Low Shear Viscosity Research Articles

A novel procedure for the evaluation of anti-rutting potential of asphalt binders

Asphalt binders play an important role in the rutting performance of road pavements, and therefore their characterisation is crucial in preventing this type of distress. Several studies have been carried out to replace the G*/sin δ Superpave criteria which were found to be inadequate to capture the anti-rutting potential of these materials. In this paper, a novel testing procedure combining single creep-recovery and multiple stress creep (MSC) tests is proposed. Five asphalt binders of different type and origin were considered. For comparison purposes, two available standard methods, based on low shear viscosity and MSC recovery tests, were included in the study. The obtained experimental results indicated the effectiveness of the test method in highlighting fundamental material properties related to rutting, overcoming some of the drawbacks of existing standard protocols.

Disintegration of periodate–chlorite oxidized hardwood pulp fibres to cellulose microfibrils: kinetics and charge threshold

Periodate–chlorite oxidized bleached hardwood kraft pulp fibre samples with six levels of charge densities ranging from 0.5 to 1.8 mmol/g were gradually disintegrated to microfibrils using a high-shear homogenizer. The disintegration kinetics and mechanisms were studied by a flow fractionation method, and the properties of the resulting particles were determined using low shear viscosity and transmittance measurements. The particles formed during the disintegration were visualized with a charge-coupled device camera and by field-emission scanning electron microscopy. The result showed that cellulose fibres with a low charge density disintegrated at a low rate and produced ragged fibres and bunches of microfibrils via bursting of the fibre walls, whereas those with a higher charge density broke down at a high rate and microfibrils were formed through swelling and the creation of balloon structures. A carboxyl content of 1.2 mmol/g was found to be the threshold value for the efficient formation of high aspect ratio microfibrils and also for the change in the disintegration mechanism in the high-shear homogenizer.

Rheological behavior of bitumen mixed with Trinidad lake asphalt

Trinidad lake asphalt (TLA) has been utilized as a modifier to blend with conventional petroleum bitumen for road and bridge applications where highly stable surfacings are required. The aim of this work was to evaluate the effect of TLA on rheological properties of Trinidad lake modified asphalt (TLMA). The critical content of TLA in the modified blend by weight was determined as the interaction of mineral particles occurred. Test results showed that TLA stiffened asphalts, but the degree of stiffening varied significantly with the TLA concentration levels. An increase in complex modulus (G*) and elastic response (δ) resulting from the introduction of TLA to asphalt binders had the potential benefit of improving resistance to rutting. In addition, zero shear viscosities (ZSVs) obtained from the Cross model were equal to the low shear viscosities (LSVs) at a frequency of 0.05Hz, while the ZSVs from the Carreau model were close to the LSVs at 0.1Hz. Steady state viscosities (SSVs), having the lowest values, approximately equaled the LSVs at 0.5Hz. The concentration of TLA was recommended to be in the range of 20–33% by the weight of naturally modified asphalt according to the SSV stiffening effect.

Control of the particle distribution in inkjet printing through an evaporation-driven sol-gel transition.

A ring stain is often an undesirable consequence of droplet drying. Particles inside evaporating droplets with a pinned contact line are transported toward the periphery by radial flow. In this paper, we demonstrate how suspensions of laponite can be used to control the radial flow inside picoliter droplets and produce uniform deposits. The improvement in homogeneity arises from a sol-gel transition during evaporation. Droplets gel from the contact line inward, reducing the radial motion of particles and thus inhibiting the formation of a ring stain. The internal flows and propagation of the gelling front were followed by high-speed imaging of tracer particles during evaporation of the picoliter droplets of water. In the inkjet nozzle, the laponite network is broken down under high shear. Recovery of the low shear viscosity of laponite suspensions was shown to be fast with respect to the lifetime of the droplet, which was instrumental in controlling the deposit morphology. The radial and vertical particle distributions within dried deposits were measured for water droplets loaded with 1 and 5 wt % polystyrene spheres and various concentrations of laponite. Aggregation of the polystyrene spheres was suppressed by the addition of colloidal silica. The formulation can be tuned to vary the deposit profile from a ring to a pancake or a dome.

Interaction between hydrophobically modified 2-hydroxyethyl cellulose and sodium dodecyl sulfate studied by viscometry and two-dimensional NOE NMR spectroscopy.

Interaction between an anionic surfactant, sodium dodecyl sulfate (SDS), and a nonionic polymer, 2-hydroxyethyl cellulose (HEC) hydrophobically modified with benzoyl chloride (bmHEC), is studied by viscometry and two-dimensional nuclear Overhauser effect NMR spectroscopy (2D NOESY) in a semidilute regime of bmHEC. The hydrophobicity of bmHEC was varied with different substitution of benzoyl group to HEC macromolecules. In general, the low-shear viscosity of 1 wt % bmHEC aqueous solution is increased with added SDS surfactant having concentration from 0 to 0.5 wt %, and then decreased significantly with a further addition of surfactant to 3 wt %. The activation energy of transient network formation in 1 wt % bmHEC aqueous solution present with SDS surfactant is found to be dependent with SDS concentration, which varies from 32.7 to 69.80 kJ/mol. The maximum activation energy takes place when 0.5 wt % SDS is added, which coincides with that of the maximal viscosity. The 2D NOESY displays that the surfactants actually interact with bmHEC not only on the hydrophobes, namely benzoyl groups, but also the polymer backbone, i.e., glucose units. In contrast, no interaction is revealed by 2D NOESY in the aqueous system containing SDS surfactant and HEC polymer.

Mechanisms of pulmonary embolism and/or deep vein thrombosis secondary to chronic obstructive pulmonary disease exacerbation in elders

Objective To explore the inflammatory mechanisms of pulmonary embolism (PTE) and/or deep venous thrombosis (DVT) in elders secondary to chronic obstructive pulmonary disease (COPD) exacerbation. Methods A total of 26 elders with acute exacerbation of high-risk COPD secondary PTE and/or DVT and 26 patients with low-risk COPD during stable phase diagnosed during the period of January 2008 to December 2012 were enrolled. The relevant parameters of routine blood examination, blood viscosity, D-dimer, fibrinogen (FIB), arterial blood gas, blood cytokine, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were retrospectively analyzed. Results The major nonspecific symptoms were cough, sputum and dyspnea. The mean of neutrophile percentage (N%), D-dimer, FIB, interleukin-6 (IL-6), tumor necrosis factor (TNF), C-reactive protein (CRP), low and high shear blood viscosity in blood samples of patients with acute exacerbation of high-risk COPD secondary PTE and (or) DVT were higher than those of the control group (t=3.339, 2.700, 2.207, 2.431, 2.257, 2.143, 2.223, 2.797, all P<0.05). However arterial partial pressure of oxygen (PaO2) was lower than that of lower-risk COPD patients (t=4.312, P<0.05). IL-6 in blood of patients with acute exacerbation of high-risk COPD secondary PTE and (or) DVT was positively correlated with low-shear blood viscosity, D-dimer and FIB (r=0.437, 0.624, 0.429, all P<0.05). TNF in blood of patients with acute exacerbation of high-risk COPD secondary PTE and (or) DVT was positively correlated to FIB, low and high cut blood viscosity (r=0.624, 0.519, 0.513, all P<0.05). Plasma CRP in blood of patients with acute exacerbation of high-risk COPD secondary PTE and/or DVT was positively correlated with D-dimer, FIB, IL-6 and TNF (r=0.478, 0.541, 0.533, 0.491, all P<0.05). Conclusions Inflammation may exist in elders with acute exacerbation of high-risk COPD secondary thrombotic disease. IL-6 and TNF may promote thrombosis secondary to acute exacerbation of COPD disease. Early screening and/or prophylactic anticoagulation are necessary for prevention. Key words: Pulmonary disease, chronic obstructive; Pulmonary embolism; Venous thrombosis

Effect of acupuncture on inflammatory cytokines expression of spastic cerebral palsy rats

ObjectiveTo To investigate the effect of acupuncture on the tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), nitric oxide synthase (NOS) content and muscular tension of spasticity cerebral palsy rat model. MethodsThe rats with spastic cerebral palsy were randomly divided into the control group, model group and acupuncture group. After successful modeling, the muscular tension and the content of TNF-α, IL-6, CRP, NOS were measured. ResultsThe serum TNF-α, IL-6, CRP, NOS content were significantly decreased in the acupuncture group (P<0.05). The low and high shear viscosity of whole blood of the acupuncture group were significantly lower than the control group and the model group (P<0.05). The erythrocyte electrophoresis indexes in the acupuncture group were significantly lower than that in the model group and the control group (P<0.05). Acupuncture significantly reduced the muscular tension of spastic cerebral palsy rat and increased the active extent in the paralytic extremity (P<0.05), but it could not be restored to normal level. Compared with the control group, the difference had significant (P<0.05). ConclusionsAcupuncture treatment can inhibit the release of inflammatory cells after brain injury, then reduce immune injury, relieve muscle spasms and reduce muscular tension.

A novel slurry concept for the fabrication of lithium-ion battery electrodes with beneficial properties

A novel slurry concept for the fabrication of Li-ion battery electrodes focusing on water based formulations is presented. Taking advantage of capillary forces inferred by adding a small fraction of a second fluid immiscible with the bulk continuous phase the low shear viscosity can be varied in a wide range without conventional polymeric rheology control agents disturbing the electric properties of the dry electrode. The new slurries provide superior storage stability and excellent shape accuracy of the final dry film. This reduces waste cut-off at the edges and increases the density of active ingredients, thus improving cost-efficiency. The viscosity at high shear rates remains unaffected, thus the slurries can be processed and coated using established equipment and process parameters. Adhesion to the conductor foil and electrochemical properties of the electrode layers and corresponding cells are similar to those made from conventional slurries.

Simplified viscosity evaluating method of high viscosity asphalt binders

In order to establish a simplified viscosity evaluating method of high viscosity asphalt binders (HVABs), shear rate sweep test in the shear rate range of 1.25 × 10−6–1,250 s−1 was performed. Results showed that HVABs exhibited yield pseudo-plastic fluid behavior at 60 °C and the overlapped range of the first Newtonian region was 8 × 10−5–2 × 10−2 s−1. Based on the results, the simplified shear rate sweep test in the shear rate range of 0.001–0.1 s−1 was proposed and low shear viscosity at 0.01 s−1 (LSV0.01) was suggested as the viscosity evaluating indicator of HVABs, which exhibited both close values to zero shear viscosity and significant correlation with rutting resistance of porous asphalt.

Self-diffusion and linear viscoelasticity of solvent-free nanoparticle-organic hybrid materials

Nanoparticle-organic hybrid materials consist of 10 nm diameter spherical inorganic core particles functionalized with oligomeric organic molecules. Although these systems contain no added solvent, they exhibit fluid behavior with the fluidity provided by the attached oligomers. We solve for the nonequilibrium probability density function for pairs of particles subject to a weak applied flow without hydrodynamic interactions. The intercore forces include hard-sphere repulsion and a many-body potential force resulting from the entropy of tethered oligomers filling the interstitial space. The latter potential is weak, O(a3/Rg3), when the oligomer radius of gyration Rg is much greater than the core radius a. While the long-time self-diffusivity of the cores and steady low shear viscosity of the system obtained from the analysis are similar to hard sphere suspensions at higher core volume fraction or with longer oligomeric chains, the material exhibits stronger resistance to the motion of core particles as the tethered hairs feel more entropic penalty to fill the space at low volume fractions and with shorter chains. This trend agrees qualitatively with experiments and molecular dynamics simulations and is a unique feature of the solvent-free nanoparticle fluid. The high frequency limit shear modulus is a linear function of ω1∕2 and the intercept provides information about many-body forces. Thus, the high frequency behavior shows characteristics of both hard and soft potentials.

Dissolution and rheological behaviour of hematite and quartz particles in aqueous media at pH 1

In this study we investigate isothermal, atmospheric acid dissolution behaviour of quartz and hematite minerals which constitute two of the predominant host gangue phases of typical low grade limonitic laterite ores. Batch dissolution tests were carried out on 57wt.% solid dispersions for 4h at pH 1 and 25 and 70°C to establish the influential role of oxide mineralogy/chemistry on rheology and leaching behaviour. The results show that the two minerals displayed a weakly temperature and time-independent, non-Newtonian rheological behaviour with low shear yield stresses (<4Pa) and viscosities (9–17mPas). Hematite dissolution rate was significantly higher compared with that of quartz under similar conditions. Quartz dissolution mechanism was substantially volume diffusion controlled at lower agitation rate (600rpm) whilst for hematite it was both volume diffusion and chemical reaction controlled. These mechanisms reflected activation energies of 17.7±0.9 and 28.5±1.4kJ/mol, respectively, for quartz and hematite. At 800 and 1000rpm, dissolution of both minerals was chemical reaction-controlled with similar activation energies (32.6±1.7 and 32.2±1.6kJ/mol). The findings underscore the need for higher agitation rates and elevated temperatures, to overcome both volume diffusion and chemical reaction limitations for enhanced acid leaching of these two fairly refractory oxides studied herein.

Effect of angelica polysaccharides on the hemorheology in flap ischemia reperfusion injury: an experimental study in rats

Objective To investigate the hemorheology changes in flap ischemia reperfusion injury and the protective effect of angelica polysaccharides (APS).Methods Fifty adult SD rats were divided into a sham group,a control group,a 2 mg/kg APS group,a 4 mg/kg APS group,and a 8 mg/kg APS group.After a 5 cm × 4 cm epigastric flap was elevated,flaps in the sham group were sutured back into its place without inducing any ischemia.Flaps in the control group and APS treatment groups were subject to a 6-hour ischemic period.Five minutes prior to the repeffusion,0.2 ml saline was injected via intraperitoneal route in the control group while 0.2 ml of corresponding doses of angelica polysaccharides were injected in the APS groups.Following a 12-hour reperfusion,the levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in the flap tissue were measured.Polymorphonuclear neutrophils (PMN) in the peripheral blood were counted.Flow cytometry was used to detect the expression of CD11a/CD18 and CD11b/CD18 on the polynorphonuclear neutrophils.Hemorheology parameters were detected in the rats of each group.Results Compared with the control group,8 mg/kg APS group showed significant decrease of MDA content and CD11a/CD18,CD11b/CD18 expression levels after 12-hour repeffusion (P ＜ 0.05).The level of SOD increased significantly (P ＜ 0.05).The PMN number,the low shear viscosity,the middle shear viscosity and high shear viscosity of the APS groups were significantly lower than those of the control group (P ＜ 0.05).Plasma viscosity,RBC aggregation index of the APS groups were not significantly different from the control group (P ＞ 0.05).Conclusion APS can reduce ischemia reperfusion injury of skin flaps in rats via reducing the number of neutrophils,down-regulating the expression of CD11a/CD18 and CD11b/CD18 on neutrophil surface,and decreasing blood viscosity,so as to improve blood supply of the flap. Key words: Angelica polysaccharides; Flaps; Ischemia reperfusion injury; Hemorheology

Both protein adsorption and aggregation contribute to shear yielding and viscosity increase in protein solutions

A combination of sensitive rotational rheometry and surface rheometry with a double-wall ring were used to identify the origins of the viscosity increase at low shear rates in protein solutions. The rheology of two high molecular weight proteins is discussed: Bovine Serum Albumin (BSA) in a Phosphate Buffered Saline solution and an IgG1 monoclonal antibody (mAb) in a formulation buffer containing small quantities of a non-ionic surfactant. For surfactant-free BSA solutions, the interfacial viscosity dominates the low shear viscosity measured in rotational rheometers, while the surfactant-laden mAb solution has an interfacial viscosity that is small compared to that from aggregation in the bulk. A viscoelastic film forms at the air/water interface in the absence of surfactant, contributing to an apparent yield stress (thus a low shear viscosity increase) in conventional bulk rheology measurements. Addition of surfactant eliminates the interfacial yield stress. Evidence of a bulk yield stress arising from protein aggregation is presented, and correlated with results from standard characterization techniques used in the bio-pharmaceutical industry. The protein film at the air/water interface and bulk aggregates both lead to an apparent viscosity increase and their contributions are quantified using a dimensionless ratio of the interfacial and total yield stress. While steady shear viscosities at shear rates below ∼1 s(-1) contain rich information about the stability of protein solutions, embodied in the measured yield stress, such low shear rate data are regrettably often not measured and reported in the literature.

Influence of parenteral nutrition on blood rheology and platelet aggregation in vitro.

Parenteral nutrition (PN) is a hyperosmolar solution composed of glucose, amino acids and a lipid emulsion, which is often used despite well-known side effects and complications. In this study the hypothesis was tested that PN could affect hemorheology. The influence of increasing plasma concentrations (0, 4, 10 and 25%) of the 3-in-1-mixture of PN on various rheological parameters were studied in vitro. The influence of the individual components was studied with plasma concentrations of 10, 10 and 5%, respectively. Hematological and coagulation tests were performed. Blood viscosity and red blood cell (RBC) aggregation were measured and platelet aggregation in flowing blood was assessed with a PFA-100 instrument. It was found that PN induced RBC shrinkage, which was partially reversible. It reduced RBC aggregation measured by low shear viscosity or RBC sedimentation. Platelet aggregation was strongly inhibited. Coagulation tests were not affected. Investigations with the single components of PN showed that the RBC shrinkage was mainly caused by the amino acid solution and the inhibition of platelet aggregation by all 3 components. The lipid emulsion in higher plasma concentrations led to echinocytosis, indicating that the lipids interact with the outer half of the membrane lipid bilayer. High concentrations of PN affect blood rheology in several ways. The strongest effect was an inhibition of platelet aggregation, which may have a clinical relevance. Other effects such as RBC shrinkage and decreased RBC aggregation occurred only at high PN concentrations, which are reached in vivo at the infusion site.

Production of Environment-Friendly Coated Paper with PCC Manufactured with Emission Gas

Effects of blending of PCC manufactured with emission gas occurred at mill on the characteristics of coating color, optical and printing properties of coated paper were investigated in order to evaluate the possibility of its use as a raw material for producing environmentally friendly coated paper. Low shear viscosity and water retention value of ground PCC 1(d50 = <TEX>$6.303{\mu}m$</TEX>) were higher than those of ground PCC 2(d50 = <TEX>$3.149{\mu}m$</TEX>). Ink set properties of ground PCC 1 and ground PCC 2 were inferior to that of PCC 3. Thus, the reducing of particle size was required in order to overcome the inferior ink set properties. Ground PCC 1 had a similar properties to clay, and it showed the possibility that ground PCC 1 could be used to produce matte grade coated papers. However, it was required to improve the stability(particle shape, particle size, and compatibility with chemicals used in coating color formulation) in the case of blending with GCC in order to keep the qualities of coated paper.

The temperature and pressure dependence of the dynamic properties of branched perfluoropolyethers

The relative volume and the limiting low shear viscosity have been accurately determined as functions of temperature and pressure for a series of eight branched perfluoropolyether liquids. The Murnaghan equation of state was fitted to the volumes and three correlations for viscosity were examined: the Doolittle free volume, the Bair and Casalini thermodynamic scaling, and the improved Yasutomi. The ambient-pressure bulk modulus increases gradually with molecular weight and is low compared with conventional lubricants. The Doolittle parameter increases with molecular mass as does the occupied volume fraction. The Ashurst–Hoover interaction parameter decreases with increasing molecular mass. The improved Yasutomi model provides accuracy comparable to models requiring an equation of state. When the kinematic viscosity at 40℃ is greater than about 200 mm2/s, fragility is independent of pressure. When the kinematic viscosity is less than about 200 mm2/s fragility increases with pressure. The pressure counterpart to the Angell plot and to the Vogel, Tammann, and Fulcher equation suggested by Drozd-Rzoska et al. is shown to be workable using stability limit pressures in the tensile domain. Clearly, progress in quantitative elastohydrodynamic lubrication must rely upon accurate measurements of the dynamic properties as a function of temperature and pressure and upon accurate temperature and pressure correlations for these properties. Only then can precise predictions of film thickness and friction be made.

Divergence in the low shear viscosity for Brownian hard-sphere dispersions: At random close packing or the glass transition?

Models, theories, and simulations for the low shear viscosity of Brownian, hard-sphere dispersions are examined and evaluated against literature data. Hydrodynamic and thermodynamic contributions are explicitly treated and the volume fraction dependence of the experimental data is validated against the high frequency or high shear viscosity. A good description of the data is realized by a new, semiempirical model based on mode coupling theory, where ϕm=ϕg=0.57, supporting dynamical arrest at the ideal glass transition.

Shear viscosity in the Nambu–Jona-Lasinio model withΦ-derivable approximations

Within the Nambu--Jona-Lasinio model the temperature dependence of the shear viscosity is calculated to the first nontrivial order in the $1/{N}_{c}$ expansion with $\ensuremath{\Phi}$-derivable approximations. The two-particle irreducible effective action is computed to next-to-leading order, from which the integral equations for the 3- and 4-point vertices are obtained. These sum infinite sets of diagrams contributing to the shear viscosity at the same order in the $1/{N}_{c}$ expansion. We find that the shear viscosity decreases rapidly when the chiral crossover is approached. Comparing with the hadron phase, the quark-gluon plasma phase has a low shear viscosity, which is consistent with the measurements. The ratio of the shear viscosity to entropy density is also calculated.

The emulsion crystallization of hydrogenated castor oil into long thin fibers

The present study discusses the optimal crystal growth conditions required for the emulsion crystallization of hydrogenated castor oil (HCO) into several crystal morphologies. The best possible crystal shape is furthermore identified in case high rheology modifying performance is required. HCO was crystallized in a meso- and micro-continuous process which allowed for a controlled and fast screening of several crystal morphologies at different crystallization conditions. Applying high isothermal temperatures (above 55°C) resulted in a combination of rosettes, thick fibers and thin fibers. At lower isothermal temperatures (below 55°C) the shape gradually evolved to a combination of short needles, spherically shaped and/or irregularly shaped crystals. Crystals with the highest aspect ratio were obtained when crystals were grown between 30°C and 45°C and were subsequently reheated above 63°C, forming high amounts of large thin fibrous crystals. When diluted to 0.25wt% these fibrous crystals increased the low shear viscosity far better compared to the other crystal shapes.

Synthesis and ring-opening copolymerization of cyclic aryl ester dimers

Abstract Two kinds of cyclic aryl ester dimers have been synthesized by reaction of phthaloyl dichloride with bisphenols via interfacial polycondensation. The cyclic dimers readily undergo anionic ring-opening polymerization or copolymerization in the melt by using sodium benzoate as the initiator, producing linear, high molecular weight polyesters. The contents of cyclic dimers in the homopolymers P1, P2, and copolymer P12 are 13.7%, 10.2%, 2.9%, respectively, which indicates that ring-opening copolymerization of cyclic dimers may impel the conversion of cyclic dimers and decrease the content of cyclic dimers in the resulting copolymer. Moreover, the isothermal chemorheology of the ring-opening copolymerization of cyclic dimers indicates that the reactive molten mixture has low shear viscosity and the viscosity increases slowly in the initial stage of ring-opening polymerization.