On the apparent relation between adhesive failure and melt fracture

Hill, Davide A.; Hasegawa, Tomiichi; Denn, Morton M.

doi:10.1122/1.550105

Cited by 141 publications

(55 citation statements)

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“…Table IV lists values of the exponent, m, that we calculated from the results of various previously published works. The exponent of 6 for a LLDPE was reported by Hill et al (1990). It can be observed from Table IV that the values for the various high density polyethylenes agree very well.…”

Section: Dependence On Molecular Characteristicssupporting

confidence: 71%

“…Kalika and Denn (1987) found that the slip velocity was a function of the LID ratio of a capillary, decreasing with increasing LID, and Hill et al (1990) concluded from this that the slip velocity depends on the pressure. The effect of pressure on slip velocity had been noted some years earlier by Vinogradov and Ivanova (1967), who carried out capillary experiments for an elastomer and argued that wall slip must increase considerably as the polymer approaches the outlet of the die, 10, 20, 40, 60 10, 20, 40, 80, 100 10, 40, 60, 80, 100 i.e., as the pressure approaches atmospheric.…”

Section: A Effect Of Geometry Versus Effect Of Pressurementioning

confidence: 99%

See 1 more Smart Citation

Wall slip of molten high density polyethylenes. II. Capillary rheometer studies

Hatzikiriakos¹,

Dealy²

1992

Journal of Rheology

363

178

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Section: Dependence On Molecular Characteristicssupporting

confidence: 71%

Section: A Effect Of Geometry Versus Effect Of Pressurementioning

confidence: 99%

Wall slip of molten high density polyethylenes. II. Capillary rheometer studies

Hatzikiriakos¹,

Dealy²

1992

Journal of Rheology

363

178

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“…Until now, it was assumed that the interactions resulting from contact between the plastic surface and the metal surface influence the wall-slip effect. [5,[14][15][16][17] This is confirmed by studies of the flow behavior of plastics in capillaries made of various materials. [9,12,14] The difficulty is to establish suitable descriptive characteristics from this data and to quantify their influence.…”

Section: Theoretical Description Of Wall Slip In the Rheometersupporting

confidence: 56%

Global Concept for Describing and Investigation of Wall Slip Effects in the Extrusion Process

Potente

Ridder

Cunha

2002

Macro Materials & Eng

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When it comes to the design of extrusion line components such as single‐screw extruders or extrusion dies, no one has yet succeeded in developing a well‐functioning concept for wall‐slipping materials. This article examines the fundamental influences of the wall slippage effect on flow behavior in the extrusion die and plastification unit. New and extended methods of calculation for describing this flow phenomenon are presented for both these extrusion line components, and the general possibilities for linking the two approaches are discussed. Diagram of the flow curve (τ = shear stress, $\dot \gamma$ = shear rate) of wall‐slipping plastics for constant pressure.magnified imageDiagram of the flow curve (τ = shear stress, $\dot \gamma$ = shear rate) of wall‐slipping plastics for constant pressure.

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“…It is known that the slip velocity depends on the shear stress at the wall, and a power-law equation (84,85) can be used to correlate them in some cases. Actually, the wall slip could also appear in a rotational rheometer; however, it is much evident in a capillary rheometer due to its higher shear rate.…”

Section: Rotational Rheometermentioning

confidence: 99%

Rheological Measurements

2013

Encyclopedia of Polymer Science and Technology

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Rheology is the science to study the flow and deformation of matter. It becomes an important field in material science and engineering, food, biotechnology, and so on. The objects in rheological study are not the ideal solid and ideal fluid, which can be described by the Hookean elastic model and the Newtonian viscous model, respectively. Instead, the rheological study often focuses on materials that can exhibit viscous, elastic, and plastic behavior under different flow conditions. They are often termed as complex fluids or soft matter, which include polymers, gels, suspensions, emulsions, biofluids, foods, inks (1). In contrast to hydrodynamics, which often accounts for the complex flow behavior of simple fluids, simple geometry is utilized in rheological measurements to understand the rather complicated relationship between the mechanical input and output of complex fluids. The real flow fields encountered in many applications (such as polymer extrusion, injection molding, blow molding, fiber spinning, inkjet printing, coating) are rather complicated (2). It becomes a problem whether the rheological measurements that performed under simple flow fields are useful in understanding the complicated flow behaviors of complex fluids. Fortunately, it has been proved in many examples that the properties determined from simple rheological measurements are sufficient to quantify the material parameters in various constitutive equations, which have been used widely and successfully to simulate the flow behaviors in polymer processing (3-11). The most frequently used simple flow fields are simple shear flow and simple extensional flow.The simplest geometry that defines the simple shear is two infinite parallel plates separated by a distance h. The liquid is set between two plates with one plate moving parallel to the other (Fig. 1). In reality, when the length L and the width B are much larger than the gap h, the flow in the center regime resembles the flow between two infinite plates. It means that the edge effects are ignored in most experimental shear geometries. In rheological measurements, the flow between two plates should be laminar. Moreover, it is usually assumed that the velocity across the gap satisfies a linear profile. As shown in Fig. 1, if the bottom plate is fixed and the upper plate moves horizontally with the velocity V, the fluid velocity varies linearly from 0 at the bottom plate to V at the upper plate if the no-slip boundary condition is satisfied. The linear velocity profile generates a constant velocity gradient, which is known as the shear rate. Then, the flow field between two parallel plates is homogeneous in the shear rate. The homogeneous assumption is nontrivial in the rheological tests since the actual velocity

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On the apparent relation between adhesive failure and melt fracture

Cited by 141 publications

References 0 publications

Wall slip of molten high density polyethylenes. II. Capillary rheometer studies

Wall slip of molten high density polyethylenes. II. Capillary rheometer studies

Global Concept for Describing and Investigation of Wall Slip Effects in the Extrusion Process

Rheological Measurements

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