Browsing Polymers Research Group Technical Report Series by Title
Now showing items 120 of 48

Bubble Growth From First Principles
(20160705)We consider the simplest relevant problem in the foaming of molten plastics, the growth of a single bubble in a sea of highly viscous Newtonian fluid, and without interference from other bubbles. This simplest problem has ... 
Chain Extended Poly(3—hydroxybutyrate) With Improved Rheological Properties and Thermal Stability, Through Reactive Modification in the Melt State
(20151004)Branching and crosslinking of polyhydroxybutyrate (PHB) is accomplished for the first time through reactive modification in the melt state, using dicumyl peroxide (DCP) as the freeradical initiator and a trifunctional ... 
Complex Polymer Orientation
(201507)Previously, we explored the dynamics of a dilute suspension of rigid dumbbells as a model for polymeric liquids in largeamplitude oscillatory shear (LAOS) flow. We derived the expression for the polymer orientation ... 
Degradation in ConePlate Rheometry
(201807)We analyze quantitatively the oxidative degradation of a sample in a coneplate rheometer, as oxygen diffuses inward, radially, from the free boundary. We examine rheometer error mitigation by means of nitrogen blanketing, ... 
Degradation in ParallelDisk Rheometry
(201808)We analyze quantitatively the oxidative degradation of a sample in a paralleldisk rheometer, as oxygen diffuses inward, radially, from the free boundary. We examine rheometer error mitigation by means of nitrogen blanketing, ... 
Die Drool and Polymer Degradation
(20150624)Die drool is an operational problem associated with polymer extrusion. Extrudate collects outside of the die, necessitating periodic disruptions for cleaning. There exists some debate as to the mechanism that produces ... 
Elastomers in LargeAmplitude Oscillatory Uniaxial Extension Revisited
(201707)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 ... 
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 ... 
Ethermodynamic 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 ... 
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 ... 
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, ...