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). 1 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. 2 Blowing Agents and Foaming Processes 2005 Stuttgart, Germany 10-11 May 2005 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. 3 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 4 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 5 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. 6 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
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