Papers by Keyword: Viscosity

Abstract: The hard capsule market growth is mainly driven by the demand for gelatin capsules made of animals. Plant-based hard capsules, such as hydroxypropyl methylcellulose are currently in high demand for drug delivery, but the manufacturing process is costly with limited reagent supply. As an alternative, carrageenan from seaweed was used as a film-forming agent in this work. Carrageenan film possesses low mechanical strength, thus gum Arabic is incorporated to strengthen the biocomposite film. The films and hard capsules were produced with different concentrations of gum Arabic, ranging from 0 to 2.0 w/v%. The tensile strength and elongation at break were enhanced to 56.8 MPa and 23.7%, respectively. The highest capsule loop strength is 32.5 N, which was achieved at 1.2 w/v% of gum Arabic. All biocomposite films were kept at a moisture content of 13%, which is comparable to gelatin hard capsules. These results demonstrate that gum Arabic can strengthen the carrageenan biocomposite to be an alternative to gelatin hard capsules.

Abstract: C₃A content of cement is of great importance in connection with the fresh and early age mechanical properties of cementitious systems. In this study, the effects of different C₃A content on the static and dynamic yield stress and viscosity values of paste mixtures were examined. Consequently, the use of polycarboxylate ether-based water reducing admixture (PCE) up to a certain dosage affected adversely the rheological characteristics of the mixtures. The dispersion effect, which increased with the increment of the PCE dosage, increased the hydration rate of C₃A by increment its contact with water by dispersing it. Therefore, dynamic yield stress and viscosity were adversely affected by the increment in PCE dosage in high C₃A-containing mixtures, while rheological parameters improved after a certain dosage in low C₃A ones.

Abstract: The thermodynamic, structural, surface and transport properties of PbSn eutectic alloys at 1050 K have been analyzed employing self association model. The model parameters have been evaluated on utilizing the experimental data of free energy of mixing of PbSn liquid alloys at 1050 K. For the validation of the model parameters, the calculated values of the excess free energy of mixing and activity of the components of PbSn liquid alloys have been compared with the experimentally measured data. Further, the estimated model parameters have been used to determine the thermodynamic functions i.e. the free energy of mixing, thermodynamic activity, entropy of mixing and heat (or enthalpy) of mixing, and the structural properties such as the concentration fluctuations and shortrange order parameter. The theoretical and experimental values are compared. A good agreement is observed. Again, the surface properties of PbSn liquid alloys at 1050 K have been investigated using the Butler model in the framework of self association model. The calculated values of surface tension of PbSn liquid alloys at 1050 K are in reasonable agreement with the data available in the literature. The transport properties like the diffusivity and viscosity of PbSn liquid alloys at 1050 K have been theoretically analyzed. For the computation of viscosity, the simple formula developed by Moelwin- Hughes has been used in conjunction with self association model. The present study reveals that PbSn eutectic liquid alloys at 1050 K are segregating in nature. Further, the model parameters are found to depend on temperature.Keywords: Gibbsfree energy; concentration fluctuations; short-range order parameter; surface tension; diffusivity; viscosity

Abstract: The Cu-MOF has outstanding catalytic activity because of its capacity to buffer oxygen. As a result, when added to diesel fuel, this additive reduces nitrogen dioxide emissions while also oxidising hydrocarbon emissions. The current study examines the impact of Cu-MOF nanoparticles on diesel engine efficiency and emissions. The SEM, and XRD methods were utilised to characterise the nanoparticles of Cu-MOF, which were generated by chemical approach. In a two-step method, Cu-MOF was combined with diesel using a conventional ultrasonic shaker in order to get a stable suspension, Extensive experiments using ASTM-standard testing procedures have also examined the impact of nanoparticles on several physicochemical parameters of diesel fuel. For the purpose of examining the impact of nanoparticles on engine efficiency and emissions, a diesel engine load test was conducted. Also included are side-by-side comparisons of fuel qualities with and without additives.

Abstract: Extinguishing fires in ecosystems has features compared to extinguishing fires in residential and industrial buildings, due to the composition and structure of combustible materials, which can form many foci of smoldering and have the ability to re-ignite, have a relatively low fire load compared to man-made ones. All this leads to high costs of water for extinguishing, carrying out operations for additional extinguishing of fires that occur after the main extinguishing and sets special requirements for aqueous extinguishing agents for their extinguishing.The paper analyzes the current state of the availability and trends of development in the world and domestic practice of effective water extinguishing agents and technologies for their use. Possible ways to improve recipes and increase the efficiency of fire extinguishing substances are outlined, taking into account, first of all, the criteria of efficiency, economy and environmental friendliness.It is noted that the main direction of increasing the fire extinguishing capacity of water is to create combined fire extinguishing solutions that can combine several methods of extinguishing in one technological operation: cooling, isolation and inhibition, which, other things being equal, reduces fire extinguishing consumption and extinguishing efficiency. An integrated direction of increasing the fire-extinguishing capacity of water can be considered to increase the coefficient of active use of water by reducing the surface tension of the fire-extinguishing solution, increasing the wettability and viscosity of water by introducing appropriate additives, obtaining optimal droplet dispersion.

Abstract: To overcome the inlet temperature uncertainties during an in-line thermo-rheological characterization and to further apply a differential convection method for an injection molding process, a concept of device designing is proposed in this work. An analytical and numerical investigation proves that the proposed concept can provide information on the viscosity of the material via thermal measurements, despite a poorly known inlet temperature.

Abstract: A two-phase flow is the simplest form of multi-phase flow. Two-phase flow has basic parameters, including flow behavior, flow pattern, void fraction, pressure gradient, or pressure drop. The development and application of fluid flow in small channels (mini and micro) are in the Micro Electromechanical System (MEMS). In general, the application of two-phase flow can be found in various applications in the industrial world, such as boilers, cores, and steam generators in nuclear reactors, petroleum transportation, electronic cooling, and different other types of chemical reactors. One of the most common challenges is void fractions and flow patterns in horizontal and vertical pipelines. The purpose of this study was to find out the significant difference in the characteristic value of fundamental parameters, primarily void fractions and flow patterns that occur in capillary pipes with a slope of 15o to horizontal. The fraction value and shape of this flow pattern are essential because it determines the pressure drop value, which means determining the level of danger that can occur if the pressure drop value reaches the extreme value. The fluid used a mixture of air-water and glycerin with 0, 10, 20, and 30% concentrations. To determine the void fraction is used digital image processing method with MATLAB R2014a application. A 1200 fps high-speed camera and 640 x 480-pixel resolution are used for video shooting. The experiment was conducted at superficial gas (JG) velocities of 0.025 - 66.3 m/s and superficial fluid velocities (JG) intervals of 0.033 – 4.935 m/s. The experiment results showed a significant difference between the void fraction value for the bubbly flow pattern and the churn flow pattern, which has not been widely discussed in previous studies. The analysis concluded that the higher the velocity of superficial gases, the void fraction value increases. This increase in the void fraction is why there is a significant change in flow patterns from bubble flow patterns to churn. In addition, it was also found that the increased viscosity of the fluid significantly affected changes in flow patterns, incredibly bubbly and plug, but its velocity decreased. It is also the result that the higher homogeneous void fraction (β) value affects the increase in the length of bubbly flow patterns and plugs.

Abstract: Based on the flow equation of the ferromagnetic liquid lubricant for the “thin layer”, the continuity equation and the Darcy equation describing the flow of a lubricant in a porous body, the paper presents an accurate self-similar solution of the V-shaped sliding support with a porous coating of the base ring surface taking into account the rheological properties of the lubricant with ferromagnetic properties when the working gap is partially filled at the laminar flow mode. Analytical dependencies were obtained for the field of velocities and pressures in lubricating and porous layers. Besides, the main working characteristics of the studied friction pair are determined: bearing capacity and friction force. The paper provides the assessment of the influence of parameters characterizing ferromagnetic rheological properties, length of the loaded region of the Hartmann number and parameter characterizing the presence of electromagnetic field on the bearing capacity and friction force.

Abstract: This paper presents the feasibility of developing an electromechanical in-situ viscosity measurement technique by analyzing the detectability of small variations in the viscosity of different shear thickening fluids and their different compositions. Shear thickening fluid (STF) is a kind of non-Newtonian fluid showing an increasing viscosity profile under loading. STF is utilized in several applications to take advantage of its tunable rheology. However, process control in different STF applications requires rheological measurements, which cause a costly investment and long-lasting labor. Therefore, one of the most commonly used in-situ structural health monitoring techniques, electromechanical impedance (EMI), was used in this study. In order to actuate the medium electromechanically, a piezoelectric wafer active sensor (PWAS) was used. The variations in the spectral response of PWAS resonator that can be submerged into shear thickening fluid are analyzed by the root mean square deviation, mean absolute percentage deviation and correlation coefficient deviation. According to the results, EMI metrics provide good correlations with the rheological parameters of STF and thereby enabling quick and low-cost rheological control for STF applications such as vibration dampers or stiffness control systems.

Abstract: 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.