Structural Rheological Properties Research Articles

From Seaweeds to Hydrogels: Recent Progress in Kappa-2 Carrageenans.

Hybrid carrageenans, also called kappa-2 (K2) or weak kappa, are a class of sulfated polysaccharides with thermo-reversible gelling properties in water and are extracted from a specific family of red seaweeds. K2 are known in the industry for their texturizing properties which are intermediate between those of kappa-carrageenans (K) and iota-carrageenans (I). As such, K2 are gaining industrial interest, as they can replace blends of K and I (K + I) in some niche applications. Over the last decade or so, some progress has been made in unravelling K2's chemical structure. The understanding of K2 gel's structure-rheological properties' relationships has also improved. Such recent progress is reported here, reviewing the literature on gelling K2 published since the last review on the topic. The focus is on the seaweeds used for extracting K2, their block copolymer chemical structures, and how these impact on the gel's formation and rheological properties. The outcome of this review is that additional rheological and structural studies of K2 hydrogels are needed, in particular to understand their viscoelastic behavior under large deformation and to unravel the differences between the texturizing properties of K2 and K + I.

Rheological properties and group chemical composition of oxidized bitumen in the presence of fibrous materials of various structures

The rheological properties of oxidized bitumen in the presence of fibrous materials based on cellulose and chrysotile asbestos used as stabilizing additives in the production of crushed stone-mastic asphalt concrete mixtures have been studied. It has been established that the supramolecular structure of fibers characterizing the interaction between macromolecules largely determines the effectiveness of their structuring action for oxidized bitumen. Thus, the introduction of cellulose fiber leads to an increase in the ability of the bitumen colloidal structure to the simultaneous occurrence of elastic and plastic components of deformation. This is due to the uniform distribution of the fiber in the dispersion medium of bitumen due to the penetration of hydrocarbon components of bitumen into the interfibrillary space of cellulose and the rupture of hydrogen bonds between hydroxyl groups. Тhe presence of strong structural bonds between chrysotile-asbestos macromolecules prevents the formation of strong reinforcing mesh in bitumen oils. As a result, the values of the structural and rheological parameters Pk1, Pk2 and Pm of the bitumen/chrysotile-asbestos composition are 1.5–2 times lower compared to the values for the bitumen/cellulose composition. The results of the study of the group composition and structural-rheological properties of bitumen compositions after heating at T = 163 °C indicate a higher stability of the bitumen-cellulose structure to the processes of thermal oxidative degradation compared to the structure formed in the bitumen/chrysotile-asbestos composition. By the method of thin-layer chromatography, it was found that the concentration of oils in the bitumen/chrysotile-asbestos composition is higher as compared to the bitumen/cellulose composition, indicating that the weakening of rheological properties and thermal stability in the presence of chrysotile-asbestos is not related to the microstructure of its fibers, which, according to some researchers, is prone to selective diffusion of oils into the capillaries of fibrils.

Features of the hot recycling method used to repair asphalt concrete pavements

Abstract The recycling methods used in the construction and repairing of asphalt concrete pavements are being constantly improved, and the improvements mostly fall under one of the following common avenues of innovation: developing new binders based on bitumen and cement; developing new varieties of asphalt concrete and other materials having an equivalent utility and function; and developing additives that can be used in the production of new types of binders that can enhance the performance properties of the pavements. This article aims to develop the composition and determine the physical-mechanical and structural-rheological properties of asphalt concrete reclaimed by the hot recycling method and reinforced by fiber of fly ash from thermal power plants (TPP). The author of this article developed a mechanism for the interaction between fiber and bitumen in asphalt binder and acquired an optimum composition of hot granular asphalt concrete. During the research, the author evaluated the utility of fiber used as an additive in reclaimed asphalt concrete, studied its effect on the properties of hot reclaimed asphalt concrete, and examined the technological and performance properties and durability of the material obtained. The fiber of fly ash used in the hot recycling method made it possible to reduce the cost and ensure the high quality and durability of the structural layer of road pavement. Our experiments with analyses of the obtained composition indicated that employing it in the construction of the structural layer of road payment would result in superior structural integrity. Hot recycling made it possible to obtain thick bound layers characterized by the homogeneity of the material. For the first time, the author studied the effect of using fiber of fly ash from Chinese TPP in hot reclaimed asphalt concrete, and the results have proved the rationality of using this composition.

Structural-rheological properties of systems based on polymeric hydrogels and anionic surfactants

The effect of sodium dodecyl sulfate and sodium oleate on the structural-rheological properties of a dispersed hydrogel based on polyacrylic acid was studied. It was shown that the viscosity of hydrogel compositions with surfactants is higher than the viscosity of the individual components and increases with increasing temperature from 20 to 40 °C. Compositions with sodium oleate are non-Newton liquids and exhibit thixotropic properties.

Complications in the drilling of wells projected to VIII horizon of Bulla-deniz field and the measures towards their elimination

The paper reviews the main reasons for the failures and complications with further specific recommendations for completing the well to the project depth in Bulla-deniz field. The practicability of the application of water-based drilling muds characterized with the wall-plastering and managed structural-rheological properties instead of the hydrocarbon-based drilling mud to the 2700 m. It is recommended to use hydrocarbon-based drilling mud only in the revelation of production horizon via drilling. Regardless of the drilling mud’s type and properties, the time of the tool remaining stationary while drilling and round trip operations should not exceed 3-5 minutes. In order to avoid the loss of the drilling mud into the formation, the casing of production string in consolidated clay rock is recommended.

GEOMETRIC AND ELECTRONIC STRUCTURE OF HEAVY HIGHLY VISCOUS OIL COMPONENTS

Physical-chemical and structural-rheological properties of the oil disperse system are determined by the structure, size and composition of the complex structures resulting from the association of paraffins and tarry asphaltene components. Therefore, data about hydrocarbon composition, especially the structure of paraffins, tars and asphaltenes, required to choose recovery method in the extraction, field treatment, transportation and processing of heavy oils. In article parameters of the geometric and electronic structure of the tars and asphaltenes model molecules to determine reactivity indexes and, consequently, the possibility of a new oil dispersed system formation were calculated. Based on the density functional method B3LYP/6-311+G(d,p), quantum chemical calculations of the electronic structure and geometry of model tar molecules are given in the work. It was found that the number of benzene rings does not have a significant impact on the geometric and electronic structure of hydrocarbon fragments. The heteroatoms N, S and -OH functional group have a significant influence on the characteristics of model molecules. The nitrogen atom significantly increases the molecule dipole moment, compared to the sulfur and hydroxyl group, and the greatest change in geometric and electronic structure is observed in the presence of a sulfur atom. To choose recovery method in the heavy hydrocarbon crude treatment, the elemental composition is quite important, since it is heteroatoms in multi-core systems with condensed nuclei that affect the reactivity indices and provides generation of a free radical form and creation of a new oil dispersion system.

Structurization of poly mineral is highly concentrated poly disperse systems based on organic binders

At present, the quality of bitumen-mineral mixtures both on the territory of the Russian Federation and abroad is estimated by a set of em-pirical methods based on many years of experience in the use of asphalt in road construction. In different years, numerous attempts were made to theoretically substantiate the basic patterns of material behavior under the influence of various factors. The article describes the solution of this problem using the basic provisions of phys-chemical mechanics of highly concentrated disperse systems taking into account the specifics of contact interactions. As a result of researches the quantitative correlations of indicators of physical-mechanical and structural-rheological properties forming at compaction of mixtures mixes, quantitative interconnections between formative and Destructive factors with structural-mechanical and construction-technical properties of asphalt in road coverings. It has been established that the changes in the structure of asphalt have physical-chemical nature and are reliably described taking into account the basic provisions of phys-chemical mechanics and theories of contact interactions.

Modeling of structural-rheological properties of sunflower oil miscella

Modeling of structural-rheological properties of sunflower oil miscella

Effect of modifiers on properties and curing of aqueous emulsions of ED-20 epoxy resin in the presence of еpilink 701 cross-linking agent

The dependence of the stability and structural-rheological properties of aqueous emulsions of an epoxy resin on the type and concentration of the modifier was examined. The working time, degree of curing, microstructure, and physicomechanical properties of polymer materials were studied in relation to the modifier type and its concentration in emulsions.

Effect of adsorption of nonionic surfactants on the stabilizing ability of latexes in preparation of epoxy emulsions

The effect exerted by adsorption of nonionic surfactants on the stabilizing ability of latexes in preparation of epoxy emulsions and on the structural-rheological properties of these emulsions was examined. The stabilizing effect was attributed to heterostabilization of particles of the mixed dispersed phase and to the strength of the structural framework formed.

Improving the structural-rheological properties of high-paraffin crude oil using chemical reagents and vibrational treatment

The effect of a number of polymer additives and vibroacoustic action on the structural-rheological properties of problematic high-paraffin crude oil is studied. It is shown that complex treatment makes it possible to attain synergetic effects from the improvement of the rheological properties of crude oil. The depressor effect remains during the time required to pump oil from reservoirs and transport it for subsequent processing.

Effect of the concentration factor and emulsifier nature on the type, stability, and structural-rheological properties of emulsion based on an epoxy oligomer

Formation conditions and structural-rheological properties of emulsions produced on the basis of ED-20 epoxy oligomer in the presence of OS-20 (B and V brands) and LCN-287 nonionogenic emulsifiers were studied.

Water-soluble polyelectrolytes based on polyacrylonitrile for wastewater treatment

The possibility of modifying oxidized asphalt by performing polycondensation of maleic anhydride with aliphatic amines of various chemical structures in the dispersion medium was considered. The influence of the reactant structures and reaction conditions on the physicomechanical and structural-rheological properties of the polymer-modified asphalt was examined.

Synthesis of aliphatic polyamides in the dispersion medium of oxidized asphalt

The possibility of modifying oxidized asphalt by performing polycondensation of maleic anhydride with aliphatic amines of various chemical structures in the dispersion medium was considered. The influence of the reactant structures and reaction conditions on the physicomechanical and structural-rheological properties of the polymer-modified asphalt was examined.

Modification of oxidized bitumen with styrene-butadiene-styrene copolymers of various structures

Mechanical and structural-rheological properties of oxidized bitumen modified with styrene butadiene-styrene copolymers side vinyl groups in their butadiene fragment were studied. A comparative analysis of the modified and unmodified bitumen composites was performed.