Chemistry Reference
In-Depth Information
Figure 6.
CLD and CC
D
of three model single-site polyolefin with different reactivity ratio products,
r
1
r
2
. Model
parameters: F
¼
0
:
5,
t ¼
0.001.
Figure 9. Both profiles can be well repre-
sented with four site types. It should be
noticed, however, that TREF and Crystaf
profiles are related to, but are not in fact the
CCD described by Equation (17). There-
fore, the mathematical treatment illustra-
ted in Figure 9 is only a first over simplified
approximation. The development of funda-
mental models for TREF and Crystaf is a
hard subject that is beyond the scope of this
short review.
[9,10]
polyolefin as a function of elution tempera-
ture or comonomer fraction. This technique
provides a complementary analysis to the
other hyphenated technique, GPC-IR, des-
cribed above. Similar information can also
obtained by projecting the CFC results
onto the TREF elution temperature plane
and computing the
M
w
for each elution
temperature.
Figure 10 shows one analytical result for
an ethylene/
a
-olefin copolymer with rather
complex microstructure. We notice that
there is a strong correlation between the
elution temperature (or comonomer frac-
tion) and the weight average molecular
weigh of the polymer. The trends for the
Hyphenated Techniques: TREF-LS
When a light-scattering detector is added
to TREF, it is possible to measure the
weight average molecular weight (M
w
)of
