Electroconductive qualities of the membranes МС-40 and МА-41, researched by the method of impedance high-frequency spectroscopy

One of the most important factors defining the complex of operational characteristics of heterogeneous ion-exchange membranes that represent a composite material is their structure. Composite material electroconductivity depends on the nature of phases setting the system and on their relative position. Impedance spectroscopy is one of the effective methods of structure definition and electrochemical characteristics not only of the composite material generaly but also the phases which it consists of. In this paper by the method of impedance spectroscopy the electrochemical characteristics of the heterogeneous ion-exchange membranes МС-40 (H+, Na+, К+, NH4+ - forms) and МА-41 (Cl- and NO3- - forms) in the range of the alternating current frequencies 100 KHz – 20 MHz are researched. The comparison of the contact and contact-differential ways of measuring membrane impedance is done. It is shown that in the case of impedance contact measuring of the sample the borders “electrode/membrane” influence the electrochemical impedance system spectrum greatly. In connection with this the contact-differential variant of the experimental procedure in the impedance measuring of the membrane system is more preferable. The interpretation of the received electrochemical impedance spectra in terms of the composite material conductivity is given. Basing on the method of equivalent circuits it is suggested representing the impedance of the heterogeneous ion-exchange membrane as a sum of pure resistance (resistance of ion-exchanger particles), sequentially connected with the impedance of the dielectric layers (resistance and capacity of polyethylene and dissolvent). The analysis of the spectra of electrochemical impedance of ion-exchange membranes in different ion forms showed that the quantity of the semicircle locus impedance radius is inversely proportional to the coefficient of counter-ion diffusion and directly proportional to the part of the membrane intergel phase

THE IMPROVEMENT OF PHYSICAL AND MECHANICAL PROPERTIES ELASTOMERS USING LIQUID PHASE FILLING

The physic-mechanical properties of vulcanizates derived from elastomeric compositions filled with calcium carbonate to hydrophobic stage latex and the traditional method on the rollers. It is determined that the maximum degree of filling of the rubber mixtures produced on the rollers, is 200 parts by weight rubber during the filling stage on latex 400 parts by weight 100 parts polymer. It is noted that during the preparation of rubber mixtures based on natural rubber, latex filled in step, there is a better process ability and reduced mixing time from 27 to 17 minutes. However, compositions with a degree of filling of 400 parts by weight "Sticky" on the rollers, du e to the high content of fatty acids, which contribute to adhesion due to the swelling of the polymer phase. When filled with 50 parts by weight 100 parts Rubber physical properties of the compositions prepared by liquid-phase method, higher than the values of standard samples. With increasing degree of filling of up to 100 parts by weight 100 parts by weight of rubber increased rates of tensile strength, but reduced rates of elongation. Further increase in the degree of filling reduces the physical and mechanical properties of vulcanizates than Shore hardness. The effect of stearic acid and oleic acid for processing rubber compounds. Found that oleic acid is involved in the curing process and increase the mechanical properties of the vulcanizates by formation of π-π bonds with a matrix rubber, and stearic plays the role of the interfacial structure plasticizer. The method of equilibrium swelling in toluene determined density chemically bonded chains of the polymer network. The lowest equilibrium degree of swelling is observed in a sample prepared on a mill

Modification of asphaltic concrete with a mineral polymeric additive based on butadiene-styrene rubber and chemically precipitated calcium carbonate

Modification of asphaltic concrete with a mineral polymeric additive based on butadiene – styrene rubber and chemically precipitated calcium carbonate. This paper presents the results of the study of physical – mechanical and service properties of the asphaltic concrete modified with the mineral polymeric composition. Calcium carbonate is used both as a filler and a coagulant. The chalk was preliminarily ground and hydrophobizated by stearic acid. These operations contribute to even distribution of the filler and interfere with lump coagulation. As a result of the experiments, it was found that the best results were obtained by combining the operations of dispersion and hydrophobization. The optimal amount of stearic acid providing the finest grinding in a ball mill is a content from 3 to 5% by weight. The optimal grinding time of the filler was found (4–6 hours). With increasing dispersion time the particles form agglomerates. Filling the butadiene styrene latex with the hydrophobic fine-grained calcium carbonate was carried out in the laboratory mixer. As a result of the experimental works, it was found that the best distribution of the filler takes place with ratio of rubber: chalk – 100:400. The resulting modifier was subjected to the thermal analysis on the derivatograph to determine its application temperature interval. A marked reduction in weight of the mineral polymeric modifier begins at 350 °C. Thus, high temperature of the modifier destruction allows to use it at the temperature of the technological process of asphaltic concrete preparation (up to 170 °C). It was found that an increase in the amount of the carbonate filler in the rubber SKS 30АRК significantly increases its thermal resistance and connection of the polymer with the chalk in the composition

INVESTIGATION RHEOLOGICAL PROPERTIES OF PVC-BASED

Summary. Obtained hydrophobic filler compositions based on PVC from calcium carbonate, which is a byproduct in the preparation of mineral nitrogen fertilizers. The methods for pretreatment of the chalk used as a filler in PVC compositions. Conducted modifying the properties of chalk with hydrophobic additives: stearic acid, zinc stearate, calcium stearate. When stearic acid treated chalk heating leads to an interaction with the surface layers of calcium carbonate, a thin film of calcium stearate. Therefore, more cost-effective to create compositions with PVC content of one percent of calcium stearate as its hydrophobic surface is easily wetted by the polymer matrix, which provides rapid mixing of PVC compounds. As a result, the excipient serves as an additional stabilizer, providing higher thermal stability of PVC products, compared with its values for the composition of the compared with the other ingredients. Extrusion processes that are central to the processing of PVC compounds filled by acting them filler, fractional increase heat and accelerate melting and increase output. The rheological properties of polymeric compositions created PVC. A significant reduction in viscosity observed for water repellent based on stearic acid. Study viscosity characteristics for hydrophobic additives showed that their activity increased in the series: zinc stearate, calcium stearate, stearic acid. It was established that modifying additives used in the preparation of hydrophobic carbonate filler PVC compositions exhibit both plasticizers and stabilizing properties

Prospects for the use of liquid waste from the production of sodium carbonate as a coolant based on the ternary system CaCl2-K2Cr2O7-H2O

Currently, the urgent problem is the secondary use of distillation liquid - a waste product from the production of sodium carbonate, which is an aqueous solution containing about 10 % calcium chloride and a small amount of other salts. It is proposed to use a solution based on a distiller liquid as a coolant in a heat exchange system in the production of soda. The introduction of potassium dichromate into the system creates an inhibitory effect and prevents pipe corrosion. To study phase equilibria in the CaCl2 - K2Cr2O7 - H2O system, state diagrams were constructed at temperatures of 20, 3, and -7°C. With decreasing temperature, the homogeneous region noticeably decreases and shifts to the CaCl2 - H2O axis. The eutectic point is limited to a very narrow area in which the weight fraction of potassium dichromate does not exceed 3%.Using the Skrynemakers method, it was found that in a region with a calcium chloride content of less than 40 %, potassium dichromate crystallizes. For the region adjacent to the apex of calcium chloride, it is impossible to establish the composition of the solid phase and the boundaries of its crystallization using the Skrynemakers method. This is due to the fact that the binary system CaCl2 - K2Cr2O7 is a ternary reciprocal system K +, Ca2 + Cl-, Cr2O72- . In this area, the formation of solid solutions or compounds based on the binary system K2Cr2O7 - CaCr2O7 is supposed. For the temperature range from -7 ?С to 50 ?С, the refrigerant composition was proposed: 3 % K2Cr2O7 - 10.2 % CaCl2 - 86.8 % H2O. In the temperature range from 20 ?С to 60 ?С, the composition of the solution is: 6 % K2Cr2O7 – 10 % CaCl2 – 84 % H2O

Hydrophobic chalk as a filler for paints and varnishes

Study of the properties of the chemically precipitated chalk and the development of activities, which enable us to get from the secondary product of the manufacture different fertilizers, high-quality carbonate fillers for paints and varnishes, primers and putty

ELECTRODIALYSIS IN THE CONVERSION STEP OF THE CONCENTRATED SALT SOLUTIONS IN THE PROCESS OF BATTERY SCRAP

Summary. The concentrated sodium sulfate solution is formed during the processing of waste battery scrap. A promising way to further treatment of the concentrated salt solution could be the conversion of these salts into acid and bases by electrodialysis, that can be reused in the same technical process cycle. For carrying out the process of conversion of salts into the corresponding acid and base several cells schemes with different combinations of cation, anion and bipolar membranes are used. At this article a comparative analysis of these cells is carried out. In the cells there were used the membranes МC-40, МА-41 and МB-2I. Acid and base solutions with higher concentration may be obtained during the process of electrodialysis in the circulation mode, when a predetermined amount of salt in the closed loop is run through a set of membranes to obtain the desired concentration of the product. The disadvantages of this method are the high cost of buffer tanks and the need to work with small volumes of treated solutions. In industrial applications it is advisable to use continuous electrodialysis with bipolar membranes, since this configuration allows to increase the number of repeating sections, which is necessary to reduce the energy costs. The increase of the removal rate of salts can be achieved by increasing the process steps, and to produce a more concentrated products after the conversion step can be applied electrodialysis-concentrator or evaporator

Corrosion of steel St3 in technological water solutions of calcium nitrate

By the voltammetry method studied corrosion behavior of low carbon alloy structural steel St3 in aqueous solution of calcium nitrate. The effect of ammonation solution and additions of monoethanolamine and potassium dichromate on the basic parameters of the corrosion process was detected