Existence of optimal cooling conditions in the film blowing process

Lee, Joo Sung; Shin, Dong‐Myeong; Song, Hyun‐Seob; Jung, Hyun Wook; Hyun, Jae Chun

doi:10.1016/j.jnnfm.2005.12.011

Cited by 15 publications

(12 citation statements)

References 17 publications

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“…Hyun and coworkers18–22 solved periodic draw resonance instability for nonisothermal viscoelastic cases with or without crystallization effect that incorporated the orthogonal collocation on finite elements (OCFE), which quite well predicted experimentally observed unstable phenomena. Stability windows for various fluids can be established from linear stability work 3, 4, 10, 16, 19, 20, 23. Cain and Denn4 presented detailed stability windows for Newtonian and Maxwell fluids under different boundary condition sets.…”

Section: Introductionmentioning

confidence: 77%

“…Also, they recently introduced multiplicity and instability in film blowing process accompanied with crystallization kinetics using the linear stability and transient simulation of thin‐shell model, emphasizing the role of cooling or heat transfer coefficient 15. Hyun and coworkers18–22 solved periodic draw resonance instability for nonisothermal viscoelastic cases with or without crystallization effect that incorporated the orthogonal collocation on finite elements (OCFE), which quite well predicted experimentally observed unstable phenomena. Stability windows for various fluids can be established from linear stability work 3, 4, 10, 16, 19, 20, 23.…”

Section: Introductionmentioning

confidence: 88%

“…To construct neutral stability curves in the BUR‐TR diagram, linear stability method described in Lee et al19 has been employed, determining the system stability with respect to infinitesimal perturbations from the sign of the real part of the first leading eigenvalue.…”

Section: Time‐dependent Governing Equations Of Nonisothermal Film Blomentioning

confidence: 99%

“…Mathematical modeling for the steady analysis of film blowing process was pioneered by Pearson and Petrie1, 2 for an isothermal Newtonian fluid. Since then, much work, both theoretical and experimental, has shed light on the dynamics of this complex process 3–23. Transient responses during film blowing operation were studied intensively by Pirkle and Braatz12 group that successfully established transient routes between two steady states and systematically explained the effects of oscillating heat transfer, bubble pressure, and machine tension on film thickness.…”

Section: Introductionmentioning

confidence: 99%

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Frequency response analysis of nonisothermal film blowing process using transient simulations

Kim

Lee²,

Jung

et al. 2011

J of Applied Polymer Sci

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Frequency response of the nonisothermal viscoelastic film blowing process to the ongoing sinusoidal disturbances has been investigated using transient simulation techniques. Of the many state variables exhibiting resonant peaks with the input frequency, amplitude ratio of the film cross-sectional area at the freezeline height has been used as an indicator of the process sensitivity. The effects of operating conditions and viscoelasticity on the sensitivity have been scrutinized around the middle point of three multiple steady states under the given conditions. The sensitivity results have been interpreted through their correlation with results from linear stability analysis. Increasing draw ratio generally makes the system more sensitive to sinusoidal disturbances, whereas the cooling induces more sensitive or less sensitive system, according to the location of a steady state. Also, the viscoelasticity makes the system of extensional thickening fluids more sensitive at low Deborah number and less sensitive at high Deborah number.

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Section: Introductionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 88%

Section: Time‐dependent Governing Equations Of Nonisothermal Film Blomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Frequency response analysis of nonisothermal film blowing process using transient simulations

Kim

Lee²,

Jung

et al. 2011

J of Applied Polymer Sci

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“…So these eigenvalues are assumed to be spurious and not considered for the stability analysis. Tsamopoulos (1998, 2000) Table 1): • complex eigenvalues (expected), ¤ real eigenvalues (unexpected) as Hyun et al (2004) and Lee et al (2006) do not mention the existence of such real eigenvalues. Such problems are sometime encountered when a development according to a small parameter is used.…”

Section: Axisymmetric Stability Resultsmentioning

confidence: 99%

Investigation of Polymer Stretching Instabilities: Application to Film Blowing

Laffargue

Demay

Agassant

2010

International Polymer Processing

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International audienceFilm blowing, as other elongational polymer forming processes, may present marked drawing instabilities leading to unacceptable products. But in film blowing, these instabilities are much more complex than for example in fibre spinning: there is no stabilizing effect of the polymer cooling, and the symmetry of the process may be broken, leading in some processing conditions to so called helical instabilities. Stability of the process has been investigated using a strategy inspired from shell or homogeneisation theory: as the classical approach uses a frame locally affixed to the membrane, the equations of the problemare now written in the cartesian laboratory frame. Making the equations dimensionless introduces naturally a small parameter defined as an aspect ratio (ratio of the film thickness to the bubble radius). Kinematic and stress variables are expanded as a function of this small parameter and introduced in the equations. It leads classically to a sequence of equations at successive orders. This strategy is used to obtain a time dependent membrane model. The stationary solution is equivalent to the one obtained using the classical approach. This model allows to develop a stability analysis, first in the axisymmetric case and then in the non axisymmetric one. Even a crude Newtonian temperature dependent rheology allows to capture qualitatively the observed instability phenomena

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