## Search

Now showing items 1-10 of 52

#### Die Drool and Polymer Degradation

(2015-06-24)

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 ...

#### Extruding Plastic Pipe From Eccentric Dies

(2015-05-25)

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 self-weight ...

#### Exact Analytical Solution for Large-Amplitude Oscillatory Shear Flow from Oldroyd 8-Constant Framework: Shear Stress

(2017-01)

The Oldroyd 8-constant model is a continuum framework containing, as special cases, many important constitutive equations for elastic liquids. When polymeric liquids undergo large-amplitude oscillatory shear flow, the shear ...

#### Large-Amplitude Oscillatory Shear Flow Loops for Long-Chain Branching From General Rigid Bead-Rod Theory

(2020-04)

General rigid bead-rod theory [Hassager, J Chem Phys, 60, 4001 (1974)] explains polymer viscoelasticity from macromolecular orientation. By means of this theory, we relate the complex viscosity of polymeric liquids to the ...

#### Van Gurp-Palmen Relations for Long-Chain Branching From General Rigid Bead-Rod Theory

(2020-02)

Empirically, we find that parametric plots of mechanical loss angle versus complex shear modulus may depend neither on temperature [van Gurp and Palmen, Rheol Bull (SoR), 67, 5 (1998)], nor on average molecular weight ...

#### Wall Slip Heating

(2015-01-05)

When molten plastic is extruded, the upper limiting throughput is often dictated by fine irregular distortions of the extrudate surface. Called sharkskin melt fracture, plastics engineers spike plastics formulations with ...

#### Exact Analytical Solution for Large-Amplitude Oscillatory Shear Flow

(2015-03-16)

When polymeric liquids undergo large-amplitude shearing oscillations, the shear stress responds as a Fourier series, the higher harmonics of which are caused by fluid nonlinearity. Previous work on large-amplitude oscillatory ...

#### Padé Approximants for Large-Amplitude Oscillatory Shear Flow

(2015-03-17)

Analytical solutions for either the shear stress or the normal stress differences in large-amplitude oscillatory shear flow, both for continuum or molecular models, often take the form of the first few terms of a power ...

#### Fourier Decomposition of Polymer Orientation in Large-Amplitude Oscillatory Shear Flow

(2015-03-17)

In our previous work, we explored the dynamics of a dilute suspension of rigid dumbbells as a model for polymeric liquids in large-amplitude oscillatory shear flow, a flow experiment that has gained a significant following ...

#### Orientation in Large-Amplitude Oscillatory Shear

(2014-09-30)

We examine the simplest relevant molecular model for large-amplitude oscillatory shear flow of a polymeric liquid: the dilute suspension of rigid dumbbells in a Newtonian solvent. We find explicit analytical expressions ...