Chemistry Reference
In-Depth Information
a
0,6
35
0,5
0,4
0,3
0,2
31
34
0,1
33
32
0,0
0
50
100 150 200 250 300 350 400 450 500
r
b
0,35
33
34
0,30
32
31
0,25
35
0,20
0,15
0,10
0,05
0,00
0
50
100 150 200 250 300 350 400 450 500
r
Fig. 15 Influence of the temperature gradient on the fractionation according the segment number
for different temperature gradients: (a) linear temperature gradient, (b) nonlinear temperature
gradient. The
numbers
indicate the final fraction number
better choice, because the obtained distribution functions are narrower and the
overlapping of the distribution functions is less pronounced.
Additionally, the same calculations were performed in order to investigate
whether a more effective fractionation could be achieved using solvent mixtures
such as solvent 1 and solvent 2. This situation allows, from the theoretical point of
view, a combination of the solvent gradient and a temperature gradient. However,
the calculation results make it clear that no improvement could be seen if both
gradients were applied. The most important criterion for effective fractionation was
equal amounts of polymer in every final fraction. This criterion can be achieved by
solvent gradient or temperature gradient, or both. For the solution of a practical
fractionation problem, the search for a suitable solvent combination, in particular if
