Elastomeric composites for Arctic conditions: operation features and development experience

A key feature in developing rubber compounds for mining equipment is the necessity to achieve a high level of frost resistance, wear resistance, and chemical resistance within a single material. Various methods for influencing the elastomer’s structure have been tested to comprehensively improve rubber properties—such as modifying them with nanofillers and applying a compositional principle, where two or more polymers are selected, one of which possesses high frost resistance, and the others possess chemical and wear resistance. The high potential of using high frost-resistant rubbers has been demonstrated: propylene oxide rubber (SKPO, Tg = –74°C) and epichlorohydrin rubber HYDRIN T6000 (ECO, Tg = –74°C), whose wear and chemical resistance can be significantly enhanced by introducing natural bentonites or carbon nanotubes. It has been shown that when modifying SKPO with bentonites in amounts of up to 3 phr (parts per hundred parts of rubber), an exfoliated structure is formed, and the surface layer is enriched with bentonite, which leads to a significant improvement in surface properties. The introduction of multi-walled nanotubes into ECO in an amount of 1 phr results in an increase in modulus and tensile strength, a 40% reduction in wear, and a 43% increase in resistance in VMGZ oil. Rubbers based on SKPO and ECO possess a high level of low-temperature characteristics: the frost resistance coefficient (Kv) at –50°C ranges from 0.7 to 0.9. The compositional principle allows to gain the properties of each polymer component and develop new characteristics. The benefits of this approach are demonstrated using mixtures of SKPO and ultrafine polytetrafluoropolyethylene (UPTFE), BNKS-18, and BNKS-28 with UPTFE, and mixtures based on three rubbers: BNKS-18, SKI-3, SKD. The use of UPTFE in elastomeric compositions, which has a low coefficient of friction, imparts high wear resistance, oil resistance, and resistance to mine brines. The composition based on BNKS-18, SKI-3, and SKD incorporates common, mass-produced rubbers and possesses a balanced set of properties, including a sufficiently high level of low-temperature characteristics (Kv at –50°C = 0.5) and wear resistance. The study of the rubber’s climatic stability was conducted in Yakutsk under exposure to Talakan oil field petroleum. The results were compared with the dynamics of property changes in an industrial rubber based on BNKS-28 containing a plasticizer. In both cases, intensive leaching of the dibutyl phthalate plasticizer occurs, accompanied by an irreversible decrease in Kv. However, the frost resistance of the elastomeric composite based on rubber blends is higher because, in this case, frost resistance is provided by the polymer itself, not by an additive that is irreversibly lost during operation due to diffusion. Testing of the rubber in the settlement of Tiksi, with exposure to air, showed that the loss of plasticizer occurs at a slightly slower rate. The use of elastomeric composite based on rubber blends should be considered a priority method for creating rubbers for mining equipment, compared to the traditional introduction of large amounts of plasticizers.

The article discusses the influence of complex additives on the strength and resistance of cement composites to environmental impacts. One of the additives - PFM-NLK (concrete modifier)- a factory fabricated mixture of a superplasticizer with the addition of air-retaining and water proofing substances. Another one is a complex additive containing a superplasticizer, sodium tetraborate and boric acid.Common denominator is the content of the superplasticizer. It allows reducing the W / C ratio of the mixture thereby increasing the density and strength of the composite, and, accordingly, its frost and corrosion resistance. PFM-NLK water-proofing and air-retaining substances additionally work toward the formation of a material structure with increased frost resistance. The components of the other additive, boric acid and sodium tetraborate, form a borate buffer system, which leads to the softening of the “chemical impact” and thus further increases the corrosion resistance. The research findings revealed the effectiveness of complex additives and substantiated the regularity that if each factor is separatelyfacilitative forproperty improvement, then, when they are combined, the effect is multiplied. The PFM-NLKcomponents, when combined, contribute to obtaining a material structure with high frost resistance. An additive containing a hyper-plasticizer, boric acid and sodium tetraborate leads to an increase in strength and acid resistance.

The problem of resistance of winter wheat to low negative temperatures is one of the most important in the agriculture economy, the solution of which will contribute to the increase of yield and gross grain harvesting in the Russian Federation. Therefore, the creation of winter wheat varieties capable of resisting the effects of frost during winter is very relevant. The aim of the study is to identify high frost-resistant winter wheat varieties for use in the breeding process by direct and indirect methods of assessment, and to define the possibility of using free proline content to detect genotypes resistant to low negative temperatures. The paper presents the results of complex studies on frost resistance of winter soft wheat varieties by three scientific centers: Agricultural Scientific Center Donskoi, National Grain Center named after P.P. Lukyanenko and Federal Rostov Agrarian Scientific Center. Therein is shown the possibility of using an indirect method - defining free proline content as a method of assessing frost resistance of samples. After freezing plants grown in sowing boxes at four different temperatures, varieties were identified that significantly exceeded the Tarasovskaya 29 classifier in plant safety: Polina, Volnitsa, Volny Don, Ascetic, Don Bezostaya, and Don 107. Samples that were distinguished by the safety of plants in direct evaluation methods also showed a high content of free proline in laboratory and field experiments. Correlation analysis between the values of various methods for assessing frost resistance showed their close relationship. Varieties of winter soft wheat characterized by high frost resistance, on average, accumulate more of this amino acid in the leaves in laboratory and field experiments.

Genotypic difference in postharvest characteristics of hardy kiwifruit (Actinidia arguta and its hybrids), as a new commercial crop Part I. Sensory profiling and physicochemical differences

Don wheat: productivity and grain quality, competitiveness and varietal diversity In the structure of grain crops, winter wheat occupies 74% of the area, and yields about 80% of gross amount. Therefore, wheat grain on the Don area, its productivity and quality is the most important source of income of its producers. The main sowing areas in the south of Russia are occupied by new varieties of such three research institutes as ARC ‘Donskoy’, ‘RCG named after P.P. Lukyanenko’ and DGRIA with the leading varieties ‘Ermak’, ‘Grom’, ‘Gubernator Dona’. Many modern winter wheat varieties are sown in the inter-station variety testing in the department for winter wheat selection and seed-growing of the ARC ‘Donskoy’, which makes it possible to compare them both in grain quality and productivity and to reveal their differences and features. The analysis of the allelic composition of prolamins showed that among the Krasnodar varieties there are a lot of alleles (78%) that negatively affect on the quality of flour (Gli 1B3, 1B2) and there are very few alleles with high frost resistance (Gli 1D4, 1D7 - 30%). At the same time, the varieties of Don selection have a visa versa effect. These alleles give an advantage in frost resistance, but lead to productivity decrease.

Introduction: Geopolymers are the modern inorganic materials obtained as a result of chemical reaction under strongly alkaline conditions. The main advantages of these materials are: high strength parameters, fire resistance, frost resistance and resistance to aggressive environment. Because of lower CO2 emission during production process, they are also considered as environmentally friendly materials in comparison to ordinary Portland cement (OPC) systems. Objectives: The aim of the investigation was to define the impact of recycled ground glass addition on mechanical properties of geopolymeric binder made from tungsten mine waste. Methods: The strength parameters of geopolymeric samples were determined on the basis of three-point flexural test and uniaxial compression test. Results: The geopolymer samples that contain 20%, 40% and 80% of recycled ground glass present similar flexural strength. The compressive strength of glass-based geopolymers increases with growing content of recycled ground glass. Conclusions: In terms of flexural strength, the most favourable composition was the mixture composed of 60% recycled ground glass and 40% tungsten mine waste. In terms of compressive strength, the most favourable composition was the mixture composed of 80% recycled ground glass and 20% tungsten mine waste.

Polymer materials with low-temperature characteristics must ensure the reliability of machinery, structures and structures when exposed to both external and internal factors capable of destroying the material. Analyzing the scientific and technical literature in the field of materials science, in particular elastomeric materials that can work in various hydrocarbon environments in cold climates, it was decided to continue research aimed at increasing the frost resistance and durability of elastomeric materials resistant to fuel. The paper describes the results of a study of nitrile butadiene rubbers by modification with vulcanization agents and polymer additives in order to improve the complex of operational properties of elastomeric sealing materials. The properties of vulcanizates of standard rubber compounds based on butadiene-nitrile rubbers with different contents of nitrilacrylic acid are investigated. Organic 2di-(2-tretbutylperoxyisopropyl)-benzene peroxide of the Luperox F-40 trademark and a combination of sulfur with an accelerator were selected as vulcanization agents. Their rheological properties are determined depending on the type of vulcanizing agent. The physicomechanical and low-temperature properties of the obtained vulcanizates have been studied. The effect of a type of vulcanizing agent in a rubber compound based on polar rubbers on the low-temperature properties of vulcanizates has been studied. Formulations of rubber compounds based on butadiene-nitrile rubber modified with semi-crystalline and styrene-butylene-styrene block copolymer for increasing low-temperature properties are studied. The physicomechanical properties of the obtained materials have been studied. Formulation and technological solutions are proposed to increase the frost resistance of polymer composite materials based on elastomers operated at low temperatures. Research aimed at developing new methods for modifying elastomeric materials based on BNC will effectively solve the problems of creating multifunctional rubbers for regions with a cold climate.

This paper reports the development of an Alkali Activated Binder (AAB) with an emphasis on the performance and the durability of the AAB-matrix. For the development of the matrix, the reactive components granulated slag and coal fly ash were used, which were alkali activated with a mixture of sodium hydroxide (2 - 10 mol/l) and aqueous sodium silicate solution (SiO2/Na2O molar ratio: 2.1) at ambient temperature. A sodium hydroxide concentration of 5.5 mol/l revealed the best compromise between setting time and mechanical strengths of the AAB. With this sodium hydroxide concentration, the compressive and the 3-point bending tensile strength of the hardened AAB were 53.4 and 5.5 MPa respectively after 14 days. As a result of the investigation of the acid resistance, the AAB-matrix showed a very high acid resistance in comparison to ordinary Portland cement concrete. In addition, the AAB had a high frost resistance, which had been validated by the capillary suction, internal damage and freeze thaw test with a relative dynamic E-Modulus of 93% and a total amount of scaled material of 30 g/m2 after 28 freeze-thaw cycles (exposure class: XF3).

In this paper, chitosan (CS), which is naturally degradable and low‐cost, was incorporated into nitrile butadiene rubber (NBR), the effects of chitosan amount on the properties of the NBR composites were investigated, and the optimal amount of chitosan was determined. On this basis, CS, silica and Si69 were modified by ball milling and plasma to prepare NBR composites with higher oil resistance and high temperature resistance. The results showed that the overall properties of NBR composites filled with 2phr CS is better. FTIR and SEM demonstrated the surface polarity of ball milling combined with plasma co‐modified CS/silica was weakened, the dispersion of fillers in the NBR matrix was promoted, the oil resistance and high‐temperature resistance of the composites were enhanced, the cross‐linking density and tear strength were improved by 28.12%, and 51.76% compared with that of the NBR composites without CS. The investigation on the oil and high‐temperature resistance of NBR composites for blowout preventer cores has been carried out, which promotes the development of blowout preventer cores toward high safety, low cost, and sustainability. Highlights The effect of chitosan amount on nitrile butadiene rubber (NBR) composites was explored. Chitosan, silica, and coupling agent were modified by ball milling and plasma. The oil and high‐temperature resistance of NBR composites were improved. The tear strength was increased by 28% under double destructive environment.

Shoot proliferation is a very important micropropagation phase, decisive for economic efficiency of this method for a given taxon. To obtain a high multiplication ratio and a good quality of microshoots a detailed propagation protocol must be developed for particular species or even cultivars. Rhododendron ‘Kazimierz Odnowiciel’ is a relatively new cultivar distinguished by large, beautiful flowers and high frost resistance so there is a need to develop an efficient method of its propagation to satisfy a growing demand for this plant. The aim of the experiment was to evaluate effects of cytokinins: meta-Topolin (mT), zeatin (ZEA), 6-benzyladenine (BA), thidiazuron (TDZ), 2-isopentenyladenine (2iP), or the combination of 2iP+ZEA on proliferation of shoots in R. ‘Kazimierz Odnowiciel’ cultured on Anderson’s medium (AN). Biochemical changes in plant material affected by cytokinins during this phase of micropropagation were determined and occurrence of genetical changes was followed using ISSR markers. TDZ, ZEA or the combination of ZEA+2iP resulted in 100% explant regeneration. On the medium with TDZ or ZEA over two new shoots per explant were produced but the highest proliferation was attained on the medium containing ZEA+2iP – over three shoots per explant. Microshoots developed in this treatment had also the highest contents of chlorophyll, carotenoids and soluble sugars as well as the highest catalase activity. Microshoots formed on the medium with zeatin showed the lowest polymorphism (below 4%) relative to a stock plant.

The long-term durability of hydraulic concrete infrastructure is severely compromised by water penetration, carbonation, and chloride ion erosion, necessitating the development of high-performance protective coatings. This study designed two polyaspartic ester polyurea coatings, PAE-PTMEG and PAE-PPG, derived from isocyanate prepolymers with polytetramethylene ether glycol (PTMEG) and polypropylene glycol (PPG) soft segments, respectively. The results demonstrated that the PTMEG-based prepolymer exhibited higher reactivity, leading to shorter curing times. The resulting PAE-PTMEG coating showed outstanding mechanical properties (tensile strength: 43.8 Mpa; elongation: 646.1%) and excellent water resistance (<1% absorption), attributable to its well-defined microphase-separated structure. When formulated into a practical paint (PAE-C), it surpassed mechanical standards for waterproofing and demonstrated exceptional resistance to chloride ion penetration (1.3 × 10-4 mg·cm-2·d-1), complete carbonation resistance, and high frost resistance (200 cycles). This work confirms that tailoring the soft segment structure is a crucial strategy for developing durable polyurea coatings, with PAE-PTMEG showing significant potential for protecting critical water conservancy infrastructure.

For the construction in the Far North, it is important to use high-strength building materials with high frost resistance, strength and low density. Such materials include nano concrete, which includes stabilized dispersions of carbon nano-tubes. The strength and relatively light weight of the reinforced concrete product based on nano concrete determines its high characteristics of the object, which leads to a reduction in transportation costs, labor intensity, installation of structural elements and reduces the cost of the construction object by 20%. A 6x6-meter garage has been proposed as an experimental building in the conditions of the Far North. For the construction, three-layer nano concrete wall panels were man-ufactured using mobile plant technology. The use of nano concrete made it possible to reduce the thickness of the concrete layer in the structural element on each side to 25 mm and reduce the weight of the product, as well as reduce the consumption of cement in the concrete mixture.

The modern level of technological development involves the use of traditional materials modified with additives of various types and functional purposes, as well as composite materials allowing to obtain a product with improved properties. Expanding the area of application of products based on gypsum for facade systems involves the creation of weather-resistant, and, first of all, waterproof materials based on gypsum polymers. The purpose of the experiment, the results of which are presented in the article, was to assess the possibility of using polycondensation polymers as a component of gypsum polymer, to model the properties of the material and to evaluate its characteristics as a result of climatic and humidity influences. The modeling and optimization of gypsum polymer properties were based on statistical methods as well as methods of mathematical analysis of functions of several variables. The assessment of the water resistance of gypsum polymer samples was carried out under test conditions in an open reservoir with an almost unlimited reaction capacity of the medium. The weather resistance was checked according to the results of tests in a climatic chamber. Experiments have shown that the strength of samples with 20% modified melamine-formaldehyde resin in compression and in bending for 80 days of storage in air increases by 30% and 25%, respectively. The compressive strength is 60 MPa, and the flexural strength is 12 MPa. Gypsum polymer has high frost resistance up to 150 cycles of alternate freezing and thawing. The result of the research was the confirmation of the possibility of using polycondensation resins and the foundations of the method for selecting the composition of the gypsum polymer were developed. The results obtained can be used in the development of the technology of gypsum polymer products, and, in particular, piece products (building cladding tiles).

This study investigates the influence of waste-based materials, namely drinking water treatment sludge (DWTS) and expanded glass production waste (EGPW), on the properties of fine-grained concrete when used as partial Portland cement replacements. Fine-grained concrete mixtures containing different proportions of DWTS and EGPW were evaluated in terms of hydration behavior, microstructural development, mechanical performance, durability, and dimensional stability. Density, ultrasonic pulse velocity, water absorption, flexural and compressive strengths, drying shrinkage, and porosity parameters were determined, while frost resistance was assessed and predicted based on porosity characteristics. Hydration kinetics were analyzed using X-ray diffraction and semi-adiabatic calorimetry. The results showed that increasing EGPW content enhanced cement hydration processes and promoted matrix densification through pozzolanic reactions, resulting in reduced water absorption and improved mechanical properties. In contrast, DWTS exhibited an inhibiting effect on hydration due to its inert nature and high Fe2O3 content, acting primarily as a micro-filler; however, when combined with EGPW at moderate dosages, DWTS contributed positively to flexural strength and slightly reduced drying shrinkage. The combined use of DWTS and EGPW enabled the formation of a balanced pore structure and improved the durability of fine-grained concrete. Among the tested mixtures, ED-3 (7.5% EGPW + 5% DWTS) provided the most favorable balance between hydration activation and binder reduction, while the highest frost resistance was achieved by the ED-4 mixture, reaching approximately 603 predicted freeze–thaw cycles. Overall, the results indicate that properly optimized combinations of EGPW and DWTS can significantly enhance the performance and durability of fine-grained concrete while controlling drying shrinkage.

The foliar frost resistance of Pittosporum eugenioides, P. obcordatum, P. tenuifolium , and P. crassifolium increased from ‐6°C to ‐8°C in March and April to between ‐9°C and ‐10°C in July. Leaves of P. obcordatum had the lowest frost resistance (‐7°C) in April, but showed the highest resistance (&lt;‐10°C) in July. The foliar frost resistance of P. eugenioides is greater than that previously recorded, similar to that of P. crassifolium and P. tenuifolium , and is consistent with the widespread distribution of this species within New Zealand. The relatively high frost resistance of leaves of P. obcordatum is in accord with its occurrence in frost‐prone habitats. Seedlings of P. eugenioides subjected to short days and night‐time temperatures around 0°C became about 1°C more frost resistant than untreated seedlings in autumn (April and May). The maximum frost resistance (‐11°C) attained by treated seedlings of this species was no greater than that of untreated seedlings, but was 2°C greater than that of adult plants in the field. The youngest and oldest leaves of seedlings were less frost resistant than leaves of intermediate age.