher molecular
weight than that of the more crystalline
population eluting at higher temperatures.
This product is a good example of materials
with very heterogeneous and multimodal
chemical composition distributions. This
can also be seen very clearly the recon-
structed TREF profile shown in Figure 14.
8
Figure 13.
3D-surface plot (left) and 2-dimensional contour plot (right) of a multiple reactor polyethylene sample.
