Development of a Rheology Die and Flow Characterization of Gas-Containing Polymer Melts

We present a novel measurement die for characterizing the flow behavior of gas-containing polymer melts. The die is mounted directly on the injection-molding cylinder in place of the mold cavity and thus enables near-process measurement of viscosity (i.e., under the conditions that would be present were a mold attached). This integration also resolves the issue of keeping gas-containing polymer melts under pressure during measurement to prevent desorption. After thermal characterization of the die, various correction approaches were compared against each other to identify the most suitable one for our case. We conducted measurements using polypropylene in combination with two different chemical blowing agents. Increasing the blowing-agent content to up to 6% revealed an interestingly low influence of gases on melt viscosity, which was confirmed by elongational viscosity measurements. For verification, we compared our results to corresponding measurements taken on a high-pressure capillary rheometer and found that they were in excellent agreement. Our die cannot only be used for rheological characterization. Combined with ultrasound sensors, it provides an innovative way of measuring the volumetric flow rate. This development represents an important step in improving the sustainability of gas-containing polymer processing.

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Rheological Characterization of a Concentrated Phosphate Slurry

Fluids ◽

10.3390/fluids6050178 ◽

2021 ◽

Vol 6 (5) ◽

pp. 178

Author(s):

Souhail Maazioui ◽

Abderrahim Maazouz ◽

Fayssal Benkhaldoun ◽

Driss Ouazar ◽

Khalid Lamnawar

Keyword(s):

Flow Behavior ◽

Continuous Phase ◽

Raw Material ◽

Rheological Characterization ◽

Phosphate Ore ◽

Insoluble Particles ◽

Experimental Protocols ◽

Solid Liquid

Phosphate ore slurry is a suspension of insoluble particles of phosphate rock, the primary raw material for fertilizer and phosphoric acid, in a continuous phase of water. This suspension has a non-Newtonian flow behavior and exhibits yield stress as the shear rate tends toward zero. The suspended particles in the present study were assumed to be noncolloidal. Various grades and phosphate ore concentrations were chosen for this rheological investigation. We created some experimental protocols to determine the main characteristics of these complex fluids and established relevant rheological models with a view to simulate the numerical flow in a cylindrical pipeline. Rheograms of these slurries were obtained using a rotational rheometer and were accurately modeled with commonly used yield-pseudoplastic models. The results show that the concentration of solids in a solid–liquid mixture could be increased while maintaining a desired apparent viscosity. Finally, the design equations for the laminar pipe flow of yield pseudoplastics were investigated to highlight the role of rheological studies in this context.

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Rheological Characterization of a New Alloy for Thixoforming

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.141-143.301 ◽

2008 ◽

Vol 141-143 ◽

pp. 301-306 ◽

Cited By ~ 7

Author(s):

Annalisa Pola ◽

Roberto Roberti ◽

Michael Modigell ◽

Lars Pape

Keyword(s):

Flow Behavior ◽

Thermodynamic Simulation ◽

Semisolid State ◽

Rheological Characterization ◽

Scanning Calorimetry ◽

Globule Size ◽

Semisolid Alloy ◽

Dependent Flow ◽

Mechanical Performances

A new aluminum alloy (AlSi5Mg0.5Cu0.3Ag) for semisolid die-casting applications was designed, starting from computational thermodynamics calculations by Computherm Database. The goal was to obtain a combination of good castability and proper concentration of hardening elements for strengthening precipitation treatment. The predicted thixotropic properties were verified by measuring the microstructural conventional parameters, such as globule size and shape factor, and the solidification range, by means of differential scanning calorimetry. To complete the characterization of this new alloy and to evaluate its applicability in industrial production, the shear rate and time-dependent flow behavior of the alloy in the semisolid state was studied in a Searle-type rheometer. A future aim of the present research is to try to use rheology testing as the tool to optimize the chemical composition, in order to design an alloy characterized by good mechanical performances and easy processability. Considering the strong influence of the solid fraction content on semisolid alloy viscosity, the rheology tests were interrupted after a certain time and the alloy was deeply freezed using vaporized liquid nitrogen, in order to fix the microstructure and verify the correctness of the thermodynamic simulation.

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Assessing the practical utility of the hole-pressure method for the in-line rheological characterization of polymer melts

Rheologica Acta ◽

10.1007/s00397-013-0695-5 ◽

2013 ◽

Vol 52 (7) ◽

pp. 661-672 ◽

Cited By ~ 12

Author(s):

Paulo F. Teixeira ◽

Loic Hilliou ◽

José A. Covas ◽

João M. Maia

Keyword(s):

Polymer Melts ◽

Rheological Characterization ◽

Practical Utility ◽

Hole Pressure ◽

Pressure Method

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Printing of Zirconia Parts via Fused Filament Fabrication

Materials ◽

10.3390/ma14195467 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5467

Author(s):

Dorit Nötzel ◽

Ralf Eickhoff ◽

Christoph Pfeifer ◽

Thomas Hanemann

Keyword(s):

Flow Behavior ◽

Special Focus ◽

Fused Filament Fabrication ◽

Rheological Characterization ◽

Structural Details ◽

Low Shear Stress ◽

Flow Situation ◽

The Individual ◽

Low Shear

In this work, a process chain for the fabrication of dense zirconia parts will be presented covering the individual steps feedstock compounding, 3D printing via Fused Filament Fabrication (FFF) and thermal postprocessing including debinding and sintering. A special focus was set on the comprehensive rheological characterization of the feedstock systems applying high-pressure capillary and oscillation rheometry. The latter allowed the representation of the flow situation especially in the nozzle of the print head with the occurring low-shear stress. Oscillation rheometry enabled the clarification of the surfactant’s concentration, here stearic acid, or more general, the feedstocks composition influence on the resulting feedstock flow behavior. Finally, dense ceramic parts (best values around 99 % of theory) were realized with structural details smaller than 100 µm.

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A Review on Flow Characteristics of the Straight and Coiled Capillary Tubes

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132521300044 ◽

2021 ◽

Vol 29 (03) ◽

Author(s):

Pravin Jadhav ◽

Neeraj Agrawal

Keyword(s):

Capillary Tube ◽

Numerical Study ◽

Flow Behavior ◽

Flow Characteristics ◽

Operating Conditions ◽

Capillary Tubes ◽

Numerical Studies ◽

Geometric Conditions ◽

Flow Characterization

A detailed literature review on the flow characterization of the capillary tubes is presented in this paper. The flow behavior is reviewed for straight, helically, and spirally coiled capillary tubes at different operating and geometric conditions by considering various aspects in the tube. This paper summarizes experimental and numerical study on the adiabatic and nonadiabatic straight and coiled capillary tubes at different geometries conditions. The vital information of the range of the tube geometry and operating conditions are discussed, which can be utilized for further studies on the capillary tube. Various methodologies with generalized correlations are indicated. It has been observed that there are even more studies need to do with environmentally friendly refrigerants with various practical aspects in the capillary tube. It would be interesting to find the coiling effect on the design and simulation of the capillary tube. In addition to that more experimental and numerical studies need to explore the nonadiabatic coiled capillary tube. It would be fascinating to study the metastable condition in the capillary tube and set suitable relations to present its effect on the mass flow rate.

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Physicochemical, Microstructural, and Rheological Characterization of Tigernut (Cyperus esculentus) Starch

International Journal of Food Science ◽

10.1155/2019/3830651 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

P. T. Akonor ◽

C. Tortoe ◽

C. Oduro-Yeboah ◽

E. A. Saka ◽

J. Ewool

Keyword(s):

Physicochemical Properties ◽

Amylose Content ◽

Flow Behavior ◽

Pasting Properties ◽

Cyperus Esculentus ◽

Rheological Characterization ◽

Freeze Thaw ◽

Starch Gels

The aim of this study was to characterize the physicochemical properties of starch isolated from two varieties of tigernuts. The results showed wide variations between the two types of tigernuts. Mean granule sizes were 11.1 and 6.1 μm, respectively, for starch from the yellow and black while amylose content ranged from 19 to 21%. Starch gels from the yellow variety were more stable to freeze-thaw and recorded 37.1% syneresis, compared to 56.5% after the first storage cycle. Pasting properties were significantly different (p < 0.05) among starch from the two tigernut varieties, with black recording higher peak viscosity, lower breakdown, and higher setback viscosity. Gels made from the yellow variety were clearer, softer, more adhesive, and more cohesive. Both gels showed a pseudoplastic flow behavior without thixotropy.

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Characterization of foam flowing in a granular medium in the presence of oil by small angle neutron scattering

Soft Matter ◽

10.1039/c9sm01936g ◽

2020 ◽

Vol 16 (7) ◽

pp. 1771-1778 ◽

Cited By ~ 3

Author(s):

Raphaël Poryles ◽

Thibaud Chevalier ◽

Nicolas Gland ◽

Elisabeth Rosenberg ◽

Loïc Barré

Keyword(s):

Experimental Study ◽

Small Angle ◽

Granular Medium ◽

Small Angle Neutron Scattering ◽

Granular Media ◽

Flow Behavior ◽

Foam Flow ◽

Flow Characterization ◽

A Cell

We present an experimental study of foam-flow characterization inside a 3D granular media packed in a cell. We show that flow behavior is related to foam microstructure.

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