High-melting Components Research Articles

Rheological and thermal properties of reinforced monoglyceride-carnauba wax oleogels.

Oleogels can be used in the food industry to reduce the consumption of solid fat in the human diet and diminish some of the industrial-technological issues of using oil instead of fat. Regarding the structural weakness of neat monoglyceride oleogel and the waxy mouthfeel of pure carnauba wax oleogel, as a result of the high melting and crystallization points, the present study aimed to diminish these defects. Carnauba wax (CBW) was used as a co-gelator with distilled monoglyceride (DMG) at different weight ratios (100:0, 85:15, 70:30, 55:45, 40:60, and 0:100) (DMG: CBW) and two total gelator concentrations (50 and 100 g kg-1 ) to improve the DMG oleogel characteristics. The addition of CBW strengthened the DMG network and decreased the polymorphic transition. Thermal analysis showed just co-crystallization at the 85:15 ratio, whereas, in the other combinations, high melting components of CBW crystalized at first. As a result of the crystal homogeneity and long-time development, the oleogel properties improved at the 85:15 ratio. The low concentration of CBW and the formation of the eutectic system were efficient in the waxy mouthfeel reduction of oleogel at the 85:15 ratio in food applications. The DMG/CBW oleogel at the 85:15 ratio, with better structural and sensorial properties than DMG and CBW oleogels, respectively, has the potential for use instead of fat in food formulations. © 2023 Society of Chemical Industry.

Improving the quality of fuel through the use of forced gas boiling in a vacuum

Basic physical processes proceeding in hydrocarbon fuels during operation are the following: evaporation, stratification, contamination with impurities (gaseous, liquid, and mechanical), and settling of high-melting components during cooling, as well as the mixing of hydrocarbon fuels of various groups and grades in tanks and hauling equipment as well as during pipeline transportation. The fuel quality changes the most when products that differ significantly in their physical and chemical properties are mixed. The principle of the technology for adjusting the fractional composition of the fuel proposed in the article is as follows: a mixture of petroleum products is bubbled with gas (air, nitrogen), while the free volume is continuously pumped out by a vacuum system, a vacuum close to saturated is maintained in the technological tank, the vapor pressure of the more volatile component of the liquid mixture. The article assesses the possibility of using this technology for separating a mixture, derives a formula for determining the mass of a highly volatile liquid separated from a mixture, and gives recommendations on the technological parameters of improving the quality of fuel in terms of fractional composition by the method of forced gas boiling (PGV) in a vacuum and presents a theoretical justification of the proposed technology.

Mechanisms of structural-phase transformations during crystallization of solder melt under conditions of magnetic-dynamic influences for carbide tools

The processes of melt formation were studied by methods of optical and electron scanning microscopy. These processes occur during induction brazing of a hard alloy to a steel holder and contact interaction of low-melting (copper-zinc system alloy) and refractory (iron-nickel) components of the solders. It is shown that the effect of a thermal and magnetic-dynamic high-frequency electromagnetic field on the components of the composite solder is how a high-strength solder joint is formed. The structure is forming by disperse hardening mechanism. The research of the contact interaction process for low-melting and high-melting components of solders during the soldering process of the tool showed that the formation of solder in brazed seams occurs through a number of stages and this does not lead to the formation of microstructures that are characteristic of alloys based on copper-iron-phosphorus, copper-zinc-nickel and copper-zinc-iron. Thus, the use of composite solders can reduce the soldering temperature by 40-50 K and increase the concentration of alloying species in the solder and change its structure. These advantages of composite solders reduce the thermal impact on contact materials, increase the strength of the weld and allow you to control the thickness of the brazed weld, and this is important when soldering hard alloys of WC-TiC (TaC) systems. High initial dissolution rates of nickel particles in the copper-zinc melt and the solubility of copper, zinc in nickel lead to the formation in the melt of quasi-liquid particles of the nickel alloy. When the melt is cooled, particles other than the surrounding alloy composition are formed. They are morphologically related to the grain structure of the solder. The formed alloy (solder) has the structure of a composite material in which the metal particles are enriched in nickel, and have the role of a reinforcing element.

Storage stability of proteins in a liquid-based formulation: Liquid vs. solid self-emulsifying drug delivery.

The objective of the present study was the development of self-emulsifying drug delivery systems (SEDDS) for oral delivery of therapeutic proteins providing storage stability. Horseradish peroxidase (HRP) serving as model protein was ion paired with docusate and incorporated into three liquid and three solid SEDDS formulations. Storage stability of HRP was determined over three weeks by quantifying its enzymatic activity. Generally, HRP maintained 78% of its initial enzymatic activity after complexation and loading into SEDDS. Having been incorporated in liquid SEDDS the protein showed limited stability and precipitated within a few hours. In contrast, in all solid SEDDS comprising of hard fats such as Witepsol W45 and solid surfactants such as Gelucire 44/14 and 48/16 as solidifying agents HRP was successfully stabilized. No decrease in HRP activity could be observed over the entire observation period. Solid SEDDS based on high-melting components can provide storage stability of incorporated proteins, whereas liquid SEDDS cannot.

Интенсификация процесса получения базовых основ как основных компонентов низкозастывающих смазочных материалов

Variants of the intensification of the solvent dewaxing process, which increase the yield of base oils, are described. One of the promising ways to improve the technical and economic indicators of the dewaxing process is the use of modifying additives. The work shows that the introduction of a polymer additive requires a decrease in the filtration rate and, accordingly, an increase in the performance of the dewaxing unit. This results in a petrolatum with a reduced oil content, which is a qualifying factor for the production of high-melting ceresins, protective-wax components, and lubricants for various purposes.

Electrodeposition of iron–molybdenum–tungsten coatings from citrate electrolytes

Specific features of the electrodeposition of iron–molybdenum–tungsten coatings from citrate electrolytes based on iron(III) sulfate in the dc mode and with a unipolar pulsed current were studied. It was shown that varying the relative concentrations of salts of alloy-forming metals and the solution pH makes it possible to obtain lustrous compact coatings with low porosity and various contents of high-melting components. The effect of temperature on the coating composition and current efficiency was examined. The current density ranges providing high electrolysis efficiency were found and it was demonstrated that using a pulsed current favors formation of more compositionally homogeneous surface layers at a smaller amount of adsorbed nonmetallic impurities in the coatings. The iron–molybdenum–tungsten coatings are X-ray-amorphous and have better physicomechanical properties and corrosion resistance as compared with the base, which makes it possible to recommend these coatings for application in techniques for surface reinforcement and restoration of worn-out articles.

Synthesis and Analysis of an Alkenone-Free Biodiesel from Isochrysis sp.

Some marine microalgae, such as Isochrysis sp., produce high-melting (∼70 °C) lipids known as long-chain alkenones that detrimentally affect biodiesel fuel quality. A method has been developed for the production of an alkenone-free Isochrysis biodiesel. This material was prepared on sufficient scale to allow for extensive analysis according to ASTM standards. Results revealed that while cold flow improved by removal of these high-melting components and lubricity and glycerol content were below maximum levels prescribed in the standards, other properties dependent on fatty acid methyl ester (FAME) structure and composition such as oxidative stability failed to meet ASTM specifications. Both the cetane number and kinematic viscosity were lower than what would be calculated based on FAME content. This has been explained in part by 6–8% non-FAME contaminants in the tested samples.

Effect of Fractional Crystallyzation on Composition and Thermal Behavior of Coconut Oil

This study was aimed to fractionate coconut oil into its high- and low-melting fractions and determine the compositional and thermal property changes. A sample of coconut oil was dissolved in acetone, and allowed to crystallize isothermally at a desired temperature to separate into the low- and high-melting components. The isolated fractions were compared to the original sample with respect to fatty acid and triacylglycerol compositions as well as thermal behavior. There were considerable deviations in the fatty acid and triacylglycerol compositions of the two components with respect to those of the original sample. As a consequence, the overall melting behaviors of the two components differed considerably from that of the original sample. In the high-melting fraction, the onset and endset were shifted toward the higher temperature region with a concurrent reduction in its melting range, and vice-versa, the onset and endset of the low-melting fraction had shifted toward the low-temperature region with an increase in its melting range. The reduction of the melting range of the high-melting fraction could make it a specialty fat for applications in confectionery.

Comparison of Ternary Bilayer Mixtures with Asymmetric or Symmetric Unsaturated Phosphatidylcholine Lipids by Coarse Grained Molecular Dynamics Simulations

We studied the phase behavior of various ternary bilayer mixtures composed of cholesterol, an unsaturated lipid, and a fully saturated lipid, by means of molecular dynamics simulations of the MARTINI coarse grain model. We aimed at comparing lateral organization and local properties of bilayers containing phosphatidylcholine (PC) lipids, either with two unsaturated tails (symmetric), or one unsaturated and one saturated tail (asymmetric), as the low-melting component of the mixture. The number of unsaturations per chain was systematically varied in both classes of unsaturated lipids, to account for its consequences in segregation. In the asymmetric unsaturated PCs, the saturated tail was kept identical to the hydrophobic chains of the fully saturated lipid component. Membranes with a symmetric or an asymmetric unsaturated lipid, with the same kind of unsaturated chain, show different phase behavior. Symmetric polyunsaturated PCs set the separation in two phases. Instead, the asymmetric polyunsaturated lipids induced nonideal mixing of components in single-phase bilayers. A significative drop of temperature, within the accessible temperature range, enhances the segregation in mixtures with the more unsaturated asymmetric PC, but still within a single phase. This different phase behavior between membranes with symmetric and asymmetric unsaturated PCs is also observed for lipids with the same total number of unsaturations. On the other hand, the degree of unsaturation per se enhances the segregation, by increasing the composition fluctuations in single-phase membranes with asymmetric PC lipids, and raising the line tension in the two-phase bilayer mixtures with symmetric polyunsaturated PCs. Dynamic clusters of unsaturated asymmetric lipids can be identified. The clusters show no correlation between leaflets, as observed for the phase domains in mixtures with the symmetric polyunsaturated PCs. Interestingly, we found that asymmetric PC lipids have a preferential orientation such that their saturated tails increase their density toward the periphery of the clusters, facing regions enriched in the fully saturated lipids and cholesterol. The degree of unsaturation increases the cluster size and also enhances the anisotropy of the orientation. The surface density of cholesterol follows a gradient that favors its interaction with the saturated tails. Such gradients in composition lead to gradients in order parameters, such as the conformational order and the area of the tails, which increases away from the unsaturated lipid clusters. We compared, in addition, differences in hydrophobic length mismatch between acyl chains of the low-melting and high-melting components, in mixtures containing either symmetric or asymmetric unsaturated lipids.

Numerical modeling of laser sintering of two-component powder mixtures

The process of direct sintering of metal powders induced by laser radiation is investigated. A two-component mix of powders consisting of low- and high-melting components is considered. The model is based on a self-consistent nonlinear equation of continuity for volume fractions of low- and high-melting components of the mixture and on the equation of energy transfer in the melt-powder mixture system. It includes the motion of hard particles due to shrinkage associated with the changed density of the powder mixture and with convective fluxes caused by the forces of surface stress and gravitation. The liquid flow is determined by the Darcy law of filtration. The effect of the finite width of the region of phase transition of the high-melting powder has been detected. The rate of melting zone expansion is shown to depend on both the parameters of laser radiation (beam power) and on the physical characteristics of the substance of particles, and to grow with the increase in penetrability or phase transition heat. A diagram of the evolution quality of the melting front is obtained, by which it is possible to predict the solution behavior depending on the parameters of the powder mixture (penetrability and melting heat).

Technologies for producing the low-pore infiltrated powder composite materials (Review)

This analytical review deals with the technologies of infiltration of powder composite materials. It shows high efficiency of multilayer “infiltrate-substrate” blanks by means of physical contact of low-melting and high-melting components at the stage of blank molding. The classification of dosed infiltration methods (spontaneous and under pressure), using bimetal infiltrate-substrate blanks, is shown.

Synergism of depressants in petroleum systems

Systems of the coking gasoil type with residual and distillate cracking residues were investigated by electrophysical methods. Electrical processes, in particular, electrostatic blocking of high-melting components and formation of asphalt-resin complexes on electrically active centers, as well as mechanical factors, are responsible for the synergism and depressant activity. At 25–30 wt. % concentrations of additives in the mixtures investigated, a depressant effect was revealed for the first time.

Application of Granulated Raw Concentrate in Glass Technology

The possibility of using substandard materials in the form of granulated concentrates in glass technology is analyzed. It is established that using granulated concentrates in glass melting intensifies the chemical activity of batches at the stage of silicate and glass formation, which is due to the finely dispersed and defective structure of the material, close contact of the high-melting components with soda, and increased homogeneity of the batch.

Nanovoids in the milkfat and its high-melting components

The nanovoids in the fatty acid triglycerides and in the milkfat are studied by means of the positron annihilation spectroscopy. The mean radii of the nanovoids are measured using annihilation characteristics of the hydrogen-like positronium atoms, which annihilate inside the nanovoids. It is shown that both the milkfat and its six purified fractions (high- and low-melting components) contain the most stable nanovoids, whose mean radius ( R void=0.35 nm) coincides, within the error limits, with that of the most stable C 60 fullerene molecule.

Interactions of Milk Fat and Milk Fat Fractions with Confectionery Fats

The objectives of this study were to provide a better understanding of the effects of triacylglycerol (TAG) and non-TAG compononents (minor lipids) of milk fat on phase and crystallization behavior of binary mixtures palm kernel oil (PKO) and the physical properties of corresponding compound coatings. Binary mixtures of a fractionatedd PKO with the different milk fats were examined for melting profiles, crystallization kinetics, and crystalline microstructures, and polymorphic changes during storage. Compound coatings were made with equivalent binary fat mixtures and measured for hardness and bloom formation. Milk fat and milk fat fractions affected crystallization rates of fractionated PKO, depending on the melting point of the fat. High-melting components resulted in more rapid crystallization, whereas the original milk fat and low-melting components inhibited crystallization. The crystal structure (e.g., number, size, shape) of the PKO crystals was influenced significantly by the addition of milk fat fractions and was influenced by the presence or absence of the minor lipids in milk fat. Milk fat and milk fat fractions had a softening effect on fractionated PKO, which was apparent in the binary mixtures as well as the compound coatings. In general, as the solide fat content (at 25°C) of the binary mixtures increased, the hardness of the respective coatings increased. This also was related to an increased rate of bloom formation during storage.

Application of the sol-gel process to lower the melting temperature of glaze

Applications of the sol-gel process have been studied to lower the melting temperature of glaze in the system Na 2OK 2OCaOZnOAl 2O 3SiO 2. The high melting components such as SiO 2 and Al 2O 3 in the raw materials were replaced partly by the metal alkoxides, and the powders of raw materials were processed to be coated by the hydrolized metal alkoxides. It was found that the melting temperature lowered by 50–200°C depending on the amounts of the metal alkoxides used for replacement.

Thermal expansion of coal-derived liquids

The thermal expansion of two coal-derived liquids in the pressure range 1–4 kBar at temperatures up to 450 K has been measured calorimetrically. The high-temperature isotherms demonstrate a crossing point on the diagram of thermal expansion vs. pressure. The low-temperature isotherms demonstrate unusual behavior caused probably by the precipitation of high-melting components.

Studies in palm oil crystallization

AbstractThe melting and crystallization behaviors of palm oil were examined by nuclear magnetic resonance, differential scanning calorimetry, and plasticity measurements and were correlated with composition and chemical characteristics. Fractionation into high melting and low melting components is adversely affected by increase in free fatty acids (FFA), diglyceride content, and degree of oxidation, and hence, for an oil that is to be fractionated, both hydrolysis and oxidation should be kept to a minimum. Palm oil with very low FFA content, obtained from ripe, unbruised fruit, contains substantially more diglycerides than would be expected from the level of FFA present. Liquid and solid palm oil fractions manufactured in the producing countries showed large variation in characteristics, due in part to the use of various fractionation processes. The characteristics used to define the quality of palm oil are also applicable to its fractions.

Change in fine structures of isotactic polpropylene during isothermal crystallization

AbstractThe objects of this study were to examine the change of the fine structure in isotactic polypropylene during isothermal crystallization and to determine whether the theory of molecular weight fractionation induced by crystallization or the lamellae thickening, due to longitudinal translation or sliding diffusion of polymer chains in a crystal state (sliding diffusion theory) is important in the crystallization process. As crystallization proceeds, low melting crystals are produced, irrespective of molecular weight and molecular weight distribution. For high molecular weight polymers, the peak of the thermogram shifts to higher temperatures, and the high melting components are produced mainly by the sliding diffusion mechanism. If the difference between the molecular weights of both components in a polymer blend is not too great, a peak is found in the DSC thermogram of such a crystallized blend which occurs roughly midway between those of each separately component crystallized under the same conditions as the blend. If the molecular weights of the two components differ greatly the DSC thermograms of the blend show that each component tends to crystallize separately. The experimental evidences, obtained by KAWAI, HOSOI, and KAMIDE in the case of linear polyethylene, against the fractionation theory are examined in detail for isotactic polypropylene.

Formatin of Atomic Groups in Borosilicate Glasses, (II)

For the borosilicate glasses in which the mol ratio of SiO2 to B2O3 is larger than 3:2, the decrease of the fiber elongation rate with time under constant temperature and weight was found at the viscosity of about 1.5×1012 poises provided that the glass did not contain much alumina. It was deduced to be due to the “xy4-group” formation in these glasses on the grounds of several experimental facts. Also the “xy4-group” formation in these glasses should be accompanied by the separation of the glass into two phases, one is rich in SiO2 and the other in Na2O and B2O3, i.e., one is high and the other is low in the temperature of melting. It is related to the phenomenon of the faint milkiness or opalescence which borosilicate glasses often assame during heating. By the considerations based on various experimental facts, it was concluded that when a small amount of the network modifying oxide of the cation with the valence three and upwards is added to the low alkali borosilicate glasses in which the mol ratio of SiO2 to B2O3 is larger than 3:2, several “xy4-groups” are gathered together by the cations of the modifying oxide causing a larger separation, and by the crystalization of silica in the SiO2 rich phase in the form of ultra-microscopical crystals of cristobalite, the opalization takes place.In the course of the above experiments on elongation and opalization, it was noted that the alumina content of the glass seems to greatly decrease the “xy4-group” formation. It was deduced and also experimentally verified that by the formation of the “xy4-groups” in the glass, the thermal expansion coefficient is reduced, and by the accompanying separation of the glass into the low melting and the high melting components, the transition temperature is lowered and the contraction temperature is raised. It is, therefore, very desirable to increase the number of “xy4-groups” in glass with a view to improving its properties especially for glass-working. For this purpose, two methods may be available, namely, (1) by cooling the glass slowly through the “xy4-group” formation temperature range, or (2) by decreasing the alumina content of the glass. By applying the latter method to the glass used for the production of the large type transmitting tubes, the failure of glass due to fracture in the process of sealing was reduced than heretofore as much as about 1/7. The decrease of the chemical durability accompanied by the decrease of the alumina content was satisfactorily compensated by the use of two kinds of alkali oxides instead of one.