Experimental Determination of the Elongational Viscosity of Polymer Solutions

1991 ◽  
Vol 44 (11S) ◽  
pp. S46-S50 ◽  
Author(s):  
A. E. Chavez ◽  
O. Manero ◽  
H. Y. Bao ◽  
R. K. Gupta
Keyword(s):  
Polymer Solutions ◽  
Extensional Flow ◽  
Elongational Flow ◽  
Fiber Spinning ◽  
Momentum Balance ◽  
Test Fluid ◽  
Sodium Acrylate ◽  
Flow Data ◽  
Hydrodynamic Friction

A comparative study is performed between elongational flow data obtained from fiber spinning and a numerical scheme based on the expressions derived from an anisotropic FENE dumbbell model, with conformation-dependent hydrodynamic friction, coupled with a differential momentum balance made along the spinning filament. Extensional flow data was obtained by using the Gupta-Sridhar extensional viscometer. The test fluid was an aqueous solution of a copolymer of sodium acrylate and acrylamide (Alcomer 120). From the information obtained by this comparison, we assess the influence of preshearing and other factors on the rheological behavior of polymer solutions using this technique.

scholarly journals Recoverable Extensional Flow of Polymer Melts and Its Relevance for Processing

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1512
Author(s):  
Helmut Münstedt
Keyword(s):  
Polymer Melts ◽  
Extensional Flow ◽  
Elongational Flow ◽  
Fused Deposition Modelling ◽  
Extrudate Swell ◽  
Fused Deposition ◽  
Rigid Particles ◽  
Experimental Parameters ◽  
Slit Die

While the uniaxial elongational viscosity is widely investigated, and its relevance for processing is described in the literature, much less has been published on the recoverable extensional flow of polymer melts. This paper presents a short overview of the dependencies of the recoverable elongation on the molecular structure of a polymer, and on some experimental parameters. Its main focus lies on the discussion of processing operations and applications that are largely affected by the elastic components of elongational flow. The recoverable portions of stretched films are considered, and the exploitation of the shrinkage of films, due to the recovery of frozen recoverable deformations, and its role for applications are addressed. The analysis of measurements of velocity fields in the entry region of a slit die and results on the determination of the recoverable elongation from uniaxial experiments, according to the literature, lead to the conclusion of dominant elastic extensions. Considering these facts, the assumptions for Cogswell’s widely used method of determining elongational viscosities under processing conditions from entrance flow are not realistic. As examples of a direct application of extrudate swell from short dies for processing, pelletizing and fused deposition modelling within additive manufacturing are addressed. The special features of extrudate swell from short dies, and uniaxial recoverable elongation for a polymer filled with rigid particles in comparison to an immiscible polymer blend, are presented and discussed.

AGGLUTINATION INHIBITION REACTIONS FOR THE DETERMINATION OF GONADOTROPHINS

1969 ◽  
Vol 62 (1_Suppl) ◽  
pp. S95-S112 ◽  
Author(s):  
A. H. W. M. Schuurs
Keyword(s):  
Immune System ◽  
Quantitative Determination ◽  
Haemagglutination Inhibition ◽  
Latex Agglutination ◽  
Literature Survey ◽  
New Method ◽  
Test Fluid ◽  
Main Application ◽  
Test Systems

ABSTRACT Various techniques for sensitising erythrocytes and latex particles with gonadotrophins, particularly with HCG, are described. The haemagglutination inhibition reactions are generally interpreted by means of »erythrocyte settling patterns«. By a new method of evaluating these patterns a relatively precise quantitative determination is possible. Latex agglutination inhibition reactions on slides are particularly suitable as rapid qualitative tests. In cases where the maximum attainable sensitivity of the agglutination inhibition tests is insufficient, e. g. for determining LH concentrations in urine, the hormone in the test fluid has to be concentrated or extracted. An alternative method is a modified haemagglutination inhibition test for large volumes which is applicable to unconcentrated urine. Due to non-specific inhibitions the above-mentioned tests cannot be applied to unprocessed serum. Agglutination inhibition tests with HCG are already well advanced, pregnancy diagnosis being their main application. Now that highly purified HCG is available, a satisfactory specificity for these tests can be attained. If the immune system for HCG is used for estimating LH, it has to meet additional specificity requirements. Furthermore, the measure of cross-reaction and the choice of standard merit special attention. Finally, a literature survey is given of test systems in which LH and FSH were used as antigens.

A Graphical Method for Storage Coefficient Determination from Quasi-Steady State Flow Data

1996 ◽  
Vol 27 (4) ◽  
pp. 247-254 ◽  
Author(s):  
Zekâi Şen
Keyword(s):  
Steady State ◽  
Graphical Method ◽  
Pumping Test ◽  
Quasi Steady State ◽  
Flow Data ◽  
Steady State Flow ◽  
Storage Coefficient ◽  
State Flow ◽  
Aquifer Test

A simple, approximate but practical graphical method is proposed for estimating the storage coefficient independently from the transmissivity value, provided that quasi-steady state flow data are available from a pumping test. In the past, quasi-steady state flow distance-drawdown data have been used for the determination of transmissivity only. The method is applicable to confined and leaky aquifers. The application of the method has been performed for various aquifer test data available in the groundwater literature. The results are within the practical limits of approximation compared with the unsteady state flow solutions.

The determination of the pressure—viscosity coefficient of a lubricant through an accurate film thickness formula and accurate film thickness measurements

2009 ◽  
Vol 223 (8) ◽  
pp. 1143-1163 ◽  
Author(s):  
H van Leeuwen
Keyword(s):  
Film Thickness ◽  
Viscosity Coefficient ◽  
Test Fluid ◽  
Limited Data ◽  
Ehd Lubrication ◽  
Spacer Layer ◽  
Wide Range ◽  
Approximation Formulas ◽  
Thickness Measurements

The pressure—viscosity coefficient is an indispensable property in the elastohydrodynamic (EHD) lubrication of hard contacts, but often not known. A guess will easily lead to enormous errors in the film thickness. This article describes a method to deduct this coefficient by adapting the value of the pressure—viscosity coefficient until the differences between accurate film thickness approxi-mation values and accurate film thickness measurements over a wide range of values are at a minimum. Eleven film thickness approximation formulas are compared in describing the film thickness of a test fluid with known value of the pressure—viscosity coefficient. The measurement method is based on spacer layer interferometry. It is concluded that for circular contacts the newer more versatile expressions are not better than some older approximations, which are limited to a smaller region of conditions, and that the older fits are as least as appropriate to find the pressure—viscosity coefficient of fluids, in spite of the limited data where they have been based on.

Determination of plasticizer vapour pressure over polymer solutions by the effusion method

1970 ◽  
Vol 12 (3) ◽  
pp. 551-556 ◽  
Author(s):  
A.I. Suvorova ◽  
V.V. Serpinskii ◽  
A.A. Tager ◽  
L.N. Khavrenko
Keyword(s):  
Vapour Pressure ◽  
Polymer Solutions ◽  
Effusion Method
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