Chemistry Reference
In-Depth Information
(
M
w
=
M
n
) varied from 2.58 to 3.28, higher
than the value of 2.0 expected for homo-
geneous single-site catalysts, suggesting
some heterogeneity in the nature of the
active sites.
[28]
Melting and crystallization
temperatures decreased with increasing
comonomer content, as expected.
Figure 1 shows the Crystaf profiles of the
polymers produced with (nBuCp)
2
ZrCl
2
/
MAO supported on SiO
2
and SiO
2
-Al
2
O
3
.
Crystallization temperatures are correlated
to the comonomer content.
[29]
As all of
them have narrow, unimodal CCDs, they
are useful to create a calibration curve since
it covers a broad range of comonomer
incorporation.
[30]
The linear relationship
between Crystaf peak temperature,
Figure 2.
Crystaf calibration curve for poly(ethylene-
co-1-hexene) made with (nBuCp)
2
ZrCl
2
/MAO sup-
ported on commercial carriers.
T
peak
,
and the molar fraction of 1-hexene mea-
sured by
13
C NMR is illustrated in Figure 2.
Figure 1.
Crystaf profiles of poly(ethylene-
co
-1-hexene) made with (nBuCp)
2
ZrCl
2
/MAO supported on commercial carriers:
SiO
2
and
SiO
2
-Al
2
O
3
.
&
*
