Chemistry Reference
In-Depth Information
Table 1.
Physical properties of the supports.
Support
SiO
2
SiO
2
-Al
2
O
3
MCM-41 Si/Al
SBA-15 swelling agent
15
60
infinite
none
n-decane
TMB
Average pore diameter (nm)
a)
28.5
18.2
2.1
2.4
2.5
8.8
11.3
22.7
BET surface area (m
2
/g)
285
370
837
1015
1129
628
608
588
Pore volume (cm
3
/g)
1.55
1.29
0.58
0.77
0.77
1.16
0.78
1.73
a)
Determined from the maximum of BJH pore size distribution.
scan are reported, because the former is
influenced by the mechanical and thermal
history of the samples.
Chemical composition distributions were
measured by Crystaf (Polymer Char) using
1,2,4-trichlorobenzene as a solvent. Dis-
solution took place at 160
8
C for 90 min
followed by equilibration at 95
marized in Table 1. The nitrogen adsorp-
tion-desorption isotherms at 77 K (not
shown) belonged to type IVof the I.U.P.A.C
classification corresponding to mesoporous
materials. As it can been observed in the
table, three MCM-41 materials with similar
pore diameter and different silicon to alu-
minium molar ratio were obtained, and
three SBA-15 carriers with different pore
size, as a function of the swelling agent
employed in the synthesis, were prepared.
The effect of the structure and chemical
properties of support material on the
ethylene-1-hexene copolymerization has
been investigated using these materials
as
C for 45min.
The crystallization rates were 0.1
8
C/min
from 95 to 19
8
C. A two channel infrared
detector was used to measure the concen-
tration of polymer in the solution during
crystallization.
A BRUKER AC300 spectrometer at
75 MHz was used to characterize the
copolymers by
13
C NMR measurement
and determine their 1-hexene molar
fraction. The samples were added into
sample tube (a diameter of 5 mm) with
the mixture of 1,2,4-trichlorobenzene and
1,1,2,2-tetrachloroethylane-
8
supports of
the
catalytic
system
(nBuCp)
2
ZrCl
2
/MAO.
All the supported catalysts had good
activities for polymerization, with activities
varying from 0.46 to 9.91
10
6
g PE/mol
d
2
in a concen-
tration of 10 vol%. Each sample was mea-
sured with 10 s pulse repetition.
Zr
bar, observing a positive comonomer
effect with a different maximum value
depending on the support employed.
Molecular weight averages of polymers
made with (nBuCp)
2
ZrCl
2
/MAO suppor-
ted on the commercial carriers were not
affected significantly when 1-hexene was
added (Table 2). The polydispersity index
h
Results and Discussion
The main physical properties of the com-
mercial and synthesized materials are sum-
Table 2.
Characterization of poly(ethylene-co-1-hexene) samples made with (nBuCp)
2
ZrCl
2
/MAO supported on commer-
cial carriers.
Support
mL 1-hexene
0
5
15
25
35
50
60
75
SiO
2
81061
53853
55415
58336
64847
67197
73903
75450
M
n
(g
/m
ol)
M
w
=
M
n
2.91
3.06
2.76
2.58
2.59
2.58
2.79
2.91
T
m
(
8
C)
133
122
113
108
104
95
94
91
T
c
(
8
C)
116
112
98
98
91
86
86
73
Cr
ystallinity (%)
64
51
40
37
22
27
25
19
SiO
2
-Al
2
O
3
M
n
(
g/
mol)
70613
48307
44687
47541
78729
67887
77617
52250
2.89
2.70
2.63
2.78
2.62
2.87
3.09
3.28
M
w
=
M
n
T
m
(
8
C)
132
122
115
109
104
96
104
94
T
c
(
8
C)
117
111
102
95
87
78
85
79
Crystallinity (%)
64
51
43
36
30
24
28
24
