Chemistry Reference
In-Depth Information
Sample E:
t
0
5
151
:
8s
;
t
1
5
209
:
2s
;
t
5
176
:
1s
1
2
½η 5
2
209
:
2
1
4
ð
176
:
1
Þ 2
3
ð
151
:
8
Þ
2:08310
23
3151:8
5126:05 cm
3
=g
A plot of ln [η] vs. ln M will yield the MarkHouwink constants for the system of interest:
M
ln M
ln [η]
37,000
10.5
2.76
102,000
11.5
3.22
269,000
12.5
3.75
690,000
13.4
4.22
2,402,000
14.7
4.84
5
4
ln[η]
3
4.5 - 2.5
14-10
2
Slope
= a
≈
= 0.5
1
ln
K =
-2.5 ⇒
K =
0.08 cm
3
/g
0
10.0
11.0
12.0
13.0
14.0
15.0
ln
M
The polystyrene chains are in their unperturbed state since a50.5.
3.3.4
Single-Point Intrinsic Viscosities
It is interesting to note that the intrinsic viscosity can often be determined to
within a few percent from a relative flow time measurement at a single concentra-
tion only. A number of such mathematical techniques have been proposed.
Several of these are very useful but all should be verified with standard multipoint
