Chemistry Reference
In-Depth Information
ln
φ
1
ln
γ
1
5
1
1
χ
x
1
1
ln
φ
1
x
1
χ
5
ln
γ
1
2
1
2
0
@
1
A
1
1
ln
φ
1
x
1
5
lnγ
1
2
(b) Geometric mean assumption
-
i.e., χ
$
0.
1
1
ln
φ
1
x
1
0
5
lnγ
1
2
0
@
1
A
0
001
0
:
lnγ
1
5
1
1
ln
:
02
ln
γ
1
52
2
:
0
γ
1
5
0
:
135
(c)
ln
0
:
001
0:02
χ
5
ln
ð
0
:
2
Þ
2
1
0
:
39
1
5
55
2
0:39
5
Þ
ðδ
s
2
δ
p
Þ
ð
1
:
987
Þð
373
ðδ
s
2
δ
p
Þ
5
2:3 ðcal=cm
3
1=2
Þ
Huggins theory has been modified and improved and other models
for polymer solution behavior have been presented. Many of these theories are
more satisfying intellectually than the solubility parameter model but the latter is
still the simplest model for predictive uses. The following discussion will there-
fore focus mainly on solubility parameter concepts.
The Flory
5.2.3
Modified Solubility Parameter Models
The great advantage of the solubility parameter model is in its simplicity, conve-
nience, and predictive ability. The stability of polymer mixtures can be predicted
from knowledge of the solubility parameters and hydrogen-bonding tendencies of
the components. The predictions are not always very accurate, however, because
the model is so oversimplified. Some examples have been given in the preceding
section. More sophisticated solution theories are not predictive. They contain
parameters that can only be determined by analysis of particular mixtures, and it
