Browsing Polymers Research Group Technical Report Series by Title
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Order in Oscillatory Shear Flow
(201812)We examine the second order orientation tensor for the simplest molecular model relevant to a polymeric liquid in largeamplitude oscillatory shear flow (LAOS), the rigid dumbbell suspension. For this we use an approximate ... 
Orientation Distribution Function Pattern for Rigid Dumbell Suspensions In Any Simply Shear Flow
(201809)For rigid dumbbells suspended in a Newtonian solvent, the viscoelastic response depends exclusively on the dynamics of dumbbell orientation. The orientation distribution function ψ (θ ,φ ,t) represents the probability of ... 
Orientation in LargeAmplitude Oscillatory Shear
(20140930)We examine the simplest relevant molecular model for largeamplitude oscillatory shear flow of a polymeric liquid: the dilute suspension of rigid dumbbells in a Newtonian solvent. We find explicit analytical expressions ... 
Padé Approximant for Normal Stress Differences in LargeAmplitude Oscillatory Shear Flow
(201711)Analytical solutions for the normal stress differences in largeamplitude oscillatory shear flow (LAOS), for continuum or molecular models, normally take the form of the first few terms of a series expansion in the shear ... 
Padé Approximants for LargeAmplitude Oscillatory Shear Flow
(20150317)Analytical solutions for either the shear stress or the normal stress differences in largeamplitude oscillatory shear flow, both for continuum or molecular models, often take the form of the first few terms of a power ... 
Plastic Pipe Solidification: Exact Solutions in Cylindrical Coordinates
(201512)For polymer melt solidification in plastic pipe extrusion, we perform an energy balance on the pipe extrudate in cylindrical coordinates to arrive at exact solutions for the temperature, and for the solidification rate. ... 
Polymer Fluid Dynamics: Continuum and Molecular Approaches
(20160620)To solve problems in polymer fluid dynamics, one needs the equation of continuity, motion, and energy. The last two equations contain the stress tensor and the heatflux vector for the material. There are two ways to ... 
Polymer Orientation Contributions in LargeAmplitude Oscillatory Shear Flow
(201701)Previously, we used a dilute suspension of rigid dumbbells as a model for the dynamics for polymeric liquids in largeamplitude oscillatory shear (LAOS) flow. We then use dumbbell orientation to explain fluid elasticity. ... 
Polymer Processing Partitioning Approach: Extruding Plastic Pipe
(201601)The proposed thesis research aims at deepening our understanding of the flow of polymer melts through eccentric plastic pipe extrusion dies. Specifically, the proposed thesis research will explore how viscoelasticity affects ... 
Power Series for Normal Stress Differences of Polymeric Liquids in LargeAmplitude Oscillator Shear Flow
(201804)Exact solutions for normal stress differences in polymeric liquids subjected to largeamplitude oscillatory shear flow (LAOS) contain many Bessel functions, each appearing in infinite sums. For the simplest relevant model ... 
Power Series for Shear Stress of Polymeric Liquid in LargeAmplitude Oscillatory Shear Flow
(201804)xact solutions for shear stress in a polymeric liquid subjected to largeamplitude oscillatory shear flow (LAOS) contain many Bessel functions. For the simplest of these, for instance, the corotational Maxwell fluid, in ... 
Reflections on Inflections
(20151111)In plastics processing, the single most important rheological property is the steady shear viscosity curve: the logarithm of the steady shear viscosity versus the logarithm of the shear rate. This curve governs the volumetric ... 
Review of Nonlinear Oscillatory Shear Flow Notations and Presentations: Polymeric Liquids
(201812)We review notations for, along with ways of presenting, the shear stress responses to largeamplitude oscillatory shear flow (LAOS). We find that the Fourier loss and storage viscosities to be the simplest primal notations ... 
Series Expansion for Shear Stress in LargeAmplitude Oscillatory Shear Flow From Oldroyd 8Constant Framework
(201806)When polymeric liquids undergo largeamplitude oscillatory shear flow (LAOS), the shear stress responds as a Fourier series, the higher harmonics of which are caused by the fluid nonlinearity, and the first harmonic of ... 
Simple Accurate Expressions for Shear Stress in LargeAmplitude Oscillatory Shear Flow
(201705)Analytical solutions for shear stress in largeamplitude oscillatory shear flow (LAOS), for continuum or molecular models, often take the form of the first few terms of a power series in the shear rate amplitude. For ... 
Slip Heating in Die Drool
(20140514)When molten plastic is extruded from a die, it can collect on the open die face. Called die drool, this phenomenon costs plastics manufacturers by requiring shutdown for die cleaning. This has been attributed to cohesive ... 
Slip Heating in Die Drool with Viscous Dissipation
(20141006)Plastics can buildup on the die lip during extrusion. This phenomenon is called die drool and can be costly for plastics producers, requiring periodic shutdowns for die cleaning. Die drool has been attributed to the ... 
Startup Steady Shear Flow from the Oldroyd 8Constant Framework
(201901)One good way to explore fluid microstructure, experimentally, is to suddenly subject the fluid to a large steady shearing deformation, and to then observe the evolving stress response. If the steady shear rate is high ... 
Temperature Rise in a Verging Annular Die
(20151207)Plastic pipes, tubes or catheters are extruded by pressure‑driven flows through annular dies. Whereas die lands are straight, the section connecting the die land to the extruder either converges or diverges, converging ... 
Thermodynamic Instability of Polymeric Liquids in LargeAmplitude Oscillatory Shear Flow from Corotational Maxwell Fluid
(201804)When polymeric liquids are subjected to oscillatory shear flow, if the amplitude of the shear rate is high enough, the shear stress response will become aperiodic. This has been variously attributed to fracture, common ...