catalyst–polymer grains, which changes during the polymerization, is necessary.
To overcome this “density problem” [64], which is an unsolved question in the
literature, the densities during the course of polymerization have to be determined
with additional experimental series for each system [64] (see Figs. 28 and 29).
Projection areas
of growing particles
Particle growth evaluation
Projection area measurement
Equivalent circle diameter (ECD)
Equivalent sphere volume (ESV)
dESV / dt
polymerization rate (v p )
activation energy (E A )
reaction order
600µm
6 0 0 µm
600µm
600µm
a
b
Fig. 25 Video microscopy: particle growth evaluation
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
0
20
40
60
80
100
120
140
160
180
polymerization time [min]
ESV [1nl=1.000.000µm³]
0,00
0,05
0,10
0,15
0,20
0,25
0,30
0
5
10
15
Ethylene polymerization (1MPa)
at 60° C
bridged metallocenecatalyst
supported on MAO/SiO 2
evaluation of 40 single grain
microreactors
Fig. 26 Video microscopy kinetics: “time conversion curves”
Contributions to the Ziegler–Natta Catalysis: An Anthology
31