scholarly journals Nano- and Micro-Modification of Building Reinforcing Bars of Various Types

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 323
Author(s):  
Aleksandr Rudenko ◽  
Alexander Biryukov ◽  
Oleg Kerzhentsev ◽  
Roman Fediuk ◽  
Nikolai Vatin ◽  
...  
Keyword(s):  
Modulus Of Elasticity ◽  
Average Distance ◽  
Polymeric Materials ◽  
High Strength ◽  
Polymer Materials ◽  
Reinforcing Bars ◽  
Nanosized Powders ◽  
Plastic Properties ◽  
Resistance Decrease ◽  
Composite Reinforcement

Fiber-reinforced plastic (FRP) rebar has drawbacks that can limit its scope, such as poor heat resistance, decrease its strength over time, and under the influence of substances with an alkaline medium, as well as the drawback of a low modulus of elasticity and deformation. Thus, the aim of the article is the nano- and micro-modification of building reinforcing bars using FRP rebars made of basalt fibers, which were impregnated with a thermosetting polymer binder with micro- or nanoparticles. The research discusses the major results of the developed composite reinforcement with the addition of micro- and nanosized particles. The microstructure of FRP has been studied using scanning electron microscopy. It was revealed that dispersion-strengthened polymer composites with the inclusion of microsilica (SiO2) and nanosized aluminum oxide (Al2O3) particles have a much higher modulus of elasticity and strength when compared with the original polymer materials. In the course of the experiment, we also studied the retained plastic properties that are characterized by the absence of fragility. However, it was found that the high strength of materials was attained with a particle size of 10–500 nm, evenly distributed in the matrix, with an average distance between particles of 100–500 nm. It was also exhibited that composite reinforcement had improved the adhesion characteristics in comparison with both steel reinforcement (1.5–2 times, depending on the diameter), and with traditional unmodified FRP rebar (about 1.5 times). Thus, the use of micro-/nanosized powders increased the limit of the possible temperature range for the use and application of polymeric materials by almost two times, up to 286–320 °C, which will undoubtedly expand the range of the technological applications of products made of these materials.

scholarly journals INFLUENCE OF SHUNGITE ON PERFORMANCE PROPERTIES OF POLYMERIC COMPOSITE MATERIAL

2020 ◽  
pp. 96-105
Author(s):  
N. Klyuchnikova ◽  
A. Piskareva ◽  
K. Urvanov ◽  
S. Gordeev ◽  
I. Genov
Keyword(s):  
Food Industry ◽  
Chemical Resistance ◽  
Natural Fibers ◽  
Polymeric Composite ◽  
Polymeric Materials ◽  
High Strength ◽  
Polymer Materials ◽  
Polymeric Composite Material ◽  
Bactericidal Properties ◽  
Production Technologies

Polymers are increasingly replacing conventional materials such as wood, metals, natural fibers. This is due to a number of advantages of polymer materials over classic ones: increased chemical resistance to aggressive environments, high strength indicators and durability in the operation of products. In addition, polymeric materials are actively used in the food industry. The use of polymer packaging is reaching global proportions. Improving production technologies and formulations allows to create new polymer composites with improved properties, which gives the rapid growth of the polymer industry. In order to impart the necessary properties, fillers are introduced into the polymeric material. By introducing such additives into the polymer, it is possible to control the properties of the material obtained, for example, viscosity, density, transparency, bactericidal and other important properties. The article considers the influence of shungite on the operational properties of the finished composite based on low-pressure polyethylene. The research results showed that the composite obtained provides the highest characteristics with respect to light reflection and absorption for all wavelength regions that are important during operation, has bactericidal properties, and it has been proved that in the shungite-filled polymer, a shift in the temperature of the onset of thermal degradation towards higher temperatures is observed. The composite acquires higher operational and physico-mechanical properties.

Prediction of Deformation Processes of Polymeric Materials Taking into Account Plastic Irreversible Deformation

2021 ◽  
Vol 1022 ◽  
pp. 52-61
Author(s):  
Aleksey V. Demidov ◽  
Avinir G. Makarov ◽  
Nina V. Pereborova
Keyword(s):  
Hollow Structure ◽  
Polymeric Materials ◽  
High Strength ◽  
Textile Yarn ◽  
Polymer Materials ◽  
Prediction Errors ◽  
Synthetic Fibers ◽  
Plastic Component ◽  
Innovative Materials ◽  
Deformation Processes

The need to develop new methods for predicting the properties of polymeric materials is also justified by the goal of designing new innovative materials with the required functional properties and increased competitiveness. The classical methods for predicting deformation processes of polymeric materials are based on the numerical solution of integral constitutive equations for polymer viscoelasticity of the Boltzmann-Volterra type, which do not consider corrections for the irreversibility of the plastic component of deformation and therefore can lead to significant prediction errors. To improve the accuracy of predicting the deformation processes of polymer materials it is proposed to introduce a physically justified correction with account for the irreversibility of the plastic component of deformation. The introduction of this correction significantly increases the reliability and accuracy of predicting the functional and operational properties of polymer materials. The article suggests demonstrating the methods for predicting deformation processes with the example of the polyester textile yarn made of polyester fibers. Unlike many other synthetic fibers, the polyester ones have such important properties as structural stability, softness along with high strength, elasticity, resilience, tensile strength, crease and pilling resistance, temperature regulation, shape retention, etc. The polyester fiber has a hollow structure and its single components have the form of spiral springs which give the effect of a springy base when intertwined.

Possibilities of using biodegradable polymeric materials in the agricultural sector

2020 ◽  
Vol 67 (2) ◽  
pp. 115-120
Author(s):  
Raisa A. Alekhina ◽  
Victoriya E. Slavkina ◽  
Yuliya A. Lopatina
Keyword(s):  
Mechanical Properties ◽  
Biodegradable Polymers ◽  
Biodegradable Polymer ◽  
Agricultural Sector ◽  
Polymeric Materials ◽  
Polymer Materials ◽  
Limiting Factors ◽  
Research Purpose ◽  
Biodegradable Materials ◽  
Advantages And Disadvantages

The article presents options for recycling polymers. The use of biodegradable materials is promising. This is a special class of polymers that can decompose under aerobic or anaerobic conditions under the action of microorganisms or enzymes forming natural products such as carbon dioxide, nitrogen, water, biomass, and inorganic salts. (Research purpose) The research purpose is in reviewing biodegradable materials that can be used for the manufacture of products used in agriculture. (Materials and methods) The study are based on open information sources containing information about biodegradable materials. Research methods are collecting, studying and comparative analysis of information. (Results and discussion) The article presents the advantages and disadvantages of biodegradable materials, mechanical properties of the main groups of biodegradable polymers. The article provides a summary list of agricultural products that can be made from biodegradable polymer materials. It was found that products from the general group are widely used in agriculture. Authors have found that products from a special group can only be made from biodegradable polymers with a controlled decomposition period in the soil, their use contributes to increasing the productivity of crops. (Conclusions) It was found that biodegradable polymer materials, along with environmental safety, have mechanical properties that allow them producing products that do not carry significant loads during operation. We have shown that the creation of responsible products (machine parts) from biodegradable polymers requires an increase in their strength properties, which is achievable by creating composites based on them. It was found that the technological complexity of their manufacture and high cost are the limiting factors for the widespread use of biodegradable polymers at this stage.

scholarly journals Study on the Bending and Joint Performances of Reinforced Concrete Beams Using High-Strength Rebars

2021 ◽  
Vol 13 (6) ◽  
pp. 3482
Author(s):  
Seoungho Cho ◽  
Myungkwan Lim ◽  
Changhee Lee
Keyword(s):  
Yield Strength ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
High Yield ◽  
Performance Tests ◽  
Reinforcing Bars ◽  
Joint Performance ◽  
Lap Splice ◽  
Reinforcing Bar ◽  
Nominal Strength

High-strength reinforcing bars have high yield strengths. It is possible to reduce the number of reinforcing bars placed in a building. Accordingly, as the amount of reinforcement decreases, the spacing of reinforcing bars increases, workability improves, and the construction period shortens. To evaluate the structural performance of high-strength reinforcing bars and the joint performance of high-strength threaded reinforcing bars, flexural performance tests were performed in this study on 12 beam members with the compressive strength of concrete, the yield strength of the tensile reinforcing bars, and the tensile reinforcing bar ratio as variables. The yield strengths of the tensile reinforcement and joint methods were used as variables, and joint performance tests were performed for six beam members. Based on this study, the foundation for using high-strength reinforcing bars with a design standard yield strength equal to 600 MPa was established. Accordingly, mechanical joints of high-strength threaded reinforcing bars (600 and 670 MPa) can be used. All six specimens were destroyed under more than the expected nominal strength. Lap splice caused brittle fractures because it was not reinforced in stirrup. Increases of 21% to 47% in the loads of specimens using a coupler and a lock nut were observed. Shape yield represents destruction—a section must ensure sufficient ductility after yielding. Therefore, a coupler and lock nut are effective.

Effect of CO2 Curing on the Strength of High Strength Pervious Concrete

2020 ◽  
Vol 846 ◽  
pp. 207-212
Author(s):  
Ming Gin Lee ◽  
Yung Chih Wang ◽  
Wan Xuan Xiao ◽  
Ming Ju Lee ◽  
Tuz Yuan Huang
Keyword(s):  
Carbon Dioxide ◽  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
High Strength ◽  
Pervious Concrete ◽  
Control Group ◽  
Curing Time ◽  
Compressive Strength Of Concrete ◽  
Curing Pressure

This study was conducted to assess the effect of CO2 curing on the compressive strength of high strength pervious concrete. The factors studied to evaluate compressive strength of concrete on CO2 curing pressure, curing time, and age of specimen at testing. Three Aggregate sizes, three CO2 curing pressures, three CO2 curing time, and three testing ages were used in this investigation. The research tried to produce a high strength pervious concrete and use carbon dioxide for curing to find out whether it could enhance the compressive strength. The results show that the compressive strength of the control group increases rapidly and its 90-day compressive strength closed to 60 MPa. The 1-day compressive strength has a major impact after CO2 curing and their strength decreased by about 0% to 50% as compared to the control group. However, it is observed that there is only slight difference in relationship between modulus of elasticity and compressive strength obtained from 100 by 200mm cylinders with CO2 curing.

Effects of Two Polypropylene Fibers on the Properties of High Strength Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 1328-1331
Author(s):  
Bai Rui Zhou ◽  
Dong Dong Han ◽  
Jian Hua Yang ◽  
Yi Liang Peng ◽  
Guo Xin Li
Keyword(s):  
Portland Cement ◽  
Modulus Of Elasticity ◽  
High Strength Concrete ◽  
Polypropylene Fiber ◽  
High Strength ◽  
Polypropylene Fibers ◽  
Strength Concrete ◽  
Reticular Fiber ◽  
Binder Ratio ◽  
Water To Binder Ratio

Portland cement, crushed stone, sand and superplasticizer were used to obtain a high strength concrete with a low water to binder ratio. A reticular polypropylene fiber and a single polypropylene fiber were used to improve the strength of the high strength concrete, but the effects of the two fibers on the slump and strengths were quite different. The reasons of the differences were the surface area and the modulus of elasticity of the fibers. The results show the reticular fiber was better to used in high strength concretes.

Light-Driven Integration of Graphitic Carbon Nitride into Polymer Materials

2021 ◽  
Vol 7 (1) ◽  
pp. 9
Author(s):  
Cansu Esen ◽  
Baris Kumru
Keyword(s):  
Visible Light ◽  
Carbon Nitride ◽  
Dye Degradation ◽  
Polymer Networks ◽  
Co2 Reduction ◽  
Polymeric Materials ◽  
Polymer Materials ◽  
Visible Range ◽  
Light Illumination ◽  
Present Contribution

As a metal-free polymeric semiconductor with an absorption in the visible range, carbon nitride has numerous advantages for photo-based applications spanning hydrogen evolution, CO2 reduction, ion transport, organic synthesis and organic dye degradation. The combination of g-C3N4 and polymer networks grants mutual benefit for both platforms, as networks are upgraded with photoactivity or formed by photoinitiation, and g-C3N4 is integrated into novel applications. In the present contribution, some of the recently published projects regarding g-C3N4 and polymeric materials will be highlighted. In the first study, organodispersible g-C3N4 were incorporated into a highly commercialized porous resin called poly(styrene-co-divinylbenzene) through suspension photopolymerization, and performances of resulting beads were investigated as recyclable photocatalysts. In the other study, g-C3N4 nanosheets were embedded in porous hydrogel networks, and so-formed hydrogels with photoactivity were transformed either into a ‘hydrophobic hydrogel’ or pore-patched materials via secondary network introduction, where both processes were accomplished via visible light. Since g-C3N4 is an organic semiconductor exhibiting sufficient charge separation under visible light illumination, a novel method for the oxidative photopolymerization of EDOT was successfully accomplished. As a result of the absence of dissolved anions during polymerization, so-formed neutral PEDOT is a highly viscous liquid that can be processed and post-doped easily, and grants facile coating processes.

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