Melt spinning and draw resonance studies on a poly (α‐methyl styrene/silicone) block copolymer

Blyler, L. L.; Gieniewski, C.

doi:10.1002/pen.760200205

Cited by 20 publications

(16 citation statements)

References 31 publications

(9 reference statements)

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“…In this work, we consider a melt-spinning (MS) process for materials possessing a step-like change in viscosity with temperature. Important classes of materials such as block copolymers and multicomponent polymer melts 6,7 have a viscosity that behaves in this way, making it essential to investigate their MS behavior. Nonisothermal MS studies have thus far largely been confined to materials showing an exponential variation of viscosity with temperature.…”

Section: Introductionmentioning

confidence: 99%

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Draw ratio enhancement in nonisothermal melt spinning

Suman

Kumar

2009

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com).Nonisothermal melt spinning of materials having a step-like viscosity variation with temperature is studied in this work. A set of nonlinear equations is used to describe the fiber behavior and to obtain the draw ratio, the square of the ratio of the fiber diameter at the entrance to that at the exit of the fiber-spinning device. The fluid-flow equation is based on a slender-jet approximation, and external heating and cooling have been accounted for with a one-dimensional model in order to obtain the fiber temperature and viscosity along the fiber length. The model is similar to that used by Wylie et al. (J Fluid Mech. 2007;570:1-16) but accounts for inertia, shear stress at the fiber surface, surface tension, gravity, cooling, and larger heating rates. Steadystate analysis reveals that the draw ratio increases with an increase in the pulling force, passes through a maximum, and then starts increasing again, resulting in three possible pulling forces for the same draw ratio. However, linear stability analysis reveals that depending on the strength of heating and/or cooling, at most two of the steady states are stable. The stability analysis also predicts complicated oscillatory and nonoscillatory dynamical behavior as the pulling force varies. Nonlinear simulations reveal that an unstable system always tends to limit-cycle behavior. Systems predicted as stable by the linear stability analysis are also stable for large-amplitude perturbations. External heating is found to dramatically enhance the draw ratio of the melt-spinning process. The addition of a cooling section suppresses the draw ratio, but this can be compensated for with a higher heating strength.

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Section: Introductionmentioning

confidence: 99%

“…11,12 However, important classes of materials, such as block copolymers and multicomponent polymer melts, show abrupt changes in viscosity with temperature. 6,7 Polymer crystallization is also accompanied by steep changes in viscosity. 19 Step-functions have been used to model these sharp variations in viscosity with temperature.…”

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confidence: 97%

Draw ratio enhancement in nonisothermal melt spinning

Suman

Kumar

2009

AIChE Journal

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“…Ghiljels and Ente (1980) identified directly the occurrence of these instabilities by recording continuously the stretching force which is obviously very small (of the order of several milliNewton). When increasing the stretching distance, the process becomes progressively non isothermal and the critical Draw ratio * Dr increases too (Blyler and Gieniewski, 1980;Gupta and Drechsel, 1981;Demay, 1983). When the stretching distance L is sufficiently large, more complex phenomena occur as stress induced crystallization involving changes in the temperature field.…”

Section: Methodsmentioning

confidence: 99%

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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“…In the case of fiber spinning, when the stretching distance is increased, the critical Draw ratio Dr* increases, which is explained by non-isothermal effects [2,3,4]. Silagy et al investigated the stability of the cast of film process using different constitutive equations.…”

Section: Figure 1 (A) Schematic Of the Coating Process (B) Half Flomentioning

confidence: 99%

“…( 1 ) where is the Cauchy stress tensor defined by : ( 2 ) and is the velocity vector, is the rate of deformation tensor, is the dynamic viscosity of the fluid and p is the pressure inside the fluid. In addition, the fluid is assumed to be incompressible, so we have :…”

Section: Stokes Problemmentioning

confidence: 99%

Stability analysis of a polymer coating process

Kallel

Hachem

Demay

et al. 2015

AIP Conference Proceedings

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Abstract.A new coating process involving a short stretching distance (1 mm) and a high draw ratio (around 200) is considered. The resulting thin molten polymer film (around 10 micrometers) is set down on a solid primary film and then covered by another solid secondary film. In experimental studies, periodical fluctuation in the thickness of the coated layer may be observed. The processing conditions markedly influence the onset and the development of these defects and modeling will help our understanding of their origins. The membrane approach which has been commonly used for cast film modeling is no longer valid and two dimensional time dependent models (within the thickness) are developed in the whole domain (upstream die and stretching path). A boundary-value problem with a free surface for the Stokes equations is considered and stability of the free surface is assessed using two different numerical strategies: a tracking strategy combined with linear stability analysis involving computation of leading eigenvalues, and a Level Set capturing strategy coupled with transient stability analysis.

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Melt spinning and draw resonance studies on a poly (α‐methyl styrene/silicone) block copolymer

Cited by 20 publications

References 31 publications

Draw ratio enhancement in nonisothermal melt spinning

Draw ratio enhancement in nonisothermal melt spinning

An Overview of Molten Polymer Drawing Instabilities

Stability analysis of a polymer coating process

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