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Licensed Unlicensed Requires Authentication Published by De Gruyter April 6, 2013

Effect of Sparse Long-chain Branching on the Film-casting Behavior for a Series of Well-defined HDPEs

C. D. McGrady , C. W. Seay and D. G. Baird

Abstract

The effect of sparse long chain branching, LCB, on the film-casting process is analyzed using a molecular model for the rheological behavior for a series of well-characterized, high-density polyethylene (HDPE) resins and a low-density polyethylene (LDPE) resin at various drawdown ratios. A full rheological characterization in both shear and shear-free flows is also presented. At low drawdown ratios, the LDPE exhibited the least degree of necking at distances less than the HDPE frostline. The sparsely-branched HDPE resins films had similar final film-widths that were larger than those of the linear HDPE. As the drawdown ratio was increased, film width profiles separated based on branching level. Small amounts of LCB were found to reduce the amount of necking at intermediate drawdown ratios. At higher drawdown ratios, the sparsely-branched HDPE resins of lower LCB content had film-widths that mimicked that of the linear HDPE, while the sparsely-branched HDPE resins of higher LCB content retained a larger film width. Molecular structural analysis via the Pom-Pom constitutive model suggested that branching that was distributed across a larger range of backbone lengths served to improve resistance to necking. As the drawdown ratio increased, the length of the backbones dominating the response decreased, so that the linear chains were controlling the necking behavior of the sparsely-branched resins of lower LCB content while remaining in the branched regime for higher LCB content HDPEs. Other processing variables such as shear viscosity magnitude, extrudate swell, and non-isothermal processing conditions were eliminated as contributing factors to the differences in the film width profile.


Mail address: Donald G. Baird, Department of Chemical Engineering, Virginia Tech., 128 Randolph Hall, Blacksburg, VA, 24061-0211, USA. E-mail:

References

Auhl, D., et al., “Linear and Nonlinear Shear Flow Behavior of Monodisperse Polyisoprene Melts with a Large Range of Molecular Weights”, J. Rheol., 52, 801835(2008) DOI: 10.1122/1.2890780Search in Google Scholar

Auhl, D., et al., “Long-Chain Branched Polypropylenes by Electron Beam Irradiation and Their Rheological Properties”, Macromolecules, 37, 94659472(2004) DOI: 10.1021/ma030579wSearch in Google Scholar

Bach, A., et al., “Extensional Viscosity for Polymer Melts Measured in the Filament Stretching Rheometer”, J. Rheol., 47, 429441(2003) DOI: 10.1122/1.1545072Search in Google Scholar

Baird, D. G., Collias, D. I.: Polymer Processing, John Wiley & Sons, New York(2003)Search in Google Scholar

Bin Wadud, S. E., Baird, D. G., “Shear and Extensional Rheology of Sparsely Branched Metallocene-Catalyzed Polyethylenes”, J. Rheol., 44, 11511167(2000) DOI: 10.1122/1.1289280Search in Google Scholar

Bird, R. B., et al.: Dynamics of Polymeric Liquids, John Wiley & Sons, Hoboken(1987)Search in Google Scholar

Blackwell, R. J., et al., “Molecular Drag-strain Coupling in Branched Polymer Melts”, J. Rheol., 44, 121136(2000) DOI: 10.1122/1.551081Search in Google Scholar

Canning, K., Co, A., “Edge Effects in Film Casting of Molten Polymers”, J. Plast. Film Sheeting, 16, 188203(2000) DOI: 10.1177/875608700772677553Search in Google Scholar

Collis, M. W., et al., “Constriction Flows of Monodisperse Linear Entangled Polymers: Multiscale Modeling and Flow Visualization”, J. Rheol., 49, 501522(2005) DOI: 10.1122/1.1849180Search in Google Scholar

Das, C., et al., “Computational Linear Rheology of General Branch-on-branch Polymers”, J. Rheol., 50, 207234(2006) DOI: 10.1122/1.2167487Search in Google Scholar

de Gennes, P. G., “Reptation of a Polymer Chain in the Presence of Fixed Obstacles”, J. Chem. Phys., 55, 572–??? (1971)10.1063/1.1675789Search in Google Scholar

Dobroth, T., Erwin, L., “Causes of Edge Beads in Cast Films”, Polym. Eng. Sci., 26, 462467(1986) DOI: 10.1002/pen.760260704Search in Google Scholar

Doerpinghaus, P. J.: Flow Behavior of Sparsely Branched Metallocene-Catalyzed Polyethylenes, Ph.D. Dissertation, Virginia Tech, Blacksburg (2002)Search in Google Scholar

Doerpinghaus, P. J., Baird, D. G., “Assessing the Branching Architecture of Sparsely Branched Metallocene-Catalyzed Polyethylenes Using the Pompom Constitutive Model”, Macromolecules, 35, 1008710095(2002) DOI: 10.1021/ma021332mSearch in Google Scholar

Doerpinghaus, P. J., Barid, D. G., “Separating the Effects of Sparse Long-Chain Branching on Rheology from those Due to Molecular Weight in Polyethylenes”, J. Rheol., 47, 717736(2003) DOI: 10.1122/1.1567751Search in Google Scholar

Doi, M., Edwards, S. F.: The Theory of Polymer Dynamics, Oxford University Press, Oxford(1988)Search in Google Scholar

Fetters, L. J., et al., “Rheological Behavior of Star-shaped Polymers”, Macromolecules, 26, 64754(1993) DOI: 10.1021/ma00056a015Search in Google Scholar

Gabriel, C., et al., “Influence of Molecular Structure on Rheological Properties of Polyethylenes. Part 1. Creep Recovery Measurements in Shear”, Rheol. Acta, 37, 720(1998) DOI: 10.1007/s003970050086Search in Google Scholar

Inkson, N.J., et al., “Modeling Low Density Polyethylene Rheology Using the Pom-Pom Model”, Prog. Trends Rheol. V, Proc. 5th Eur. Rheol. Conf., 336337(1998)10.1007/978-3-642-51062-5_159Search in Google Scholar

Inkson, N. J., et al., “Predicting Low Density Polyethylene Melt Rheology in Elongational and Shear Flows with “Pom-Pom” Constitutive Equations”, J. Rheol., 43, 873896(1999) DOI: 10.1122/1.551036Search in Google Scholar

Ito, H., et al., “A Model of Neck-in Phenomenon in Film Casting Process”, J. Soc. Rheol., Jpn., 31, 157163(2003)10.1678/rheology.31.157Search in Google Scholar

Iyengar, V. R., Co, A., “Film Casting of a Modified Giesekus Fluid: Stability Analysis”, Chem. Eng. Sci., 51, 14171430(1996) DOI: 10.1016/0009-2509(95)00316-9Search in Google Scholar

Janzen, J., Colby, R. H., “Rheological Detection of Long-chain Branching in High-density Polyethylenes”, Polym. Mater. Sci. Eng., 82, 128129(2000)Search in Google Scholar

Kajiwara, T., et al., “Relationship Between Neck-in Phenomena and Rheological Properties in Film Casting”, Nihon Reoroji Gakkaishi, 34, 97103(2006) DOI: 10.1678/rheology.34.97Search in Google Scholar

Kim, J., et al., “Transient Solutions of the Dynamics of Film Casting Process Using a 2-D Viscoelastic Model”, J. Non-Newtonian Fluid Mech., 132, 5360(2005) DOI: 10.1016/j.jnnfm.2005.10.002Search in Google Scholar

Lai, S., et al., “Flexible Substantially Linear Olefin Polymers”, PCT Int. Appl., (1993)Search in Google Scholar

Lee, J. S., et al., “Kinematic Waves and Draw Resonance in Film Casting Process”, J. Non-Newtonian Fluid Mech., 101, 4354(2001) DOI: 10.1016/S0377-0257(01)00155-0Search in Google Scholar

Linster, J. J., Meissner, J., “Melt Elongation and Structure of Linear Polyethylene (HDPE)”, Polymer Bulletin, 16, 18794(1986) DOI: 10.1007/BF00955490Search in Google Scholar

Lohse, D., et al., “Well-Defined, Model Long Chain Branched Polyethylene. 2. Melt Rheological Behavior”, Macromolecules, 35, 30663075(2002) DOI: 10.1021/ma0117559Search in Google Scholar

McGrady, C. D., Baird, D. G., “Method for Overcoming Ductile Failure in Munstedt-type Extensional Rheometers”, J. Rheol., 53, 539545(2009) DOI: 10.1122/1.3109574Search in Google Scholar

McLeish, T., et al., “Dynamics of Entangled H-polymers: Theory, Rheology, and Neutron-scattering”, Macromolecules, 32, 67346758(1999) DOI: 10.1021/ma990323jSearch in Google Scholar

McLeish, T., Larson, R., “Molecular Constitutive Equations for a Class of Branched Polymers: The Pom-Pom Polymer”, J. Rheol., 42, 81110(1998) DOI: 10.1122/1.550933Search in Google Scholar

Minoshima, W., White, J. L., “Instability Phenomena in Tubular Film, and Melt Spinning of Rheologically Characterized High-density, Low-density and Linear Low-density Polyethylenes”, J. Non-Newtonian Fluid Mech., 19, 275302(1986) DOI: 10.1016/0377-0257(86)80053-2Search in Google Scholar

Münstedt, H., Auhl, D.Rheological Measuring Techniques and Their Relevance for the Molecular Charecterization of Polymers”, J. Non-Newtonian Fluid Mech., 128, 6269(2005) DOI: 10.1016/j.jnnfm.2005.03.011Search in Google Scholar

Munstedt, H., Kurzbeck, S., “Elongational Behavior and Molecular Structure of Polymer Melts”, Prog. Trends Rheol. V, Proc. 5th Eur. Rheol. Conf., 41–44 (1998)10.1007/978-3-642-51062-5_13Search in Google Scholar

Münstedt, H., Laun, H., “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, 492504(1979)10.1007/BF01736955Search in Google Scholar

Nielsen, J., et al.Elongational Viscosity of Monodisperse and Bidisperse Polystyrene Melts”, J. Rheol.50, 453(2006) DOI: 10.1122/1.2206711Search in Google Scholar

Pis-Lopez, M., Co, A., “Multilayer Film Casting of Modified Giesekus Fluids. Part 1. Steady-state Analysis”, J. Non-Newtonian Fluid Mech, 66, 7193(1996)10.1016/0377-0257(96)01468-1Search in Google Scholar

Pis-Lopez, M., Co, A., “Multilayer Film Casting of Modified Giesekus Fluids. Part 2. Linear Stability Analysis”, J. Non-Newtonian Fluid Mech., 66, 95114(1996) DOI: 10.1016/0377-0257(96)01469-3Search in Google Scholar

Roovers, J., “Properties of the Plateau Zone of Star-branched Polybutadienes and Polystyrenes”, Polymer, 26, 1091(1985)10.1016/0032-3861(85)90234-4Search in Google Scholar

Sakaki, K., et al., “Three-dimensional Flow Simulation of a Film-casting Process”, Polym. Eng. Sci., 36, 18211831(1996) DOI: 10.1002/pen.10577Search in Google Scholar

Satoh, N., et al., “Viscoelastic Simulation of Film Casting Process for a Polymer Melt”, Polym. Eng. Sci., 41, 15641579(2001) DOI: 10.1002/pen.10855Search in Google Scholar

Seay, C. W., Baird, D. G., “Sparse Long-chain Branching's Effect on the Film-casting Behavior of PE”, Int. Polym. Proc., 24, 4149(2009) DOI: 10.3139/217.2184Search in Google Scholar

Sentmanat, M. L., et al., “Measuring the Transient Extensional Rheology of Polyethylene Melts Using the SER Universal Testing Platform”, J. Rheol., 49, 585606(2005) DOI: 10.1122/1.1896956Search in Google Scholar

Sentmanat, M. L., “Miniature Universal Testing Platform: From Extensional Melt Rheology to Solid-state Deformation Behavior”, Rheol. Acta, 43, 657669(2004) DOI: 10.1007/s00397-004-0405-4Search in Google Scholar

Silagy, D., et al., “Study of the Stability of the Film Casting Process”, Polym. Eng. Sci., 36, 26142625(1996) DOI: 10.1002/pen.10661Search in Google Scholar

Silagy, D., et al., “Stationary and Stability Analysis of the Film Casting Process”, J. Non-Newtonian Fluid Mech., 79, 563584(1998) DOI: 10.1016/S0377-0257(98)00119-0Search in Google Scholar

Smith, S., Stolle, D., “Numerical Simulation of Film Casting Using an Updated Lagrangian Finite Element Algorithm”, Polym. Eng. Sci., 43, 11051122(2003) DOI: 10.1002/pen.10094Search in Google Scholar

Sollogoub, C., et al., “Non-isothermal Viscoelastic Numerical Model of the Cast-film Process”, J. Non-Newtonian Fluid Mech., 138, 7686(2006) DOI: 10.1016/j.jnnfm.2005.11.011Search in Google Scholar

Tanner, R. I., “Theory of Die-swell”, J. Polym. Sci., Polym. Phys. Ed., 8, 20672078(1970)Search in Google Scholar

Wood-Adams, P., “The Effect of Long Chain Branches on the Shear Flow Behavior of Polyethylene”, J. Rheol., 45, 203210(2001) DOI: 10.1122/1.1332785Search in Google Scholar

Wood-Adams, P., Dealy, J., “Using Rheological Data to Determine the Branching Level in Metallocene Polyethylenes”, Macromolecules, 33, 74817488(2000) DOI: 10.1021/ma991534rSearch in Google Scholar

Wood-Adams, P., et al., “Effect of Molecular Structure on the Linear Viscoelastic Behavior of Polyethylene”, Macromolecules, 33, 74897499(2000) DOI: 10.1021/ma991533zSearch in Google Scholar

Zheng, H., et al.Three-dimensional Simulation of the Non-isothermal Cast Film Process of Polymer Melts”, J. Polym. Res., 13, 433440(2006) DOI: 10.1007/s10965-006-9064-8Search in Google Scholar

Received: 2009-05-13
Accepted: 2009-09-04
Published Online: 2013-04-06
Published in Print: 2009-11-01

© 2009, Carl Hanser Verlag, Munich

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