scholarly journals Investigação do comportamento viscoelástico de amostras de licor negro oriundas do processo de polpação Kraft da Cenibra-MG à 25 oc

2021 ◽  
Vol 3 (4) ◽  
pp. 2411-2425
Author(s):  
Ângelo M. L. Denadai ◽  
Euler T. Dos Santos ◽  
Humberto L. Dos Santos ◽  
José M. Q. Moreira ◽  
Fernando C. De Oliveira ◽  
...  
Keyword(s):  
Shear Rate ◽  
Yield Stress ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Shear Thickening ◽  
Complex Viscosity ◽  
Kraft Pulping ◽  
Chemical Recovery ◽  
Molecular Fragmentation ◽  
Black Liquors

RESUMO O comportamento viscoelástico dos licores negros de eucalipto (LN) do processo de polpação Kraft da CENIBRA foi avaliado a 25 oC, na ausência (LNSC) e na presença (LNCC) de cinzas da ebulição da recuperação química, que são geralmente misturadas com licores negros para melhorar a eficiência da recuperação química. As amostras foram tosquiadas em campos rotativos e oscilatórios, mostrando os comportamentos de cisalhamento e cisalhamento dependentes da taxa de cisalhamento aplicada. A viscosidade complexa - *, o módulo de armazenamento e perda - G' e G'', e a tensão de rendimento 0 para LNSC foram todos muito superiores ao LNCC, provavelmente devido à fragmentação molecular causada pela adição de cinzas.   ABSTRACT The viscoelastic behavior of eucalyptus black liquors (LN) from CENIBRA Kraft pulping process was evaluated at 25 oC, in absence (LNSC) and in presence (LNCC) of ash from chemical recovery boiling, which are usually mixed with black liquors to improve the efficiency of chemical recovery. The samples were sheared upon rotational and oscillatory fields, showing booth shear-thickening and shear-thinning behaviors dependent of applied shear rate. The complex viscosity – h*, storage and loss modulus – G’ and G’’, and yield stress s0 for LNSC were all very higher than LNCC, probably due the molecular fragmentation caused by addition of ashes.

Influence of κ-Carrageenan, Modified Starch and Inulin Addition on Rheological and Sensory Properties of Non-fat and Non-added Sugar Dairy Dessert

2020 ◽  
Vol 16 (4) ◽  
pp. 462-469
Author(s):  
Zhaleh Sheidaei ◽  
Bahareh Sarmadi ◽  
Seyede M. Hosseini ◽  
Fardin Javanmardi ◽  
Kianoush Khosravi-Darani ◽  
...  
Keyword(s):  
Storage Modulus ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Textural Properties ◽  
Complex Viscosity ◽  
Sensory Properties ◽  
Modified Starch ◽  
Consumer Health ◽  
Added Sugar ◽  
Textural Parameters

<P>Background: The high amounts of fat, sugar and calorie existing in dairy desserts can lead to increase the risk of health problems. Therefore, the development of functional and dietary forms of these products can help the consumer health. </P><P> Objective: This study aims to investigate the effects of &#954;-carrageenan, modified starch and inulin addition on rheological and sensory properties of non-fat and non-added sugar dairy dessert. </P><P> Methods: In order to determine the viscoelastic behavior of samples, oscillatory test was carried out and the values of storage modulus (G′), loss modulus (G″), loss angle tangent (tan &#948;) and complex viscosity (&#951;*) were measured. TPA test was used for analysis of the desserts’ texture and textural parameters of samples containing different concentrations of carrageenan, starch and inulin were calculated. </P><P> Results: All treatments showed a viscoelastic gel structure with the storage modulus higher than the loss modulus values. Increasing amounts of &#954;-carrageenan and modified starch caused an increase in G′ and G″ as well as &#951;* and a decrease in tan &#948;. Also, firmness and cohesiveness were enhanced. The trained panelists gave the highest score to the treatment with 0.1% &#954;-carrageenan, 2.5% starch and 5.5% inulin (sucralose as constant = 0.25%) and this sample was the best treatment with desirable attributes for the production of non-fat and non-added sugar dairy dessert. </P><P> Conclusion: It can be concluded that the concentration of &#954;-carrageenan and starch strongly influenced the rheological and textural properties of dairy desserts, whereas the inulin content had little effect on these attributes.</P>

Preparation of SiO2/PEG Shear Thickening System by Centrifugal Dispersion

2012 ◽  
Vol 560-561 ◽  
pp. 586-590 ◽  
Author(s):  
Biao Yang ◽  
Sheng Wang ◽  
Guo Zhi Xu ◽  
Fei Xin
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
High Speed ◽  
Rotation Speed ◽  
Loss Modulus ◽  
Shear Thickening ◽  
Angular Frequency ◽  
Revolution Speed ◽  
Centrifugal Dispersion ◽  
The Revolution

The nano-SiO2/polyethylene glycol (PEG) dispersion system was prepared by centrifugal mixing, and its rheological properties were investigated. The results showed the revolution and rotation speed during the centrifugal mixing have a significant effect on the rheological properties of SiO2/PEG system. When the revolution speed of the centrifugal mixer was fixed at a high speed of 1200rpm, the shear thickening effect of SiO2/PEG was gradually increased with the decrease of rotation speed, and the maximum viscosity (η) of 12340 mPa•s appeared at the rotation speed of 200 rpm. At the low revolution speed of 700 rpm, the increase of the rotation speed significantly enhanced the shear thickening effect. When the rotation speed was 700rpm, the maximum viscosity was up to 86130mPa s. In steady state experiments, the systems show a shear-thinning property under low shear rate. When the shear rate exceeded a critical value (γ= 24.92 s-1), the viscosity first increased, and then decreased sharply. In the dynamic experiments, with the increase of angular frequency (ω), the loss modulus (G″) also increased and the systems behaved as a shear-thickening fluid.

Shear Thickening Behaviour of Composite Propellant Suspension under Oscillatory Shear

2016 ◽  
Vol 66 (3) ◽  
pp. 222 ◽  
Author(s):  
D. Singh ◽  
G. Dombe ◽  
C. Bhongale ◽  
P. P. Singh ◽  
Mehilal Maurya ◽  
...  
Keyword(s):  
Strain Amplitude ◽  
Loss Modulus ◽  
Shear Thickening ◽  
Rheological Behaviour ◽  
Complex Viscosity ◽  
Solid Particles ◽  
Dynamic Moduli ◽  
Composite Propellant ◽  
Plateau Region ◽  
Temperature Constant

Composite propellant suspensions consist of highly filled polymeric system wherein solid particles of different sizes and shapes are dispersed in a polymeric matrix. The rheological behaviour of a propellant suspension is characterised by viscoplasticity and shear rate and time dependant viscosity. The behaviour of composite propellant suspension has been studied under amplitude sweep test where tests were performed by continuously varying strain amplitude (strain in %, γ) by keeping the frequency and temperature constant and results are plotted in terms of log γ (strain amplitude) vs logGʹ and logGʺ (Storage modulus and loss modulus, respectively). It is clear from amplitude sweep test that dynamic moduli and complex viscosity show marked increase at critical strain amplitude after a plateau region, infering a shear thickening behaviour.

Viscoelastic Properties of Thixotropic Semisolid Alloy Relating the Microstructure

2019 ◽  
Vol 285 ◽  
pp. 380-384
Author(s):  
Gerardo Sanjuan-Sanjuan ◽  
Ángel Enrique Chavez-Castellanos
Keyword(s):  
Storage Modulus ◽  
Viscoelastic Properties ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Complex Viscosity ◽  
Plateau Modulus ◽  
Complex Shear ◽  
Different Temperatures ◽  
Semisolid Alloy ◽  
The Subject

The subject of this work is to investigate viscoelastic properties such as loss modulus (G ́ ́), storage modulus (G ́), complex shear modulus (G*), complex viscosity (η*) and loss angle () at different temperatures by means of a small-amplitude oscillatory test. These properties allow to provide information about materials structure. For this purpose, we employed a tin-lead alloy (Sn-15%Pb) which exhibits a similar microstructure to aluminum alloys and is the classic alloy for semisolid thixotropic studies. It is interesting to note that the Sn-15%Pb alloy exhibits a slightly decrease in storage modulus (G ́) over the entire frequency (0.01-10Hz) at high temperatures, showing its viscoelastic behavior. In addition, a detailed analysis of master curves (oscillatory tests) was made to relate the semisolid microstructure (solid fraction) with the plateau modulus (GN0) which is directly related with both molecular weight or percolation threshold in polymer and gels science respectively.

Effects of concentration and temperature on the rheological behavior of concentrated sodium lignosulfonate (NaLS) solutions

Holzforschung ◽  
2015 ◽  
Vol 69 (3) ◽  
pp. 265-271 ◽  
Author(s):  
Qianqian Tang ◽  
Mingsong Zhou ◽  
Dongjie Yang ◽  
Xueqing Qiu
Keyword(s):  
Viscoelastic Properties ◽  
Loss Modulus ◽  
Relaxation Times ◽  
Viscoelastic Behavior ◽  
Complex Viscosity ◽  
Industrial Applications ◽  
Sodium Lignosulfonate ◽  
All Solutions ◽  
Effects Of Temperature ◽  
Rheological Experiments

Abstract Concentrated sodium lignosulfonate (NaLS) solutions have wide industrial applications. Therefore, the viscoelastic properties of NaLS in concentrations of 55%–63% have been investigated between 5°C and 55°C by means of a dynamic rheological technique, namely, the oscillatory rheological experiments were conducted in a rheometer in the small amplitude oscillatory mode. All solutions showed “shear-thinning” behavior over frequency. The complex viscosity (η*) increased and the loss tangent (tanδ) decreased with increasing concentrations. Both the storage modulus (G′) and the loss modulus (G″) increased with increasing frequencies and concentrations. The change in viscoelastic behavior was probably caused by stronger aggregation effects. However, the effects of temperature on the viscoelastic properties are more complex. For 60% NaLS, G′, G″, and η* decreased, but tanδ increased with increasing temperatures. When the temperature exceeded 20°C, G′, G″, and η* increased, but tanδ decreased, and the relaxation times were increased as a function of temperature. The change in viscoelasticity as a function of temperature may also be related to intermolecular aggregation and the swelling of aggregates. The conductivity experiments indicated that the formation of a greater strength of network structures at higher levels of concentrations between 55% and 63% and temperatures between 20°C and 55°C was probably responsible for elasticity enhancement.

Composition – Property Relations in Shear Thickening Fluids

2014 ◽  
Vol 87 ◽  
pp. 91-97
Author(s):  
Łukasz Wierzbicki ◽  
Marcin Leonowicz
Keyword(s):  
High Strain ◽  
Volume Fraction ◽  
Solid Phase ◽  
Loss Modulus ◽  
Shear Thickening ◽  
Complex Viscosity ◽  
High Viscosity ◽  
Polypropylene Glycol ◽  
Shear Thickening Fluids ◽  
Composition Property

It was shown that fumed silica particles (FS), dispersed in polypropylene glycol (PPG), form shear thickening fluids (STF). PPGs with different molar mass were tested. The best combination of the properties (high viscosity, obtained at high shear rate) present the fluids composed of 7 nm FS and PPG 425. The highest volume fraction of FS, which was possible to disperse in PPG 425, was 25%. This fluid exhibited the highest viscosity. The highest magnitude of shear thickening effect was obtained, however, for 17.5 vol.% of the solid phase. Dynamic oscillatory shear experiments were conducted at either a constant amplitude or frequency. The constant strain amplitude tests showed, that for the frequency sweep, the systems showed viscous properties, except that of 25 vol.% of FS in PPG 425, which exhibited elastic properties in almost entire range of the frequency investigated. For the constant strain sweep, for low strains, the elastic modulus and loss modulus were hardly dependent on the strain, but for relatively high strain, this dependency was increasing. Also the complex viscosity was also growing for high strain values.

scholarly journals The elastics – viscosity propertis of printing role offset inks according to relacxation rheometry

2021 ◽  
pp. 37-48
Author(s):  
A.K. Dorosh ◽  
A.V. Shevchuk
Keyword(s):  
Shear Stress ◽  
Elastic Modulus ◽  
Shear Rate ◽  
Strain Rate ◽  
Loss Modulus ◽  
Complex Viscosity ◽  
Shear Strain Rate ◽  
Loss Angle ◽  
Flow Curves ◽  
Quantitative Measurements

Dire relacxation rheometry methods carried out quantitative measurements and established quvalitative patterns of the dependencies of the main elastic-viscous characteristics for the Cybo black ink system in the temperature range of ( 293-333)°K of its technological resistence, namely : the equilibrium elastic modulus and the angle loss modulus and loss angle tangent; complex viscosity and full reological flow curves of the first shear rate and second (viscosity) of the species; degree of destraction of elastic and viscous properties depending on the value: shear stress; shear strain rate ; relative or absolute deformation on the sample and its temperature.

scholarly journals Tuning Rheological Performance of Silica Concentrated Shear Thickening Fluid by Using Graphene Oxide

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Wenchao Huang ◽  
Yanzhe Wu ◽  
Ling Qiu ◽  
Cunku Dong ◽  
Jie Ding ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Shear Rate ◽  
Storage Modulus ◽  
Colloidal Silica ◽  
Loss Modulus ◽  
Shear Thickening ◽  
Light Weight ◽  
Critical Shear Rate ◽  
Shear Thickening Fluid ◽  
Significant Change

The addition of a small amount of graphene oxide into a traditional colloidal silica-based shear thickening fluid (STF) can lead to a significant change in viscosity, critical shear rate, storage modulus, and loss modulus of STF. This finding provides an effective way to prepare stronger and light-weight STFs.

scholarly journals Using Coupled Rheometer-FBRM to Study Rheological Properties and Microstructure of Cemented Paste Backfill

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Hongjiang Wang ◽  
Liuhua Yang ◽  
Hong Li ◽  
Xu Zhou ◽  
Xiaotian Wang
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Yield Stress ◽  
Rheological Behavior ◽  
Shear Thickening ◽  
Threshold Value ◽  
Rheological Parameters ◽  
Cemented Paste Backfill ◽  
Reflectance Measurement ◽  
Paste Backfill

Rheological properties, such as the yield stress, viscosity, and thixotropy, are related to the microstructure of cemented paste backfill (CPB). To highlight the relationship, two instruments were combined to measure the changes in the microstructure and the rheological properties of CPB simultaneously. In this way, the particle/agglomerate size distribution characterized by the focused beam reflectance measurement (FBRM) and the rheological factors measured by the rheometers could be directly linked. The results show that when under shearing, the intrinsic network structure of CPB responds to the shear-induced stresses with the interference of interparticle forces, leading to changes in the rheological behavior. Shear thinning can be found in CPB suspensions with a microstructure that is either loose interconnection or random. With an increase in the shear rate, random collisions among particles become organized in the flow, lowering the yield stress and viscosity. However, when the shear rate exceeds a certain threshold value, the rheological parameters change as a result of shear thickening. The results of this study contribute to better understanding of the complex rheological behavior of CPB.

scholarly journals Rheological analysis of hybrid hydrogels during polymerization processes

2017 ◽  
Vol 3 (2) ◽  
pp. 699-702
Author(s):  
Sabine Illner ◽  
Olga Sahmel ◽  
Stefan Siewert ◽  
Thomas Eickner ◽  
Niels Grabow
Keyword(s):  
Ionic Liquid ◽  
Drug Release ◽  
Loss Modulus ◽  
Sol Gel ◽  
Crosslinking Agent ◽  
Viscoelastic Behavior ◽  
Complex Viscosity ◽  
Compound System ◽  
Hybrid Hydrogels ◽  
Implant Coatings

AbstractDevelopment of new implant coatings with temperature-controlled drug release to treat infections after device implantation can be triggered by highly elastic hydrogels with adequate stability and adhesive strength in the swollen state. By using an ionic liquid (IL [ViPrIm]+[Br]−) as additive to N-isopropylacrylamide (NIPAAm) unique effects on volumetric changes and mechanical properties as well as thermoresponsive drug release of the obtained hybrid hydrogels were observed. In this context, rheological measurements allow the monitoring of gelation processes as well as chemical, mechanical, and thermal treatments and effects of additives. Hybrid hydrogels of pNIPAAm and poly (ionic liquid) (PIL) were prepared by radical emulsion polymerization with N,N′-methylenebis(acrylamide) as 3D crosslinking agent. By varying monomer, initiator and crosslinker amounts the multi-compound system during polymerization was monitored by oscillatory time sweep experiments. The time dependence of the storage modulus (G′) and the loss modulus (G″) was measured, whereby the intersection of G′ and G″ indicates the sol-gel transition. Viscoelastic behavior and complex viscosity of crosslinked and non-crosslinked hydrogels were obtained. Within material characterization rheology can be used to determine process capability and optimal working conditions. For biomedical applications complete hydrogelation inter-connecting all compounds can be received providing the possibility to process mechanically stable, swellable implant coatings or wound closures.

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