Transient solutions of the dynamics of film casting process using a 2-D viscoelastic model

Kim, Ju Min; Lee, Joo Sung; Shin, Dong‐Myeong; Jung, Hyun Wook; Hyun, Jae Chun

doi:10.1016/j.jnnfm.2005.10.002

Cited by 33 publications

(11 citation statements)

References 27 publications

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“…This is not a mathematical artifact and an US patent has been applied (Chambon et al, 1998) to draw films in these super-stable conditions. Silagy et al (1998) and Kim et al (2005) coupled the UCM model with a 2D membrane model accounting for width and thickness reduction. Kim et al (2005) computed the transient thickness and width responses to small perturbations using a time-space numerical scheme.…”

Section: Influence Of the Rheologymentioning

confidence: 99%

“…Silagy et al (1998) and Kim et al (2005) coupled the UCM model with a 2D membrane model accounting for width and thickness reduction. Kim et al (2005) computed the transient thickness and width responses to small perturbations using a time-space numerical scheme. Shin et al (2007a) developed the same approach but with a Phan-Thien Tanner model which limits the increase of the elongation viscosity.…”

Section: Influence Of the Rheologymentioning

confidence: 99%

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An Overview of Molten Polymer Drawing Instabilities

Agassant¹,

Demay²

2014

Film Processing Advances

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Drawing instabilities and rupture are a serious limitation in polymer fibre and film processing. Onset of these defects depends on the processing conditions, on heat transfer, and on the rheology of the polymer even if some may be encountered for Newtonian fluids. The main part of this paper is devoted to the different forms of the draw resonance instability encountered in fibre spinning, cast-film and film blowing. The time dependent equations are presented for the simplified situation of constant width cast-film. Results of the two possible modelling strategies, linear stability analysis and direct simulation, applied to the different fibre and film processes are discussed.

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Section: Influence Of the Rheologymentioning

confidence: 99%

Section: Influence Of the Rheologymentioning

confidence: 99%

An Overview of Molten Polymer Drawing Instabilities

Agassant¹,

Demay²

2014

Film Processing Advances

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“…The dimensionless governing equations for 2-D isothermal film casting system are expressed below based on the models by Silagy et al [12] and Kim et al [4]. The Phan-Thien Tanner constitutive equation, which is well known for delineating the extensional behavior of polymeric liquids, is incorporated here for describing the viscoelastic nature [5,19].…”

Section: Time-dependent Governing Equationsmentioning

confidence: 99%

“…Draw resonance instability, which is distinguished by periodic oscillations of state variables such as film thickness, film width, and tension, arises as the drawdown ratio (ratio of fluid velocities at take-up roll and slit die) is raised beyond its onset [3][4][5][6]. The same phenomenon can be also manifested in other extensional deformation processes, e.g., fiber spinning and film blowing [2,7].…”

Section: Introductionmentioning

confidence: 99%

“…Agassant's group developed varying width 1-D models to explain the neck-in defect and also predicted both edge bead and neck-in as well as draw resonance using 2-D models [12][13][14][15]. Hyun's group [4,5], for the first time, calculated the transient behavior of film profiles in 2-D isothermal/nonisothermal film casting processes with viscoelastic fluids, e.g., upper-convected Maxwell and PhanThien and Tanner fluids, confirming good agreement with experimental observations. Also, a sensitivity analysis, as well as the conventional stability one, is indispensable to ensure optimal process conditions for the film uniformity.…”

Section: Introductionmentioning

confidence: 99%

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Transient responses of two-dimensional viscoelastic film casting processes to sinusoidal disturbances

Choi

Shin

Lee³

et al. 2009

Korean J. Chem. Eng.

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The sensitivity of two-dimensional isothermal film casting processes to ongoing sinusoidal disturbances has been investigated by using the frequency response method with transient simulation techniques. Amplitude ratios of state variables such as cross-sectional area, film width and film thickness at the take-up position with respect to a sinusoidal disturbance show resonant peaks along the frequency domain. Effects of operating conditions, such as drawdown ratio and aspect ratio, on the process sensitivity have been examined. Increasing drawdown ratio and decreasing aspect ratio make the system more sensitive to disturbances. Also, the dichotomous behavior in the sensitivity analysis using viscoelastic Phan-Thien and Tanner fluids has been elucidated. This frequency response method can be a useful tool to optimally design process systems for better processability and product quality.

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Stability analysis of a polymer film casting problem

Kallel

Hachem

Rapetti³

et al. 2015

Numerical Methods in Fluids

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This is the accepted version of the following article: Kallel, A, Hachem, E, Rapetti, F, Demay, Y, and Agassant, JF (2015), Stability analysis of a polymer film casting problem. Int. J. Numer. Meth. Fluids, 78, 436–454. doi: 10.1002/fld.4024, which has been published in final form at http://dx.doi.org/10.1002/fld.4024International audienceThe polymer cast film process consists of stretching a molten polymer film between a flat die and a drawing roll. Drawing instabilities are often encountered and represent a drastic limitation to the process. Newtonian fluid film stretching stability is investigated using two numerical strategies. The first one is a ‘tracking’ method, which consists of solving Stokes equations in the whole fluid area (extrusion die and stretching path) by finite elements. The interface is determined to satisfy a kinematic equation. A domain decomposition meshing technique is used in order to account for a flow singularity resulting from the change in the boundary conditions between the die flow region and the stretching path region. A linear stability method is then applied to this transient kinematic equation in order to investigate the stability of the stationary solution. The second method is a direct finite element simulation in an extended area including the fluid and the surrounding air. The time-dependent interface is captured by solving an appropriate level-set function. The agreement between the two methods is fair. The influence of the stretching parameters (Draw ratio and drawing length) is investigated. For a long stretching distance, a critical Draw ratio around 20 delimitating stable and unstable drawing conditions is obtained, and this agrees well with the standard membrane models, which have been developed 40 years ago. When decreasing the stretching distance, the membrane model is no longer valid. The 2D models presented here point out a significant increase of the critical Draw ratio, and this is consistent with experimental results

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Transient solutions of the dynamics of film casting process using a 2-D viscoelastic model

Cited by 33 publications

References 27 publications

An Overview of Molten Polymer Drawing Instabilities

An Overview of Molten Polymer Drawing Instabilities

Transient responses of two-dimensional viscoelastic film casting processes to sinusoidal disturbances

Stability analysis of a polymer film casting problem

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