Adsorption-entanglement layers in flowing high molecular weight polymer solutions IV. The rates of layer formation and decay

1986 ◽  
Vol 264 (11) ◽  
pp. 917-923 ◽  
Author(s):  
P. J. Barham
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Polymer Solutions ◽  
Layer Formation ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer

Rheological properties of high molecular weight polymer solutions

1973 ◽  
Vol 25 (6) ◽  
pp. 1554-1558
Author(s):  
Z. R. Gorbis ◽  
T. A. Rogovskii ◽  
S. P. Shul'gin
Keyword(s):  
Molecular Weight ◽  
Rheological Properties ◽  
High Molecular Weight ◽  
Polymer Solutions ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer

Experimental Study on Flow-Front Fingering Instabilities in Injection Molding of Polymer Solutions and Melts

2004 ◽  
Author(s):  
Kalonji K. Kabanemi ◽  
Jean-Franc¸ois He´tu ◽  
Samira H. Sammoun
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Polymer Solutions ◽  
Low Molecular Weight ◽  
Flow Front ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Polymer Molecules ◽  
Molecular Weights ◽  
Solvent Molecules

An experimental investigation of the flow behavior of dilute, semi-dilute and concentrated polymer solutions has been carried out to gain a better understanding of the underlying mechanisms leading to the occurrence of instabilities at the advancing flow front during the filling of a mold cavity. Experiments were performed using various mass concentrations of low and high molecular weight polyacrylamide polymers in corn syrup and water. This paper reports a new type of elastic fingering instabilities at the advancing flow front that has been observed only in semi-dilute polymer solutions of high molecular weight polymers. These flow front elastic instabilities seem to arise as a result of a mixture of widely separated high molecular weight polymer molecules and low molecular weight solvent molecules, which gives rise to a largely non-uniform polydisperse solution, with respect to all the kinds of molecules in the resulting mixture (solvent molecules and polymer molecules). The occurrence of these instabilities appears to be independent of the injection flow rate and the cavity thickness. Moreover, these instabilities do not manifest themselves in dilute or concentrated regimes, where respectively, polymer molecules and solvent molecules are minor perturbation of the resulting solution. In those regimes, smooth flow fronts are confirmed from our experiments. Based on these findings, the experimental investigations have been extended to polymer melts. Different mixtures of polycarbonate melts of widely separated molecular weights (low and high molecular weights) were first prepared. The effect of the large polydispersity of the resulting mixtures on the flow front behavior was subsequently studied. The same instabilities at the flow front were observed only in the experiments where a very small amount of high molecular weight polycarbonate polymer has been mixed to a low molecular weight polycarbonate melt (oligomers).

VISCOUS FINGERING PATTERNS IN HIGH MOLECULAR WEIGHT POLYMER SOLUTIONS

Fractals ◽  
1996 ◽  
Vol 04 (02) ◽  
pp. 181-185 ◽  
Author(s):  
MASAMI KAWAGUCHI ◽  
KYOKO MAKINO ◽  
TADAYA KATO
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Polymer Solutions ◽  
Methyl Cellulose ◽  
Injection Pressure ◽  
Viscous Fingering ◽  
Chain Entanglement ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
A Chain

Characteristics of viscous fingering patterns in polymer solutions were investigated by introducing air into a radial Hele-Shaw cell, in which high molecular weight Hydroxypropyl Methyl Cellulose (HPMC) solution was placed. HPMC chains form a chain entanglement easily, which leads to an increase in elasticity. The resulting patterns showed a drastic morphological change from highly branched patterns to tip-splitting patterns to skewering patterns, with an increase in injection pressure. Such a crossover in the fingering patterns could be well correlated with the characteristic quantities of pattern growth, such as the finger width and tip velocity.

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