Document 6501818

Blowing Agents and Foaming Processes 2005
Stuttgart, Germany 10-11 May 2005
How to choose a Polyolefin grade for Physical Foaming
Important parameters for the Physical Foamability of Polyolefins
Henk Ruinaard
Sabic EuroPetrochemicals B.V.
P.O. Box 475, 6160AL Geleen, The Netherlands
BIOGRAPHICAL NOTE
Henk Ruinaard studied Chemical Engineering in Dordrecht, The Netherlands. He started to work at the United
Sales Office of DSM and AKZO in Zeist as processing Engineer for LDPE film in 1968. Two years later he had
his first foam experience with the chemical foaming of LDPE blown film. As processing engineer he specialised
over the years in LDPE shrink film, melt fracture of blow-moulded bottles and cans, vacuum forming of ABS,
PVC and PP, melt fracture of HDPE blown film, sealing of PE films in general and seal layers for multi layer
barrier films and laminating films in particular. After the foundation and the move of the DSM Technical Service
Department to Geleen in 1982 he became Project Manager for octene LLDPE film applications with the technical
responsibility for DSM film customers all over Europe. In 1990 he became responsible as Technical Marketing
Engineer for the West European masterbatch customers of DSM. In 1998 he returned to his first love: the
foaming of LDPE, this time however as Technical Marketing Engineer for the West European foam customers of
DSM and today for SEPC (Sabic Euro Petro Chemicals) after the integration with SABIC in 2001.
ABSTRACT
The foaming of Polyolefins by direct gas injection or Physical Foaming process is a delicate balance between
the melt strength of the expanding polymer and the pressure of the blowing gas in the growing cells. This
process takes place at a melt temperature very close to the crystallization temperature of the polymer and stops
with the transition of the cell walls into the solid phase.
This paper explains the most important parameters of the Physical Foaming process and the important melt
related properties of a Polyolefin grade that are required for a good Physical foamability i.e.:
- Melting and crystallization temperature of the polyolefin grade
- Viscosity during melting, mixing and cooling of the molten polyolefin
- Viscosity in the crystallization temperature range
- Elongational viscosity in the crystallization temperature range.
In particular the increase in elongational viscosity or so-called strain hardening is vital for a successful foam
structure. Examples are shown for different types of Polyolefins produced by different polymerization processes
such as LDPE tubular and autoclave grades, LLDPE gas phase and solution grades, HDPE slurry grades,
RCPP and HMS PP grades and mPE Plastomers grades.
Finally relations are shown between elongational viscosity (in particular strain hardening), polymer properties
and Physical foamability.
INTRODUCTION
Physical Foaming Process
Extrusion of PO foams by direct gas injection or so-called Physical Foaming can be separated into 5 distinctive
steps, i.e.: melting of the solid PO pellets, injection and mixing of the liquid gas in the molten PO, cooling and
shaping of the melt into the expansion condition, foaming of the melt by the expanding gas and finally cooling of
the foam.
Although viscosity and melting/crystallization behaviour plays an important role in each or most of these process
steps, the gas expansion is the crucial step in the foam process.
In order to obtain a good foam quality (regular fine cell size and high closed cell content), the gas laden melt
needs to be cooled down to a temperature close to the crystallization temperature of the semi-crystalline
polyolefin to increase the melt viscosity and reduce the time needed for the transition from melt to solid phase. In
practice this means for semi-crystalline PO’s that the temperature of the melt at the die exit is always a few
degrees centigrade above the crystallization temperature Tc-peak (with the exception of the very low crystalline
mPE Plastomers).
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Blowing Agents and Foaming Processes 2005
Stuttgart, Germany 10-11 May 2005
This condition is the starting point of the cell growth process, in which the molten PO is elongated biaxially by the
expanding gas and cooling down at the same time by endothermic heat loss of the expansion and heat loss to
the environment. The melt elongation will be stopped by the transition into the solid phase when the
crystallization temperature Tc-peak is reached.
In this crystallizing environment, the cell growth and consequently the final cell size is a struggle between the
expanding gas and the increasing melt strength due to strain hardening and increasing crystallinity fraction of the
polyolefin melt.
Requirements for Physical Foaming
Successful Physical Foaming needs a very homogeneous temperature distribution (preferably ± 0,5°C) to
prevent an irregular cell size distribution due to viscosity differences. The melt temperature at the die exit is an
equilibrium between heat input via the extruder barrel, heat generation in the melt by friction in the extruder as
well as in the melt cooler and extrusion die and the cooling of the melt by the cooling section of the extruder
and/or melt cooler.
An important parameter in this game is the friction heat generation in the melt, which depends on the shear
viscosity character of the PO and the shear rate in each particular part of the extrusion process. To reduce the
friction heat generation, extruders for Physical Foaming always run at relatively low screw speeds (10 – 50 rpm).
On the other hand the friction heat generation is very much depending on the Molecular Mass and the Molecular
Weight Distribution (MWD) of the PO grade. The general trend is that a higher Molecular Mass (= lower Melt
Flow Index) and a narrower MWD generates more friction heat.
The gas expansion causes a biaxial elongation of the PO melt. Experiences from the past have shown that,
apart from a very good nucleation, a high elongational viscosity and an increase of the elongational viscosity
during the expansion (so called “strain hardening”) are required to get a good foam quality.
IMPORTANT POLYOLEFIN PROPERTIES FOR FOAMING
Melting and crystallisation temperature
The melting and crystallization behaviour of a PO is best shown by the Differential Scanning Calorimetric curve
(DSC curve; see Fig.1). When decreasing the melt temperature with a rate of 10°C/min, the first crystallization
starts at the crystallisation onset temperature (Tc-onset) at a few degrees centigrade before the crystallization
temperature peak Tc-peak.
This is the lower end of the melt temperature-processing window as a lower temperature setting and actual melt
temperature will induce freezing of the melt in the die opening. In practice, the temperature at the die exit should
always be a few degrees centigrade above Tc-onset.
Viscosity in the crystallization area
The crystallisation causes an increase in the shear viscosity as is very clearly shown by the DMS temperature
sweep curve. This viscosity curve is measured at a fixed frequency and a variable temperature starting in the
molten phase at 200°C and decreasing with a rate of 5°C/min into the solid phase down to 90°C (see Fig.2).
The viscosity in the molten phase is slowly increasing with decreasing temperature until Tc-onset is reached. The
first crystalline domains in the melt cause a very steep increase in viscosity, which flattens off when most of the
molecules have entered the solid phase at Tc-peak. For most PO’s, this increase in viscosity between Tc-onset and
Tc-peak is very steep and does not allow much variation in the melt temperature at the die exit. For PO types with
a low crystallinity or a low crystallization speed, like mPE Plastomers or RCPP grades, the crystallisation
temperature range is wider which allows a wider processing range.
In PO blends, the individual crystallisation behaviour of the separate blend component is not changing so each
blend component shows it’s own characteristic viscosity increase.
Shear viscosity
A common way to measure the shear viscosity is the DMS frequency sweep curve, in which the melt
temperature is fixed and the frequency of the vibrating disk is varied between 10–2 and 102 rad/sec. This can be
done at temperatures ranging from 130°C up to 320°C, however for PO’s this is commonly done at 190°C (see
Fig. 3).
In general the viscosity decreases with increasing frequency, however this decrease is higher for a polyolefin
with a wide MWD like LDPE than for a polyolefin with a narrow MWD like mPE. Obviously a high molecular mass
(= low MFI) results in a high shear viscosity, so the highest viscosities at high shear rates can be expected for
low MFI LLDPE C4- and C6-Gasphase grades and mPE Plastomer grades.
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Blowing Agents and Foaming Processes 2005
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Elongational viscosity
Strain hardening can only be measured accurately by the Rheological Melt Extension (RME) method as
developed by Dr. Meissner (lit.1) in 1994. The elongational viscosity ηel is measured by elongating a well-defined
compression moulded sample in a hot nitrogen filled oven at a well-defined temperature and strain rate. The ηel
is calculated from the measured force and strain as a function of time (lit 2).
The work of Meissner et al shows that the elongational viscosity at a given temperature, strain rate and strain
equals 3 times the shear viscosity ηsh at the same conditions as shown in the following formulae:
ηel+ (t) = 3 ηsh+ (t)
However ηel will increase more than proportional with increasing time due to disentanglements of the Long Chain
Branching (LCB) of the polyolefin with increasing strain, whereas ηsh will only increase slowly and less than
proportional with time. The difference between ηel and 3 ηsh is called strain hardening.
This strain hardening is known to be of a different magnitude for different PO grades (lit. 3), depending on their
MWD and LCB. It is also known that some PO grades show a very good foamability while others are not
foamable at all with the Physical Foaming process.
For the purpose of comparing the strain hardening of different PO grades (Lit. 4), the so-called Strain Hardening
Ratio (SHR) was calculated as the ratio between the maximum ηel of the RME curve and 3 ηsh of the DMS
frequency sweep curve at the same strain as ηel max (see Fig.4) or in formulae:
SHR = ηel max / 3 ηsh at t max
The temperature conditions for these RME experiments were based on the Tc-peak of the specific PO grade and
were chosen close to the practical foaming conditions, i.e. approx. 10°C above the Tc-peak of the PO types, to
prevent variations in the measurements due to premature crystallization. All RME experiments were performed
at the same strain rate setting of 1/sec, which is expected to show the best differentiation and is also close to the
practical conditions (cell growth speed).
Molecular Weight Distribution
The strain hardening of a PO grade depends strongly on it’s MWD. A good way to measure the MWD of long
chain branched PO’s is Size Exclusion Chromatography (SEC) coupled to both a refractive index (RI) and a
Multi Laser Light Scattering (MALLS) detector. This technique will further be called SEC-MALLS.
From the MWD, the following averages can be calculated: the number average molecular mass Mn (most
influenced by the shorter molecules), the weight average molecular mass Mw and the z-average molecular mass
Mz (most influenced by the longer and strongly branched molecules).
The width or polydispersity of the MWD can be expressed in the ratios Mw/Mn and Mz/Mw . The shape of the
MWD curve and as a consequence the polydispersity ratios depend strongly on the degree of LCB of the PO
grade. Non-LCB grades show typically an MWD with only one peak and rather low Mw/Mn and Mz/Mw ratios.
PO’s with high LCB show a broad MWD with an extra peak (shoulder) at the high molecular mass side of the
MWD. The Mw/Mn and Mz/Mw ratios are dependant on the polymer type and reaction process.
Using the SEC-MALLS technique, the branching degree can be determined by the g-parameter, which is the
ratio of the radius of gyration of the branched versus the linear polymer of a certain molecular mass. By
definition, non- branched polymers have a g-value of one. The higher the branching degree, the lower the gparameter, so values vary between one and zero (see Fig.5).
COMPARISON OF POLYOLEFINS
Polyolefin grades
PO grades from different polymerization processes (High Pressure Tubular, High Pressure Autoclave, Low
Pressure Slurry, Low Pressure Gas Phase, Low Pressure Solution), catalysts (Ziegler- Natta, metallocene) and
co-monomers (propene, butene, hexene, octene), were chosen for this comparison.
Table 1 shows the characteristic properties of these grades.
SEC-MALLS curves
The MWD measured by SEC-MALLS shows big differences in polydispersity and g-parameter as is shown in
Fig. 6 and 7. In general LDPE Autoclave grades have a very broad MWD with an extra peak (shoulder) at the
high molecular mass side caused by LCB. This is also expressed by the rather low values of the g-parameter in
this molecular mass range. LDPE Tubular grades exhibit a lower polydispersity than Autoclave grades and no
shoulder at higher molecular mass. The g-parameter shows that the LCB is more present at a higher molecular
mass than for Autoclave grades.
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Blowing Agents and Foaming Processes 2005
Stuttgart, Germany 10-11 May 2005
C4-, C6- and C8-LLDPE grades have a narrower MWD than LDPE Tubular grades and in general no LCB at all or
only very little LCB at very high molecular mass. mPE Plastomers even have a narrower MWD than ZieglerNatta catalysed LLDPE’s, however they show slightly more LCB.
HDPE grades in general have a relatively narrow MWD, which is demonstrated by their low polydispersity, and
have no or only very little LCB.
Table 1: Comparison of the characteristic properties of 9 Polyolefin grades
PO Type/process
MFI
Density DSC curve
DMS temp. sw. DMS freq. sw. RME curve
2
Tc-onset ηshear at Tc-onset ηshear at 10 /sec ηel max
Tm
SHR
kg/m
3
°C
°C
Pa.sec
-
-
-
-
x 10
x 10
1 = LDPE Tubular
1,9
921
108,4
100,1
2,2
468
2 = LDPE Autoclave
3 = LLDPE C4-Gasphase
2,0
1,0
921
918
107,1
121,4
98,0
110,6
1,9
3,3
4 = LLDPE C6-Gasphase
0,8
921
125,3
115,8
5 = LLDPE C8-Solution
1,0
919
123,3
112,8
6 = mPE C8-Solution
1,0
902
96,4
84,4
Unit dg/min
Pa.sec
-
-
-
-
-
8,1
7,3
11,8
12,8
429
1873
8,3
0,4
8,2
1,3
28,4
4,7
6,1
5,4
2,1
1847
1,2
1,3
4,2
5,5
2,1
1227
1,1
1,3
3,8
3,2
4,1
1429
1,7
1,8
2,4
2,1
4
4
Pa.sec
SEC-MALLS
Mw/Mn Mz/Mw
5
x 10
-
7 = HDPE Slurry
3,5
953
131,8
120,8
0,8
1098
4,5
1,4
6,4
5,0
8 = RCPP Slurry
9 = HMS PP
0,6
2,8
910
912
142,9
159,3
116,3
134,6
3,1
1,0
1147
325
4,7
22,2
1,2
49,0
3,5
8,5
10,7
4,5
PP grades (Homo Copolymers, Block Copolymers as well as Random Copolymers are characterised by a very
narrow MWD with a low polydispersity and no LCB at all. However the HMS PP grades, which have obtained
LCB by a special grafting process, show a much wider MWD. Like LDPE Autoclave grades, HMS PP grades
show a small shoulder at higher molecular mass as indication for their LCB. (Note: Due to the absence of a
reference “linear high molecular PP grade”, the g-parameter could not be calculated).
DSC curves
DSC curves are the fingerprints of PO’s and are a useful tool to identify an unknown PO sample. Characteristic
values in the DSC curve are the melting temperature Tm, the crystallization peak temperature Tc-peak, the
crystallization onset temperature Tc-onset and the heat of fusion δH. These characteristic values are related to the
crystallinity and the density of the PO grades as is demonstrated in table 2.
Table 2: Comparison of the thermal properties of Polyolefins
PO type/process
mPE Plastomer
LDPE Tubular
MD LLDPE Gasphase
HDPE Slurry
HMS PP
HOPP
Density in kg/m3
Crystallinity in %
Tm in °C
Tc-peak in °C
882
24
72
58
70
921
37
108
98
108
934
53
124
113
154
963
78
135
119
230
912
912
49
53
159
165
129
125
95
105
δH in J/g
The biggest differences in Tc-onset are found between mPE Plastomers with a very low crystallinity and HMS PP
grades with a high crystallinity, as is demonstrated by the crystallisation curves of Fig.8 and Fig.9. As a
consequence, the temperature settings on the die should be very low for mPE and rather high for HMS PP.
Also the melting temperatures show big differences for mPE Plastomer, LDPE, LLDPE, HDPE and PP as is
shown in Fig.10 and Fig. 11. In particular for PP this requires higher temperature settings on the extruder.
DMS temperature sweep curves
The speed of the viscosity increase in the DMS temperature sweep curve at Tc-onset depends very much on the
crystallinity of the PO type. High crystalline HDPE grades and Medium Density LLDPE grades show a very steep
viscosity increase whereas Very Low Density mPE Plastomers exhibit not only a very low Tc-onset, but also a
slower viscosity increase (see Fig.12 and Fig.13). This allows a wider processing temperature window for these
mPE’s as a small fraction of crystallisation will increase the viscosity but will not cause freezing of the die exit.
Differences in MFI show up in the DMS frequency sweep curves as a shift upwards or downwards in the slowly
increasing viscosity line in the molten phase (see Fig.12). As the DMS temperature sweep curve is only
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Blowing Agents and Foaming Processes 2005
Stuttgart, Germany 10-11 May 2005
measured at one frequency (or shear rate) it is better to look at the DSM frequency sweep curve to evaluate the
viscosity behaviour in the extruder.
DMS frequency sweep curves
Commonly, DMS frequency curves for PO’s are measured at 190°C or higher. For foam applications is makes
more sense to do this at lower temperatures in order to comply better with practice conditions. The usual
temperature for LDPE foam grades is 130°C, however as this is too low for PP grades, the comparison for the
PO grades was made at 190°C (see Fig.14 and Fig.15).
The decline of the shear viscosity with increasing shear rate depends on the MWD. At approximately the same
MFI, a broader MWD results in a bigger decrease of viscosity. So LDPE autoclave grades show the biggest
decrease in viscosity and linear molecules like LLDPE C4-Gasphase and HDPE Slurry show the smallest
decrease in viscosity at increasing shear rate.
RME curves
The RME curves of the LDPE Autoclave and the LDPE Tubular grade show a strong strain hardening and
consequently a high SHR value. The difference in SHR between the autoclave grade (SHR = 8,2) and the
Tubular grade (SHR = 7,3) is smaller than expected on the bases of the difference in polydispersity (see
Fig.16). Obviously the lower degree of LCB in the Tubular grade is compensated by the fact that the LCB
molecules have a higher molecular mass. The experience in foam production learns that the foamability of both
types of LDPE is very good. Experiences over the last 20 years have learned that Tubular LDPE grades are
used today for the major part of the Physical Foam applications.
As expected on the basis of the lack of LCB in the SEC-MALLS curve, the LLDPE C4-Gasphase grade shows
almost no strain hardening (SHR = 1.3). This is the same for C6-LLDPE Gasphase grade and the C8-LLDPE
Solution grade (see Fig. 17) and is in line with the experience in the production of physically blown foams.
Surprisingly the mPE Plastomer grade shows a better strain hardening and thus a higher SHR value (SHR = 1.8)
than the LLDPE gasphase grades, in spite of the narrower MWD (polydispersity is the lowest of all PO Grades).
This is caused by the small amount of LCB that was detected in the SEC-MALLS curve and probably also by the
high content of Short Chain Branching of the octene co-monomer. As earlier mentioned, another advantage for
the Physical foamability is the low crystallinity and consequently the lower foaming temperatures.
In general the linear molecules of HDPE and PP homo polymers, block copolymers and random copolymers do
not show any strain hardening. The only difference in elongational viscosity that was observed is caused by the
differences in molecular mass. However the HMS PP grades exhibit a very strong strain hardening due to the
grafted LCB. The resulting SHR of 49 is much even bigger than for Autoclave LDPE grades (SHR of 8).
HOW TO CHOOSE?
Up to now, the focus of this presentation has been on fitness for the Physical Foaming process. However to
make a choice between Polyolefin grades, one has to realize that the first priority for a foam application are the
mechanical or physical properties of the foam like softness, flexibility, compression set, rigidity, thermal
stability, tear resistance, impact strength, appearance, chemical resistance etc.
Table 3: Comparison of the mechanical and physical properties for the different PO types.
PO Type/process
Softness Stiffness
Impact
(flexibility) (E-modulus) Strength
Tear
Tensile
High
Low
Strenght
Strenght
Temp.
Temp.
Resistance Resistance
1 = LDPE Tubular
0
0
0
0
0
0
0
2 = LDPE Autoclave
3 = LLDPE C4-Gasphase
0
0
0
0
0
0/+
0
0/+
0
0/+
0
0/+
0
0
4 = LLDPE C6-Gasphase
0
0
+
+
0/+
0/+
0/+
5 = LLDPE C8-Solution
0
0
+/++
+/++
0/+
0/+
+
6 = mPE C8-Solution
++
--
++
++
--
--
++
7 = HDPE Slurry
--
++
+
+
++
++
0
8 = RCPP Slurry
9 = HMS PP
-
+
+
+
+
+
+
+
+
+
+
---
0 = reference value
+ = higher value
- = lower value
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Blowing Agents and Foaming Processes 2005
Stuttgart, Germany 10-11 May 2005
These properties are primarily dictated by the MFI and the density, or in the case of PP by the modulus of
elasticity, of the PO Grade. For this part of the choice it is good to know that the following properties depend on
MFI and density/E-modulus:
MFI
Density/E-modulus
Toughness
Softness
Impact resistance
Flexibility/Stiffness
Tear resistance
Melting temperature = Thermal stability
For the processing and foaming part of the choice it is good to know that most of the viscosity related
properties depend on the MFI and the MWD:
MFI
Density/E-modulus
Melt pressure at the die exit
Crystallisation temperature
Friction heat in extruder and die
Temperature setting of extruder
Shear viscosity
Elongational viscosity
Expansion ratio = foam cross section dimensions
Table 4: Comparison of the processing properties for the different PO types.
PO Type/process
Melt-
Strain
Friction
Shear
Foaming
Strength
Hardening
Heat
Viscosity
Temp.
(SHR)
1 = LDPE Tubular
0
0
0
0
0
2 = LDPE Autoclave
3 = LLDPE C4-Gasphase
+
--
+
--
0/+
0/+
0
+
4 = LLDPE C6-Gasphase
--
--
+
+
+
5 = LLDPE C8-Solution
--
--
+
+
+
6 = mPE C8-Solution
-
-
+/++
+/++
--
7 = HDPE Slurry
--
--
++
++
++
8 = RCPP Slurry
9 = HMS PP
-+/++
-+/++
+
+
+
+
++
++
0 = reference value
+ = higher value
- = lower value
Once the first choice for the PO type in relation to stiffness/softness/flexibility/thermal stability is made, it is
important to find the right balance between the shape and cross section surface of the die exit and the
MFI/viscosity related parameters of the PO type. This presentation tries to make this choice easier by showing
the relations between the PO characteristics and the requirements for Physical Foaming.
ACKNOWLEDGMENT
The author likes to thank Dr. M. Reimker of Berstorff GmbH, Hannover for the use of the scheme of the
“Schaumtandemlinie ZE/KE”, Mrs. R. Tandler and Mr. T. Sleypen of DSM Research for the DMS curves,
Mr. P. Meijers of DSM Research for the DSC curves, Mr. H. Wallink of DSM Research for the RME curves, Mr.
E. Gelade and Mr. S. Jacobs of DSM Research for the SEC-MALLS curves and Mr. J. Krist of SABIC
EuroPetrochemicals for his help with the illustrations.
LITERATURE
Lit. 1 =
Meissner J (1971) Dehnungsverhalten von Polyäthylenschmelzen. Rheol Acta 10:230-240
Lit. 2 =
Meissner J, Hostettler J (1994) A new elongational rheometer for polymer melts and ather highly viscoelastic liquids. Rheol Acta
33:1-21
Lit. 3 = Wagner MH, Bastian H, Hachmann P, Meissner J, Kurzbeck S, Münstedt H, Langouche F (2000) The strain-hardening behaviour
of linear and long-chain-branched polyethylene melts in extensional flows. Rheol Acta 39:97-109
Lit. 4 = Ruinaard H (2005) Elongational viscosity as a tool to predict the foamability of Polyolefins. ANTEC 2005
Paper 102267.
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Blowing Agents and Foaming Processes 2005
Stuttgart, Germany 10-11 May 2005
Fig. 1
Fig. 4
RME curve of SABIC ® LDPE 2102TX00
DSC curve of SABIC ® LDPE 2102TX00
40
ηel max
1,0E+07
35
1,0E+06
30
Viscosity [Pa.s]
Tc-onset
Crystallization curve
dq/dt in mW
Tm
25
Melting curve
1,0E+05
3 ηshear
1,0E+04
20
Tc
15
1,0E+03
40
50
60
70
80
90
100
110
120
130
140
150
Time [s]
0,1
1
10
T in °C
Fig. 2
Fig. 5
DMS Temp. sweep curve of SABIC ® LDPE 2102TX00
0,8
1,2
1,0E+07
1=LDPE Tubular
2=LDPE Autoclave
1=LDPE Tubular
2=LDPE Autoclave
0,7
1,0
0,6
1,0E+05
1,0E+04
0,8
0,5
1
0,4
0,6
0,3
0,4
0,2
2
0,2
0,0
1,0E+03
80
100
120
140
g
d W(M) / d (log M)
Eta* in Pa.s
1,0E+06
160
0,1
2
3
4
T in °C
5
6
7
8
0,0
log M
Fig. 3
Fig. 6
DMS Freq. Sweep curve of SABIC ® LDPE 2102TX00
1,2
0,8
1=LDPE Tubular
2=LDPE Autoclave
3=LLDPE C4 Gasphase
6=mPE C8 Solution
1,0
1=LDPE Tubular
2=LDPE Autoclave
0,7
3=LLDPE C4 Gasphase
6=mPE C8 Solution
6
0,6
3
Eta* in Pa.s
d W(M) / d (log M)
1,0E+04
1,0E+03
0,8
0,5
1
0,6
0,4
0,3
0,4
1,0E+02
1,0E-03
0,0
1,0E-02
1,0E-01
1,0E+00
Freq
in rad/s
1,0E+01
1,0E+02
1,0E+03
7
0,2
2
0,2
0,1
2
3
4
5
log M
6
7
8
0,0
g
1,0E+05
Blowing Agents and Foaming Processes 2005
Stuttgart, Germany 10-11 May 2005
Fig. 7
Fig. 10
1,2
1,2
Melting curves of LDPE, LLDPE, mPE and PP grades
35
9 = HMS PP
5=LLDPE C8 Solution
8=RCPP Slurry
9=HMS PP
7=HDPE Slurry
4=LLDPE C6 Gasphase
5=LLDPE C8 Solution
4=LLDPEC6 Gasphase
5
4 = LLDPE C6-Gasphase
1 = LDPE Tubular
1,0
2 = LDPE Autoclave
6 = mPE C8-Solution
30
4
8
0,8
4
0,8
1
2
0,6
9
0,4
0,4
0,2
0,2
dq/dt in mW
0,6
g
7
9
25
6
20
0,0
2
3
4
5
6
7
8
0,0
15
40
50
60
70
80
90
100
110
120
130
140
150
160
170
160
170
T in °C
log M
Fig. 8
Fig. 11
Cryst. curves of LDPE, LLDPE, mPE and PP grades
Melting curves of LLDPE, HDPE and PP grades
45
40
5 = LLDPE C8-Solution
7
7 = HDPE Slurry
35
3 = LLDPE C4-Gasphase
40
8 = RCPP Slurry
9 = HMS PP
30
35
dq/dt in mW
dq/dt in mW
25
6
20
2
1
30
3
9
9
15
25
4
9 = HMS PP
8
5
4 = LLDPE C6-Gasphase
10
1 = LDPE Tubular
20
2 = LDPE Autoclave
5
6 = mPE C8-Solution
15
0
40
50
60
70
80
90
100
110
120
130
140
40
150
50
60
70
80
90
100
110
120
130
140
150
T in °C
T in °C
Fig. 9
Fig. 12
Crystallization curves of LLDPE, HDPE and PP grades
Temp. sweep curves of LDPE, LLDPE, mPE and HDPE
40
1,0E+07
1
35
7
3
2
6
5
30
8
1,0E+06
25
7 = HDPE Slurry
15
3
5 = LLDPE C8-Solution
9
3 = LLDPE C4-Gasphase
10
Eta* in Pa.s
20
dq/dt in mW
d W(M) / d (log M)
1,0
7
8 = RCPP Slurry
1,0E+05
9 = HMS PP
5
1 = LDPE Tubular
1,0E+04
2 = LDPE Autoclave
3 = LLDPE C4-Gasphase
0
40
50
60
70
80
90
100
110
120
130
140
150
6 = mPE C8-Solution
7 = HDPE Slurry
-5
1,0E+03
-10
70
T in °C
8
90
110
T in °C
130
Blowing Agents and Foaming Processes 2005
Stuttgart, Germany 10-11 May 2005
Fig. 13
Fig. 16
DMS Temperature Sweep curves
1,0E+07
1,0E+08
2 = LDPE Tubular
1 = LDPE Autoclave
1,0E+07
3 = LLDPE C4-Gasphase
9
8
4
6 = mPE Plastomer
1,0E+06
7
1
2
Viscosity [Pa.s]
Eta* in Pa.s
5
1,0E+06
1,0E+05
6
1,0E+05
3
1,0E+04
4 = LLDPE C6-Gasphase
5 = LLDPE C8-Solution
1,0E+04
7 = HDPE Slurry
8 = RCPP Slurry
9 = HMS PP
1,0E+03
1,0E+03
80
100
120
140
160
Time [s]
0,1
T in °C
Fig. 14
1
10
Fig. 17
DMS Frequency sweep curves
1,0E+07
1,0E+05
8 = RCPP Slurry
9 = HMS PP
7 = HDPE Slurry
4 = LLDPE C6-Gasphase
1,0E+06
2
7
6
Viscosity [Pa.s]
Eta* in Pa.s
1,0E+04
3
1
1,0E+03
1 = LDPE Tubular
5 = LLDPE C8-Solution
9
1,0E+05
4
8
5
7
1,0E+04
2 = LDPE Autoclave
3 = LLDPE C4-Gasphase
6 = mPE C8-Solution
7 = HDPE Slurry
1,0E+03
1,0E+02
1,0E-03
1,0E-02
1,0E-01
1,0E+00
Freq
1,0E+01
1,0E+02
1,0E+03
1,0E+02
1,0E+03
0,1
in rad/s
Fig. 15
DMS Frequency Sweep curves
1,0E+05
8
1,0E+04
Eta* in Pa.s
4
7
5
9
1,0E+03
4 = LLDPE C6-Gasphase
5 = LLDPE C8-Solution
7 = HDPE Slurry
8 = RCPP Slurry
9 = HMS PP
1,0E+02
1,0E-03
1,0E-02
1,0E-01
1,0E+00
Freq
1,0E+01
in rad/s
9
Time [s]
1
10