Browsing Polymers Research Group Technical Report Series by Title
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Elastomers in Oscillatory Uniaxial Extension
(201602)In this work, we subject elastomers to a fixed prestretch in uniaxial extension, ε p , upon which a largeamplitude, ε 0 , oscillatory uniaxial extensional (LAOE) deformation is superposed. We find that if both ε p and ε ... 
Exact Analytical Interconversion between Durometer Hardness Scales
(201702)Previous work has related Young’s modulus to durometer hardness for any standardized scale. In this paper, we build on this work to solve explicitly and exactly for the hardness in any one standardized durometer hardness ... 
Exact Analytical Solution for LargeAmplitude Oscillatory Shear Flow
(20150316)When polymeric liquids undergo largeamplitude shearing oscillations, the shear stress responds as a Fourier series, the higher harmonics of which are caused by fluid nonlinearity. Previous work on largeamplitude oscillatory ... 
Exact Analytical Solution for LargeAmplitude Oscillatory Shear Flow from Oldroyd 8Constant Framework: Shear Stress
(201701)The Oldroyd 8constant model is a continuum framework containing, as special cases, many important constitutive equations for elastic liquids. When polymeric liquids undergo largeamplitude oscillatory shear flow, the shear ... 
Exact Coefficients for Rigid Dumbbell Suspensions for Steady Shear Flow Material Function Expansions
(200807)From kinetic molecular theory, we can attribute the elasticity of polymeric liquids to macromolecular orientation. For a suspension of rigid dumbbells, subject to a particular flow field, we must first solve the diffusion ... 
Exact Solutions for Oscillatory Shear Sweep Behaviors of Complex Fluids from the Oldroyd 8constant Framework
(201705)Largeamplitude oscillatory shear flow (LAOS) is a popular for studying the nonlinear physics of complex fluids. Specifically, the strain rate sweep (also called the strain sweep) is used routinely to identify the onset ... 
Exactsolution for Coneplate Viscometry
(201708)The viscosity of a Newtonian fluid is often measured by confining the fluid to the gap between a rotating cone that is perpendicular to a fixed disk. We call this experiment coneplate viscometry. When the cone angle ... 
Extruding Plastic Pipe From Eccentric Dies
(20150525)To solidify plastic pipe, the pipe is transported through a long cooling chamber. Inside this chamber, inside the pipe, the plastic remains molten, and this inner surface solidifies last. The flow due to the selfweight ... 
Fluid Elasticity in Plastic Pipe Extrusion: Loads on Die Barrel
(201707)In large thick plastic pipe extrusion, the residence in the cooling chamber is long, and the melt inside the pipe sags under its own weight, causing the product to thicken on the bottom (and to thin on the top). To compensate ... 
Fourier Decomposition of Polymer Orientation in LargeAmplitude Oscillatory Shear Flow
(20150317)In our previous work, we explored the dynamics of a dilute suspension of rigid dumbbells as a model for polymeric liquids in largeamplitude oscillatory shear flow, a flow experiment that has gained a significant following ... 
Hydrodynamic Interaction for Rigid Dumbbell Suspensions in Steady Shear Flow
(201812)From kinetic molecular theory, we can attribute the rheological behaviors of polymeric liquids to macromolecular orientation. The simplest model to capture the orientation of macromolecules is the rigid dumbbell. For a ... 
Knuckle Formation From Melt Elasticity in Plastic Pipe Extrusion
(201607)When plastic pipe is solidified, it proceeds through a long cooling chamber. Inside the chamber, inside the extrudate, the plastic is molten, and this inner surface solidifies last. Sag then happens inside this cooling ... 
LargeAmplitude Oscillatory Shear: Comparing ParallelDisk with ConePlate Flow
(20140930)We compare the ratio of the amplitudes of the third to the first harmonic of the torque, T3/T1, measured in rotational paralleldisk flow, with the ratio of the corresponding harmonics of the shear stress, T3/T1, ... 
Macromolecular Origins of Fifth ShearStress Harmonic in LargeAmplitude Oscillatory Shear Flow
(201608)This study examines the simplest relevant molecular model of a polymeric liquid in largeamplitude oscillatory shear (LAOS) flow: the suspension of rigid dumbbells in a Newtonian solvent. For such suspensions, the viscoelastic ... 
Macromolecular Tumbling and Wobbling in LargeAmplitude Oscillatory Shear Flow
(201811)For a suspension of rigid dumbbells, in any simple shear flow, we recently solved for the diffusion equation for the orientation distribution function by a power series expansion in the shear rate magnitude. In this paper, ... 
Molecular Continua for Polymeric Liquids in LargeAmplitude Oscillatory Shear Flow
(201705)In this paper, we connect a molecular description of the rheology of a polymeric liquid to a continuum description, and then test this connection for largeamplitude oscillatory shear flow (LAOS). Specifically, for the ... 
Molecular Origins of Higher Harmonics in LargeAmplitude Oscillatory Shear Flow: Shear Stress Response
(20161101)Recent work has focused on deepening our understanding of the molecular origins of the higher harmonics that arise in the shear stress response of polymeric liquids in largeamplitude oscillatory shear flow. For instance, ... 
Nonlinear Core Deflection in Injection Molding
(201802)Injection molding of thin slender parts is often complicated by core deflection. This deflection is caused by molten plastics race tracking through the slit between the core and the rigid cavity wall. The pressure of this ... 
Normal Stress Differences from Oldroyd 8Constant Framework: Exact Analytical Solution for LargeAmplitude Oscillatory Shear Flow
(201703)The Oldroyd 8constant framework for continuum constitutive theory contains a rich diversity of popular special cases for polymeric liquids. In this paper, we use part of our exact solution for shear stress to arrive at ... 
Normal Stress Differences in LargeAmplitude Oscillatory Shear Flow for Dilute Rigid Dumbbell Suspensions
(20140825)We examine the simplest relevant molecular model for largeamplitude oscillatory shear (LAOS) flow of a polymeric liquid: the suspension of rigid dumbbells in a Newtonian solvent. We find explicit analytical expressions ...