Browsing Polymers Research Group Technical Report Series by Author "ab8ce3c155e9453c9c9808d6ba940eac"
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Degradation in ParallelDisk Rheometry
Giacomin, A. Jeffrey; Pasquino, R.; Saengow, Chaimongkol; Gilbert, Peter H. (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, ... 
Elastomers in LargeAmplitude Oscillatory Uniaxial Extension Revisited
Dessi, Claudia; Vlassopoulos, Dimitris; Giacomin, A. Jeffrey; Saengow, Chaimongkol (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
Dessi, Claudia; Vlassopoulos, Dimitris; Giacomin, A. Jeffrey; Saengow, Chaimongkol (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
Saengow, Chaimongkol; Giacomin, A. Jeffrey (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 Coefficients for Rigid Dumbbell Suspensions for Steady Shear Flow Material Function Expansions
Piette, Jourdain H.; Jbara, Layal; Saengow, Chaimongkol; Giacomin, A. Jeffrey (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
Saengow, Chaimongkol; Giacomin, A. Jeffrey (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 ... 
Fluid Elasticity in Plastic Pipe Extrusion: Loads on Die Barrel
Saengow, Chaimongkol; Giacomin, A. Jeffrey (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 ... 
Hydrodynamic Interaction for Rigid Dumbbell Suspensions in Steady Shear Flow
Piette, Jourdain H.; Saengow, Chaimongkol; Giacomin, A. Jeffrey (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 ... 
Molecular Continua for Polymeric Liquids in LargeAmplitude Oscillatory Shear Flow
Giacomin, A. Jeffrey; Saengow, Chaimongkol (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 ... 
Nonlinear Core Deflection in Injection Molding
Poungthong, P.; Giacomin, A. Jeffrey; Saengow, Chaimongkol; Kolitawong, Chanyut; Liao, H.C.; Tseng, S.C. (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 ... 
Order in Oscillatory Shear Flow
Kanso, Mona A.; Giacomin, A. Jeffrey; Saengow, Chaimongkol; Gilbert, Peter H. (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 ... 
Padé Approximant for Normal Stress Differences in LargeAmplitude Oscillatory Shear Flow
Poungthong, P.; Saengow, Chaimongkol; Giacomin, A. Jeffrey; Kolitawong, Chanyut; Merger, D.; Wilhelm, M. (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 ... 
Power Series for Normal Stress Differences of Polymeric Liquids in LargeAmplitude Oscillator Shear Flow
Poungthong, P.; Giacomin, A. Jeffrey; Saengow, Chaimongkol; Kolitawong, Chanyut (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
Poungthong, P.; Saengow, Chaimongkol; Giacomin, A. Jeffrey; Kolitawong, Chanyut (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 ... 
Review of Nonlinear Oscillatory Shear Flow Notations and Presentations: Polymeric Liquids
Saengow, Chaimongkol; Giacomin, A. Jeffrey (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
Poungthong, P.; Giacomin, A. Jeffrey; Saengow, Chaimongkol; Kolitawong, Chanyut (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
Saengow, Chaimongkol; Giacomin, A. Jeffrey; Khalaf, N.; Guay, Martin (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 ... 
Startup Steady Shear Flow from the Oldroyd 8Constant Framework
Saengow, Chaimongkol; Giacomin, A. Jeffrey; Grizutti, Nino; Pasquino, R. (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 ...