Papers by Keyword: Surface Tension

Abstract: The article deals with the mechanism of interaction of super-plasticizers and hyper-plasticizers additives with mixing water, the formation of micelles and organized water. The interaction of mixing water and additives with Portland cement particles, surface tension, specific surface of bindings and their significance in setting and hardening processes are considered. It is shown that a local effect plays a decisive role in micro-heterogeneous organized media associated with the dissolution of hydrophilic and hydrophobic molecules in the volume of the micellar system or the receptor molecule cavity. In this case, the change of dissolved substances properties is due to the change of the medium state only in the microenvironment, and not in the whole solvent - water. The surface energy of the dispersed material and the degree of dispersion are very important for the concrete technology. All dispersed materials of the system are unstable. The aggregation of powder particles of building materials spontaneously takes place in highly dispersed powders and if such powders get pressure, it is possible to get a hard and strong material without water and additives.

Abstract: The composition of mineral wool was selected for the research, based on the chemical composition of the raw materials, the determination of the acidity module to obtain the thermal insulation material with the best characteristics and the lowest cost of the production of basalt mineral wool. The paper deals with compositions of raw materials and selection chemical compositions of charges for production of basalt mineral wool, and the experiments of welded samples were made and tested for viscosity, surface tension, chemical analysis and x-ray analysis.

Abstract: We chose two glass compositions suitable for the synthesis of foam glass. The influence of additive at the amorphous silica charge in the amount of 20% and 100%, a by-product in the leaching of serpentinite, was studied. By the method of stable temperature drop, the crystallization ability of the welded glass compositions was studied. The surface tension was measured by the sessile drop method.

Abstract: The results of the investigation of new surfactant additives for concrete are given in the article. Their values of density and surface tension are determined at temperatures of 10-50 oC in steps of 10 degrees. Dependences of the surface tension on temperature, the dependence of density on temperature, the dependence of the surface tension on the density for six types of additives for concrete are obtained.

Abstract: The article is devoted to the effect of surface-active substances on the interface of phases. The hydrophobization and hydrophilization of surfactants, their role in building composites are considered. The dependence of the surface tension on temperature, the dependence of the density on the temperature of various kinds of additives for concrete, is given.

Abstract: Analytical prediction of capillary pattern collapse is done by balancing the capillary forcesdue to the curved liquid interface with the elastic forces due to the bending of the structure. This paperintroduces a more realistic model where there is an array of repeating lines and spaces, and compares itto the traditional model of two single lines with liquid-filled space in between. This paper also includesthe influence of a non-vertical sidewall angle, and its effect on the overall elastic force. Results showthat the repeating structures and non-vertical sidewall angles both predict a higher critical height beforecollapse occurs compared to the traditional model.

Abstract: The current work involves the measurement of thermo physical properties of commercial available blue dyed Kerosene, examining their behavior with alumina nano particles. It was found that the particle size of alumina ranged from 32 nm – 50 nm from the scanning electron microscope (SEM) analysis. Low volume concentrations (0.01%, 0.05% and 0.10% by volume) were used for this study. The parameters studied were thermal conductivity, viscosity and surface tension. The study was conducted at different range of temperatures (25-60 °C). Oleic acid was added as surfactant and the nanofluid was found to be stable for more than a week. The conductivity of the blue dyed kerosene alumina nanofluid increased with an increase in temperature and volume concentration. An enhancement of 9.33 % in conductivity was observed with a temperature of 60 °C for a volume concentration of 0.10%. The viscosity of the blue dyed kerosene decreased with increase in temperature. An average enhancement of 20% in viscosity of blue dyed kerosene alumina nanoparticles has been noted for a volume concentration of 0.10% as compared to the base kerosene. The surface tension of the kerosene alumina nanofluid decreased with an increase in temperature and decrease in concentration. An enhancement of 7.9 % in surface tension has been noted for volume concentration of 0.1% as compared to base kerosene at same temperature. The effect of temperature on thermo physical properties was determined by a linear decrease in surface tension as the temperature was raised. The results provide a strong proof that the addition of nano particles intensified the thermo physical properties to a considerable rate.

Abstract: Rheological properties of liquid metals are difficult to investigate experimentally because of the extreme border conditions to consider. One difficulty is related to the low viscosity of liquid metals. Surface tension effects can cause forces that can be considerably higher than the viscous forces in the liquid metals. Evaluating the experimental data without considering these effects leads to an apparent shear thinning behavior of the material. In the present study, experiments were performed by means of a Searle rheometer changing the dimension of the measuring system with metals of high surface tension, as mercury and tin. It became evident that surface tension plays a significant role in the effects that falsify measurements at low shear rate. Conclusions can be drawn to what extent measurements of semi-solid metals are affected.

Abstract: Due to the good performance of thermal conductivity, nanofluids are regarded as a new type of heat transfer working medium, which have huge potential value. The addition of nanoparticles makes nanofluids exhibit different thermal properties from the base fluids. In this experiment, the maximum bubble pressure method was adopted to measure the surface tension of Al₂O₃-H₂O nanofluids whose nanoparticle sizes are 10 nm and 20 nm with four different volume fractions (1%, 1.5%, 2% and 1.5%), and 50 nm and 100 nm with the volume fraction of 2.5%. The temperatures of nanofluids are within the scope of 18 °C to 30 °C. The surface tension ratio (the ratio of surface tension value of nanofluids to its base fluids) is also calculated at different temperature points. Results show that the surface tension of nanofluids decreases with the elevation of temperature and decreases with the increase of volume fraction. For different temperatures and particle sizes of nanofluids, there exists a corresponding critical concentration value. Only reaching the value, the addition of nanoparticles can reduce the surface tension of the base fluids.

Abstract: A series of MDI-50 based non-ionic waterborne polyurethane dispersions (MDI-NPUD) were prepared by the mixing of 2,4’-diphenylmethane diisocianate (2,4’-MDI) and 4,4’-MDI (MDI-50) which reacted with hydroxylated tung oil (HTO) and polyethylene glycol-800 (PEG-800), Fourier Transform Infrared Spectroscopy (FTIR) and Proton-Nuclear Magnetic Resonance (¹H-NMR) were used to characterize and analyze their molecular structures. The results indicated that MDI-50 and HTO were introduced as hard segment while PEG acted as soft segment. The surface tension, Hydrophile-Lipophile Balance (HLB) and stability were investigated. All MDI-NPUDs had much lower surface tension than the dicyclohexyl methane diisocyanate (HMDI) based NPUD (HMDI-NPUD). By changing the feed ratio of MDI-NPUD, the properties of MDI-NPUD could be controlled