Chemistry Reference
In-Depth Information
Table 1 Calculated fractionation data for CPF, where the original copolymer has a Stockmayer
distribution (
15
)
Fraction no.
T
(K)
y
W
r
N
U
1
520
0.49567
74.8
0.673
2
530
0.50651
216.8
0.058
3
540
0.50696
266.0
0.039
4
550
0.50766
311.7
0.037
5
550
0.51159
427.9
0.071
Fig. 27 Influence of the number of theoretical plates,
m
Max
, on the fractionation efficiency with
respect to the segment number of CPF, if the original copolymer distribution is given by (
15
). The
stars
represent the values of the sol fraction and the
crosses
the values from the gel fractions
slightly higher for copolymers in comparison with homopolymers [
49
], showing the
influence of chemical heterogeneity on the fractionation with respect to the molec-
ular weight, even if the polydispersity with respect to the chemical composition is
small. The following optimization procedure aims for a much stronger fractionation
effect with respect to the chemical composition and, at the same time, to keep the
effectivity for the fractionation with respect to the molecular weight. Furthermore,
during the optimization it is assumed that the both solvents and the thermodynamic
properties, expressed by the parameter of the
G
E
model, cannot be changed. This
means we focus our attention on the optimization of the operative conditions, which
can also be changed in practice.
First, the influence of the number of theoretical plates of the CPF column is
studied (Fig.
27
). The discussion can be done using the nonuniformities in the
resulting sol and gel phases. Independently of the isolated phase (sol or gel), the
nonuniformity decreases with increasing number of theoretical plates present in
the CPF column. However, the decline is only very limited if the column has more
