Peculiarities of flow and viscoelastic properties of solutions of polymers with a narrow molecular-weight distribution

Vinogradov, G. V.; Malkin, A. Ya.; Blinova, N. K.; Sergeyenkov, S.I.; Zabugina, M.P.; Titkova, L.V.; Yanovsky, Yuri G.; Shalganova, V. G.

doi:10.1016/0014-3057(73)90123-7

Cited by 42 publications

(7 citation statements)

References 9 publications

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“…If the modulus is estimated from the measured shear and normal stress functions, it is found that the critical value of SR ranges form 2 to 5, although the shear stresses are two orders of magnitude less than those at which instability occurs for melts. The latter authors (Southern and Paul, 1974;Paul and Southern, 1975) have correlated their solution data and those of Vinogradov et al (1973) by using an entanglement theory and find results consistent with those of Vlachopoulos and Alam (1972) for melts [Equation (20) 1.…”

Section: Page 224mentioning

confidence: 64%

“…Finally, the stability of flow of polymer solutions is like that of melts. Instability in the entry flow and for the extrudate has been reported by Vinogradov and Manin ( 1965), Giesekus ( 1968), Brenschede and Klein ( 1970), den Otter (1970), Tomita and Shimbo (1973), Pearson and Pickup (1973), Vinogradov et al (1973), Rama Murthy (1974), Southern and Paul (1974), and Cable and Boger (1975). The polystyrene solutions of Southern and Paul ( 1974) were characterized rheogoniometrically.…”

Section: Page 224mentioning

confidence: 74%

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Instabilities in polymer processing

1976

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Instabilities which arise in shear and extensional flows in the processing of polymeric liquids are reviewed. The experimental observations and the extent of theoretical understanding of the instabilities are discussed. Department of Chemical EngineeringUniversity of Delaware Newark, Delaware 1971 1 SCOPEIn many polymer processing operations, the rate of sional and shear flows, including draw resonance and filaproduction is limited by the onset of flow instabilities. ment breakage in melt spinning, and melt fracture in The instabilities often occur at extremely low Reynolds extrusion. We also review the theoretical studies of numbers, where low molecular weight liquids do not these process instabilities and establish the extent to show similar unstable behavior. In this paper, we rewhich the mechanisms are understood and the onset view the experimental studies of instabilities in extenpredictable. CONCLUSIONS AND SIGNIFICANCEThere are two distinct instabilities in spinning. A regular and sustained periodic variation in the drawn filament diameter known as draw resonance may be encountered when the point of solidification is carefully controlled. The onset of draw resonance is well understood theoretically, and quantitative predictions can be made. Filament breakage is usually an entirely different phenomenon, and it may occur either because of the growth of surface perturbations (capillarity and necking) or because of cohesive fracture. The theoretical understanding of breakage is only qualitative. Low Reynolds number instabilities in shear flow and extrusion, commonly referred to collectively as melt fracture, represent at least two different phenomena. One, characteristic of linear polymers, is probably an instability of the shear flow in the die. The other, characteristic of branched polymers, is probably an instability of the converging flow at the die entry. Both instabilities occur at a value of the recoverable shear (shear stress/ shear modulus) of order 1 to 10. A die flow instability at a critical value of the recoverable shear is predicted by several different theoretical approaches, and the dominant mechanism cannot be identified with confidence.

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Section: Page 224mentioning

confidence: 64%

Section: Page 224mentioning

confidence: 74%

Instabilities in polymer processing

1976

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“…The observations [19] of a more pronounced S-form in the flow rate -pressure drop curves with an increase in the sharpness of the MWD of the polymers were further developed in [21][22][23] for a number of polymers with narrow MWDs. The rheological properties of the polymers and, in particular, the onset of rapid wall-slip were investigated in detail.…”

Section: A Concept Of Polymer Fluidity Loss At Large Shear Rates (Strmentioning

confidence: 90%

“…In [21][22][23][24][25][26] a concept was formulated that under large strain rates the polymer liquids could lose their fluidity because of a deformation orientation and so gain the properties reminiscent of polymer behaviour in the solid rubber-like state. Such a "transition" of trivial form can be established in pre-steady situations in which the characteristic flow time l~ V is less than characteristic relaxation time O0 [7,8].…”

Section: A Concept Of Polymer Fluidity Loss At Large Shear Rates (Strmentioning

confidence: 99%

A linear model of the stick-slip phenomena in polymer flow in rheometers

Leonov¹

1984

Rheol Acta

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A linear approach was employed for the qualitative theoretical study of the stick-slip phenomena in polymer flows in rheometers. For this purpose, the familiar three-constant rheological equation and a linear wall friction law (i.e. wall stress -slip velocity dependence) were used with some additional hypotheses about the onset of the stick-slip behaviour. The friction law used was derived from a crude molecular approach. On the basis of these equations the inertialess stickslip behaviour of a viscoelastic liquid flowing through a capillary at a constant flow rate was considered. To be able to describe some transient phenomena in this problem, inertial effects (as an example) were taken into account. Furthermore, the distortions on the extrudate surface due to the slip phenomena inside the capillary were described theoretically within the framework of a linear approximation. In the final part of the study the possibility of rapid stochastization was discussed for rotational stick-slip flow of polymers in a cone-plate rheometer.

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“…The aromatic polyhydrazide [2] results discussed here document the &dquo;solution fracture&dquo; barrier to increased wet spinning speeds and molecular weights necessary for improved fiber economics and properties, respectively. Elastic fracture of polymer solutions is a relatively recent finding [ 1,4,5,[8][9][10][11][12][13] and may not be widely known. Analogous with polymer melt fracture, the flow instability occurs at a critical extensional stress, as the solution is accelerated from a wide diameter reservoir into a much smaller diameter capillary [3,9].…”

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confidence: 99%

Solution Fracture Barrier in Wet Spinning

Southern

Ballman

1983

Textile Research Journal

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The dry jet wet spinning of various molecular weight aromatic polyhydrazide solutions is used to exemplify tenacity and spinnability reduction due to solution fracture, an elastic flow instability initiating in the capillary entrance region. Significantly, fiber spun at shear rates an order of magnitude above that required for fracture initiation evidences no tenacity loss. A flow visualization apparatus, used to photograph the solution orientation changes resulting from fracture, verified reduced instability amplitude at high shear rates...

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Peculiarities of flow and viscoelastic properties of solutions of polymers with a narrow molecular-weight distribution

Cited by 42 publications

References 9 publications

Instabilities in polymer processing

Instabilities in polymer processing

A linear model of the stick-slip phenomena in polymer flow in rheometers

Solution Fracture Barrier in Wet Spinning

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