An experimental evaluation of the formation of an instability in monodisperse and polydisperse polystyrenes

Hassell, David; Embery, John; McLeish, Tom; Mackley, M. R.

doi:10.1016/j.jnnfm.2008.08.010

Cited by 18 publications

(10 citation statements)

References 33 publications

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“…For academic study, it is possible to synthesize and isolate small quantities of nearly monodisperse polymers, but practically all industrial polymers are polydisperse, comprising a broad distribution of molecular weights. It is widely recognized that polydispersity, especially as it pertains to the longest chains, is an important factor in rheological and processing behavior and can have a significant influence on the transient and steady state response to the flow of polymeric systems [1][2][3].…”

Section: A Polydispersity In Entangled Polymersmentioning

confidence: 99%

Nonlinear rheology of polydisperse blends of entangled linear polymers: Rolie-Double-Poly models

Boudara

Peterson

Leal

et al. 2018

Journal of Rheology

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While there has been much success in modeling the linear and nonlinear rheology of monodisperse entangled linear polymers, progress in the constitutive modeling of polymeric materials continues to lag behind the needs of industry. Industrially sourced polymers are typically polydisperse (comprising a broad distribution of molecular weights), making their rheology more suitable for processing but also more difficult to predict. To date, there are no molecular-based constitutive models that are practically suitable for describing industrially relevant polymers in industrially relevant flows. In this article, we extend but strongly simplify the model of Read et al. [J. Rheol. 56, 823-873 (2012)], which is able to predict the linear and nonlinear rheology of bidisperse blends but is prohibitively complex for industrial use. We propose a pair of simplified tube models for polydisperse melts of entangled linear polymers that combine the success of the double reptation approximation [des Cloizeaux, Europhys. Lett. 5, 437-442 (1988)] in the linear regime with the success of the Rolie-Poly constitutive equation [Likhtman et al., J. Non Newtonian Fluid Mech. 114, 1-12 (2003)] in the nonlinear regime. We first review the key concepts of the double reptation approximation and the original (monodisperse) Rolie-Poly constitutive model. Subsequently, we provide the details of our approximate models for the particular case of a bidisperse blend and show that these models naturally identify the effects from couplings between constraint release and chain retraction (i.e., the so-called "enhanced stretch relaxation time"). Finally, we generalize to a multicomponent (polydisperse) model, based on the same underlying principles. Along the way, we also show that both of our models are in qualitative, and largely quantitative, agreement with experimental data for bidisperse and polydisperse melts of entangled linear polymers.

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Section: A Polydispersity In Entangled Polymersmentioning

confidence: 99%

Nonlinear rheology of polydisperse blends of entangled linear polymers: Rolie-Double-Poly models

Boudara

Peterson

Leal

et al. 2018

Journal of Rheology

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“…Subsequent rheo-optical experiments have focused on the behaviour of both mono-disperse [41,42,78,79] and polydisperse materials [79]. The observation of an instability in a contraction-expansion (CE) slit flow was first reported by Collis and Mackley, and was termed "viscoelastic disturbance".…”

Section: Instabilitiesmentioning

confidence: 99%

“…The observation of an instability in a contraction-expansion (CE) slit flow was first reported by Collis and Mackley, and was termed "viscoelastic disturbance". Later work [79] identified in detail the form and behaviour of this instability for a range of mono-disperse polystrenes.…”

Section: Instabilitiesmentioning

confidence: 99%

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The multipass rheometer a review

Mackley¹,

Hassell²

2011

Journal of Non-Newtonian Fluid Mechanics

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“…However, no stability calculations were performed. Hassell et al [23] present an experimental study of the formation of a polymer flow instability seen in a range of polystyrene melts flowing through contraction−expansion slit geometries and found that the underlying instability mechanism -an oscillating flow perpendicular to the bulk flow -is the same for both polydispersed and monodispersed materials. Although no single critical Weissenberg number was found, stability maps of Weissenberg numbers against material molecular weight in relation to both orientation and chain stretch were obtained.…”

Section: Introductionmentioning

confidence: 99%

Rolie-Poly fluid flowing through constrictions: Two distinct instabilities

Reis

Wilson

2013

Journal of Non-Newtonian Fluid Mechanics

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Elastic instabilities of entangled polymer melts are common in industrial processes but the physics responsible is not well understood. We present a numerical linear stability study of a molecular based constitutive model which grants us physical insight into the underlying mechanics involved. Two constriction flows are considered -one shear dominated, the other extension dominated -and two distinct instabilities are found. The influence of the molecular structure and the behaviour of the polymer dynamics are investigated and in both cases chain relaxation and orientation play a crucial role. This suggests a molecular-based physical interpretation of the underlying mechanisms responsible for flow instabilities.

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An experimental evaluation of the formation of an instability in monodisperse and polydisperse polystyrenes

Cited by 18 publications

References 33 publications

Nonlinear rheology of polydisperse blends of entangled linear polymers: Rolie-Double-Poly models

Nonlinear rheology of polydisperse blends of entangled linear polymers: Rolie-Double-Poly models

The multipass rheometer a review

Rolie-Poly fluid flowing through constrictions: Two distinct instabilities

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