An analysis of flow behaviour of polymer molecules, I

Hlaváček, B.; Seyer, F. A.

doi:10.1007/bf01500612

Cited by 13 publications

(5 citation statements)

References 20 publications

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“…In essence this interpretation is in line with publications which suggest (11,(14)(15)(16)(17) that the growth of the backbones is strongly promoted by the longitudinal velocity gradient at their tips, rather by the transversal gradient at the lateral surfaces which may be even considerably smaller for various reasons.…”

Section: Free-growthsupporting

confidence: 69%

“…This result implies that the exceptionally large growth rates for the surface-growth cannot be interpreted in terms of the extensive coil extension [14] by the large velocity gradients as this occurs anywhere in the flow field, and other factors should be involved. To emphasize this point we may introduce the relative growth rate A defined as (~)el) free-growth gsurface-growth LJ = (?el)surface-growth X Gfree-growth .…”

Section: Nq-~(vt--g)mentioning

confidence: 80%

“…To emphasize this point we may introduce the relative growth rate A defined as (~)el) free-growth gsurface-growth LJ = (?el)surface-growth X Gfree-growth . [14] Tab. 5 shows that indeed the surface-growth after accounting for the effect of the velocity gradient is still remarkably faster in particular for the silanized sand-blasted glass rotor where a value for d of 350 was calculated using equation [14].…”

Section: Nq-~(vt--g)mentioning

confidence: 96%

“…[14] Tab. 5 shows that indeed the surface-growth after accounting for the effect of the velocity gradient is still remarkably faster in particular for the silanized sand-blasted glass rotor where a value for d of 350 was calculated using equation [14]. For a smooth glass rotor the value of A is only 12, approaching the conditions for free-growth•…”

Section: Nq-~(vt--g)mentioning

confidence: 96%

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Longitudinal growth of polymer crystals from flowing solutions III. Polyethylene crystals in Couette flow

Zwijnenburg

Pennings

1976

Colloid Polymer Sci

189

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Section: Free-growthsupporting

confidence: 69%

Section: Nq-~(vt--g)mentioning

confidence: 80%

Section: Nq-~(vt--g)mentioning

confidence: 96%

Section: Nq-~(vt--g)mentioning

confidence: 96%

See 2 more Smart Citations

Longitudinal growth of polymer crystals from flowing solutions III. Polyethylene crystals in Couette flow

Zwijnenburg

Pennings

1976

Colloid Polymer Sci

189

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“…The analysis of Hermans (1944) and Peterlin (1967) for transverse velocity gradients and those of Ziabicki (1949) and Peterlin (1966) for longitudinal velocity gradients will be given in outline. Another theory although formulated in a different way leads essentially to similar results (Hlavacek & Seyer 1971).…”

Section: (Ii) Chain Extension In Velocity Gradientsmentioning

confidence: 75%

Flow induced polymer chain extension and its relation to fibrous crystallization

1975

Phil. Trans. R. Soc. Lond. A

138

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This work examines the effect that appreciable molecular extension has on the crystallization of long chain molecules. Elementary theoretical considerations presented indicate that to achieve high molecular extensions in solution a longitudinal velocity gradient of strain rate about 103s-1 is required. A method of generating such a velocity gradient, involving flow between opposed jets, is reported and the nature of this flow pattern is examined and quantitatively analysed. The behaviour of polyethylene-xylene solutions in the flow field is presented, notably birefringence observations and measurements indicate that a high degree of molecular alinement can be achieved in specific localized areas of the flow field; also concentration effects are observed which are discussed in terms of entanglement concepts. The effect chain alinement has on crystallization is examined in detail, in particular the ‘shish kebab ’ morphology of the crystals so produced is examined in relation to the hydrodynamic conditions in which they were grown.

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Quantitative analogies between the linear and non‐linear viscoelastic functions

1973

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A method of determination of linear and non‐linear viscoelastic functions is proposed. Through this method it is possible to calculate the non‐linear functions P11 ‐ P22 and η(γ) assuming that linear viscoelastic function (ω) is known. Alternatively from the function P11 ‐ P22 we are able to calculate η(γ) and y'(ω) etc. The method is based on the assumption that the change from linear to non‐linear functions is proportional to a molecular deformation for shear stress components P12, and is dependent on the square of the deformation for the first normal stress difference, P11 ‐ P22. The obtained results suggest straightforward modification of equations of state, this being demonstrated with the White‐Metzner model of the convected Maxwell element. Consideration of available experimental data shows that this theory is capable of predicting the various functions, at least as well as currently available constitutive equations, while requiring less experimental information.

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An analysis of flow behaviour of polymer molecules, I

Cited by 13 publications

References 20 publications

Longitudinal growth of polymer crystals from flowing solutions III. Polyethylene crystals in Couette flow

Longitudinal growth of polymer crystals from flowing solutions III. Polyethylene crystals in Couette flow

Flow induced polymer chain extension and its relation to fibrous crystallization

Quantitative analogies between the linear and non‐linear viscoelastic functions

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