Rotational Viscometer Research Articles

ВЛИЯНИЕ ОЛИВКОВОГО МАСЛА НА РЕОЛОГИЧЕСКИЕ ХАРАКТЕРИСТИКИ МАЙОНЕЗА

Rheological properties are an important parameter for the quality of mayonnaise. This article in-vestigated the effect of adding olive oil on the rheological properties and color change of mayon-naise. The influence of the storage time of mayonnaise in the refrigerator on the change in rheo-logical properties was also investigated. Mayonnaise was prepared on a laboratory rotary disperser of the Turrex type with a rotor / stator system with a rotor speed range (10000-30000 rpm) at room temperature. Mayonnaise contains 75% oil with varying proportions of sunflower oil and ol-ive oil. Rheological measurements were carried out on a Brookfield rotary viscometer with con-centric cylinders at temperatures of 10 ° C and 25 ° C. Based on the data obtained, the consistency coefficient of the rheological parameters, the flow index and the apparent viscosity were calculat-ed. The color of the test samples of mayonnaise was measured using a three-color colorimeter. All mayonnaise samples exhibit non-Newtonian pseudoplastic flow with a defined thixotropic loop area. Research results have shown that the addition of olive oil affects the rheological properties and color of mayonnaise. The addition of olive oil to the oil phase of mayonnaise reduces shear stress, apparent viscosity, consistency factor and color change at 25 ° C and 10 ° C. When storing mayonnaise in the refrigerator for 15 days, the rheological parameters change. Sunflower oil may-onnaise (75%) has the highest value (L), which means it is measured instrumentally as the bright-est.

Optimization of the Composition of the Ointment with Phytoecdysteroids Serpisten

Introduction. Phytoecdysteroids are a group of natural compounds related in structure and physiological effect to ecdysone - the hormone of insect molting. Phytoecdisteroids have been found to have an antiflammatory effect, which suggests that they have regenerative properties. The development of a soft dosage form containing phytoecdysteroids is of interest.Aim. Improvement of ointment compositions with phytoecdysteroids by optimizing the composition of base adjuvants.Materials and methods. As an active substance was used Serpisten, containing the sum of phytoecdysteroids, the main of which is 20-hydroxyecdysone and obtained from the leaves of Serratulaecoronatae. Raw materials "Serpukhi crowned leaves" were registered by the Federal Service Rospotrebnadzor (Moscow) for the production of dietary supplements (Gr. No. 77.99.23.3.U.1922.3.08), substance Serpisten (Gr. No. 77.99.23.3.U.1923.3.08. TU 9369-002-15092611-2008). In work were used the excipients allowed for medical use: the monoglycerides distilled, T-2 emulsifier, tween 80, sodium - carboxymethylcellulose, polyvinyl alcohol, hydroxide of aluminum, aero forces, vaseline, oil vaseline, sunflower oil. Optimization of ointment auxiliary substances composition was carried out according to the Greco-Latin 4 x 4 square plan with repeated observations. The concentration of hydrogen ions from aqueous ointments was evaluated as process parameters; acid number; release of serpistene from ointment into agar gel, thermal stability of structure. The structural and mechanical properties of the optimal composition ointment composition were determined on a RV type REOTEST 2.1 rotary viscometer (RHEOTEST Medingen GmbH, Germany). Ointment Bepanten (GP Grenzach Produktions GmbH, Germany) was used as a comparison preparation.Results and discussion. During optimization of the composition of the diphilic ointment with serpistene, was found that the ratio of hydrophobic and hydrophilic phases should be 1 : 1, it is advisable to introduce into the ointment base an emulsifier T-2, aerosil and a mixture of vaseline and vaseline oil in the proportion of 1 : 1. As a result of the carried out studies on the optimization of ointment compositions, the following serpisten ointment composition is proposed: serpisten - 0.02; emulsifier T-2 - 3.0; aerosil - 3.0; vaseline - 23.0; vaseline oil - 23.0; ethyl alcohol 40 % - 1 ml; purified water to 100.0. Comparative analysis of effective viscosity showed that the proposed composition is as close as possible to the Bepanten ointment.Conclusion. A set of technological studies was carried out to optimize the composition of the Serpisten, 0.02 °% ointment on a diphilic basis. The developed composition and technology made it possible to obtain a composition with thermal stability, bring the hydrogen index of the ointment closer to the pH of human skin and achieve the parameters included in the rheological optimum for dermatological ointments (0.34-108 Pa • s).

FORMULATION, DEVELOPMENT AND IN-VITRO EVALUATION OF A BAMBUTEROL HYDROCHLORIDE IN-SITU GELLING SYSTEM FOR NASAL DELIVERY

The goal of this project was to design, develop, and in-vitro evaluation of an in-situ gelling system for nasal administration of Bambuterol hydrochloride. All of the batches were prepared using different concentration of pectin, given different doses of simulated nasal electrolyte solution (SNES) i.e., 0.1 ml to 2.0 ml. All batches and formulation batches with a composition of 0.8 percent low methoxyl pectin underwent an in vitro gelation testing. The pH of the formulation reduced as the pectin content increased due to the acidic nature of pectin. The drug concentration was greater than 95%, and the apparent viscosity of the sol and gel was measured using a Brookfield viscometer (Rotational Viscometer Model). When the concentration of gelling polymer was increased from 0.5 to 1.0 percent, the gel strength (SOL) increased from 0.6 to 1 sec. The gel strength (GEL) increased from 0.7 to 13 seconds as a result of gelation. In vitro drug release experiments showed that the resulting formulations could release the medication for up to 10 hours when Higuchi kinetics were applied to all of them. The gels were stable across the six-month test period, according to the accelerated stability studies. There was no drug-polymer interaction, according to DSC and XRD analyses. Based on these findings, in situ nasal gel could be a possible drug delivery strategy for bambuterol hydrochloride, allowing it to bypass first-pass metabolism and hence improve bioavailability.

FORMULATION, DEVELOPMENT AND IN-VITRO EVALUATION OF A BAMBUTEROL HYDROCHLORIDE IN-SITU GELLING SYSTEM FOR NASAL DELIVERY

The goal of this project was to design, develop, and in-vitro evaluation of an in-situ gelling system for nasal administration of Bambuterol hydrochloride. All of the batches were prepared using different concentration of pectin, given different doses of simulated nasal electrolyte solution (SNES) i.e., 0.1 ml to 2.0 ml. All batches and formulation batches with a composition of 0.8 percent low methoxyl pectin underwent an in vitro gelation testing. The pH of the formulation reduced as the pectin content increased due to the acidic nature of pectin. The drug concentration was greater than 95%, and the apparent viscosity of the sol and gel was measured using a Brookfield viscometer (Rotational Viscometer Model). When the concentration of gelling polymer was increased from 0.5 to 1.0 percent, the gel strength (SOL) increased from 0.6 to 1 sec. The gel strength (GEL) increased from 0.7 to 13 seconds as a result of gelation. In vitro drug release experiments showed that the resulting formulations could release the medication for up to 10 hours when Higuchi kinetics were applied to all of them. The gels were stable across the six-month test period, according to the accelerated stability studies. There was no drug-polymer interaction, according to DSC and XRD analyses. Based on these findings, in situ nasal gel could be a possible drug delivery strategy for bambuterol hydrochloride, allowing it to bypass first-pass metabolism and hence improve bioavailability.

The influence of flushing fluids rheological properties on rock breaking efficiency when drilling wells by pellet impact drilling method

Introduction. Pellet impact drilling method which is basically the destruction of rocks by blows of pellets, has been studied by many researchers. Despite this, the rheological properties of the drilling fluid used in pellet impact drilling have not been investigated yet. All bench and field tests were carried out using service water. The use of a drilling fluid with a higher viscosity than water has the potential to expand the field of application of pellet impact drilling. Therefore, it becomes urgent to study the effectiveness of destruction of rocks when using flushing fluids with different rheological parameters. Objective of this research is to investigate the efficiency of rock destruction in the process of drilling wells using the pellet impact drilling method at various rheological parameters of the drilling fluid. Methods of research. A scaled laboratory bench was used in the research. The bench was a closed system of circulation of the drilling fluid (drilling mud). The solution was prepared separately on a high-speed mixer. The main part of the bench was a scaled pellet drill bit located in a simulated well. After the experiment, the destructed rock volume and the rheological parameters of the flushing fluid were measured. A series of experiments was carried out with a gradual increase in the viscosity of the flushing fluid. A biopolymer (xanthan gum) in various concentrations was used to thicken the flushing fluid. Drilling fluid rheological parameters were measured using an eight-speed rotary viscometer and a Marsh funnel. Results. For the first time, a relationship has been established between the efficiency of rock destruction during pellet impact drilling and the rheological parameters of the drilling fluid used. It was found that with an increase in the concentration of biopolymer and an increase in viscosity, at first, there was a significant increase in the volume of drilled rock per unit time, and with a further increase in concentration, a gradual decrease occurs. Conclusions. The results obtained expand the field of application of pellet impact drilling. The reliability of predicting the drilling speed is improved depending on changes in the properties of the drilling fluid. Based on the results, recommendations were made for the selection of the optimal parameters of the drilling fluid, depending on the drilling conditions.

Rheological and morphological evaluation of nanoclay modified asphalt binder

The performance characteristics of asphalt can be improved by using nanomaterials. In this study, the effect of nanoclay as an additive on the performance features of the asphalt binder was assessed; this nanoclay was produced from montmorillonite modified with organic compounds and hexadecyltrimethylammonium bromide additive. The structural properties of the additive were investigated using X-ray diffraction analysis. The morphological structure and modification mechanism of modified asphalt binders formed by adding the nanoclay to the asphalt were determined by two analyses namely scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. In addition, differential scanning calorimetry analysis was used in order to investigate the thermal properties of the additive and modified asphalt binders. The rheological and physical properties of the modified asphalt were measured using penetration, ductility, softening point, dynamic shear rheometer, rotational viscometer, rolling thin film oven test, and pressure-aging vessel. The results indicated that the additive increased the asphalt’s consistency rutting, and short-term aging resistance, and decreased fatigue resistance after long-term aging. In addition, the optimal additive concentration to enhance the performance features of the asphalt binder was found to be 8% based on the experimental data.

Investigation of the Rheological Properties of Ointment Bases as a Justification of the Ointment Composition for Herpes Treatment

Combinatorial drugs are among the leading pharmacotherapeutic agents, including those used for the treatment of herpetic infections, which require complex treatment. We have developed a soft dosage form of ointment, which includes acyclovir and miramistin, which have antimicrobial, anti-inflammatory, and local immunoadjuvant activity. The study aimed to investigate the rheological properties of ointment bases in order to substantiate the composition of a soft dosage form with antiviral effect using the active ingredients miramistin and acyclovir. The object of the study was to determine the heterogeneous and homogeneous composition models of the bases made using a wide range of excipients. Structural and mechanical studies were performed using the "Rheolab QC" rotary viscometer by Anton Paar (Austria) with coaxial cylinders CC27/S-SN29766. The rheological parameters were investigated at a temperature of 25°C±0.5°C. The samples were thermostated using a thermostat MLM U15c. The batch of sample weighing about 15.0±0.5 g was placed in the container of an external stationary cylinder. The required temperature of the experiment was set and the thermostating time was 20 min. The device is equipped with RheoPlus 32 V3.62 software. The rheological behavior of the model compositions was analyzed in terms of indicators, such as yield strength, hysteresis square, coefficients of dynamic flow, and mechanical stability. It was found that all samples have a non-Newtonian pseudoplastic type of flow. The model of spreading optimums was used to evaluate consumer properties. According to the rheological parameters, it is advisable to use the sample based on paraffin and vaseline oil for further research. The findings from this study will be relevant in the development of the soft dosage form for the treatment of herpes viral diseases.

The choice of materials for the production of new reference materials of liquid viscosity certified in the interval of allowed temperature values from -40 °C to -5 °C

The article presents the results of research aimed at the selection of materials for the production of new reference materials intendedfor verification, calibration, and testing for type approval of means of measuring the viscosity of liquids, as well as certification of methods for measuring the viscosity of liquid media at temperatures below 0 °C. The developed reference materials are certified in the interval of allowed temperature values from -40 °C to -5 °C. This allows providing a wide range of modern methods for measuring the viscosity of liquids such as glass capillary viscometers, rotational viscometers, rheometers, etc.

Polyphosphoric acid and plasticizer modified asphalt: Rheological properties and modification mechanism

Plasticizers have been proven to be effective in improving the low temperature flexibility of asphalt; however, plasticizer modified asphalts exhibit compromised high temperature stability. In this regard, polyphosphoric acid (PPA) may offer some advantages. This study aims to investigate the conventional properties, rheological behavior, thermal storage stability, and microstructure of plasticizer and PPA (plasticizer/PPA) modified asphalts. The experimental design comprises two plasticizers (dioctyl phthalate (DOP) and trioctyl trimelliate (TOTM)) and four PPA contents (0.5, 1, 1.5, and 2 wt%). The prepared plasticizer/PPA modified asphalts are examined by rotational viscometer, dynamic shear rheometer, bending beam rheometer, thermal storage, and Fourier transform infrared (FTIR) spectroscopy tests. The results show that the high temperature deformation resistance and elastic recovery ability of the plasticizer modified asphalts are effectively improved by the addition of PPA, and the improvement degree is positively correlated to the PPA content. PPA also has a beneficial effect on the low temperature performance of the plasticizer modified asphalts; however, the effect weakens with the PPA content increase. Moreover, the results of Analysis of Variance - Tukey’s HSD analysis show that DOP/PPA and TOTM/PPA modified asphalts have significant difference in high and low temperature performance. The results of the thermal storage tests demonstrate that the plasticizer/PPA modified asphalts have excellent storage ability. The FTIR results show that the plasticizers are physically mixed with base asphalt, whereas there is a chemical reaction between PPA and the plasticizer modified asphalts. In general, the preparation process of plasticizer/PPA modified asphalts is simple and they have good comprehensive performance, which illustrate that combined plasticizer and PPA modification is a promising technology.

Evaluation of zeta potential of calcined clays and time-dependent flowability of blended cements with customized polycarboxylate-based superplasticizers

Workability of cementitious systems is often limited when blending them with calcined clays. The first part of the study compares for the first time results of zeta potential measurements on both, raw/calcined clays in water and synthetic cement pore solution as well as on a Portland limestone cement replaced by 30 wt% of calcined clay. This helps to identify critical parameters that reduce the workability, also over time. The second part evaluates the time-related flow behavior via mini slump test and rotational viscometer and, by using isothermal calorimetry, early hydration kinetics of different calcined common clays with two polycarboxylate-based (PCE) superplasticizers. The results reveal a high negative zeta potential resulting from high kaolinite content. A large specific surface area enhances flocculation and nucleation, while an increasing amount of phyllosilicates and soluble aluminum ions accelerate ettringite formation also with the addition of PCE. Tailor-made PCE, however, can compensate rapid loss in flowability and enable a sufficient workability period without affecting early strength development significantly for most calcined clay blended systems.

Study of the rheological properties of the highly-filled paste-like fuel composition based on oligomeric rubber and dispersed fillers

We present the results of creation of paste-like fuel compositions with a high degree of filling (up to 90 wt.%) and investigation of their rheological properties. The developed composition contained the following components: a polymer matrix (type SNBR-N butadiene rubber) and a mixture of inorganic fillers (preliminarily surface-modified highly disperse potassium chloride, that was microencapsulated by using oligomeric products of polyehtyleneterepthalate glycerolize, and highly dispersed aluminum powder. A surface-active compound (oligomeric polioxypropylene glycol) and plasticizers of different natures were used as additional components, which were introduced in order to increase the degree of filling of the resulting paste-like compositions while maintaining a low level of their viscosity. The dynamic viscosity of the compositions was evaluated in the range of the shear stresses of 1 to 30 kPa and the temperatures of 293 to 323 K by using a rotary viscometer (cone–plane system). The viscosity of the composition which is a mixture of saturated and unsaturated methyl ester fatty acids at the maximum degree of filling (90 wt.%) was at the level of viscosity of the individual binder.

INFLUENCE OF THE COMBINATION OF EMULSIFIERS ON THE PROPERTIES OF RICE GLUTEN-FREE DOUGH AND THE QUALITY OF BREAD

The article investigates the influence of low-fat lecithin, sunflower oil, and dry egg white on the rheological properties and microstructure of gluten-free rice dough and quality indicators of ready-made bread. To determine the effectiveness of the use of these emulsifiers, the bread technology with implementation of enzyme modificated (by amylolytic enzymes) flour starch was used. To assess the rheological state of the dough, its viscoplastic properties (shear stress and effective viscosity of the test systems) were analyzed using a rotary viscometer. The dough microstructure was examined by microscopy. Traditional methods to determine physical and chemical indicators of ready-made bread quality were used. The results showed that the emulsifiers implementation changed the behavior of rice dough, and had the positive effect on the qualitative (specific volume and porosity). It has been found that the use of a combination of emulsifiers from low-fat lecithin, sunflower oil, and dried egg white in rice bread technology in combination with enzymatic modification of flour starch significantly improves the rheological properties and structure of gluten-free dough and provides high indicators of specific volume and porosity of ready-made products.

Development of a Novel Ultrasonic Spectroscopy Method for Estimation of Viscosity Change during Milk Clotting.

Ultrasonic testing is an emerging non-destructive testing technology with high repeatability and precision. Milk is a very complex liquid and the change of its viscosity is a highly relevant property throughout conversion into other dairy products. In the following paper, we propose a novel method for the monitoring of viscosity during enzymatic milk clotting by ultrasonic spectroscopy. An ultrasonic transducer–receiver couple with a 250 kHz nominal frequency was submerged in the samples and an enveloped sweep (“chirp”) signal was applied in a through-transmission mode. Simultaneously, the change in viscosity was measured with a rotational viscometer at a constant shearing speed. The data were analyzed with an algorithm developed by the authors for spectral ultrasonic testing. Estimations yielded a high adjusted R2 (0.963–0.998) and low cross-validated estimation error (RPD: 4.38–14.22), suggesting that the method is suitable for industrial use given the right instrumentation.

Influence of Water-Cement Ratio on Viscosity Variation of Cement Grout in Permeation Grouting

Diffusion radius is an important construction parameter, because it can significantly influence the grouting effectiveness. Theoretical models in predicting diffusion radius have been practiced, but there are still significant discrepancies between theoretical calculations and realistic results in the practical construction. One of the critical reasons for the misprediction is the time-dependent behavior of the cement grout, which is significantly affected by the water-cement ratio (W/C). Therefore, this paper experimentally and numerically studies the influence of W/C on the viscosity variation of the grout and grouting process. Firstly, the apparent viscosity of the cement grout under different W/C is tested by a rotational viscometer in a laboratory experiment. Subsequently, based on the laboratory tests, numerical models are established to investigate the influence of W/C on the diffusion process of cement grout in sand layers. According to the laboratory results, the apparent viscosity of cement grouts decreases with the increase of W/C. Besides, the apparent viscosity increases with time, while the increasing range of apparent viscosity firstly increases and then decreases as W/C increases. Based on the simulated results, when W/C changes from 0.8 to 1.1, the diffusion radius at 60 min experiences a less and less obvious increase under the given grouting pressure for permeation grouting in the sand layer. When W/C is 0.9, the relative error reaches to 37.65% at 60 min, which is slightly lower than that of 0.8. However, when W/C changes from 0.9 to 1.0, the relative error becomes very narrow (21.36%), and this figure is much lower than that of 0.8 or 0.9. The simulation results are verified by field test, and the relative error is 6%, which proves the effectiveness of the analysis. Therefore, the cement permeation model considering viscosity variation of the grout is a reasonable alternative in the real project. At the same time, the time-dependent behavior of cement grouts should be considered, especially when using cement grouts with a low water-cement ratio in the practical engineering.

CHOUX PASTRY SEMI-FINISHED PRODUCTS WITH FILLERS: TECHNOLOGY AND QUALITY

Background. Theproblem of expanding the range of flour products of high nutritional and biological value for healthy nutrition with the use of new types of protein and mineral supplements, products of complex processing of fish and plant raw materials remains relevant. The development of technology of choux pastry products using dry fish and plant semi-finished product (NRVGL) and carrot filler (CF) is proposed. The aim of this article is to study the influence of dry fish and plant semi-finished products on the structural and mechanical properties and quality indicators of choux pastry products, to justify the rational recipe composition and to determine the nutritional value of choux pastry semi-finished products using NRVGL and CF. Materials and methods. The semi-finished fish and plant semi-finished product from hydrolyzed fish heads with wheat bran and flax seed fiber (NRVGL), which is made from dry fish and plant semi-finished products (SRRN) according to the TU U 10.2-40220843-003: 2016; boiled carrot puree with a dry matter content of 10 %; model sys­tems and baked semi-finished products from choux pastryis explored. Organoleptic indicators of baked products were evaluated according to DSTU 4683: 2006 [12]. Viscosity was measured on a rotary viscometer VPN-0.2, the total mois­ture content was determined by drying to constant weight, ash - by burning a sample with calcination of the mineral residue in a muffle furnace, fat –by extraction-weight method, protein –by modified Kieldal method according to GOST 7636–85, mass fraction of car­bohydrates –by the calculation method, mineral composition –on the atomic absorption spectrophotometer AAS-30. Results. The influence of dry and hydrated fish and plant semi-finished products on the structural and mechanical, functional technological and organoleptic properties of model systems from choux pastrydough has been established by experimental methods. It was found that the use of hydrated in milk NRVGL during brewing flour improves the techno­logical properties of choux pastry dough. The influence of CF on the structure of choux pastrydough and the quality of baked semi-finished products with NRVGL has been studied. The mechanism of action of these additives is studied, the stage of their intro­duction and rational mass fraction in the choux pastrysystem are substantiated. It is established that when using 20 % NRVGL from flour weight and 10 % CF from the mass of egg mix during the brewing of flour, the necessary plasticization of the dough structure is achieved. At the same time there is an improvement of organoleptic characteristics and quality indicators of products. Custard semi-finished products contain­ning NRVGL and CF contain 15.1 % less fat, their nutrient composition improves, in particular, the content of Calcium, Phosphorus, fiber, easily hydrolyzed polysaccharides and soluble pectin substances increases compared to the control. Conclusion. The complex of experimental researches enabled the development of the recipe composition and technology of production of baked choux pastrysemi-finished products with the use of dry fish and plant semi-finished product NRVGL and carrot filler. Choux pastrysemi-finished product is recommended for using in the production of culinary products with improved nutrient composition –profiteroles, filled with pate and fish paste, which are served as cold or banquet snacks.

Viscosity changes and gel formation during storage of liquid micellar casein concentrates

Our objective was to determine the effects of temperature and protein concentration on viscosity increase and gelation of liquid micellar casein concentrate (MCC) at protein concentrations from 6 to 20% during refrigerated storage. Skim milk (∼350 kg) was pasteurized (72°C for 16 s) and filtered through a ceramic microfiltration system to make MCC and replicated 3 times. The liquid MCC was immediately concentrated via a plate ultrafiltration system to 18% protein (wt/wt). The MCC was then diluted to various protein concentrations (6-18%, wt/wt). The highest protein concentrations of MCC formed gels almost immediately on cooling to 4°C, whereas lower concentrations of MCC were viscous liquids. Apparent viscosity (AV) determination using a rotational viscometer, gel strength using a compression test, and protein analysis of supernatants from ultracentrifugation by the Kjeldahl method were performed. The AV data were collected from MCC (6.54, 8.75, 10.66, and 13.21% protein) at 4, 20, and 37°C, and compression force test data were collected for MCC (15.6, 17.9, and 20.3% protein) over a period of 2-wk storage at 4°C. The maximum compressive load was compared at each time point to determine the changes in gel strength over time. Supernatants from MCC of 6.96 and 11.61% protein were collected after ultracentrifugation (100,605 × g for 2 h at 4, 20, and 37°C) and the nitrogen distributions (total, noncasein, casein, and nonprotein nitrogen) were determined. The protein and casein as a percent of true protein concentration in the liquid phase around casein micelles in MCC increased with increasing total MCC protein concentration and with decreasing temperature. Casein as a percent of true protein at 4°C in the liquid phase around casein micelles increased from about 16% for skim milk to about 78% for an MCC containing 11.6% protein. This increase was larger than expected, and this may promote increased viscosity. The AV of MCC solutions in the range of 6 to 13% casein increased with increasing casein concentration and decreasing temperature. We observed a temperature by protein concentration interaction, with AV increasing more rapidly with decreasing temperature at high protein concentration. The increase in AV with decreasing temperature may be due to the increase in protein concentration in the aqueous phase around the casein micelles. The MCC containing about 16 and 18% casein gelled upon cooling to form a gel that was likely a particle jamming gel. These gels increased in strength over 10 d of storage at 4°C, likely due either to the migration of casein (CN) out of the micelles and interaction of the nonmicellar CN to form a network that further strengthened the random loose jamming gel structure or to a gradual increase in voluminosity of the casein micelles during storage at 4°C.

Investigation of Non-Linear Rheological Characteristics of Barite-Free Drilling Fluids

Drilling fluids play an important role in the construction of oil and gas wells. Furthermore, drilling of oil and gas wells at offshore fields is an even more complex task that requires application of specialized drilling muds, which are non-Newtonian and complex fluids. With regard to fluid properties, it is necessary to manage the equivalent circulation density because its high values can lead to fracture in the formation, loss of circulation and wellbore instability. Thus, rheology of the used drilling mud has a significant impact on the equivalent circulation density. The aim of the present research is to develop compositions of drilling muds with a low solids load based on salts of formate acid and improve their rheological parameters for wells with a narrow drilling fluid density range. Partially hydrolyzed polyacrylamide of different molecular weights was proposed as a replacement for hydrolized polyacrylamide. The experiment was conducted on a Fann rotary viscometer. The article presents experimentally obtained data of indicators such as plastic viscosity, yield point, nonlinearity index and consistency coefficient. Experimental data were analyzed by the method of approximation. Analysis is performed in order to determine the most suitable rheological model, which describes the investigated fluids’ flow with the least error.

Development of workability based approach for assessment of production temperatures of warm mix asphalt mixtures

Warm Mix Asphalt (WMA) is a sustainable technology that allows asphalt mixtures to be produced and compacted at lower temperatures in comparison to hot mix asphalt (HMA). Several concerns have been raised regarding the determination of mixing and compaction temperatures (also termed as production temperatures) for WMA mixtures. An attempt has been made through this study to comprehensively understand and explore the procedures for appropriate measurement of production temperatures of WMA mixtures. One base asphalt binder and five different warm mix additives (with varying dosages) were used in this direction. Rotational Viscometer (RV) and Dynamic Shear Rheometer (DSR) were employed to analyse the unmodified and warm mix modified asphalt binders. A workability prototype was fabricated, and a workability-based approach was proposed to systematically assess the production temperatures. Additionally, coating ability and compactability tests were carried out to validate the obtained mixing and compaction temperatures, respectively.It was found that production temperatures determined by testing asphalt binders through RV and DSR do not yield appropriate results for warm mix modified asphalt binders. Workability analysis showed that WMA mixtures, regardless of dosage and type, exhibit improved workability in comparison to the conventional HMA mixture, at all the test temperatures. Taking HMA mixture as a reference, the maximum reduction in mixing and compaction temperatures with the inclusion of WMA technologies was found to be 22 °C and 37 °C, respectively. In addition, WMA mixtures produced and compacted at reduced temperatures exhibited similar/better coating and consistent density in comparison to the conventional HMA mixture. It is concluded that the proposed workability approach for the evaluation of production temperatures of WMA mixtures is feasible and can be adopted. The output of the present study also appreciates the use of WMA for sustainable pavement construction.

The Influence of Polyvinyl Alcohol Solutions Concentration on the Rheological and Elastic and Strength Properties of Film Materials

During the study, solutions and film materials have been obtained with a concentration of polyvinyl alcohol in distilled water in the range of 1 ... 15 %. The rheological properties of the resulting solutions have been studied by rotational viscometer HAAKE VT 550 at a temperature of 20° C and 80° C. Film materials have been molded by cast film method. The elastic and strength properties of the film materials samples have been determined with a Gotech 7000M universal testing machine. It has been shown that with an increase in polyvinyl alcohol concentration, there has been a decrease in the elastic and strength properties. Samples of film material with 1% and 5% polyvinyl alcohol content completely dissolve in water in 10 and 20 minutes, respectively.

Study on dynamic and static structural build-up of fresh cement paste with limestone powder based on structural kinetics model

The structural build-up of fresh cement-based materials is of great significance to the early forming and later performance. A structural kinetics model (SKM) used to indicate the structural build-up was developed by combining a kinetic equation described by structural parameter (λ) and a relationship between yield stress (τy) and λ in the paper. SKM transforms the structuration rate (Athix) in linear Roussel model and the characteristic time (tc) in non-linear Perrot model into more specific indicators such as initial solid volume fraction (ϕ0), rate of hydration during induction period (α̇ind), and shear rate (γ.). The yield stress (τy) obtained by RHEOLAB QC rotary viscometer was explored the dynamic and static structural build-up of fresh cement paste. The yield stress of fresh cement paste (W/C = 0.4) exhibits a quasilinear pattern with rate of 0.42 Pa/s for 210 min of mixing, with rate of 0.88 Pa/s for 100 min of resting after 4 min of mixing. The static yield stress of fresh cement paste evolves from linear to non-linear patterns within 100 min of resting after beyond 30 min of mixing. The fitting results show that SKM can well fit the evolution of yield stress including linear and nonlinear phases. Comparing with the dynamic structural build-up, the effect of limestone powder on the static structural build-up of cement paste is more obvious. When the mixing process is longer than 60 min, the content of limestone powder less than 20 wt% is beneficial to the structural build-up of fresh paste. Additionally, a declined rate of cement hydration in the induction period with increasing mixing time indicates that the rising yield stress, in this case, cannot be attributed entirely to the contribution of hydration to structural build-up.