Chemistry Reference
In-Depth Information
Figure 7.
3D-surface plot (left) and 2-dimensional contour plot (right) of a metallocene polyethylene blend.
The 3D graph on the left side of Figure 7
already gives a clear idea of the separation
and of the main structural features of the
blend components. Having higher density,
component A has an elution temperature
around 95
8
C, higher than the lower density
component B, while its molar mass is shifted
to lower values, as expected by their respec-
tives MIs. Component A has narrower com-
position distribution, resulting in a higher 3
dimensional peak. A certain tailing can also
be seen in both components in the direction
of lower TREF temperatures and molar
masses. This last effect, as well as the relative
positions in the temperature-LogM plane are
more clearly seen in the contour plot.
The MWD of the fractions, weighted
according to their relative amounts, are
presented in Figure 8 (thin lines), while the
summation of all of them, which constitutes
the distribution for the whole sample, is
presented with a thicker line in Figure 8.
For comparison purposes, and in order
to validate the procedure followed to
Figure 8.
Weighted MWD curves from all the fractions measured at every elution temperature (thin lines) overlaid with
the recovered MWD of the polyethylene blend (thicker line).
