Results Of Rheological Experiments Research Articles

Analysis and Prediction of Nonlinear Hysteretic Behaviors of Graphite Magnetorheological Grease at Different Temperatures.

Magnetorheological grease (MRG) is considered a promising alternative to magnetorheological fluids as a smart material because of its higher stability and less leakage. To enhance yield stresses in various applications, graphite is incorporated as an additive, resulting in graphite magnetorheological grease (GMRG). However, the nonlinear hysteresis properties of this new material and its prediction methods have not been investigated. Therefore, in this work, the nonlinear hysteretic properties of GMRG at different temperatures, magnetic fields, and frequencies are systematically investigated and compared with those of MRG. The results of rheological experiments show that graphite enhances the shear stress of GMRG in the hysteresis curve through its reinforcing effect on the magnetic chains. The strain hardening, elasticity, and viscosity of GMRG are enhanced, but an increase in temperature decreases this efficacy. A prediction model based on the particle swarm optimization neural network algorithm (PSO-BP) is also proposed to efficiently and accurately control the nonlinear behavior of GMRG in engineering. The hysteresis curves of GMRG under different external excitations are characterized and predicted by the particle swarm optimization neural network approach. The statistical results show that the PSO-BP-based hysteresis characteristic estimates have satisfactory accuracy. In the test data, the PSO-BP model demonstrates improvements in RMSE, MAE, and SMAPE by 19.5%, 20.6%, and 21.0%, respectively, compared to the conventional BP network, which maintains an R2 value exceeding 0.95. This method provides an efficient solution for researchers to carry out reliable performance prediction in work such as genetic engineering of materials and related engineering applications.

Rheological properties and gas channeling plugging ability in CO2 flooding of a hydrophobic nanoparticle-enhanced smart gel system constructed with wormlike micelles

Carbon Dioxide capture, oil displacement and Storage (CCUS-EOR) projects inject captured carbon dioxide into developed reservoirs suitable for gas displacement. However, due to the strong heterogeneity of the reservoir, the CO2 channeling is seriously. In this study, using tung oil as renewable chemical raw material, environmentally friendly surfactants and hydrophobic nano-SiO2 were synthesized as the main components of smart gel system. Fourier transform infrared (FT-IR), nuclear magnetic resonance spectrum (NMR) and thermogravimetric analysis (TGA) were used to characterize the chemical structure. The smart gel system was obtained through the CO2 response experiment. The system can cycle back and forth between low and high viscosity multiple times, and a good temperature resistance and salt resistance. The results of rheological experiments and dynamic light scattering show that the nanoparticles promote the growth and entanglement of WLMs. The plugging capacity and auxiliary CO2-EOR performance of the system were evaluated through the laboratory displacement test. The intelligent response system has good gas channeling plugging ability, plugging efficiency reaches 97 %, and CO2 flooding oil recovery efficiency increases by 22.2 %. In addition, in the acute toxicity assessment, the bio-based gel system from plants showed slightly toxic, which is expected to become a new generation of green oilfield chemicals.

Mathematical models of apparent viscosity as a function of water–cement/binder ratio and superplasticizer in cement pastes

The water–cement/binder ratio and the admixture of water-reducing agents strongly affect the rheological properties of cement pastes. This study develops mathematical models to predict the apparent viscosity of cement pastes with varying water-cement/binder ratios and polycarboxylate-based superplasticizer content by introducing the power law shear stress-shear strain relation of non-Newtonian fluids into the Navier–Stokes motion equations. The developed models are compared with the results of rheological experiments and verified for their accuracy in simulating the apparent viscosity of cement pastes. These models provide insight into the rheological behaviour of cement pastes and could have practical applications in the construction industry.

Novel rejuvenators for sustainable recycling of aged SBS modified bitumen: Performance evaluation and reactive mechanism analysis

The performance of aged styrene-butadiene-styrene (SBS) modified bitumen (SMB) is jointly dominated by the aging of bitumen and degradation of SBS crosslinking network structure. Despite some epoxy reactive rejuvenators which can re-crosslink SBS fragments are able to reconstruct the SBS cross-linking network compared with conventional rejuvenator, the performance of aged SMB regenerated by existing epoxy reactive reactants is unbalanced achieving good low temperature performance by sacrificing high temperature performance. In order to further improve the comprehensive road performance of regenerated SMB, a novel reactive rejuvenator was proposed and assessed in this study aiming at effectively improving the high temperature performance of regenerated SMB. The restoration effectiveness of the reactive rejuvenators was evaluated and compared by the physical properties, rheological properties and FTIR of rejuvenated SMB. The physical and rheological experimental results show that 2,2'-[1,3-phenylenebis (oxymethylene)] dioxirane (RDGE) and 1,6-hexanediol diglycidyl ether (HDDGE) are beneficial to high and low temperature performance of regenerated SMB, respectively, and their composite action can complement each other. Compared with N, N-dimthylbenzylamine (BDMA), 3,6,9,12-tetraazatetradecane-1,14-diamine (PEHA) with crosslinking effect can excellently make up for the disadvantages of epoxy rejuvenator, which has better and balanced recovery effect in consideration of both low and high temperature properties of regenerated SMB. The reactive rejuvenator containing PEHA and RDGE can further alleviate high temperature performance loss of regenerated SMB by an appropriate mix ratio. The changes of chemical functional groups of FTIR and fluorescence microscope directly prove that a novel recovery reaction for degraded SBS network structure via the introduction of PEHA (a kind of polybasic primary amines) is conducive to balancing high and low temperature performance of regenerated SMB.

Controlled oxidation and digestion of Pickering emulsions stabilized by quinoa protein and (-)-epigallocatechin-3-gallate (EGCG) hybrid particles

In this study, we prepared Pickering emulsions stabilized by quinoa protein isolate (QPI) and (-)-epigallocatechin-3-gallate (EGCG) non-covalent hybrid particles using ultrasonic emulsification technique and demonstrated lipid oxidation and in vitro digestion process of Pickering emulsions. The interaction forces between QPI and EGCG were characterized using fluorescence spectroscopy, isothermal titration calorimetry, and Fourier transform infrared spectroscopy. Results indicated that the non-covalent QPI/EGCG hybrid particles were formed mainly via hydrophobic interactions, hydrogen bonds, and electrostatic interactions at pH 5. Then, the QPI/EGCG non-covalent hybrid particles were applied to modify the Pickering emulsion with ultrasonic homogenization. The rheological experimental results showed that the energy storage modulus (G′) was higher than the loss modulus (G″), indicating that the emulsion had solid-like properties. As a physical barrier, interfacial layer fabricated by antioxidant QPI/EGCG hybrid particles limited lipid oxidation at 60 °C for 15 days. At 37 °C, the QPI/EGCG hybrid particles stabilized Pickering emulsions with robust antioxidant interfacial structure limited the lipid digestion under simulated gastrointestinal tract (gastric, small intestine phases). Thus, EGCG and quinoa proteins were more resistant to free radical oxidation and gastrointestinal digestion with the assistance of ultrasound. It provides a basis for better development of food and drug delivery systems by fully utilizing the antioxidant properties of plant polyphenols.

Soft Ionic Diode Fabricated Using Asymmetric Ion Distribution in Li+-Zn(II)/Cu(II) Metallohydrogels.

The development of metal ions-incorporated soft materials is of great importance in the present scenario due to their essential requirement in the fabrication of the components such as ionic diodes and electrochemical transistors for soft electronic devices. In the current work, to fabricate a soft ionic diode, two distinct Li+-driven conductive metallohydrogels, namely, MG-Zn and MG-Cu, have been obtained by individually treating a LiOH deprotonated pregelator (H5APL) with Zn(OAc)2 or Cu(OAc)2. The pregelator and metallohydrogels have been well characterized by using various instrumental techniques, which supports their proposed formulations. Field emission scanning electron microscopic images of metallohydrogels reveal the presence of a fibrous network, which helps to create a gel matrix, whereas the rheological experimental results ascertain the true gel phase nature of the synthesized metallohydrogels. The obtained MG-Zn and MG-Cu metallohydrogels were subjected to electrochemical impedance spectroscopic and band gap measurements. The MG-Zn and MG-Cu showed ionic conductivities of 1.02 × 10-3 and 1.14 × 10-3 S/cm, along with band gaps of 2.82 and 2.85 eV, respectively, thus claiming their suitability for device fabrication. Further, the fabricated metallohydrogel-based ionic diode shows appreciable ability to rectify the ionic current with the forward and reverse bias currents of 19 and 1.9 mA at +/-4 V bias potential. Based on all the experimental results, the mechanism has been well established for the rectification behavior in the fabricated metallohydrogel ionic diode.

Novel bigels constructed from oleogels and hydrogels with contrary thermal characteristics: Phase inversion and 3D printing applications

In this study, bigels systems with semi-solid properties were prepared by using the mixture of beeswax oleogels and hydroxypropyl methylcellulose (HPMC) hydrogels in different proportions. The observation by confocal laser scanning microscopy (CLSM) showed that bigels with varying oleogel contents presented different types of O/W (20%, 40%, and 50%), semi-bicontinuous (55%), and W/O bigels (60% and 80%), respectively. FTIR results indicated that the spectra of different types of bigels exhibited significant variations between 3600 and 3300 cm −1 (O–H stretching) and 1250-1000 cm −1 (characteristic absorption peaks of HPMC) ranges, which could be used for further determination of the type of bigels. Rheological experimental results showed that W/O bigels and O/W bigels exhibited diametrically opposed thermal properties. In terms of 3D printing capability, W/O bigels with 60% oleogel content exhibited the best printing integrity, while semi-bicontinuous bigels showed the worst extrusion capability due to the inhomogeneity of the system. By printing under different models, it was found that W/O bigels seemed to be more suitable for flat stacked models, while O/W bigels had better performance in models with small-area monolayer structures. These results guided the development of bigels systems that could be applied for food 3D printing. • The variation of oleogel/hydrogel content in bigels led to the phase inversion. • FTIR spectra can be used for further determination of the type of bigels. • W/O bigels and O/W bigels exhibited diametrically opposed thermal properties. • O/W bigels were more suitable for printing small-area monolayer structure models. • The extrusion process of printing had less destructive effect on O/W bigels.

Viscoelastic fluids formed by an ultralong-chain trimeric surfactant and its application in fracturing fluids

In this work, we investigated the structural transitions of aggregates of a trimeric cationic surfactant 3C22quinQ solutions with or without KCl using rheological measurements and molecular dynamic (MD) simulation. Steady and dynamic rheological measurements were used to investigate the rheological properties of 3C22quinQ and 3C22quinQ/KCl systems. The results show that 3C22quinQ can form wormlike micelles at 1 mM without any additives, demonstrating remarkable self-assembly and thickening ability. The addition of KCl further optimizes the molecular configuration and promotes the rapid growth of wormlike micelles. A 11.07 mM 3C22quinQ solution exhibits a zero-shear viscosity η0 of 5.1 × 105 mPa‧s together with relaxation time τR of 36.27 s at a KCl to 3C22quinQ molar ratio of 1. In addition, molecular dynamic (MD) properties such as the radial distribution function (RDF), the radius of gyration (Rg), and mean square displacement (MSD) show that KCl has a considerable influence on the structure and aggregation properties of 3C22quinQ micelles, in good agreement with rheological experimental results. More importantly, the VES fracturing fluid formed by 3C22quinQ and KCl was not only resistant to high temperature and cyclic shear, but it also exhibited excellent proppant-carrying and oil-induced gel-breaking performances. The viscoelastic fluid formed by 3C22quinQ and KCl, has shown promise as an appealing option for hydraulic fracturing procedures in unconventional oil and gas reserviors.

A Molecular Dynamics Simulation Study of Amine-Carboxyl Ionic Interactions and Their Distribution in a Polysiloxanes Network

The ionic crosslinking mechanism of polysiloxanes networks based on amine/carboxyl interactions was investigated by molecular dynamics and tensile performance experiments. The “one-chain-crosslinking” mechanism between crosslinkers and polymers was investigated based on the corresponding simulations. The experimental results showed that the tensile strength and elongation at break of amine-functional polysiloxanes (AFPs)/carboxyl-functional polysiloxanes (CFPs) (1.54 MPa@264%, respectively) were higher than that of amine and carboxyl-functional polysiloxanes (ACFPs) (0.66 MPa@45%). The simulation results indicated that the number of intrachain and interchain hydrogen bonds played an important role for improving the mechanical performance of the polymer networks. In addition, it was found that the orientation and entanglement of the polymer chains had a direct correlation with hydrogen bonding in the equilibrium state and during the stretching process. The mean square radius of gyration (R g2), the mean square end-to-end distance (R ee2), the orientation parameter, the entanglement parameter, and the mean square displacement (MSD) of the chains in the equilibrium state were calculated. The molecular dynamic simulations were verified by comparing the simulated results with the tensile and rheological experimental results of the AFPs/CFPs and ACFPs elastomers.

Performance evaluation of a novel CO2-induced clean fracturing fluid in low permeability formations

After the limitations of polymer-based fracturing due to poor clean-up property during flowback after fracturing treatment, viscoelastic surfactant (VES) received very huge attention in the last three decades, especially in low permeability reservoirs. In this study, a Novel CO 2 -induced clean fracturing fluid (SDS-TMTAD-CO 2 ) is formulated with simulated formation water (23,003 mg L −1 ) after optimization experiments according to the proposed parameters (i.e., 70 °C, economical, easily preparation, and environment-friendly). The results of rheological experiments show that the apparent viscosity of the fracturing fluid system increases to a certain extent under high salt conditions and possesses sufficient self-healing property against high shear tolerance. At different temperatures (25, 50, and 70 °C), the thermodynamic properties, fluid viscoelasticity, and proppant carrying capacity meet the requirements of the fracturing fluid industry standards. After adding kerosene (0.02 mol L −1 ); the gel breaking fluid viscosity (3.2 mPa s), anti-swelling rate (91.3%), and interfacial tension (2.3 × 10 −2 mN m −1 ) are holding promising conditions during the flowback period, clay swelling, and residual oil saturation, respectively. The filtration and core damage experimental results meet the national industry standard for fracturing fluids. The SEM results show that the fluid system after reaction forms a unified adsorption film on the core surface. Hopefully, this fluid system will be proved as a good candidate by means of excellent proppant transportation ability, anti-swelling, easy gel structure breaking, low filtration, and less formation damage in low permeable formations with an increase in productivity. • Easy preparation of an economical and environment-friendly CO 2 -induced clean fracturing fluid system (SDS-TMTAD-CO 2 ). • Rheological and functional performances of the system meet the “SY/T 6376-2008, SY/T 5107-2016, and SY/T 5971-2016” standards. • Can fracture the low permeable formations with less filtration and low formation damage.

Novel approach to promote the hydrophobic association: Introduction of short alkyl chains into hydrophobically associating polyelectrolytes

ABSTRACTA novel approach to promote hydrophobic association by incorporating short alkyl chains onto polyelectrolytes (HAPEs) was presented. A series of HAPEs was synthesized by free radical copolymerization in aqueous media with acrylamide (AM), 11‐acrylamidoundecanoic acid (C11AM), and 6‐acrylamidohexanoic acid (C6AM). The structures and compositions of the polymers were confirmed by 1H‐NMR, and the molecular weights were determined by GPC. Results of rheological experiments revealed that viscosities increased greatly in samples containing C11AM and C6AM compared with the sample without C6AM. The sample without C6AM was also characterized by critical association concentrations and critical angular frequencies. Solubilization and bridging interaction were considered as the possible reasons. Pyrene fluorescence probe data and 1H‐NMR spin–spin relaxation times further illustrated the reinforcement of hydrophobic associations by short alkyl side chains. All the results showed that the optimum content of C6AM was 1 mol % in the prepared HAPEs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47581.

Rheological Behaviour of PP Nanocomposites by Extrusion Process

The effect of organophilic clay (C15A) in PP compatibilized polymer (PP/PP-g-MA) through rheological experimental results is presented. This study focusses on the description of the rheological behaviour of the organophilic layers along the screws of a twin screw extruder by melting process, varying the screw profile as well as the processing conditions, namely screw speed, temperature and feed rate. Different levels of dispersion were found along the screws for all conditions and positions analyzed by rheology. The qualitative analysis of the images obtained by transmission electron microscopy, reinforced the results. Furthermore, the effects of the processing conditions on dispersion of C15A layers along the screw profile are analyzed using multiple linear regression techniques. The results show statistically significant differences of all rheology measures for all the processing conditions and positions along the extruder.

Gas solubility and rheological behavior study of betaine and alanine based natural deep eutectic solvents (NADES)

Natural deep eutectic solvent (NADES) produced herein this work by mixing betaine and alanine with lactic acid and malic acid with 1:1M mixing ratios. Thermophysical properties including water content, thermal stability, density and gas solubility of CO2 and N2 were experimented at different isotherms for wide pressures range up to 50 bars. Moreover, detailed rheological experiments were conducted on the studied materials to obtain viscosity and deduce the dynamic flow behavior. A pressure driven physisorption mechanism was observed for the studied systems. Betaine based NADES materials showed superior carbon dioxide and nitrogen solubility when they are mixed with lactic acid. On the other hand, the rheological experimental results show shear-thinning effect in which the η is decreasing with shear rate at all temperatures. Low viscosity profiles NADES assure the less mass transfer resistance for lactic acid based NADES systems and it also confirmed that the high CO2 and N2 solubility for lactic acid based NADES samples.

Gas Solubility and Rheological Behavior of Natural Deep Eutectic Solvents (NADES) via Combined Experimental and Molecular Simulation Techniques

AbstractA potential of natural deep eutectic solvent (NADES) produced with the mixture of choline chloride with lactic acid, malic acid, citric acid and fructose is studied in this work. Experimental techniques are used to collect thermophysical property data including water content, thermal strength, density and gas solubility of CO2 and N2 data at pressures up to 50 bars. Detailed rheological measurements and various models have been studied to describe the dynamic flow behavior. Moreover, a density functional theory (DFT) and classical molecular dynamics (MD) methods have been used for investigating the physicochemical properties, structuring, dynamics and interfacial behavior of the studied NADES from the nanoscopic point of view to infer its viability for extensive usage. The rheological experimental results show usual shear‐thinning effect in which the η is decreasing with shear rate at all temperatures. A trend of studied NADES viscosity profiles were found as very similar to that of common ionic liquids that were previously, where the viscosities of all studied NADES decreased with increasing temperature. DFT simulations yielded with an accurate quantification of short‐range interaction but liquid state is also characterized by middle and long‐range interaction together with volumetric effects. Molecular orientations were quantified by radial distribution functions and the developed interactions are topologically characterized.

Experimental measurement and modeling of nanoparticle-stabilized emulsion rheological behavior

Emulsions have wide applications in various fields, especially in the petroleum industry. The rheological behavior of water-oil emulsions plays an important role in oil production, transportation and enhanced oil recovery methods Rheology of emulsions is affected by various factors such as dispersed phase fraction, droplet size distribution, a concentration of emulsifying agents, solid concentration, etc. Emulsion stabilization by solids, especially nanoparticles increased the stability, improved the rheological properties and consequently, incrementing the oil recovery from a subterranean formation. It can be pointed out that in very limited cases, the effects of nanoparticles on droplet size distribution of emulsion were investigated and models for prediction of the rheological behavior of solid-stabilized water-in-oil emulsions were not presented. The experiments were carried out using crude oil (petroleum) and fumed silica particle (namely Aerosil R972). In this communication, the effects of different parameters, including water volume fraction, nanoparticle concentration, shear rate, and angular frequency were investigated on the rheological behavior of water-in-oil emulsion. According to the results of rheological experiments, it can be pointed out that the influence of the nanoparticles on the viscosity of water-in-oil emulsions is mainly affected by the water/oil ratio, a number of nanoparticles, shear rate and angular frequency. Nanoparticle decreased water droplet diameter and increased the stability, elasticity and viscosity of the emulsion. In addition, for a better understanding of the effect of these parameters on the viscosity of the water-in-oil emulsions, apparent viscosity models were used. Based on the experimental data, a new equation was developed to estimate the relative viscosity of solid-free and solid-stabilized emulsions. The obtained results demonstrated that the proposed model has increased accuracy than previously published correlations.

Towards a mechanistic understanding of rheological behaviour of water-in-oil emulsion: Roles of nanoparticles, water volume fraction and aging time

The viscosity of water-oil emulsions plays an important role in oil production and transportation. The objective of this study was to improve the basic understanding of the influence of nanoparticles on the viscosity of water-in-oil emulsions. Using crude oil and different industrial nanomaterials, the droplet size distribution, droplet mean size, and rheological models of emulsions were investigated. Experimental results show that the addition of nanoparticles increases the crude oil viscosity; however, the Newtonian flow behaviour of oil is not affected by nanoparticles. It is observed that the viscosity of crude oil increased from 36.5 to 49 cP when the nanoparticle concentration was elevated from0 to 0.1 wt%. From the results of rheological experiments, it can be concluded that the influence of nanoparticles on the emulsion viscosity is mainly affected by the type and amount of nanoparticles, water/oil-ratio and aging time. Mean droplet diameter decreased from 5.68 to 4.11 micrometre when 0.1 wt% nanoparticles were added to emulsion. The results also suggest that the properties of stabilized water-in-oil emulsions are significantly time-dependent, and the droplet size and viscosity of emulsions is reduced by time. Most of previously published correlations have huge errors and could not precisely predict the apparent viscosities of non-solid stabilized and solid-stabilized emulsions. None of the previously utilized equations did ever consider the effect of added solids to the emulsion.

Estimation model for yield stress of fresh uncemented thickened tailings: Coupled effects of true solid density, bulk density, and solid concentration

Yield stress is an important issue in the dewatering process of mineral waste tailings. However, very few studies focus on yield stress affected by the tailing properties of true solid density (T) and bulk density (B), which are the two most common properties used to evaluate a tailing. In the present study, an estimation model for yield stress of fresh uncemented thickened tailings (UTT) is proposed and verified based on rheological experimental results. As the model relates to the true solid density, bulk density, and solid concentration (C) of tailings, it is referred to as the TBC model. The change trend of yield stress with the variation of TBC properties is expressed by the first derivative of the TBC model. Results show that yield stress increases with true solid density and solid concentration, whereas the variation is reversed for bulk density. This study enhances our understanding of yield stress and helps predict the yield stress of thickened tailings according to their TBC properties.

Amine-intercalated α-zirconium phosphates as lubricant additives

In this study, three types of amines intercalated α-zirconium phosphate nanosheets with different interspaces were synthesized and examined as lubricant additives to a mineral oil. Results from tribological experiments illustrated that these additives improved lubricating performance. Results of rheological experiments showed that the viscosity of the mineral oil was effectively reduced with the addition of α-zirconium phosphate nanosheets. The two-dimensional structure, with larger interspaces, resulting from amine intercalation, exhibited improved effectiveness in reducing viscosity. This study demonstrates that the nanosheet structure of α-zirconium phosphates is effective in friction reduction. The manufacture of lubricants with tailored viscosity is possible by using different intercalators.

Investigation of Oil–Asphaltene Slurry Rheological Behavior

The presence of asphaltene means additional difficulties related to transport and processing due to the increased crude oil viscosity caused by the asphaltene. For a better knowledge of the flow properties of asphaltene containing crude oils, it is necessary to understand how asphaltene affects the rheological properties. The aim of this article is to provide information on such rheological properties of oil–asphaltene slurry systems. The results of rheological experiments show that the non-Newtonian flow curves can be approximated by the Bingham plastic model to determine the apparent viscosity and the yield stress as a function of asphaltene concentration and temperature. An explanation is also provided for the observed behavior.

Influence of anisotropic pressure on viscosity and electrorheology of diethylene glycol-based MgAl2O4 nanofluids

The paper presents results of rheological experiments on viscosity under anisotropic pressure and in electric field of diethylene glycol-based MgAl2O4 nanofluids. Nanofluids have been prepared in a two-step method. The dynamic viscosity of nanofluids with various mass concentrations of nanoparticles was measured in the range of shear rates from 10 s −1 to 1,000 s −1 in constant temperature under the pressure of 7.5 MPa. In the second type of experiments, different values of the electric field up to 2,000 V/mm was used. Thixotropy structure of MgAl2O4-DG nanofluids has been studied in electrical field.