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Influence of molar mass distribution and long-chain branching on strain hardening of low density polyethylene

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Abstract

Low-density polyethylenes (LDPE) were synthesized in a laboratory-scale autoclave under high pressure. These samples were found to possess a high molar mass tail, resulting in a distinctly bimodal molar mass distribution and a lower concentration of long-chain branching than typical of commercial LDPEs. Rheological experiments in elongation showed that these samples exhibit a very pronounced strain hardening, which could be favorable for distinct processing operations. Although the samples have a rather high molar mass (\(M_{\rm w} = 2{\ldots}4 \times 10^{6}\) g/mol), their zero shear-rate viscosities η 0 and their shear thinning behavior are still in a range, where thermoplastic processing is possible. A qualitative understanding of the experimental results is tried by the model of the Cayley tree.

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Notes

  1. The fact that the injected mass is found within ±5% by the detectors is taken as a quality criterion of the measurement. Such an agreement is especially important considering the high molar masses of the CSTR-LDPEs, as they may contain insoluble (gelled) fractions.

  2. This equation is only defined for monodisperse solutions. For polydisperse cases, a slightly different equation applies (Zimm and Stockmayer 1949).

  3. A side-chain content s c of butyl chains of 27 wt.% would lead to an amorphous polymer.

  4. Please note that η max = 500,000 Pa s was taken as η 0 for CSTR-LDPE 1.

  5. LDPE 2 does not have a maximum in the strain hardening in the range under experimental investigation.

References

  • Bach A, Rasmussen HK, Hassager O (2003) Extensional viscosity for polymer melts measured in the filament stretching rheometer. J Rheol 47(2):429–441

    Article  ADS  CAS  Google Scholar 

  • Barroso VC, Ribeiro SP, Maia JM (2003) Stress relaxation after a step strain in uniaxial extension of polyisobutylene and polyethylene. Rheol Acta 42(4):345–354

    Article  CAS  Google Scholar 

  • Beer F, Capaccio G, Rose LJ (1999a) High molecular weight tail and long-chain branching in low density polyethylene. Polymer 80:2815–2822

    Google Scholar 

  • Beer F, Capaccio G, Rose LJ (1999b) High molecular weight tail and long-chain branching in SRM 1476 polyethylene. J Appl Polym Sci 73(14):2807–2812

    Article  CAS  Google Scholar 

  • Buback M, Busch M, Lovis K, Mähling FO (1994) Development of a high-pressure high-temperature stirred vessel with incidence of light for continuous operation. Chemie Ingenieur Technik 66(4):510–513

    Article  CAS  Google Scholar 

  • Buback M, Busch M, Lovis K, Mähling FO (1995) Mini-pilot plant for continuous high pressure polymerisation. Chemie Ingenieur Technik 67(12):1652–1655

    Article  CAS  Google Scholar 

  • Buback M, Busch M, Lovis K, Mähling FO (1996) High-pressure free-radical copolymerization of ethene and butyl acrylate. Macromol Chem Phys 197(1):303–313

    Article  CAS  Google Scholar 

  • Burchard W (1974) Statistics of star-shaped molecules. II. Stars with polydisperse side chains. Macromolecules 7(6):841–846

    Article  ADS  CAS  Google Scholar 

  • Coll H, Gilding DK (1970) Universal calibration in gel-permeation chromatography: study of polystyrene, poly(α-methylstyrene), and polypropylene. J Polym Sci B, Polym Phys 8:89–103

    CAS  Google Scholar 

  • Dealy J, Larson RG (2006) Structure and rheology of molten polymers—from structure to flow behavior and back again. Hanser, Munich

    Google Scholar 

  • Frater DJ, Mays JW, Jackson C (1997) Synthesis and dilute solution properties of divinylbenzene-linked polystyrene stars with mixed arm lengths: evidence for coupled stars. J Polym Sci B, Polym Phys 35(1):141–151

    Article  CAS  Google Scholar 

  • Gabriel C, Lilge D (2006) Molecular mass dependence of the zero shear-rate viscosity of LDPE melts: evidence of an exponential behaviour. Rheol Acta 45:992–1002

    Article  Google Scholar 

  • Gabriel C, Münstedt H (2002) Influence of long-chain branches in polyethylenes on linear viscoelastic flow properties in shear. Rheol Acta 41(3):232–244

    Article  CAS  Google Scholar 

  • Gabriel C, Münstedt H (2003) Strain hardening of various polyolefins in uniaxial elongational flow. J Rheol 47(3):619–630

    Article  ADS  CAS  Google Scholar 

  • Gabriel C, Kaschta J, Münstedt H (1998) Influence of molecular structure on rheological properties of polyethylenes I. Creep recovery measurements in shear. Rheol Acta 37(1):7–20

    Article  CAS  Google Scholar 

  • Hadjichristidis N, Xenidou M, Iatrou H, Pitsikalis M, Poulos Y, Avgeropoulos A, Sioula S, Paraskeva S, Velis G, Lohse DJ, Schulz DN, Fetters LJ, Wright PJ, Mendelson RA, Garcia-Franco CA, Sun T, Ruff CJ (2000) Well-defined, model long chain branched polyethylene. 1. Synthesis and characterization. Macromolecules 33(7):2424–2436

    Article  ADS  CAS  Google Scholar 

  • Laun HM, Münstedt H (1978) Elongational behaviour of a low density polyethylene melt I. Strain rate and stress dependence of viscosity and recoverable strain in the steady-state. Comparison with shear data. Influence of interfacial tension. Rheol Acta 17:415–425

    Article  CAS  Google Scholar 

  • Malmberg A, Gabriel C, Steffl T, Münstedt H, Löfgren B (2002) Long-chain branching in metallocene-catalyzed polyethylenes investigated by low oscillatory shear and uniaxial extensional rheometry. Macromolecules 35:1038–1048

    Article  ADS  CAS  Google Scholar 

  • Meissner J (1969) Rheometer for the study of mechanical properties of deformation of plastic melts under definite tensile stress. Rheol Acta 8(1):78–88

    Article  CAS  Google Scholar 

  • Münstedt H (1979) Elongational behavior of a low density polyethylene melt II. Transient behavior in constant stretching rate and tensile creep experiments. Comparison with shear data. Temperature dependence of the elongational properties. Rheol Acta 18:492–504

    Article  Google Scholar 

  • Münstedt H (1986) Polymerschmelzen. In: Kulicke W (ed) Fließverhalten von Stoffen und Stoffgemischen. Hüthig & Wepf, Basel, pp 238–279

    Google Scholar 

  • Münstedt H, Auhl D (2005) Rheological measuring techniques and their relevance for the molecular characterization of polymers. J Non-Newton Fluid Mech 128(1):62–69

    Article  Google Scholar 

  • Münstedt H, Schwetz M, Heindl M, Schmidt M (2001) Influence of molecular structure on secondary flow of polyolefin melts as investigated by laser-Doppler velocimetry. Rheol Acta 40:384–394

    Article  Google Scholar 

  • Münstedt H, Steffl T, Malmberg A (2005) Correlation between rheological behaviour in uniaxial elongation and film blowing properties of various polyethylenes. Rheol Acta 45(1):14–22

    Article  Google Scholar 

  • Piau JM, Agassant JF (1996) Rheology for melt processing. Elsevier, Amsterdam

    Google Scholar 

  • Piel C, Stadler FJ, Kaschta J, Rulhoff S, Münstedt H, Kaminsky W (2006) Structure–property relationships of linear and long-chain branched metallocene high-density polyethylenes and SEC-MALLS. Macromol Chem Phys 207(1):26–38

    Article  CAS  Google Scholar 

  • Podzimek S, Vlcek T, Johann C (2001) Characterization of branched polymers by size exclusion chromatography coupled with multiangle light scattering detector. I. Size exclusion chromatography elution behavior of branched polymers. J Appl Polym Sci 81(7):1588–1594

    Article  CAS  Google Scholar 

  • Rubio P, Wagner MH (2000) LDPE melt rheology and the pom-pom model. Polymer 92:245–259

    MATH  CAS  Google Scholar 

  • Scholte TG, Meijerink NLJ, Schoffeleers HM, Brands AMG (1984) Mark–Houwink equation and GPC calibration for linear short-chain branched polyolefins, including polypropylene and ethylene–propylene copolymers. J Appl Polym Sci 29:3763–3782

    Article  CAS  Google Scholar 

  • Schwetz M, Münstedt H, Heindl M, Merten A (2002) Investigations on the temperature dependence of the die entrance flow of various long-chain branched polyethylenes using laser-Doppler velocimetry. J Rheol 46(4):797–815

    Article  ADS  CAS  Google Scholar 

  • Stadler FJ, Bailly C (2008) A new method for the calculation of continuous relaxation spectra from dynamic-mechanical data. Rheol Acta doi:10.1007/s00397-008-0303-2

  • Stadler FJ, Münstedt H (2008a) Terminal viscous and elastic rheological characterization of ethene-/α-olefin copolymers. J Rheol 52(3):697–712. doi:10.1122/1.2892039

    Article  ADS  CAS  Google Scholar 

  • Stadler FJ, Münstedt H (2008b) Numerical description of shear viscosity functions of long-chain branched metallocene-catalyzed polyethylenes. J Non-Newton Fluid Mech 151:129–135. doi:10.1016/j.jnnfm.2008.01.010

    Article  MATH  CAS  Google Scholar 

  • Stadler FJ, Piel C, Kaminsky W, Münstedt H (2006a) Rheological characterization of long-chain branched polyethylenes and comparison with classical analytical methods. Macromol Symp 236(1):209–218

    Article  CAS  Google Scholar 

  • Stadler FJ, Piel C, Kaschta J, Rulhoff S, Kaminsky W, Münstedt H (2006b) Dependence of the zero shear-rate viscosity and the viscosity function of linear high density polyethylenes on the mass-average molar mass and polydispersity. Rheol Acta 45(5):755–764

    Article  CAS  Google Scholar 

  • Stadler FJ, Piel C, Klimke K, Kaschta J, Parkinson M, Wilhelm M, Kaminsky W, Münstedt H (2006c) Influence of type and content of very long comonomers on long-chain branching of ethene-/α-olefin copolymers. Macromolecules 39(4):1474–1482

    Article  ADS  CAS  Google Scholar 

  • Stadler FJ, Nishioka A, Stange J, Koyama K, Münstedt H (2007) Comparison of the elongational behavior of various polyolefins in uniaxial and equibiaxial flows. Rheol Acta 46(7):1003–1012. doi:10.1007/s00397-007-0190-y

    Article  CAS  Google Scholar 

  • Tackx P, Tacx JCJF (1998) Chain architecture of LDPE as a function of molar mass using size exclusion chromatography and multi-angle laser light scattering (SEC-MALLS). Polymer 39(14):3109–3113

    Article  CAS  Google Scholar 

  • Utracki LA, Schlund B (1987) Linear low density polyethylenes and their blends. Part 2. Shear flow of LLDPE’s. Polym Eng Sci 27(5):367–379

    Article  CAS  Google Scholar 

  • 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 polyolefin melts in extensional flows. Rheol Acta 39:97–109

    Article  CAS  Google Scholar 

  • Wagner MH, Rubio P, Bastian H (2001) The molecular stress function model for polydisperse polymer melts with dissipative convective constraint release. J Rheol 45(6):1387–1412

    Article  ADS  CAS  Google Scholar 

  • Ye XN, Sridhar T (2001) Shear and extensional properties of three-arm polystyrene solutions. Macromolecules 34(23):8270–8277

    Article  ADS  CAS  Google Scholar 

  • Zimm BHM, Stockmayer WH (1949) The dimensions of molecules containing branching and rings. J Chem Phys 17(12):1301–1314

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

The authors thank Mrs. I. Herzer (University Erlangen-Nürnberg) for the GPC–MALLS measurements and J. Stange (University Erlangen-Nürnberg, now Bayer Material Science) for scientific input into this project.

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Author notes

  1. Florian J. Stadler

    Present address: Unité de Physique et de Chimie des Hauts Polymères Université catholique de Louvain, Croix du Sud, 1, B-1348, Louvain-la-Neuve, Belgium

  2. Florian Becker

    Present address: BASF AG, Ludwigshafen, Germany

Authors and Affiliations

  1. Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nürnberg, Martensstr. 7, D-91058, Erlangen, Germany

    Florian J. Stadler, Joachim Kaschta & Helmut Münstedt

  2. Institute of Physical Chemistry, Georg-August-University Göttingen, Tammannstraße 6, D-37077, Göttingen, Germany

    Florian Becker & Michael Buback

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  1. Florian J. Stadler
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  2. Joachim Kaschta
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Correspondence to Helmut Münstedt.

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Stadler, F.J., Kaschta, J., Münstedt, H. et al. Influence of molar mass distribution and long-chain branching on strain hardening of low density polyethylene. Rheol Acta 48, 479–490 (2009). https://doi.org/10.1007/s00397-008-0334-8

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  • DOI: https://doi.org/10.1007/s00397-008-0334-8

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