Viscous Characteristics Research Articles

Rheological behavior and film characterization of fumed silica dispersion in carbodiimide based UV-curable coating material

Carbodiimide based UV curable coating materials, which were developed as a high refractive raw coating material, were prepared by dispersion with fumed silica inorganic particles in order to overcome low hardness and strength of the cured films. Three kinds of fumed silica particles were dispersed having various reactive surfaces, and the rheological behavior of the dispersions was observed. Compared to the hydrophilic silica (Si-hi) dispersion, two types of hydrophobic silica (Si-ho-n and Si-ho-a) dispersion showed sol behavior in high concentrations. In particular, the Si-ho-a dispersion showed viscous sol characteristics for high shear rates. The surface hardness of the film obtained by UV curing of the fumed silica dispersion increased in the more highly concentrated dispersion, and the haze of the film also increased. Further, the film was highly refractive.

The viscosity of fine-grained sediments: A comparison of low- to medium-activity and high-activity clays

Viscosity is generally recognized as an indicator of landslide mobilization. Viscous behavior at relatively low (high) shear rates is an important predictor of the motion of slow- (fast)-moving landslides. The viscosity in a modified Bingham model at low and high shear rates was examined. The viscous characteristics are primarily dependent on the physico-chemical properties of the materials in question (e.g., grain size, mineralogy, salinity). In this context, the viscous characteristics of low- to medium-activity and high-activity clays (bentonite with different salinities) were compared. Empirical relationships exist between the liquidity index and the plastic viscosity regardless of the mineralogical composition. This study also demonstrated a positive relationship between the liquidity index and the viscosity in a modified Bingham model with n=1. The results showed that low- to medium-activity and high-activity clays fall into a similar range for fine-grained sediments mixed with salt water (30g/L). However, an effect of salinity was evident when using high-activity clays mixed with fresh water. Modified Bingham model is a useful and powerful tool for describing pre- and post-yield viscosity in engineering practice. By correlating the geotechnical and rheological properties of fine-grained sediments, index properties can help to estimate the appropriate values for the rheological parameters of these soils.

901 GISにおける使用環境を再現したEPゴム0リングの劣化予測解析(OS9 オーガナイズドセッション《発電機器の材料・構造解析と評価》)

In this paper, a computational prediction method of the compression set of EP-rabber 0-rings was proposed. As the prediction method, the finite element analysis code using thermo-mechanical viscoelastic model was developed. The material model consisted of viscoelastic elements connected in parallel. A viscoelastic element consisted of a hyper elastic spring and a viscous damper, which were connected in series. The relationship between relaxation times and temperature for the viscous characteristics of this model were calculated using the Arrhenius equation. This model is possible to perform the elastic strain which is generated by stress reduction. The boundary conditions of the FEM simulation were supposed that rubber 0-rings were in the two flat plates and in the groove and lid.Surface contact algorithm with penalty Junction was applied to the FEM code.

Effect of enzymatic treatments on the rheological and oil-resisting properties of wheat flour-based frying batters

A new enzymatic approach was introduced to reduce the oil uptake of batter-coated fried foods. Cross-linking (transglutaminase) and cell wall-degrading (viscozyme) enzymes were incorporated into the formulation of wheat flour-based frying batters, and their rheological/oil-resisting effects were evaluated. The transglutaminase treatment increased the pasting viscosities of wheat flour whereas viscozyme distinctly reduced these properties. The batters treated with transglutaminase exhibited the highest steady-shear viscosity, followed by the control and viscozyme-treated samples. Dynamic viscoelastic results showed that transglutaminase improved the elastic properties of frying batters, while their viscous characteristics became more dominant when viscozyme was used. These rheological features were favorably correlated with the adhesive properties of batters. During frying, the moisture loss of frying batters was retarded by transglutaminase. The incorporation of transglutaminase reduced the oil uptake of frying batters by 19.6%, thus contributing to the enhancement of the oil-barrier property.

Evaluation on gelling properties of Shuanghuanglian in situ gel by dynamic rheology

To determine the rheological properties of shuanghuanglian in situ gel (SHL-gel) by using dynamic rheological experiments, in order to evaluate its gelling properties shuanghuanglian in situ gel and predict its gelling behavior in vivo. Rheological parameters were determined by scanning of shear rate and frequency at different temperatures. The phase transition process from liquid to semisolid was described by testing of process heating/cooling and acute heating/cooling. SHL-gel was Newtonian fluid under the conditions of a phase angle approaching 90 degrees at low temperature or room temperature, with its viscous characteristics dominated. It was shear-thinning pseudoplastic fluid under the conditions of a low phase angle at body temperature, with its elastic characteristics dominated. During the phase transition process, the phase angle delta was getting sharp, with exponential increase of the modulus. The gelling temperature (Tg) was at (35.38 +/- 0.05) degrees C, the phase transition temperature ranged from 33.71 to 37.01%, and phase transition time was 140 s. The dynamic rheological experiment characterizes the gelling properties of Shuanghuanglian in situ gel so precisely that it can be used as the basis of for in vitro evaluation and quality control of products.

Coliquefaction Reactivity of Biomass and Coal under Moderate Conditions. Part 2: Effect of Cornstalk Dosage on Viscosity of the Coliquefaction System

The viscous characteristics of the liquefaction system play a crucial rule during liquefaction, and these characteristics of the coal oil slurry (COS) have been studied. In this paper, the viscosity of the coal biomass oil slurry (CBOS) at three stages while not systematically studied by forerunners was investigated by the torque current in the autoclave during coliquefaction of coals and cornstalk. The results, therefore, show that, at the thermal calefaction stage, the torque current of the CBOS system, predicted with the exponential decay model, was larger than that of the COS. At the pyrogenation and hydrogenation stage, the torque current of COS varies slightly in the Shengli coal system compared to the Shendong coal system, which presents a maximum. At the cooling stage, the torque current of the COS system, increasing with the quantity of the CS, was greater than that of the CBOS system. The study, thus, in the thesis indicates three aspects for industrial practices as well as fundamental research: the pumpablility of feedstock in the calefaction stage, the anticarbonization in the pyrogenation and hydrogenation stage, and the kinetic foundation in coliquefaction.

Investigation of the mechanical performances of material and structural configuration of telemark ski boots

A design procedure for telemark ski boots is presented, characterized by an integrated approach by means of experimental and numerical analyses. Material properties are investigated adopting different experimental tests addressed to the characterization of the behaviour of the ski boot polymeric materials, with particular regard to elastic, viscous, temperature-dependent and degradation characteristics. Material constitutive models are provided taking into account the experimental achievement. Ski boots morphology is defined adopting solid model technique and is subsequently transposed in numerical models that allow the mechanical response of the boot structure to be defined. Specific boundary conditions are assumed to mimic the binding effects. The investigation allows for an accurate interpretation of global and local effects induced in the specific boot as a function of loading considered. The present procedure can provide a valid set of information of the mechanical response of the boot in direct relation with the real use, taking into account loading and the environmental conditions, and leading to the possibility of defining the reliability and durability properties of the product. The present work is mostly addressed to offer a preliminary report with regard to the procedure adopted for the characterization of the materials and the constitutive formulation to be assumed for the numerical model aimed at the accurate design of a specific region of the ski boot.

Overturning of Retrofitted Rocking Structures under Pulse-Type Excitations

AbstractNumerous existing structures exhibit rocking behavior during earthquakes, and there is a continuing need to retrofit these structures to prevent collapse. In addition, while rocking behavior is typically prevented instead of utilized, an increasing number of structures are being designed or retrofitted to allow rocking motion as a means of seismic isolation. This paper investigates the use of viscous damping to limit the rocking motion by characterizing the fundamental behavior of damped rocking structures through analytical modeling. A single rocking block analytical model is used to determine the viscous damping characteristics, which exploit the beneficial aspects of the rocking motion, while dissipating energy and preventing overturning collapse. To clarify the benefits of damping, overturning envelopes for pulse-type ground accelerations are presented and compared with the pertinent envelopes of the free rocking block. A semianalytical solution to the linearized equations of motion enables ra...

Laboratory Study on Fibrous and Non Fibrous Bitumen Using Brookfield Viscometer

Bitumen is available in variety of types and grades. To judge the suitability of these grades various tests are specified by the different agencies like ASTM, ISI, and IRC etc. For classifying bitumen and studying the performance of bituminous pavement, penetration and ductility tests are essential. The other tests like softening point, flash and fire point tests are more important to guide the paving technologists during field operations. In recent years it has been recognized that the above tests are not sufficient to define the temperature susceptibility of bituminous materials .The bitumen from the different sources possessing the same penetration value at the specified temperature may exhibit entirely different viscous characteristics at the application temperatures. These tests therefore may need intensive correlation with fundamental property like viscosity. Viscosity is the resistance offered by the liquids for its motion and it is the general term for consistency. The degree of fluidity of binder at the application temperature greatly influences the strength characteristics of the paving mixes. High or low viscosity during mixing or compaction will result in lower stability values. At low viscosity bituminous binder simply lubricates the aggregates instead of coating a thin film over. At high viscosity resists the compaction effort and mix results in heterogeneous character exhibiting low stability values. Thus measurement of viscosity at the application temperature is very much essential. The conventional type of measurement of viscosity involves the determination of transpiration time to flow certain quantity of flow under certain test condition. These methods give viscosity in seconds, specifying the apparatus with which it is measured. Brookfield viscometer is one which measures the viscosity directly in centipoises. Test procedure is very simple to conduct. With the Thermosel accessories viscosity can be determined to any desired temperature. Present studies made use of this one. Various types of cracks, like fatigue cracking, low temperature cracking etc. were found to develop on bituminous pavements. In recent years to prevent these cracking in bituminous pavements geosynthesis in the form of fibers are being extensively used. The present investigation envisages laboratory study of different grades of bitumen with and without fibers with respect to change in viscosity measured with Brookfield viscometer .

The Viscoelastic-Plastic Displacement Back Analysis of Rock Mass with Non-Stationary Parameters

The FEM positive analysis is made using H-K non-stationary creep constitutive model in this paper, the finite element program for non-stationary viscoelastic-plastic displacement back analysis is compiled combining the non-stationary viscoelastic-plastic program with the complex shape optimization method, and the displacement back analysis of soft tunnel engineering is conducted. The result indicates that the viscous aging characteristics of rock mass can be reflected objectively if rock mass is regarded as non-stationary viscoelastic-plastic model, and the plastic zone development of surrounding rock can be predicted considering the plastic flow of rock mass and regarding the back analysis results as the calculation parameters.

粘性流体の小歪における線形特性モデルの検討

The characteristic formula of viscous damper force is often the nonlinear viscous element model in seismic time history response analyses of structures having the dampers, but it is not always accurate. Damping force depends on properties of viscous material and its components, but the formula is not compounded from them. To make the formula more correct, the previous thesis had demonstrated some viscous material characteristics with detailed experiments. It indicated that viscous force depended on strains and frequencies, and its hysteresis loop was like that of viscoelastic in small strains. This paper shows modeling of viscous material properties with viscoelastic theories that are fractional derivative and mechanical elements models.

706 変電機器ゴムOリングの劣化予測に関する研究(OS10-2 オーガナイズドセッション《発電機器の材料・構造解析と評価》)

In this paper, a numerical analysis of thermo-mechanical viscoelastic material was investigated to predict the compression set of EP-rubber O-rings for substation facilities. Relaxation times for viscous characteristics of this model were calculated by the Arrhenius equation and temperature of rubber. Furthermore, the stress-relaxation tests in the thermal chamber were conducted to evaluate the mechanical and thermal characteristics and effect of temperature on the stress relaxation to confirm the applicability of the simulation code. From the simulated results, the developed code shows enough accuracy to predict the stress reduction of natural rubber parts under the long-term compression.

Studies on the properties and formation mechanism of flexible nanocomposite hydrogels from cellulose nanocrystals and poly(acrylic acid)

A novel series of nanocomposite hydrogels based on cellulose nanocrystals (CNCs) and poly(acrylic acid) (PAA) have been synthesized by in situ free radical polymerization within an aqueous medium. Rheological measurements were applied to monitor the gelation process and results indicated that the gelation took place as monomers (acrylic acid, AA) grafted from the CNC surface and PAA chains entangled to produce flexible CNC–PAA gels. By tailoring the concentration of CNC (CCNC) over a wide range of 0.02–1 wt%, two critical CCNC, C* and C**, were found which corresponded to polymer chains that occurred in overlapping entanglements and promoted conformational rearrangements on the basis of earlier gel precursors, respectively. The formation mechanism of CNC based nanocomposite hydrogels, in which the nanoparticles transformed from the isolated state below C* to the spatially continuous percolation structure above C**, was proposed. The CNC–PAA gels exhibited excellent, composition-dependent mechanical properties, such as a large elongation ratio (>1100%) and high tensile strength (>350 kPa). Transmission electron microscopy (TEM) revealed that the CNCs were surrounded by grafted chains and formed inter-connected network structures, where the CNCs acted as multifunctional cross-links with an average effective functionality of 75. The mechanical measurements indicated that the increase of CCNC led to an increase in the hydrogels viscous characteristics and contributed to the energy dissipating mechanism, which was responsible for CNC–PAA gels excellent flexibility. The swelling and partial dissolution behaviors of the hydrogels were examined, focusing on the effect of CCNC on the gels characteristic partial deswelling and gel-to-sol transition. Some new chain entanglements were formed under concentrated conditions after drying treatment above the glass transition temperature (Tg) which was verified by observation of the greater tensile strength and modulus. All the results corresponded to the self-consistent network structure model for CNC–PAA gels.

Simulation Technology to Predict Paper Curl Reformation by Visco-elasto-plastic Model

The simulation technology for virtual design of a decurler device in electrophotography is developed. A paper curl is a phenomenon in which arc-like residual deformation occurs, and it degrades publishing quality and printing productivity. To reform the paper curl, decurler devices are installed in electrophotography products. In the decurler devices, paper is bent in large curvature against the direction of the curl to be reformed. Reformation amount of the curl is affected by decurler parameters including radius of rollers and nip load. In addition, amount of the curl to be reformed varies with paper brand, type of fusing system and image density. For these reasons, much effort and many resources are required for designing decurler parameters. To clarify the mechanism of the curl reformation, measurements of curl amount in various decurler conditions are carried out, and it becomes apparent that the paper curl is dependent on plastic and viscous characteristics of paper. By calculating history of stress-strain state during transportation through decurler devices with visco-elasto-plastic model which reflects characteristics of the paper, prediction of curl amount in high accuracy becomes possible. By utilizing this technology for virtual design of decurler devices, reduction of the development period to one fifth was accomplished.

High Concentration of Viscous Material Pipeline Characteristics of the Discussion

The high concentration of different rheological properties of viscous materials determines the properties of the material advantages and disadvantages of piped varying degrees, this article in order to slime represented by a variety of high concentration of viscous test material for pipeline transportation, according to pipeline pressure loss of various materials to determine rheological characteristics of pipeline transportation, obtained pipeline flow equation, and then determine the delivery pressure, flow, length of experience in relationship, through the material and the wall friction and power calculation To further determine the energy loss of control resistance laid the basis for optimal design of transportation systems. Key words: viscous materials, sensing devices, pressure testing, pressure distribution, pressure drop

Effects of B<sub>2</sub>O<sub>3</sub> on Properties of Low Fluoride Content Mould Flux for Thin Slab Continuous Casting

In order to reduce fluorine pollution, partial fluoride could be replaced by B2O3 in mould flux. The effects of B2O3 on properties of low fluoride content mould flux for thin slab continuous casting were studied. The properties included melting temperature, viscous characteristics, fluidity, surface tension and Al2O3 inclusion adsorption. The results showed that with the increase of B2O3 content, melting temperature, viscosity, viscous activation energy and surface tension of mould flux decreased obviously, fluidity increased, and Al2O3 inclusion adsorption of mould flux changed little. The B2O3 could play effective role when its content was less than 6%. The results would play a guiding role in designing of low fluoride content mould flux for thin slab continuous casting.

Flow and coupled heat transfer in the cavity between the rotor and stator

The turbulent flow and coupled heat transfer in the cavity between the rotor and stator is numerically simulated. Reynolds-averaged Navier-Stokes equations closed with equations of the k-ɛ turbulence model are used to calculate the viscous compressible gas flow characteristics and heat transfer; the unsteady heat conduction equation is used to calculate the temperature field in the metal. The influence of the mass flow rate of the coolant on the flow structure and efficiency of cooling of the rotor and stator walls is studied. The calculated results are compared with experimental data.

Modification of the structure of plasmatic membranes of the liver by the action of α-tocopherol in vitro

The effect of the natural antioxidant alpha-tocopherol in a broad concentration range (10(-4) - 10(-25) M) on the viscosity characteristics and thermally induced structural transitions of a lipid bilayer of plasma membranes of murine hepatocytes in vitro has been studied. Changes in the rigidity of surface (approximately Abb) of the lipid bilayer were measured on a Bruker EMX EPR spectrometer (Germany) by the method of spin probes. Stable nitroxyl radicals of 5- and 16-doxylstearic acid, localized at different depth in the membrane served as spin probes. It was shown that the concentration dependence of the effect of alpha-tocopherol is linear and polymodal with three statistically significant increases in three ranges of its concentration: (1) in the range of traditional physiological concentrations 10(-4)-10(-9) M, (2) in the range of superlow doses 10(-9) - 10(-17) M, and (3) in the range of "imaginary" concentrations 10(-17) - 10(-25) M. The mechanisms of action of alpha-tocopherol in each of the three ranges are discussed. When studying the temperature dependences of viscous characteristics, a new thermally induced structural transition in the range of "physiological" temperatures 309-313 K for those alpha-tocopherol concentrations (including superlow ones) to which the maxima on the dose dependence curves at constant temperature of 293 K corresponded.

Time Response Model of ER Fluids for Precision Control of Motors

The improvement of control performance or new control demands of mechatronics devices using particle type electrorheological (ER) fluids requires further investigation of the response time of the fluids. Although the response time of particle type ER fluids is commonly reported to be approximately 5 ms, the formula structure of the delay remains unclear. The present study is an attempt to develop a functional damper (attenuators) that can control its own viscous characteristics in real time using an ER fluid as the working fluid. ER dampers are useful for accomplishing both high-precision positioning and high-speed movement of the motor. In order to realize such a functional damper that can be manipulated according to a situation or task, the modeling and control of ER fluids are necessary. The present article investigates the time delay effects of ER fluids and constructs an in-depth dynamic model of the fluid through a simulation and an experiment. The mathematical model has a dead time and first-order delay of the fluid and a high-voltage amplifier for the fluid.

Frequency response analysis of slot coating

AbstractFrequency responses to the slot die coating process is analyzed using empirical modal analysis to predict the effects of periodic process disturbances such as gap oscillation and variations in vacuum pressure, web velocity, and flow rate. A type of empirical modal analysis known as an experimental modal approach was used, and an oscillator basis model was assumed by using a linearized governing equation, and the coefficient of the basis model was determined by curve‐fitting. By completing the process, we were able to decompose each mode, during which process it was found that the modes are of two types: a squeeze mode related to viscous characteristics and sinuous modes that are identical to capillary waves. Observation of the meniscus shapes of each mode revealed, in the third mode near the lip edge, significant fluctuations that can induce other coating defects. © 2010 American Institute of Chemical Engineers AIChE J, 2010