Rheology of oil in water emulsions with added solids

The effect of added solids on the rheology of oil in water emulsions was investigated. The range of the oil concentration, solids free basis, was (0-70%) and the solids volume fraction was (0-0.16). The solids mean diameter was 45 μm and it was about four times larger than the oil droplets. In the absence of added solids, non-Newtonian behaviour was observed for oil concentrations above 40%. The added solids increased the emulsion viscosity in a manner similar to the addition of solids to a homogeneous fluid. The rheological data of all the emulsion-solids mixtures investigated were correlated as relative viscosity versus solids volume fraction, where the relative viscosity is defined as the ratio of the emulsion-solids mixture viscosity to the solids-free emulsion viscosity. In the case of non-Newtonian systems, the emulsion-solids mixture viscosity and the solids-free emulsion viscosity were calculated at the same shear stress. The Barnea and Mizrahi viscosity correlation was found to fit the data well.     

Effect of oil viscosity on the rheology of oil-in-water emulsions with added solids

This paper reports an experimental study on the effect of oil viscosity on the rheology of oil-in-water (o/w) emulsions with added solids. Four oils having a viscosity range of 0.0024 to 306 Pa . s were used. The size ratio of the solids to oil droplets was varied from 2 to 16. The addition of smaller size solids to the emulsions yielded a higher viscosity than that of larger solids at the same solids volume fraction. However, when the solids were sufficiently large such that the emulsions behaved as a continuous phase towards the solids, the viscosity of the emulsion-solids mixtures tended to be independent of the solids size. The critical size ratio of the solids to oil droplets, above which the emulsions behaved as a continuous phase towards the solids, increased with the oil viscosity. The critical size ratio varied between 3 and 10.     

高固含量醋酸乙烯-乙烯共聚乳液的研制

介绍了一种固含量在60％左右的醋酸乙烯-乙烯(VAE)共聚乳液的制备方法。讨论了乳化剂、聚乙烯醇、醋酸乙烯、乙烯、引发剂等对乳液合成及其性能的影响，并确定了合适的生产工艺，该工艺生产的产品固含量高、黏度低、柔韧性好，初粘性、快干性和耐水性均较常规产品有显著提高。     

Rheological properties of hydrophobically modified alkali-swellable acrysol emulsions

The rheological behaviour of aqueous solutions of two commercial anionic hydrophobically modified alkali-swellable emulsions (HASE), Acrysol TT615 and RM5, was studied. These polymeric systems, initially in the form of low-viscosity latices at low pH, tend to swell and increase their viscosity when neutralised with base. The steady-shear and dynamic properties of these polymers were measured over a wide range of concentration, at constant pH=9 and temperature of 20°C. The intrinsic and zero-shear viscosities were used to identify the concentration regimes of the polymer solutions. In the case of Acrysol TT615, the solution exhibited shear-thinning characteristics at a concentration above 500 ppm. The Carreau model described well the viscosity function of the 1000 and 2000 ppm solutions. Considerable viscosity enhancement and a change in the flow curve profile were observed at concentrations above 2000 ppm. At high polymer concentration. the zero-shear viscosity was not detectable, and the power law model was adequate to characterize these solutions. By contrast, the RM5 solutions exhibited nearly Newtonian behaviour over the whole concentration range considered. Elasticity measured from the first normal stress difference indicated that Acrysol TT615 was more elastic than Acrysol RM5. Dynamic measurements revealed that both storage (G′) and loss (G″) moduli increased with polymer concentration. In the higher frequency and concentration regions, G′ > G″ was obseved for TT615, whereas G″ > G′ for RM5.     

Organic coated solids in athabasca bitumen: Characterization and process implications

Bitumen, separated from oil sands by the hot water extraction process, contains ultra‐fine (< 200 nm), inorganic solids (BS). Surfaces of BS particles are coated with toluene insoluble organic matter (TIOM). This organic material is polar and aromatic with contributions from both humic and asphaltene‐like components. Although the surfaces of BS particles are dominated by TIOM, the coverage is patchy rather than continuous. As a result, these solids are capable of stabilizing fine water emulsions in the bitumen phase. The nature of the organic matter on the surfaces of the particles is such that it has a high propensity to form coke. Therefore, these particles can also play a role in fouling on equipment and catalysts.     

Rheological behavior of bitumen modified by reclaimed polyethylene and polypropylene from different recycling sources

This work studied the rheological, thermal, and mechanical properties of bitumen modified by reclaimed polyethylene (PE), and polypropylene (PP) from different recycling sources. The rutting resistance under high temperature of polymer modified bitumen (PMB) was investigated by rheologically temperature ramp test and multiple stress creep recovery (MSCR) test. It is found that for some modified bitumen, a plateau of complex modulus G^* could be formed with temperature increment, revealing rheological stability. Furthermore, these samples with rheological stability revealed a higher creep recovery and lower creep compliance measured by the MSCR test. Glass transition temperature (T_g) measured by dynamic mechanical analysis was used to evaluate the crack resistance under a low temperature of PMB. The influence of recycled PE on the T_g of modified bitumen was different from that of recycled PP modified bitumen, as compared with corresponding virgin polymer modified bitumen. A possible reason for the various effect of recycling sources on the service property of modified bitumen was explored by crystallization and melting behaviors of polymer in bitumen since that polymer with higher crystallinity degree could endow the modified bitumen stiffness, which was closely, related to their service property especially the rutting resistance.     

Rheological properties of emulsions containing modified soy protein isolates

The feasibility of replacing common emulsifiers with soy protein isolates (SPI) in low-calorie salad dressings was evaluated. Structural modifications of SPI were obtained by thermal-acidic treatment with or without neutralization (TH1.6N and TH1.6, respectively). Modification of flow properties of TH1.6 and TH1.6N emulsions by thermal treatment and different protein concentrations was evaluated through shear stress vs. shear rate measurements in a rotational viscometer. TH1.6N isolates generated emulsions with higher shear stress and apparent viscosity than those prepared with TH1.6. Heated TH1.6N emulsions at 10% protein gave the highest values of shear stress and plastic flow behavior. These emulsions had high consistency, viscosity, and elasticity. TH1.6N isolates had lower emulsifying capacity than TH1.6, probably due to the higher protein aggregation produced during neutralization, which prevented protein unfolding. These isolates would be suitable for the preparation of stable emulsions with adequate consistency and elasticity.     

Continuous and oscillatory flow properties of concentrated coal/water suspensions

A Theological characterization of coal/water suspensions has been carried out under continuous and oscillatory flow conditions. Shear stress - shear rate data were correlated with the Shangraw-Grim-Mattocks (SGM) equation. The analysis of the SGM parameters indicated that a limiting concentration ?₀ exists above which the suspensions exhibit plastic behavior and suggested that a strong particle aggregation still occurs at high rates of shear. Oscillatory flow tests revealed marked non-linear viscoelastic properties and analogies were found between the continuous and oscillatory flow behaviors of the coal/water suspensions, particularly under limiting flow conditions.     

Viscoelastic properties and morphological characteristics of polymer‐modified bitumen blends

The state of dispersion, the viscoelastic properties and the mechanical properties (such as Young's modulus, ductibility, penetration, and Fraas breaking point) of polymer‐modified bitumen are investigated. Bitumen was modified with low‐density polyethylene from processed bags (PE_bags) and styrene‐butadiene random block copolymer (SBR). The blends were characterized by optical microscopy, dynamic mechanical thermal analysis (DMTA), and other conventional methods. Photomicrographs indicated that different morphologies were obtained; PE_bags gave dispersions with almost spherical polymer particles; whereas in the case of SBR, fibrillar domains were observed. DMTA measurements indicated significant changes of the storage and loss moduli of modified bitumen; depending on the polymer content in the bitumen matrix, these values were three to four times higher compared with neat bitumen. Blends with SBR showed a significantly increased resistance to cracking at low temperatures due to decrease of the glass transition temperature from ?14 to ?34°C. Contrary, PE_bags gave better results at higher temperatures where as a result of the increased resistance to permanent deformation the softening point of modified bitumen was shifted from 52 to 73°C. It was also investigated the influence of mixtures of PE_bags/SBR on the properties of bitumen as function of the composition and ratio between PE_bags and SBR. It was found that the best improvement in deformation resistance, permanent deformation, and cracking of bitumen was achieved with the addition of PE_bags/SBR mixture as the rubber increased the bitumen properties at low temperatures and the polyolefin at high temperatures. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The rheological properties of shear thickening fluid reinforced with ZnO of different friction characteristics

The viscosity of shear thickening fluid (STF) changes significantly with low concentrations of additives. However, existing research has suggested that there has not been any consistent enhancement mechanism of additives. The possible reason for this research gap is that existing research has focused on the effect of the shape and content of additives on shear thickening (ST) performance, whereas the friction characteristics of additives on ST performance have not been considered. Accordingly, nanoparticle-enhanced STF with various friction characteristics of ZnO was synthesized in this study to investigate the enhancement mechanism of additives. The aspect ratio of ZnO with different shapes was obtained through SEM analysis. The friction characteristics of ZnO were examined. Lastly, the rheological behavior of reinforced STFs was evaluated. The results indicated that ST performance was enhanced compared with that of neat STF, which was significantly dependent on the friction characteristics of ZnO.     

High solids content emulsions. III. Synthesis of concentrated latices by classic emulsion polymerization

Two different methods of producing bi‐ and trimodal latices of a mixture of methyl methacrylate, butyl acrylate, and small amounts of acrylic acid were tested. It is shown that a combination of concentrating blends of seed particles by semibatch reaction, followed by a nucleation of small particles plus a second semibatch phase allowed us to obtain stable latices with solids contents over 65% and viscosities of below 2500 mPa s^?1 with little coagulum formation. The key parameter in determining latex stability, coagulum formation, and viscosity appears to be the the particle size distribution, and especially its modification attributed to secondary nucleation. Because it is not possible to eliminate water‐soluble monomers from the polymerization recipe, secondary (homogeneous) nucleation must be minimized by careful addition of the free‐radical initiator and choice of monomer feed flow rates. The nucleation of the third population in the trimodal latices is best accomplished with a mixed surfactant system because renucleation by anionic surfactant alone leads to detrimental changes in the particle size distribution (PSD) resulting from excessive flocculation of particles. In addition, it was found that the viscosity of the final products was not sensitive to small changes in the ionic strength of the latex, although neutralization to a pH of 6 effectively doubles the final latex viscosity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1916–1934, 2002; DOI 10.1002/app.10513     

In Situ Rheological Investigation of the Coagulation in Aqueous Alumina Suspensions

Electrostatically stabilized alumina suspensions can be destabilized by the enzyme-catalyzed decomposition of urea (direct coagulation casting). Depending on the conditions, this reaction can shift the pH of a suspension to the buffer pH of the reaction products or increase the ionic strength at the buffer pH. The coagulation for both mechanisms was investigated using in situ rheological measurements. Using a vane tool in oscillation mode, the measuring conditions were optimized to find a reasonable method for time-dependent measurements. Constant parameters (stress or strain) proved to be unsuitable, because the linear viscoelastic region shifted considerably during the coagulation. Furthermore, the gel structure produced on coagulation via increase of ionic strength (Δ I ) was very sensitive to the oscillation. Therefore, for long-time experiments, a short continuous measurement with a low strain was followed by amplitude sweeps with increased intervals to determine the linear values of G ' and G ". In this way, the increase of the moduli G ' and G " could be followed for longer times, and it was possible to demonstrate two results. First, the final G ' of the network was about 10 times higher for Δ I -coagulated material than for suspensions coagulated via pH shift (ΔpH). Second, particle rearrangement processes took place in Δ I -coagulated networks even after the chemical changes were finished, whereas ΔpH-coagulated samples were "frozen-in" when approaching the isoelectric point and showed no further physical changes afterward.     

Effect of Surface-Active Substances on the Rheological Properties of Silicon Carbide Suspensions in Paraffin

In this paper, the possibility of stabilization of SiC suspensions in paraffin (hot-molding slips) was investigated from the colloid science point of view. By considering the surface properties of finely dispersed silicon carbide, surface-active agents (fatty amine and alkylsuccinimide) which are suitable for surface modification by chemical adsorption on SiC were selected. Adsorption of fatty amines and alkylsuccinimide was carried out in model experiments in chloroform. Increasing the length of the carbon–hydrogen chain caused the adsorption to decrease, and the adsorption area of one molecule in the saturated adsorption layer to increase. The stabilizing effect of surface-active agents resulted in improved flow behavior of hot-molding slips. The efficiency of surface-active agents increased with increased adsorption layer thickness. In highly concentrated SiC hot-molding slips, a combination of alkylsuccinimide and fatty amine proved to be very efficient. This synergistic effect of long- and short-chained surface-active agents is discussed in terms of an adsorption layer model.     

热分析技术在沥青表征中的应用

介绍了近些年来国内外热分析技术在沥青分析中的应用进展。首先阐述了热分析技术在沥青产品的相态与结构、硬化过程、低温抗裂能力、老化、热稳定性、流变性等六方面的应用,最后展望了热分析技术在沥青表征方面的应用前景。     

Rheological properties and some applications for rhamsan and xanthan gum solutions

The rheological properties of solutions of xanthan gum (Kelzan® D) and three rhamsan gums, S-60, S-130 and S-194, are examined. Effects studied include those of temperature, concentration and (for the rhamsan gums) extent of side chain branching. Solutions of greater viscosity and elasticity at most shear rates result as the degree of branching increases. When compared with xanthan gum, S-194 is found to be less temperature sensitive and more stable to excess shear. The use of these polymers in two commercial applications, i.e. coal–water mixtures and timber preservative emulsions, is also examined. Several advantages are identified when rhamsan gums are used instead of xanthan gum in both cases.     

Correlation and prediction of gas solubility in cold lake bitumen

The solubility data for pure light gases, namely N₂, CH₄, CO₂ and C₂H₆, in Cold Lake bitumen are correlated by use of the Peng-Robinson equation of state. Modeling Cold Lake bitumen as a mixture of three pseudocomponents adequately matched two sets of the gas-solubility data. The critical properties and acentric factor for the bitumen pseudocomponents were estimated using the Kesler-Lee correlations. For each gas-bitumen pair, a single constant value of the binary interaction parameter is shown to predict the gas-solubility data with average deviations ranging from 2 to 8%. Subsequently, these calculations were extended to predict the solubility of CO₂+CH₄ gas-mixtures in Cold Lake bitumen. It is shown that the solubility predictions for the gas mixtures data are higher by approximately 6 to 9%.     

Electrokinetic and Rheological Properties of Aqueous TiN Suspensions with Ammonium Salt of Poly(methacrylic acid)

The study illustrates how rheology and electrokinetics can be utilized in the investigation and optimization of the properties of ceramic suspensions. Zeta potential studies show that the isoelectric point of TiN particulates is at pH=4, and for the pH range used, PMAA–NH₄ addition results in a more negative zeta potential value. The rheological behavior of titanium nitride in the presence of PMAA–NH₄ is strongly dependent on pH and three rheological types have been defined.     

Comparative studies of rheological properties of polyacrylamide and partially hydrolyzed polyacrylamide solutions

The present work is concerned with experimental results of rheological characteristics of polyacrylamide (PAM) and of partially hydrolyzed polyacrylamide (HPAM) (degree of hydrolysis up to 80%) in aqueous and aqueous/sodium chloride solutions with changing experimental conditions such as polymer concentration, temperature, solvent quality, and shear rate applied. It has been observed that the all‐aqueous and aqueous/NaCl solution of PAM and of HPAM exhibited the non‐Newtonian behavior with shear‐thinning and shear‐thickening areas. The onset of shear‐thickening at depends mainly on the degree of HPAM hydrolysis, as well as on solution concentration, temperature, solvent quality, and polymer molecular weight. Rheological parameters from power law (Ostwald de Waele model) and activation energy of viscous flow (E_a) are determined and discussed. The changes in apparent shear viscosity during aging of solutions of PAM and HPAM are also described. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2235–2241, 2007     

Concentrated slurry formation via drawdown and incorporation of wettable solids in a mechanically agitated vessel

This article describes the effect of vessel configurations on the drawdown and incorporation of floating solids to prepare concentrated alumina slurries in stirred tanks. The impeller speed and power draw required to incorporate all dry powder within four seconds, N_JI and P_JI, are used to evaluate incorporation performance. The effect of impeller type is assessed, with pitched blade impellers proving to be the most effective across the full range of solid contents considered. At higher solids content the energy demand is shown to increase dramatically, with a 100‐fold increase in energy required to add 1% w/w more solid at 50% by weight compared to 1% by weight. Analysis of impeller power numbers show this coincides with a transition from constant power number to a region where power number increases linearly with decreasing Reynolds number. Contrary to studies at low solids content, the presence of baffles is shown to inhibit drawdown. © 2018 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 64: 1885–1895, 2018