Rheology of Plastisols of Poly(Vinyl Chloride)

1979 ◽  
Vol 52 (3) ◽  
pp. 676-691 ◽  
Author(s):  
E. A. Collins ◽  
D. J. Hoffmann ◽  
P. L. Soni
Keyword(s):  
Flow Behavior ◽  
Basic Mechanism ◽  
Particle Sizes ◽  
Solvent Interaction ◽  
Factors Affecting ◽  
Shear Rates ◽  
Wide Range ◽  
Size Of Particles ◽  
Increasing Temperature ◽  
Future Work

Abstract The viscosity of PVC plastisols is seen to be affected by numerous variables. Increase in concentration of the resin causes the viscosity to rise, with the increase being more abrupt at the higher concentrations. Deviation from Newtonian behavior also increases with concentration. Decrease in the size of particles results in an increase in viscosity, the effect being more pronounced at low shear rates. Broadening the distribution of particle sizes results in a decrease in viscosity. Porous particles yield plastisols with higher viscosity as compared to nonporous compact particles. The type of plasticizer also affects the viscosity. A plasticizer which is a better solvent for PVC (low value of polymer-solvent interaction parameter, χ) results in a higher viscosity due to an increase in the amount of dissolved polymer. Additives such as alcohols and soaps affect the viscosity in an, as yet, unknown way. Fillers, heat stabilizers, and pigments also increase the viscosity. With increasing temperature, the viscosity first decreases, passes through a minimum and then increases until gelation. With further rise in temperature the viscosity again decreases and then levels out before degradation occurs. In future work, particular emphasis needs to be given to the understanding of the basic mechanism involved in the effect of additives on the flow behavior. Systematic experiments with a range of well-defined particle sizes and over a wide range of shear rates are also needed. A better understanding of the factors affecting the behavior of plastisols will go a long way in changing the art of plastisol formulation to a science.

Nonnewtonian Flow of Poly(Dimethyl Siloxane)

1967 ◽  
Vol 40 (5) ◽  
pp. 1483-1491
Author(s):  
Yoshio Ito
Keyword(s):  
Shear Rate ◽  
Polymer Solutions ◽  
Flow Behavior ◽  
Degree Of Polymerization ◽  
High Shear ◽  
Newtonian Viscosity ◽  
Shear Rates ◽  
Molecular Weights ◽  
Dimethyl Siloxane ◽  
Wide Range

Abstract Nonnewtonian flow of poly(dimethyl siloxanes) of various molecular weights has been studied with a short capillary viscosimeter. The experiment covered a wide range of shear rate, from 10−1 to 3×106sec−1. Results were as follows: (1) Flow behavior of the sample changes with the degree of polymerization. For siloxanes with degrees of polymerization less than 1.55×102, flow of the fluid is newtonian throughout the whole range of shear rates; for siloxanes with degrees of polymerization from 3.22×102 to 2.63×103, flow is nonnewtonian at moderate shear rates; it again becomes newtonian at high shear rates. With degrees of polymerization more than 3.31×103, the spiral flow rises to a high shear rate. (2) Plow behavior of the samples is expressed by modifying Shishido's equation proposed for nonnewtonian polymer solutions. (3) When the observed flow curve contains its inflection point, the upper newtonian viscosity can be estimated by a new method proposed here. (4) The relations among the end correction of capillary, the pressure loss, and the shear stress proposed by Shishido for polymer solutions are applicable to poly(dimethy! siloxane) also.

scholarly journals Utilization of Bitter orange seeds as a novel source for recovery of pectin: Compositional and rheological characterization

2021 ◽  
Author(s):  
Mohammad Nejatian ◽  
Diako Khodaei ◽  
Hassan Ahmadi Gavlighi ◽  
Azizollaah Zargaraan
Keyword(s):  
Flow Behavior ◽  
Rheological Characterization ◽  
Flow Behavior Index ◽  
Bitter Orange ◽  
Rheological Measurements ◽  
Wide Range ◽  
Neutral Sugars ◽  
Strain Sweep ◽  
Increasing Temperature ◽  
First Time

Abstract The seeds from bitter orange, a by-product from the juice making step, hold the potential to facilitate novel, easy yet high quality pectin extraction. To test this hypothesis, the pectin from orange seeds (OSP) were extracted by distilled water and its compositional parameters and rheological behavior then evaluated. Results showed that galacturonic acid was the major component of OSP (~ 425 mg/g) confirming the purity of extracted pectin, followed by glucose and some minor neutral sugars. Mw, Rn and, Rz for the OSP were 4511.8 (kDa), 61 (nm), and 61.1 (nm), respectively. Rheological measurements showed shear-thinning behavior for OSP that by increasing temperature from 5 to 45 oC, the viscosity of the gum decreased. Power law fitted as the best rheological model describing the flow behavior of OSP. Strain sweep dynamic rheological measurements confirmed an entangled network structure for OSP and the addition of NaCl to the gum dispersion, decreased the consistency coefficient from 35.6 to 23.18 Pa.sn, while the flow behavior index remained unchanged. These results demonstrate for the first time that the OSP can be used as a new source of pectin, with likely a wide range of applications in food industry.

The Effect of Oil and Black on the Injection Molding of EPDM Compounds. I.

1969 ◽  
Vol 42 (5) ◽  
pp. 1321-1335
Author(s):  
William G. DePierri ◽  
J. R. Hopper
Keyword(s):  
Pressure Drop ◽  
Injection Molding ◽  
Flow Behavior ◽  
Injection Pressure ◽  
Flow Properties ◽  
Pressure Drops ◽  
Factors Affecting ◽  
Shear Rates ◽  
Divergent Flow ◽  
High Shear Rates

Abstract Factors affecting the flow properties of EPDM compounds have been studied and the findings of the study applied to the injection molding of these compounds. The level of oil and of black were found to change the flow properties of EPDM compounds. Higher levels of oil decreased the compound viscosity while higher levels of black increased the compound viscosity. The viscosity of the oil influenced compound viscosities. Compounds made with the more viscous (at 210° F) oil had slightly higher viscosities. However, changing from an aromatic to a naphthenic oil of similar viscosity had little effect on the compound viscosity. Compounds made from two different polymers of similar Mooney viscosity were found to have widely divergent flow behavior at high shear rates. Injection molding of EPDM compounds was studied with a molding assembly which had a capillary rheometer as barrel and plunger. Injection pressure data from the molding experiments was found to parallel closely the rheological data. An analysis of the pressure drops in passing through different parts of the mold assembly was made. The total calculated pressure drop agreed closely with the measured pressure drop. The viscous generation of heat was found to be proportional to pressure drop, and an equation is presented which relates the temperature increase to the pressure drop.

scholarly journals Utilization of Bitter orange seeds as a novel source for recovery of pectin: Compositional and rheological characterization

2021 ◽  
Author(s):  
Mohammad Nejatian ◽  
Diako Khodaei ◽  
Hassan Ahmadi Gavlighi ◽  
Azizollaah Zargaraan
Keyword(s):  
Flow Behavior ◽  
Rheological Characterization ◽  
Flow Behavior Index ◽  
Bitter Orange ◽  
Rheological Measurements ◽  
Wide Range ◽  
Neutral Sugars ◽  
Strain Sweep ◽  
Increasing Temperature ◽  
First Time

Abstract The seeds from bitter orange, a by-product from the juice making step, hold the potential to facilitate novel, easy yet high quality pectin extraction. To test this hypothesis, the pectin from orange seeds (OSP) were extracted by distilled water and its compositional parameters and rheological behavior then evaluated. Results showed that galacturonic acid was the major component of OSP (~ 425 mg/g) confirming the purity of extracted pectin, followed by glucose and some minor neutral sugars. Mw, Rn and, Rz for the OSP were 4511.8 (kDa), 61 (nm), and 61.1 (nm), respectively. Rheological measurements showed shear-thinning behavior for OSP that by increasing temperature from 5 to 45 oC, the viscosity of the gum decreased. Power law fitted as the best rheological model describing the flow behavior of OSP. Strain sweep dynamic rheological measurements confirmed an entangled network structure for OSP and the addition of NaCl to the gum dispersion, decreased the consistency coefficient from 35.6 to 23.18 Pa.sn, while the flow behavior index remained unchanged. These results demonstrate for the first time that the OSP can be used as a new source of pectin, with likely a wide range of applications in food industry.

Experimental and theoretical investigations on the viscosity of heterogeneous asphalt binders

2017 ◽  
Vol 50 (4) ◽  
pp. 354-371 ◽  
Author(s):  
Aboelkasim Diab
Keyword(s):  
Flow Behavior ◽  
Ethylene Vinyl Acetate ◽  
Hydrated Lime ◽  
Crumb Rubber ◽  
Asphalt Binders ◽  
Zero Shear Viscosity ◽  
Shear Rates ◽  
Wide Range ◽  
Theoretical Investigations ◽  
Pavement Construction

The inherent multiphase structure of heterogeneous asphalt binders (additives containing binders) may complicate viscosity understanding and predictions in the Newtonian or non-Newtonian response. The objective of this article is to understand the viscosity characteristics of heterogeneous asphalt binders based on experimental and theoretical investigations over a wide range of conditions the matter may encounter in the field (temperatures and oxidative aging). Selected materials representing the generic additives commonly used for pavement construction including styrene–butadiene–styrene block copolymer and ethylene–vinyl acetate copolymer, crumb rubber, and two mineral fillers, namely hydrated lime and fly ash, were utilized separately at different concentrations to produce the heterogeneous materials under study. The effects of varied temperatures as well as short- and long-term aging processes were studied for the materials over a wide range of shear rates. A further theoretical investigation was carried out by addressing the capability of Tscheuschner model to predict the flow behavior under the aforementioned conditions. In addition, the zero shear viscosity said to be an intrinsic characteristic of asphalt binders was evaluated using the regression analysis of data predicted from Tscheuschner model. Overall, the shear thinning behavior of heterogeneous asphalt binders occurred at low shear rates as compared to the base binder, especially at low temperatures. Emphasis was placed on the repeatability of the model predictions under different conditions, which could be an initiative to provide a simple but accurate representation of the viscosity of heterogeneous asphalt binders.

scholarly journals Non-Newtonian Patient-specific Simulations of Left Atrial Hemodynamics

2021 ◽  
Author(s):  
Alejandro Gonzalo ◽  
Manuel Garcia-Villalba ◽  
Lorenzo Rossini ◽  
Eduardo Duran ◽  
David Vigneault ◽  
...  
Keyword(s):  
Blood Flow ◽  
Left Atrial ◽  
Flow Behavior ◽  
Blood Rheology ◽  
Patient Specific ◽  
Shear Rates ◽  
Wide Range ◽  
History Of ◽  
Slow Blood Flow ◽  
Cell Aggregations

Atrial fibrillation (AF) is the most common arrhythmia, affecting ~35M people worldwide. The irregular beating of the left atrial (LA) caused by AF impacts the LA hemodynamics increasing the risk of thrombosis and ischemic stroke. Most LA thrombi appear in its appendage (LAA), a narrow sac of varied morphology where blood is prone to stagnate. In the LAA, the combination of slow blood flow and low shear rates (<100 [1/s]) promotes the formation of red blood cell aggregations called rouleaux. Blood experiences a non-Newtonian behavior when rouleaux formed that has not been considered in previous CFD analysis of the LA. We model the anatomy and motion of the LA from 4D-CT images and solve the blood flow inside the LA geometry with our CFD in-house code, which models Non-Newtonian rheology with the shear-hematocrit-dependent Carreau-Yasuda equation. We cover a wide range of non-Newtonian effects considering a small and a large hematocrit, including an additional constitutive relation to account for themrouleaux formation time, and we compare our results with Newtonian simulations. Blood rheology influence in LAA hemostasis is studied in 6 patient-specific anatomies. Two subjects had an LAA thrombus (digitally removed before running the simulations), another had a history of TIAs, and the remaining three had normal atrial function. In our simulations, the shear rate remains below 50 [1/s] in the LAA for all non-Newtonian models considered. This triggers an increase of viscosity that alters the flow behavior in that site, which exhibits different flow patterns than Newtonian simulations. These hemodynamic changes translate into differences in the LAA hemostasis, calculated with the residence time.

scholarly journals Utilization of Bitter orange seeds as a novel source for recovery of pectin: Compositional and rheological characterization

2022 ◽  
Author(s):  
Diako Khodaei ◽  
Mohammad Nejatian ◽  
Hassan Ahmadi Gavlighi ◽  
Farhad Garavand ◽  
Ilaria Cacciotti
Keyword(s):  
Flow Behavior ◽  
Rheological Characterization ◽  
Flow Behavior Index ◽  
Bitter Orange ◽  
Rheological Measurements ◽  
Wide Range ◽  
Neutral Sugars ◽  
Strain Sweep ◽  
Increasing Temperature ◽  
First Time

Abstract The seeds from bitter orange, a by-product from the juice making step, hold the potential to facilitate novel, easy yet high quality pectin extraction. To test this hypothesis, the pectin from orange seeds (OSP) were extracted by distilled water and its compositional parameters and rheological behavior then evaluated. Results showed that galacturonic acid was the major component of OSP (~ 425 mg/g) confirming the purity of extracted pectin, followed by glucose and some minor neutral sugars. Mw, Rn and, Rz for the OSP were 4511.8 (kDa), 61 (nm), and 61.1 (nm), respectively. Rheological measurements showed shear-thinning behavior for OSP that by increasing temperature from 5 to 45 oC, the viscosity of the gum decreased. Power law fitted as the best rheological model describing the flow behavior of OSP. Strain sweep dynamic rheological measurements confirmed an entangled network structure for OSP and the addition of NaCl to the gum dispersion, decreased the consistency coefficient from 35.6 to 23.18 Pa.sn, while the flow behavior index remained unchanged. These results demonstrate for the first time that the OSP can be used as a new source of pectin, with likely a wide range of applications in food industry.

Theoretical study of the prestressing strand's stress by computer modeling methods

2020 ◽  
Vol 76 (11) ◽  
pp. 1139-1148
Author(s):  
A. G. Korchunov ◽  
E. M. Medvedeva ◽  
E. M. Golubchik
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
Pearlitic Steel ◽  
Internal Stresses ◽  
Steel Microstructure ◽  
Compressive Stresses ◽  
Wide Range ◽  
Prestressing Strands ◽  
Increasing Temperature ◽  
Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

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