Rotational Viscometer Research Articles

Effect of Parameter Variation on the Viscosity of Ethanol Gel Propellants

This research investigated how the variation of temperature and shear rate affects the viscosity of ethanol gel propellants that use methyl cellulose as gellant and, in parts, use boron as energetic additive. Using a rotational viscometer in a cone-and-plate configuration, propellant viscosity data was recorded across a range of temperatures and applied shear rates. The temperaturedependence of the viscosity was modelled using an Arrhenius-type equation. For the high shear rates, the data was modelled using the Power Law, Herrschel–Bulkley model, Carreau model, and Cross model. For low shear rates the used model was the rearranged Herrschel–Bulkley model. The temperature investigation suggested that the trend of decreasing viscosity with increasing temperature, predicted by the Arrhenius-type equation, is only applicable until approximately 320 K, after which the gel viscosity increased strongly. At high shear rates, the gel behaved in a shear thinning manner and was modelled most accurately by the Cross model. At low shear rates, the gel was shear thickening up to its elastic limit, which was found to lie at 0.41 s–1.

Rheological Properties Study of Oral Hydrogels Containing Phenobarbital for a Potiential Pediatric Use

This present study is a continuation of our work entitled “pH-thermosensitive oral chitosan-based hydrogels containing phenobarbital for a potential pediatric use”. The results of that previous study have shown their potential use in newborns in particular premature newborns while the oral form containing phenobarbital is a tablet and is unsuitable for newborns. Thus, in order to have a suitable device for the administration of hydrogels oral formulations to newborns, we have done rheology studies to complement our work. For this we have studied the variation of the viscosity of hydrogels containing phenobarbital as a function of shear rate and time. Phenobarbital is an active drug used in neonatal treatment of epilepsy. The viscosity measurements of hydrogels are carried out using a Fungilab V'PAD Rotational Viscometer (100–240V/50–60Hz) Type 'R series then ANOVA test was used to analysis the results. The results showed that the hydrogels had a non-Newtonian behavior with shear-thinning and thixotropic type which depends on the chitosan concentration, the storage temperature hydrogels, the presence of Eudragit E100 and the final solution’s pH. Rheological properties study have shown that a syringe-type device would be suitable for oral administration of hydrogels formulations to neonates.

Measurement system analysis of viscosity: a Six-Sigma gage repeatability and reproducibility analysis

Different viscometer techniques are used to measure the viscosity; however, the repeatability and reproducibility of these measurement systems have not been investigated. Literature suggests that viscometers exhibit measurement variations that can be categorised into variations due to the process, the gage, and the operators. To explore the sources of variations in viscometers, a Six-Sigma gage repeatability and reproducibility (GR&R) study is conducted. GR&R studies utilise two-way ANOVA to separate measurement variation into different components to find the precision-to-tolerance, signal-to-noise ratios and the true process capability index. A software is built to demonstrate the newly introduced measurement assessment chart that pinpoints the suggested but necessary corrective actions. The results of a real industrial data show that rotational viscometers are more reliable than orifice viscometers, however, with moderate capability due to their modest signal-to-noise ratio. The model, assessment chart and the software can be used to assess other gages.

Improving energy efficiency in well construction through the use of hydrocarbon-based muds and muds with improved lubricating properties

During the construction of directional wells in spatially curved sections of the barrel, large contact loads and huge resistance to the movement of the drill string during lifting can occur, which leads to increased wear of the drill pipes and high energy costs. One of the directions for increasing the energy efficiency of drilling such wells was the reduction of friction at the metal-metal, metal-rock, and metal-filter cake boundaries. This result can be achieved by introducing special lubricating additives or by switching to a hydrocarbon solution during drilling. The article presents the study of drilling fluids with the introduction of lubricating additives on a lubricity tester Fann EP / Lubricity Tester Model 212, a device for determining the coefficient of clay cake KTK-2, a rotary viscometer Fann 35SA, pH meter Crison GLP 21 to reduce the coefficient of friction of a pair “metal – metal” in a clay solution, which amounted to 70-75%, in an aqueous solution - up to 65%. The optimal concentration of the additive according to the study in different drilling fluids was about 1.5-2%. The results of a study of the effect of the speed and time of mixing a hydrocarbon-based solution during its preparation on the electrostability of the emulsion obtained are carried out on a BVD device, which showed a significant increase in the stability of the washing liquid to 24%, which leads to a decrease in the number of complications associated with pipe wear and a decrease torque when rotating the column.

ENTROPY INFLUENCE ON THE DEPENDENCE OF THE NANOFLUIDS VISCOSITY ON TEMPERATURE AND SHEAR RATE

A Brookfield DV-II + Pro rotational viscometer was used to study the viscosity of 7 samples of concentrated nanodispersed systems (nanofluids) with a similar viscosity (6-22 mPa ∙ s), the particles of the dispersed phase in which are nanosized surfactant micelles and conglomerates from them. It was found that for 5 out of 7 studied reagents, there is a decrease in viscosity typical for dispersed systems with an increase in the shear rate, and their flow curves, that is, the dependence of the shear stress on the shear rate, correspond to the ideal plastic flow of non-Newtonian fluids. Moreover, with high reliability, R2 ≥ 0.999 is described by the Bingham equation with a small value of the limiting shear stress (less than 0.2 Pa). It is shown that all the studied reagents are also characterized by an increase in the activation energy of a viscous flow Е with an increase in the shear rate. As a result, a decrease in viscosity with an increase in shear rate, typical for disperse systems, including nanofluids, is provided by a more significant increase in entropy changes ΔS compared to Е. It has been substantiated that, depending on the ratio between the activation energy of viscous flow Е and the change in entropy ΔS, the viscosity of concentrated micellar dispersed systems with an increase in the shear rate can decrease, remain unchanged, and increase. The last two cases, not typical for disperse systems and nanofluids, were identified and studied using the example of two demulsifiers, RIK-1 and RIK-2, with a maximum of a very narrow particle size distribution at 160 ± 5 nm, corresponding to the size of a special type of very stable micelles Surfactant — vesicle.

DEPRESSOR ADDITIVE FOR OIL PUMPING

The purpose of the research was to study rheological properties of Azerbaijani oils from the Sangachali and Muradkhanli fields. In order to improve rheological properties of the oil produced from the Muradkhanli and Sangachali fields, a Russian-made depressant СНПХ -2005 additive was used. To determine the optimal concentration of the СНПХ-2005 and confirm its positive effect on oil and oil products, control samples were prepared with this additive in oil M-8 and the oil from the above fields with the calculation of 0.5 kg/t, 0.8 kg/t and 1.0 kg/t. In parallel, similar samples were prepared with the depressant АзНИИ. The pour points of the samples were investigated at -5 0С, -100С and -200С on the rotational viscometer REOTECT-2. It found that the sample with the СНПХ -2005 additive (at the concentration of 0.8%) in the M-8 oil has a lower pour point (minus 40°C) as compared to a similar sample with the depressant АзНИИ (-32°C). The sample with the depressant СНПХ-2005 (at the concentration of 0.8%) and oil reveals the best rheological properties (minus 38°C versus -30°C). As a result of the studies carried out, it was determined that the introduction of the depressant СНПХ-2005 improves rheological parameters of the oil from the above fields, and thereby makes it possible to refuse additional heating in low temperature areas when pumping oil through the oil pipeline.

Recycling fish scale powder in improving the performance of asphalt: A sustainable utilization of fish scale waste in asphalt

Abstract Limited non-renewable resources and deteriorating ecological environment have emphasized the significance of the effective utilization of biomaterials. Many studies have specified that fish scales (FS) possess potential applications as cleaner production in various industrial sectors. However, research on the effect of this eco-friendly and sustainable biomaterial on asphalt has not been reported. Thus, this study aims to investigate the effect of fish scale powder (FSP) on the performance of asphalt binders. Four types of fish scales modified asphalts (FSMA) were prepared by adding different contents of FSP to 70# base asphalt (4%, 8%, 12%, and 16% by weight of the base asphalt). Rotational viscometer (RV), dynamic shear rheometer (DSR), and bending beam rheometer (BBR) were employed to characterize the rheologic behavior of FSMA. The phase separation and sessile drop tests were carried out to evaluate the storage stability and adhesion of FSMA. In addition, the chemical characteristics were investigated by Fourier transform infrared (FTIR) spectroscopy. It was found that FSP enhanced the adhesion, viscoelastic properties, temperature susceptibility, and resistance to permanent deformation of asphalt. Moreover, it was discovered that FSP at low content had little effect on the aging, fatigue, and cracking resistance of the asphalt. Besides, there was a physical mixing between FSP and asphalt binder, and the mixture was a storage-stable product. Overall, it is promising and feasible to use FSP as a bio-modifier for asphalt binders and reduce waste treatment costs. This method is a sustainable utilization of fish scale waste.

Effect of Isomer Composition of Hydroxy Terminated Polybutadiene (HTPB) in Low Shear Flow Behavior (Efek dari Komposisi Isomer dari Hydroxy Terminated Polybutadiene (HTPB) terhadap Sifat Alir dalam Geseran Rendah)

HTPB is the ultimate component of matrix builder for high-filled composite materials. Flow behavior of HTPB in low shear is crucial in casting the composite. Considering the characteristics of hydrocarbon, this work aims to investigate the effect of microstructure composition of HTPB on its flow behavior. In this work, HTPB with different composition of 1,4-cis, 1,2-vinyl and 1,4-trans microstructures were used. Fourier-Transform Infra-Red spectroscopy (FT-IR) was used to determine the composition. It was calculated as a ratio of peak area of 710, 910 and 970 cm-1 for 1,4-cis, 1,2-vinyl, 1,4-trans isomers respectively. Viscosity was measured using a rotational viscometer at various low shear rates. It is found that HTPB with high 1,2-vinyl/1,4-trans isomers shows shear thickening behaviour, distinguished significantly from Newtonian flow of the others. It is suggested that mechanism of shear thickening involves a certain configuration of 1,2-vinyl and 1,4-trans isomers that builds different degrees of flow resistance from one to other shear layers. The configuration and flow resistance changes among layers as shear increases.

Fluorescent Visualization of Nucleolar G-Quadruplex RNA and Dynamics of Cytoplasm and Intranuclear Viscosity

The nucleolus, the locus of ribosome biogenesis, was found to be the predominant intracellular target of a new fluorescent probe, V-P1. In solution, the probe demonstrated both a selectivity to RNA...

Chemical and rheological characteristics of accelerate aged asphalt binders using rolling thin film oven

The SUPERPAVE (Superior Performance Pavements) system and design method uses a rolling thin film oven (RTFO) test in the laboratory to simulate short-term ageing. The accelerated asphalt ageing method to simulate the long-term ageing. Whereas the method accelerated asphalt ageing using a pressure ageing vessel (PAV) takes an extended period of time to prepare the samples. In this case, the present study is an attempt to achieve accelerated long-term aged binder similar to that of PAV by running multiple cycles of RTFO maintained at 163 °C for a duration of 85 min per cycle. To achieve this, two unmodified binders of PG 70-XX were obtained from two different sources, and a styrene–butadienestyrene (SBS) modified binder of PG 64-XX was selected. The rheological characteristics such as viscosity at elevated temperature using rotational viscometer (RV), rutting and fatigue parameters using dynamic shear rheometer (DSR), the chemical characteristics such as carbonyl and sulfoxide indices using Fourier transform infrared spectroscopy (FTIR) are used to compare between the RTFO and PAV aged binders. The rheological results suggest that, to produce an accelerated aged binder using RTFO for unmodified and SBS modified asphalt binder with respect to G*sinδ, the RTFO duration of 5 h 20 min and 6 h can be used as alternative for ASTM D6521 respectively. In additions, the rutting parameter G*/sinδ shows to match its PAV aged binder properties at 256 ± 6 min for both PG 70-XX, and 269 min for PG 64-XX modified binder. Further, the variations in functional group concentration and changes in volatile mass are limited the achievement of specific RTFO duration.

Synthesis and research of photocurable protective coatings on the basis of olygoesteracrylates

In this work, photocurable protective coatings based on methacrylic acid esters have been developed and their physical and mechanical properties have been investigated. The photocurable compositions were obtained by mixing at different ratios the following methacrylic acid esters: polyethylene glycol dimethacrylate 400 and triethylene glycol dimethacrylate ether, polyethylene glycol dimethacrylate 400 and oligourethane dimethacrylate, polyethylene glycol dimethacrylate 400 and pentaerythritol tetraacrylate. For the obtained compositions, the viscosity was studied using a Brookfield rotary viscometer. To initiate polymerization, a mixture of initiators was used: benzoyl peroxide and benzoin. Curing of the obtained compositions was carried out under the influence of UV rays for 2-5 minutes. For photo-cured compositions, their physical and mechanical properties have been studied. It was found that the composition based on polyethylene glycol dimethacrylate modified with triethylene glycol dimethacrylate at a ratio of 70:30 has the highest strength.

Rheological Behavior of Glycyrrhiza glabra (Licorice) Extract as a Function of Concentration and Temperature: A Critical Reappraisal.

In the present study, rheological properties of twelve different licorice root extracts were evaluated using a rotational viscometer as a function of soluble solids content (15–45 °Bx) and temperature (30–70 °C). Response Surface Methodology was used to understand the relationships between the parameters. The experimental data were then fit into mathematical models. The results, for the first time, revealed that the licorice solutions had non-Newtonian shear-thinning behaviors with flow behavior indexes of 0.24 to 0.91, depending on the licorice extract samples, temperature, and °Bx. These observations were different from those reported in the literature and the present study elaborated on reasons for such observations. Further, the shear-thinning behavior generally increased by increasing the °Bx and decreasing the temperature. In addition, the power-law model was found to be suitable for predicting the experimental data. The newly revealed information can be particularly important in designing the unit operations for licorice extract processing.

Thermophysical Properties of Nanofluids Composed of Ethylene Glycol and Long Multi-Walled Carbon Nanotubes

In this work, thermal conductivity, viscosity, isobaric heat capacity, and density of stable carbon-based nanofluids are presented. The nanofluids under study are composed of 1,2-ethanediol (ethylene glycol, EG) and long multi-walled carbon nanotubes (MWCNTs), so-called ‘in-house 16h’ (synthesized in our laboratory via catalytic chemical vapor deposition during 16 h with a diameter of 60–80 nm and length of 770 μm). Poly(N-vinylpyrrolidone) (PVP) was used to increase the stability of nanofluids. The nanofluids were prepared via an ultrasonication-assisted, three-step method while their key thermophysical characteristics were obtained using the hot-wire technique and rotary viscometer. As a result, the addition of MWCNTs significantly improved the thermal conductivity of nanofluids by 31.5% for the highest 1.0 wt% (0.498 vol%) long MWCNT content, leaving the Newtonian character of the nanofluids practically intact.

Сравнительное изучение кинетики свертывания крови и тромбообразования реологическими и электрореологическими методами.

Цель исследования: изучить механизмы формирования и тромбодинамические свойства кровяного сгустка при тромбообразовании in vitro и представить сравнительное исследование кинетики тромбообразования с помощью реологических и электрореологических методов в условиях постоянного и осциллирующего сдвигового вискозиметрического течения; оценить свертывание цельной и консервированной крови, ее вязкоупругие свой ства и влияние фибриногена и декстранов на формирование сгустка. Материалы и методы. Вязкость и удельную электропроводимость нормальной и консервированной с CPD-A1-адениновым раствором крови измеряли ротационным вискозиметром Low Shear 30 Contraves (LS30) с коаксиальными цилиндрами и копией измерительной системы MS1/1 со встроенными электродами (разработана на базе LS30) в условиях постоянного сдвигового потока и в электрическом поле. Вязкоупругие свойства нормальной цельной крови исследовали с помощью реометра Physica MCR 301 (Anton Paar, Austria) в условиях осциллирующего синусоидального потока. Результаты. Представлены результаты кинетики динамической вязкости и удельной электропроводимости консервированной крови в процессе коагуляции в условиях постоянного сдвигового потока и в электрическом поле. Исследованы вязкоупругие свойства цельной крови в условиях синусоидального осциллирующего вискозиметрического течения и представлены зависимости упругого модуля G' (storage modulus) и модуля потерь G'' (loss modulus), а также нормальных сил как функция времени при свертывании. Приводятся данные эффекта фибриногена и декстрана на упругий модуль G' и на модуль потерь G'' цельной крови в процессе коагуляции. Заключение. В условиях вискозиметрического течения при низких скоростях сдвига кинетика тромбообразования характеризуется начальным этапом постепенного увеличения кажущейся вязкости и уменьшения удельной электропроводимости крови и периодом интенсивной коагуляции, характеризирующимся экспоненциальным ростом вязкости и параллельным уменьшением удельной электропроводимости исследуемого образца. Установлено, что коагулирующая цельная кровь обладает нелинейными вязкоупругими свойствами. Кинетика образования сгустка в условиях осциллирующего вискозиметрического течения крови характеризуется увеличением упругого модуля G' и модуля потерь G'' со временем. Одновременно зарегистрирована и отрицательная нормальная сила исследуемого образца в зазоре между пластинами при постоянной толщине зазора. Повышение содержание фибриногена ускоряет коагуляцию и увеличивает значения упругого модуля G' и модуля потерь G'', а также и нормальной силы коагулирующей цельной крови. Objectives: to study the mechanisms of thrombus formation and thrombodynamic properties of a blood clot during coagulation in vitro and to present a comparative study of clot kinetics formation under conditions of steady and oscillating shear viscometric flow and at electric field by rheological and electrorheological methods; to evaluate the coagulation of whole and preserved blood, its viscoelastic properties and the effect of fi brinogen and dextrans on clot formation. Materials/ Methods. The viscosity and electrical conductivity of normal blood and blood preserved with CPD-A1-adenine solution were measured with a Low Shear 30 Contraves (LS30) rotational viscometer with coaxial cylinders and with a copy of the measuring system MS1 / 1 with builtin electrodes at a steady viscometric shear flow and in an electric field too. The viscoelastic properties of normal whole blood were investigated using a Physica MCR 301 rheometer (Anton Paar, Austria) at an oscillating sinusoidal flow. Results. Kinetics of the dynamic viscosity and electrical conductivity of preserved blood during coagulation at a steady shear flow and at electric field were obtained. The viscoelastic properties of whole blood were investigated under conditions of sinusoidal oscillating viscometric flow. The dependences of the elastic (storage) modulus G' and the loss modulus G'', as well as the normal coagulation forces as a function of time are presented. The effect of fibrinogen and dextran on the elastic modulus G' and the loss modulus G'' of whole blood during coagulation are presented. Conclusions. The kinetics of blood coagulation at low shear rates is characterized by a gradual increase of the apparent viscosity and a decrease in blood conductivity at the initial stage and an exponential increase in viscosity during intensive coagulation and a parallel decrease of conductivity too. It was established that coagulating whole blood exhibit nonlinear viscoelastic properties under conditions of sinusoidal blood flow. The kinetics of thrombus formation is characterized by increasing the elastic modulus G' (storage modulus) and the loss modulus G'' with time. The negative normal force in the gap between the plates is also registered at a constant thickness of the gap. An increase in fibrinogen content accelerates coagulation and increases the values of elastic modulus G' and loss modulus G', as well as of the normal force of coagulating whole blood.

Effects of styrene butadiene styrene and Lucobite on stone mastic asphalt performance

This study evaluates the performance of stone mastic asphalt road paving mixtures modified with two polymer additives: styrene butadiene styrene and Lucobite. The test samples were made from limestone aggregate, pure bitumen 60/70 and polymer additives of 3 and 5% by weight. Penetration, softening point and rotational viscometer tests were conducted to assess the effects of additives on the physical properties of modified binders. Marshall stability, indirect tensile strength, moisture susceptibility, four-point beam fatigue, dynamic creep and wheel track tests were also performed to compare the performance of modified samples against an unmodified control sample. According to the test results, the additives improved binder performance and resistance against moisture, permanent deformation and fatigue compared with a conventional mixture. Based on the results, asphalt modified by styrene butadiene styrene had improved moisture sensitivity, permanent deformation performance (from wheel track tests) and fatigue behaviour up to 15, 32 and 53% better than unmodified asphalt, respectively. Lucobite-modified mixtures improved these properties up to 14, 20 and 40%, respectively.

Rheological properties and aging performance of sulfur extended asphalt modified with recycled polyethylene waste

This study examines the effect of two different recycled plastic waste (RPW) which are high and low-density polyethylene (RHDPE and RLDPE) on the rheological/viscoelastic characteristics and aging performance of virgin asphalt and sulfur extended asphalt (SEA). Four dosages of the RPW additives representing 2%, 4%, 6%, and 8% by weight of the asphalt binder were investigated. The rheological characteristics of the RPW modified binders (virgin and SEA) are characterized at original and short-term aging conditions through the Rotational Viscometer (RV) and dynamic shear rheometer (DSR) tests. Fatigue performance is also characterized at the long-term aging condition. Also, high-temperature performance, dynamic storage stability (DSS), multiple stress creep and recovery (MSCR) are studied. Testing results show that RPWs lead to improved rutting and fatigue performance. Adding RPW to the virgin and SEA binders slows the binder oxidation reactions during the short-term aging. The Aging Index (AI) is found to be dependent on the asphalt rheological properties, amount/type of RPW, binder type, and temperature. RHDPE leads to an unstable modified virgin asphalt. Less than 4% RHDPE or 8% RLDPE with virgin asphalt show good DSS in terms of degradation and separation. The RPW with SEA meets the requirement of time degradation and separation set by the Federal Highway Administration (FHWA). The temperature susceptibility of asphalt binder decreases dramatically with the RPW modification making the asphalt binder more suitable for use at a wider range of temperatures.

INVESTIGATION OF THE INFLUENCE OF STABILIZERS ON THE VISCOSITY OF THE RECOVERED MIXTURE OF A HYPERTONIC DRINK FOR ATHLETES

When introducing plant and animal protein products, in addition to nutritional value, it is advisable to assess their physicochemical properties and technological indicators, in particular, homogeneity and consistency stability. The aim of research is to determine the effect of consistency stabilizers on the viscosity of a reconstituted hypertonic drink for athletes based on flaxseed cake, sesame seeds and whey protein concentrate. The mass fraction of protein in the model dry mixture of a hypertonic drink, as well as in its individual components by the Kjeldahl method, the mass fraction of fiber – by the gravimetric method, the mass fraction of lipids – by the extraction-gravimetric method, the mass fraction of moisture – by the thermogravimetric method. The mass fraction of ash in the mixtures was carried out by the method of incineration followed by calcining the mineral residue at a temperature of 450 ... 600 °C. The effective viscosity in the reduced samples of mixtures without and with the addition of stabilizers was determined on a rotational viscometer "Rheotest 2". For the planning of the experiment and data processing, mathematical methods were applied using the Microsoft Office Excel 2003 software package. The chemical composition of individual components and a model dry mixture of a hypertonic drink for the nutrition of athletes, including the content of compounds that have a stabilizing effect on the restored product, has been investigated. It has been proved that the effective viscosity of the reconstructed model mixture in comparison with the effective viscosity of the individual components of the mixture nonaditively increases. The mutual influence of the consistency stabilizers (gum arabic (E 414) and carboxymethylcellulose (E 466)) on the value of the effective viscosity of the reconstituted hypertonic drink was investigated. The developed model mixture of a hypertonic drink is recommended to be used for the development of competitive dry mixtures of hypertonic drinks of plant and animal origin for the nutrition of athletes

Investigation of Moisture Dissipation of Water-Foamed Asphalt and Its Influence on the Viscosity.

Water-foamed asphalt is capable of improving the workability of asphalt mixture. It has been extensively used for its energy-saving and emission-reducing features. Water plays an essential part in improving the workability of water-foamed asphalt mixture. However, there is still lack in profound studies of moisture dissipation of the water-foamed asphalt over time and its influence on workability. In this study, the evolutions of residual water content and rotational viscosity of the water-foamed asphalt with time were respectively measured by the analytical balance and modified rotational viscometer (RV). The atomic force microscopy (AFM) analysis was conducted to discuss the mechanism of viscosity reduction of water-foamed asphalt. The results showed that moisture evaporation is significantly influenced by the foaming water content and ambient temperature, which results in the different stabilizing time of water-foamed asphalt. When water-foamed asphalt was stabilized, the residual water inside the asphalt was less than 0.01% relative to the asphalt mass. The AFM analysis showed that the foaming process changed the distribution of wax in the water-foamed asphalt resulting in reduction of viscosity. The viscosity reduction of asphalt is highly related to the initial foaming water content. After the foaming process, the viscosity keeps stable and is independent of moisture dissipation.

Thermophysical Properties of IoNanofluids Composed of 1-ethyl-3-methylimidazolium Thiocyanate and Carboxyl-functionalized Long Multi-walled Carbon Nanotubes

The concept of IoNanofluids (INFs) as the stable dispersions of nanoparticles in ionic liquids was proposed in 2009 by Nieto de Castro’s group. INFs characterize exciting properties such as improved thermal conductivity, non-volatility, and non-flammability. This work is a continuation of our studies on the morphology and physicochemistry of carbon-based nanomaterials affecting thermal conductivity, viscosity, and density of INFs. We focus on the characterization of dispersions composed of long carboxylic group-functionalized multi-walled carbon nanotubes and 1-ethyl-3-methylimidazolium thiocyanate. The thermal conductivity of INFs was measured using KD2 Pro Thermal Properties Analyzer (Decagon Devices Inc., Pullman, WA, USA). The viscosity was investigated using rotary viscometer LV DV-II+Pro (Brookfield Engineering, Middleboro, MA, USA). The density of INFs was measured using a vibrating tube densimeter Anton Paar DMA 5000 (Graz, Austria). The maximum thermal conductivity enhancement of 22% was observed for INF composed of 1 wt% long carboxylic group-functionalized multi-walled carbon nanotubes.

Evaluation of polymer/bentonite synergy on the properties of aqueous drilling fluids for high-temperature and high-pressure oil wells

The increasing demand for energy sources has led to oil field exploration under inhospitable conditions, where non-aqueous drilling fluids are commonly used due their physical and chemical stability. However, they exhibit a number of environmental constraints and the cuttings produced require expensive treatments before disposal. Aqueous drilling fluids are currently less thermally resistant and generally entail the use of chromium lignosulfonate as clay dispersant, which provides stability to rheological properties and filtration control under high temperature and high pressure (HTHP). This study elucidates the role played by synergic effect of a novel eco-friendly high-performance water-based drilling fluid using bentonite and vinyl polymers (polyvinylpyrrolidone (PVP) and partially hydrolyzed polyacrylamide (PHPA)) as the main constituents. Filtration and rheological properties of the drilling fluids were determined on a HTHP filtration system and on a rotational viscometer, respectively. Systems using high molar mass PVP (HMM PVP) showed higher values for viscosity, gel strength and yield stress, due to promotion of flocculation. On the other hand, dispersed systems were obtained using low molar mass PVP (LMM PVP), through ion-dipole interactions between PVP and clay particles. Dispersed systems provided stable rheological parameters over the entire range of temperature and pressure studied (up to around 120 °C and 3450 kPa). Linear clay swelling tests showed that LMM PVP and water had similar profiles, promoting clay dispersion. Profitable low filtrate volumes (12 mL) were obtained for PVP-based drilling fluids in conditions where non-aqueous fluids are currently applied.