scholarly journals Towards the Development of a Strategy to Characterize and Model the Rheological Behavior of Filled, Uncured Rubber Compounds

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4068
Author(s):  
M. M. A. Spanjaards ◽  
G. W. M. Peters ◽  
M. A. Hulsen ◽  
P. D. Anderson
Keyword(s):  
Rheological Behavior ◽  
Kinetic Equations ◽  
Model Parameters ◽  
Processing Conditions ◽  
Deformation History ◽  
Polymer Extrusion ◽  
Rheological Characterization ◽  
Shear Rates ◽  
Rubber Compounds ◽  
Thixotropic Behavior

In this paper, an experimental strategy is presented to characterize the rheological behavior of filled, uncured rubber compounds. Oscillatory shear experiments on a regular plate-plate rheometer are combined with a phenomenological thixotropy model to obtain model parameters that can be used to describe the steady shear behavior. We compare rate- and stress-controlled kinetic equations for a structure parameter that determines the deformation history-dependent spectrum and, thus, the dynamic thixotropic behavior of the material. We keep the models as simple as possible and the characterization straightforward to maximize applicability. The model can be implemented in a finite element framework as a tool to simulate realistic rubber processing. This will be the topic of another work, currently under preparation. In shaping processes, such as rubber- and polymer extrusion, with realistic processing conditions, the range of shear rates is far outside the range obtained during rheological characterization. Based on some motivated choices, we will present an approach to extend this range.

Better Process Description for the Extrusion of Silica and Carbon Black Compounds

2001 ◽  
Vol 74 (5) ◽  
pp. 899-914
Author(s):  
A. Limper ◽  
D. Schramm
Keyword(s):  
Carbon Black ◽  
Rheological Behavior ◽  
Extrusion Process ◽  
Rheological Characterization ◽  
Systematic Analysis ◽  
New Approach ◽  
Rubber Compounds ◽  
Plastics Processing ◽  
Multi Component System

Abstract In comparison to plastics processing, rubber processors handle a much more complex material. Due to active fillers used in rubber compounds, such as carbon black and silica, in some cases extraordinary filler/filler interactions occur. In general the multi-component system leads to a very complex rheological behavior. If silica compounds e.g. are processed the chemical modification of the filler surface (by organosilanes) has to be taken into account. By this the rheological behavior of the material changes dramatically. All these circumstances make rubber processing to a very complex theme. This paper presents results which are obtained within an European research project. The work is focussing on a better process description of the extrusion process of rubber compounds. It handles both applications of the extrusion process, i. e. for technical rubber goods or for making tire parts like the extrusion of tread stripes. Hence in this paper a new approach for modeling the flow in the extruder screw will be presented. Using this as a simulation tool a systematic analysis of the extrusion process is possible in reasonable time. Another field of interest in this context is the rheological characterization of rubber compounds with a so called „Extrusion-Rheometer“. The advantages of this device will be shown for the investigation of processability and gathering representative rheological data for recalculations of screw and die flow in the extrusion process.

Injection Molding of Rubber Compound with Rheology Affected by Vulcanization: Part I. Material Characterization

1996 ◽  
Vol 69 (2) ◽  
pp. 277-293 ◽  
Author(s):  
A. I. Isayec ◽  
M. Wan
Keyword(s):  
Cure Kinetics ◽  
Rheological Characterization ◽  
Cross Model ◽  
Shear Rates ◽  
Rate Dependent ◽  
Dsc Measurements ◽  
Rubber Compounds ◽  
Proposed Model ◽  
Highly Sensitive ◽  
Viscosity Function

Abstract Rheological behavior of rubber is highly sensitive to the thermal history and cure kinetics. Rheological characterization for SBR compound is carried out using a capillary rheometer and modified Mooney viscometer. The viscosity function, which is not only temperature and shear-rate dependent but also cure-level dependent, is constructed. A modification of Cross model is proposed and verified to predict the rheological and chemorheological behaviors of SBR compounds. This rheological characterization is combined with vulcanization kinetic characterization. The parameters of vulcanization are obtained from DSC measurement under several nonisothermal conditions. The significance of correcting for temperature lag in the DSC measurements and the corresponding rate-of-vulcanization lag resulting from the nonisothermal DSC scan is illustrated. The proposed rheological function is further modified to incorporate the temperature- and state-of-cure-dependent yield behavior of rubber compounds at low shear rates. The proposed model is suitable for use in the simulation of processing operations.

Experimental Study of Micronized Coal/Water Slurry Rheology at High Shear Rates

1990 ◽  
Vol 112 (1) ◽  
pp. 36-40 ◽  
Author(s):  
Y. I. Cho ◽  
U. S. Choi
Keyword(s):  
Diesel Engines ◽  
Rheological Behavior ◽  
Capillary Tube ◽  
Operating Conditions ◽  
Rheological Characterization ◽  
Shear Rates ◽  
Water Slurry ◽  
Wide Range ◽  
Coal Water Slurry ◽  
Slurry Rheology

The rheological behavior of four micronized coal water slurry (CWS) samples was studied experimentally for a wide range of shear rates between 3 and 30,000 s−1. The systematic rheological characterization of the slurry fuel shows that the rheological behavior of these CWS is very complex and depends on coal particle size, temperature, coal loading, conditioning additives, and the capillary tube diameter as well as the shear rate. This study indicates that better appreciation of the unique and complex rheological behavior of non-Newtonian CWS fuels is vital to developing high-quality slurries suitable for use in coal-fired diesel engines, and suggests that a more comprehensive data base for CWS rheology under actual diesel engine operating conditions is needed prior to using such CWS fuels in diesel engines.

scholarly journals An Experimental Study on Human Milk Rheology: Behavior Changes from External Factors

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 42 ◽  
Author(s):  
Diana Alatalo ◽  
Fatemeh Hassanipour
Keyword(s):  
Experimental Study ◽  
Shear Rate ◽  
Human Milk ◽  
Rheological Behavior ◽  
Tube Feeding ◽  
External Factors ◽  
Behavior Changes ◽  
Nutrient Losses ◽  
Thixotropic Behavior ◽  
Temperature Storage

The influence of external factors, including temperature, storage, aging, time, and shear rate, on the general rheological behavior of raw human milk is investigated. Rotational and oscillatory experiments were performed. Human milk showed non-Newtonian, shear-thinning, thixotropic behavior with both yield and flow stresses. Storage and aging increased milk density and decreased viscosity. In general, increases in temperature lowered density and viscosity with periods of inconsistent behavior noted between 6–16 ∘ C and over 40 ∘ C. Non-homogeneous breakdown between the yield and flow stresses was found which, when coupled with thixotropy, helps identify the source of nutrient losses during tube feeding.

Applicability and Significance of Rheometric Tests for Rheology of Fluid and Self-Leveling High-Strength Concrete

1997 ◽  
Vol 1574 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Moncef Nehdi ◽  
Sidney Mindess
Keyword(s):  
Ultrafine Particles ◽  
Flow Behavior ◽  
High Strength ◽  
Partial Replacement ◽  
Test Fluid ◽  
Rheological Characterization ◽  
Bingham Model ◽  
Shear Rates ◽  
Concrete Mixtures ◽  
Two Parameters

The emergence of new special concretes on construction sites has shown that concretes of the same slump may behave quite differently on the job. For these concretes, one cannot rely on the traditional workability tests for quality control and rheological characterization. It has been claimed that the flow behavior of fresh concrete closely approximates the Bingham model and that at least two parameters are therefore needed to describe its rheology. Thus, rheological measurements must be carried out at not fewer than two shear rates. This study examines the applicability of the Bingham model to fluid and self-leveling highstrength concrete (HSC). Results obtained from a rheometer are compared with results of the standard slump test. Fluid concrete mixtures were investigated that had a water/binder ratio ( w/ b) of 0.33 and slump values of 200 ± 20 mm and incorporated proportions of limestone filler, silica fume, and ground silica as partial replacement (by volume) of cement. In addition, self-leveling concrete mixtures (torque viscosity ≤ 1 Nm at 15 min) having a w/ b ratio of 0.25 and 15 percent replacement of cement by various fillers were examined. The possibility of characterizing the rheology of fluid and self-leveling HSC on the basis of only two tests carried out at two different shear rates was addressed. An effort was made to define which is more relevant in a rheometer flow curve: the ascending part, the descending part, the maximum stress requirement, the flow resistance, the torque viscosity, or combinations of these factors. The possibility of measuring the rapid stiffening behavior of fresh HSC with time and the effect of ultrafine particles on the rheology using rheometric tests were also investigated.

scholarly journals Influence of Oxidation Degree of Graphene Oxide on the Shear Rheology of Poly(ethylene glycol) Suspensions

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 41 ◽  
Author(s):  
Yago Soares ◽  
Elyff Cargnin ◽  
Mônica Naccache ◽  
Ricardo Andrade
Keyword(s):  
Graphene Oxide ◽  
Rheological Behavior ◽  
Structural Characteristics ◽  
Rheological Characterization ◽  
Polymeric Liquid ◽  
Oxidation Degree ◽  
Force Microscopy ◽  
Fluid Behavior ◽  
Atomic Force ◽  
Poly Ethylene

This work studies the influence of the concentration and oxidation degree on the rheological behavior of graphene oxide (GO) nanosheets dispersed on polyethylene glycol (PEG). The rheological characterization was fulfilled in shear flow through rotational rheometry measurements, in steady, transient and oscillatory regimes. Graphene oxide was prepared by chemical exfoliation of graphite using the modified Hummers method. The morphological and structural characteristics originating from the synthesis were analyzed by X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and atomic force microscopy. It is shown that higher oxidation times increase the functional groups, which leads to a higher dispersion and exfoliation of GO sheets in the PEG. Moreover, the addition of GO in a PEG solution results in significant growth of the suspension viscosity, and a change of the fluid behavior from Newtonian to pseudoplastic. This effect is related to the concentration and oxidation level of the obtained GO particles. The results obtained aim to contribute towards the understanding of the interactions between the GO and the polymeric liquid matrix, and their influence on the suspension rheological behavior.

Sensory Evaluation and Rheological Behavior of Commercial Mayonnaise

2007 ◽  
Vol 3 (1) ◽  
Author(s):  
Dayane Izidoro ◽  
Maria-Rita Sierakowski ◽  
Nina Waszczynskyj ◽  
Charles W. I. Haminiuk ◽  
Agnes de Paula Scheer
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Sensory Evaluation ◽  
Rheological Behavior ◽  
Oil Content ◽  
Sensory Attributes ◽  
Rheological Parameters ◽  
Low Fat ◽  
Concentric Cylinder ◽  
Rheological Characterization

The effects of ingredients on the sensory evaluation and rheological behavior of two brands of mayonnaise were examined in this work. Mayonnaise samples were examined by Analytical Descriptive Test and Ranking Test of Preference. The rheological parameters were determined at 25°C using a concentric cylinder Brookfield rheometer with a spindle SC4-34. The results showed that standard mayonnaise as opposed to low-fat mayonnaise gained higher grades for most sensory attributes. All samples were found to exhibit non-Newtonian pseudoplastic behavior described by Herschel–Bulkley model. A decrease in the yield stress, viscosity and shear stress with the decrease in oil content was observed in all products, which confirm that the rheological characterization is capable of distinguishing rather well between mayonnaises made with different formulation.

Characterization of the Rheological Behavior of Drilling Fluids

2020 ◽  
Author(s):  
Eric Cayeux ◽  
Amare Leulseged
Keyword(s):  
Shear Rate ◽  
Rheological Behavior ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Shear Rates ◽  
Operation Conditions ◽  
Fluid Systems ◽  
Different Temperatures ◽  
The One ◽  
Shear Stress Response

Abstract It is nowadays well accepted that the steady state rheological behavior of drilling fluids must be modelled by at least three parameters. One of the most often used models is the yield power law, also referred as the Herschel-Bulkley model. Other models have been proposed like the one from Robertson-Stiff, while other industries have used other three-parameter models such as the one from Heinz-Casson. Some studies have been made to compare the degree of agreement between different rheological models and rheometer measurements but in most cases, already published works have only used mechanical rheometers that have a limited number of speeds and precision. For this paper, we have taken measurements with a scientific rheometer in well-controlled conditions of temperature and evaporation, and for relevant shear rates that are representative to normally encountered drilling operation conditions. Care has been made to minimize the effect of thixotropy on measurements, as the shear stress response of drilling fluids depends on its shear history. Measurements have been made at different temperatures, for various drilling fluid systems (both water and oil-based), and with variable levels of solid contents. Also, the shear rate reported by the rheometer itself, is corrected to account for the fact that the rheometer estimates the wall shear rate on the assumption that the tested fluid is Newtonian. A measure of proximity between the measurements and a rheological model is defined, thereby allowing the ranking of different rheological behavior model candidates. Based on the 469 rheograms of various drilling fluids that have been analyzed, it appears that the Heinz-Casson model describes most accurately the rheological behavior of the fluid samples, followed by the model of Carreau, Herschel-Bulkley and Robertson-Stiff, in decreasing order of fidelity.

Numerical Studies of the Effect of Constitutive Model Parameters as Reflecting Polymer Molecular Structure on Extrudate Swell

2002 ◽  
Vol 12 (5) ◽  
pp. 252-259 ◽  
Author(s):  
Nattapong Nithi-Uthai ◽  
Ica Manas-Zloczower
Keyword(s):  
Molecular Weight ◽  
Constitutive Model ◽  
Full Range ◽  
Constitutive Models ◽  
Model Parameters ◽  
Extrudate Swell ◽  
Relaxation Spectra ◽  
Shear Rates ◽  
Swell Ratio ◽  
Numerical Predictions

Abstract PolyFlow, a software package based on the finite element method was employed to simulate the extrudate swell for polybutadiene of various molecular weight (Mw) and molecular weight distribution (MWD). We calculated the relaxation spectra for the different samples and then inserted the spectra into a standard K-BKZ constitutive model used in the numerical simulations. Accurate predictions of MWD confirm the completeness of frequency range in the oscillatory shear experimental data. In turn, the wholeness of relaxation spectra as substantiated by MWD predictions, sustain the level of confidence when using constitutive models based on these spectra. We demonstrate the importance of using the full range of relaxation spectrum rather than a short range around typical shear rates for the accuracy of the numerical predictions. We found extrudate swell ratio (ESR) to be strongly dependent on MWD and stress conditions at the die exit.

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