Now showing items 1-20 of 24

    • Degradation in Cone-Plate Rheometry 

      Giacomin, A. Jeffrey; Gilbert, Peter H. (2018-07)
      We analyze quantitatively the oxidative degradation of a sample in a cone-plate rheometer, as oxygen diffuses inward, radially, from the free boundary. We examine rheometer error mitigation by means of nitrogen blanketing, ...
    • Degradation in Parallel-Disk Rheometry 

      Giacomin, A. Jeffrey; Pasquino, R.; Saengow, Chaimongkol; Gilbert, Peter H. (2018-08)
      We analyze quantitatively the oxidative degradation of a sample in a parallel-disk rheometer, as oxygen diffuses inward, radially, from the free boundary. We examine rheometer error mitigation by means of nitrogen blanketing, ...
    • Elastomers in Large-Amplitude Oscillatory Uniaxial Extension Revisited 

      Dessi, Claudia; Vlassopoulos, Dimitris; Giacomin, A. Jeffrey; Saengow, Chaimongkol (2017-07)
      In this work, we subject elastomers to a fixed pre-stretch in uniaxial extension, ε p , upon which a large-amplitude, 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 (2016-02)
      In this work, we subject elastomers to a fixed pre-stretch in uniaxial extension, ε p , upon which a large-amplitude, ε 0 , oscillatory uniaxial extensional (LAOE) deformation is superposed. We find that if both ε p and ε ...
    • Ethermodynamic Instability of Polymeric Liquids in Large-Amplitude Oscillatory Shear Flow from Corotational Maxwell Fluid 

      Saengow, Chaimongkol; Giacomin, A. Jeffrey (2018-04)
      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 

      Gilbert, Peter H.; Giacomin, A. Jeffrey (2017-02)
      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 Coefficients for Rigid Dumbbell Suspensions for Steady Shear Flow Material Function Expansions 

      Piette, Jourdain H.; Jbara, Layal; Saengow, Chaimongkol; Giacomin, A. Jeffrey (2008-07)
      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 8-constant Framework 

      Saengow, Chaimongkol; Giacomin, A. Jeffrey (2017-05)
      Large-amplitude 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 ...
    • Exact-solution for Cone-plate Viscometry 

      Giacomin, A. Jeffrey; Gilbert, Peter H. (2017-08)
      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 cone-plate viscometry. When the cone angle ...
    • Fluid Elasticity in Plastic Pipe Extrusion: Loads on Die Barrel 

      Saengow, Chaimongkol; Giacomin, A. Jeffrey (2017-07)
      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 (2018-12)
      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 ...
    • Macromolecular Tumbling and Wobbling in Large-Amplitude Oscillatory Shear Flow 

      Jbara, Layal M.; Giacomin, A. Jeffrey (2018-11)
      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 Large-Amplitude Oscillatory Shear Flow 

      Giacomin, A. Jeffrey; Saengow, Chaimongkol (2017-05)
      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 large-amplitude 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. (2018-02)
      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. (2018-12)
      We examine the second order orientation tensor for the simplest molecular model relevant to a polymeric liquid in large-amplitude 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 

      Jbara, Layal; Giacomin, A. Jeffrey (2018-09)
      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 ...
    • Padé Approximant for Normal Stress Differences in Large-Amplitude Oscillatory Shear Flow 

      Poungthong, P.; Saengow, Chaimongkol; Giacomin, A. Jeffrey; Kolitawong, Chanyut; Merger, D.; Wilhelm, M. (2017-11)
      Analytical solutions for the normal stress differences in large-amplitude 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 ...
    • Polymer Orientation Contributions in Large-Amplitude Oscillatory Shear Flow 

      Gilbert, Peter H.; Giacomin, A. Jeffrey (2017-01)
      Previously, we used a dilute suspension of rigid dumbbells as a model for the dynamics for polymeric liquids in large-amplitude oscillatory shear (LAOS) flow. We then use dumbbell orientation to explain fluid elasticity. ...
    • Power Series for Normal Stress Differences of Polymeric Liquids in Large-Amplitude Oscillator Shear Flow 

      Poungthong, P.; Giacomin, A. Jeffrey; Saengow, Chaimongkol; Kolitawong, Chanyut (2018-04)
      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 Large-Amplitude Oscillatory Shear Flow 

      Poungthong, P.; Saengow, Chaimongkol; Giacomin, A. Jeffrey; Kolitawong, Chanyut (2018-04)
      xact solutions for shear stress in a polymeric liquid subjected to large-amplitude oscillatory shear flow (LAOS) contain many Bessel functions. For the simplest of these, for instance, the corotational Maxwell fluid, in ...