5 Product Portfolio
Polyethylene products enjoy an outstanding position in the polymer market due
to the ability of modern polymerization technologies like the cascaded process to
offer tailor-made products with new combinations of properties with respect
to processability and final product properties. The product portfolio for high-density
polyethylene grades is shown in Fig. 14.
High-density polyethylenes (PE-HD) are used in a broad field of applications.
Low molecular mass grades with low melt viscosities at high shear rates are
used in injection molding (MFR 190/5 > 5 g/10 min). In this field, the requested
product properties are best achieved by products with narrow molecular mass
distributions and uniform comonomer distributions for grades with lowered densities.
To produce these products, the cascade process is not used. Only one polymerization
reactor is operated to synthesize these grades, as discussed elsewhere [32, 33]. For
medium high and very high molecular mass grades (MFR 190/5 1.5 g/10 min)
the molecular mass distribution must be broad or even very broad, and the
commoner distribution must be non-uniform, meaning that a comonomer like
1-butene is mainly or only incorporated in the high molecular mass fraction. This
normally varies from application to application, and it also depends on the final
product density. To achieve good processability at high shear rates, the molecular
mass distribution must become broader with increasing average molecular mass
or decreasing MFR values. This is necessary to hold the melt temperature as
low as possible, even at high throughputs on the processing machine. In some
0.1
1
10
100
0.930
0.940
0.950
0.960
0.970
MFR 190/5 [g/10 min]
density [g/cm³]
pipes
average molecular mass
molecular mass distribution
standard
injection grades
special grades
for packeging
largecontainers
films
fibers
monofilaments
small containers
injection grades
specialities
light
containers
cascade process
comonomer distribution
heterogene
broad
narrow
homogene
Fig. 14 Product portfolio of high-density polyethylene grades
74
L.L. Bo ¨hm
Polyethylene products enjoy an outstanding position in the polymer market due
to the ability of modern polymerization technologies like the cascaded process to
offer tailor-made products with new combinations of properties with respect
to processability and final product properties. The product portfolio for high-density
polyethylene grades is shown in Fig. 14.
High-density polyethylenes (PE-HD) are used in a broad field of applications.
Low molecular mass grades with low melt viscosities at high shear rates are
used in injection molding (MFR 190/5 > 5 g/10 min). In this field, the requested
product properties are best achieved by products with narrow molecular mass
distributions and uniform comonomer distributions for grades with lowered densities.
To produce these products, the cascade process is not used. Only one polymerization
reactor is operated to synthesize these grades, as discussed elsewhere [32, 33]. For
medium high and very high molecular mass grades (MFR 190/5 1.5 g/10 min)
the molecular mass distribution must be broad or even very broad, and the
commoner distribution must be non-uniform, meaning that a comonomer like
1-butene is mainly or only incorporated in the high molecular mass fraction. This
normally varies from application to application, and it also depends on the final
product density. To achieve good processability at high shear rates, the molecular
mass distribution must become broader with increasing average molecular mass
or decreasing MFR values. This is necessary to hold the melt temperature as
low as possible, even at high throughputs on the processing machine. In some
0.1
1
10
100
0.930
0.940
0.950
0.960
0.970
MFR 190/5 [g/10 min]
density [g/cm³]
pipes
average molecular mass
molecular mass distribution
standard
injection grades
special grades
for packeging
largecontainers
films
fibers
monofilaments
small containers
injection grades
specialities
light
containers
cascade process
comonomer distribution
heterogene
broad
narrow
homogene
Fig. 14 Product portfolio of high-density polyethylene grades
74
L.L. Bo ¨hm