Unraveling Dynamics of Entangled Polymers in Strong Extensional Flows

2019 ◽  
Vol 52 (3) ◽  
pp. 1296-1307 ◽  
Author(s):  
Soroush Moghadam ◽  
Indranil Saha Dalal ◽  
Ronald G. Larson
Keyword(s):  
Entangled Polymers ◽  
Extensional Flows

scholarly journals Interfacial Tension Measurements in Microfluidic Quasi-Static Extensional Flows

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 272
Author(s):  
Doojin Lee ◽  
Amy Q. Shen
Keyword(s):  
Interfacial Tension ◽  
Microfluidic Device ◽  
Extensional Flow ◽  
Immiscible Fluids ◽  
Droplet Microfluidics ◽  
Channel Height ◽  
Deformation Model ◽  
Droplet Deformation ◽  
Extensional Flows ◽  
2D Model

Droplet microfluidics provides a versatile tool for measuring interfacial tensions between two immiscible fluids owing to its abilities of fast response, enhanced throughput, portability and easy manipulations of fluid compositions, comparing to conventional techniques. Purely homogeneous extension in the microfluidic device is desirable to measure the interfacial tension because the flow field enables symmetric droplet deformation along the outflow direction. To do so, we designed a microfluidic device consisting of a droplet production region to first generate emulsion droplets at a flow-focusing area. The droplets are then trapped at a stagnation point in the cross junction area, subsequently being stretched along the outflow direction under the extensional flow. These droplets in the device are either confined or unconfined in the channel walls depending on the channel height, which yields different droplet deformations. To calculate the interfacial tension for confined and unconfined droplet cases, quasi-static 2D Darcy approximation model and quasi-static 3D small deformation model are used. For the confined droplet case under the extensional flow, an effective viscosity of the two immiscible fluids, accounting for the viscosity ratio of continuous and dispersed phases, captures the droplet deformation well. However, the 2D model is limited to the case where the droplet is confined in the channel walls and deforms two-dimensionally. For the unconfined droplet case, the 3D model provides more robust estimates than the 2D model. We demonstrate that both 2D and 3D models provide good interfacial tension measurements under quasi-static extensional flows in comparison with the conventional pendant drop method.

Flow-Induced Orientation and Stretching of Entangled Polymers in the Framework of Nonequilibrium Thermodynamics

2016 ◽  
Vol 49 (8) ◽  
pp. 3161-3173 ◽  
Author(s):  
Pavlos S. Stephanou ◽  
Ioanna Ch. Tsimouri ◽  
Vlasis G. Mavrantzas
Keyword(s):  
Nonequilibrium Thermodynamics ◽  
Entangled Polymers

Rational Design of Novel Materials From Polymer Microrheology

2010 ◽  
Author(s):  
Rodrigo E. Teixeira ◽  
Richard S. Graham
Keyword(s):  
Rational Design ◽  
Molecular Level ◽  
Pressure Vessels ◽  
Novel Materials ◽  
Entangled Polymers ◽  
Stochastic Fluctuations ◽  
Safety Margins ◽  
Polymer Liquids ◽  
Entangled Polymer ◽  
High Degree

The visco-elastic properties of entangled polymer liquids arise from molecular-scale topological interactions and stochastic fluctuations under flow. Here, the evolutions of individual entangled polymers were observed in rheologically relevant shear flow histories. We uncover a high degree of molecular individualism and broad conformational distributions resulting from incessant stretch-collapse cycles. The data and insights of the present study may lead to improved molecular-level models and constitutive equations. These tools, in turn, may enable the rational design of novel materials with properties tailored to accomplish specific tasks such as high-pressure vessels and piping with greater safety margins and cost-effectiveness.

scholarly journals FIELD THEORY OF N ENTANGLED POLYMERS

2000 ◽  
Vol 14 (32) ◽  
pp. 3881-3895 ◽  
Author(s):  
FRANCO FERRARI ◽  
HAGEN KLEINERT ◽  
IGNAZIO LAZZIZZERA
Keyword(s):  
Field Theory ◽  
Canonical Ensemble ◽  
Feynman Diagrams ◽  
Linking Number ◽  
Entangled Polymers

We formulate a field theory capable of describing a canonical ensemble of N polymers subjected to linking number constraints in terms of Feynman diagrams.

Extensional flows with viscous heating

2007 ◽  
Vol 571 ◽  
pp. 359-370 ◽  
Author(s):  
JONATHAN J. WYLIE ◽  
HUAXIONG HUANG
Keyword(s):  
Critical Value ◽  
The Other ◽  
Viscous Heating ◽  
Constant Force ◽  
Temperature Dependent ◽  
Downstream Location ◽  
Temperature Dependent Viscosity ◽  
Pulling Forces ◽  
Extensional Flows ◽  
Dependent Viscosity

In this paper we investigate the role played by viscous heating in extensional flows of viscous threads with temperature-dependent viscosity. We show that there exists an interesting interplay between the effects of viscous heating, which accelerates thinning, and inertia, which prevents pinch-off. We first consider steady drawing of a thread that is fed through a fixed aperture at given speed and pulled with a constant force at a fixed downstream location. For pulling forces above a critical value, we show that inertialess solutions cannot exist and inertia is crucial in controlling the dynamics. We also consider the unsteady stretching of a thread that is fixed at one end and pulled with a constant force at the other end. In contrast to the case in which inertia is neglected, the thread will always pinch at the end where the force is applied. Our results show that viscous heating can have a profound effect on the final shape and total extension at pinching.

Self-oscillations in capillary flow of entangled polymers

1999 ◽  
Vol 43 (2) ◽  
pp. 453-460 ◽  
Author(s):  
Shi-Qing Wang ◽  
N. Plucktaveesak
Keyword(s):  
Capillary Flow ◽  
Entangled Polymers
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