Papers by Keyword: Modification

Abstract: In the last decade, a continuous increasing research activity is focused on the surface modification of natural porous materials for the efficient removal of oil contaminants from water. A continuous in-situ oil/water separation technique for oil spill cleanup had been designed using surface modified Irind mine pumice as a sorbent. Irind mine pumice is an aluminosilicate rock, with well-developed porosity, mechanical strength, high buoyancy, chemically inert and eco-friendly, therefore it must exhibit certain water-and oil absorption capacities. The modified pumice absorbs a broad variety of oils and organic solvents with high oil absorption capacity and negligible water take-up at both static and dynamic conditions. Irind mine pumice have been used with grain sizes ranging from 2.5 ... 5.0 mm. Oligomethylhydride siloxane is used as a modifier.

Abstract: The development of modern high-tech industries of industrial production is impossible without the development of new methods for processing materials with high mechanical characteristics. There is a growing need for an increase in the proportion of parts made of aluminum alloys, a more complex configuration of cast parts, an increase in their reliability and durability in operation, etc. All this poses for metallurgists and foundry workers the task of creating new technologies for producing alloys, improving the technical and economic characteristics of structural materials, improving the quality and reducing the cost of castings.Hypoeutectic silumins have good casting properties, good weldability, machinability and corrosion resistance. However, they are prone to the formation of a coarse needle-like state, which reduces their useful characteristics. To eliminate this phenomenon, it is necessary to apply special technologies and the most common is their modification, which provides grain refinement. This makes it possible to use silumins for the manufacture of castings of complex shapes with increased density and low shrinkage porosity. Such parts can withstand average loads in critical units. Aluminum-silicon alloy AK7 or (ASi7Mg0.3) is a typical silumin, which is in demand in the automotive industry, construction, aircraft construction, machine, automobile and tractor production. It is appreciated for its good casting properties, weldability, machinability and corrosion resistance.

Abstract: In this paper, the influence of the modification method applied to ground vulcanizate (GV) on the properties of elastomeric compositions based on nitrile rubber is discussed. Modified GV has been mixed with the elastomeric composition, which is used for the manufacturing of oil-petroleum-resistant rubber products.The work takes into consideration two types of GV with different chemical nature. The first GV type is rubber crumb produced from end-of-life tires. The second GV type was obtained from rubber wastes based on nitrile rubber. Three methods of the modification are compared in the research: mechanical activation in a planetary ball mill, swelling in a Polyethylene glycol (PEG-400) medium, and the mechano-chemical transformation of GV with PEG-4000. It is shown that depending on the dosage addition of GV modified with PEG-4000 reduce the compression set up for (16.1±0.7%), the strength decreases only by 2.1–8.3%, and the elongation at break increases by 0.8–10.3% compared to rubber without additives.

Abstract: This paper deals with the development of a new mortar, for cement-based inverse grouting, with an increased degree of chemical resistance. The aim of this work is to verify new mixtures optimized by suitable secondary raw materials. The studied parameters include selected physical-mechanical characteristics and chemical resistance of individual raw material variants is characterized by resistance to sulfate solution. The results of this work show that it is possible to increase the chemical resistance by optimizing the grouting mortar mixture with suitable secondary raw materials. The optimized mixture for the new grout will be part of a comprehensive material system for the remediation of sewers or shafts.

Abstract: Research results of modified composites which consist of isolated layers with different properties and their practical usages are represented in this article. A structure of the composite material is considered. The structure is combined of few layers; external layers are made of corrosive resistance material with dielectric behavior while the internal part of the composite is made of electrically conductive material with high conductive and mechanical properties. Conductive properties of each layer have been measured as well as their mechanical properties and structure. Also, the features of the joints between layers in terms of structure and properties were defined. More than that, varieties of mixtures and their possible usage are considered. Conductive properties of composite materials and ways of their adjustment have been described as well. For the first time, the measuring scheme of conductive properties for each layer was offered and heat shrinkable tubes and copper electrodes were used for it. Efficiency of modified composites and its behavior when electrical current applied can be measured by using the scheme.

Abstract: A curing system has been developed for obtaining high-strength compositions matrix, which is used in the production of composites based on reinforced carbon fiber using prepreg technology with a curing temperature of . A technology has been developed for combining an epoxy oligomer with a curing agent and modifier. The pot life of the prepared prepregs is at least 15 days.

Abstract: It was found, studying acrylonitrile copolymerization with ethyl acrylate in dimethyl sulfoxide under the action of anionic initiating system of 1,4-diazabicyclo [2.2.2] octane – ethylene oxide, that the obtained copolymers have a branched structure. An increase in the molar fraction of ethyl acrylate in the reaction medium leads to a decrease in the initial rate of acrylonitrile polymerization. Thermal behavior of copolymer samples was investigated; it was found that ethyl acrylate, being introduced into the polyacrylonitrile structure, both reduces thermal effects related to the reactions taking place during heat treatment of copolymers, and increases the half-width of the heat release peak.

Abstract: The present paper is aimed to investigate the effect of modifiers, such as poly (phenylene sulfone) and poly (aril ether ketone), on physico-mechanical and thermophysical properties of heat-resistant epoxy-anhydride binder based on EHD epoxy resin. It was found that the addition of poly (phenylene sulfone) and poly (aril ether ketone) can improve mechanical and impact strength characteristics of the binder with no reduction in heat resistance and thermal stability.

Abstract: The influence of sizing compositions on the reinforcing properties of hydrated cellulose technical yarns has been investigated. The optimal mode of modification of hydrated cellulose yarns has been determined. The evaluation of the structural properties of the modified yarns has been carried out. The kinetic features of the modified yarns wetting by an epoxy oligomer have been studied.

Abstract: This paper deals with the study of chemical resistance of new cement-based grout for invert grouting. The aim of this work is to verify new mixtures with specific admixtures. The study monitors resistance to external sulphate attack. Specimens were placed into sulphate solution 29.8 g∙l^-1 (44 g∙l^-1 Na₂SO₄) according to DIN19753 standard. Based on the results gained, new mixtures will be designed and optimized by addition of suitable secondary raw materials (fly ash, waste foundry sand, waste glass, waste filers).