Physical Andmechanical Properties Research Articles

DETERMINATION OF PHYSICAL AND MECHANICAL PROPERTIES OF POLYETHYLENE AND POLYMER NANOCOMPOSITES USING THE METHODS OF MOLECULAR DYNAMICS

Today, molecular dynamics (MD) simulation become an effective method for investigating and predicting the physical and mechanical properties (PMP) of materials at the atomic scale. In this work, initial configurations of molecular systems of pure polyethylene (PE) and carbon nanotube-reinforced nanocomposites (PE-CNT) are created and described by the united atom model and Dreiding force field. Equilibration of the initial configurations of molecular models carried out using NVT and NPT ensembles in LAMMPS. Simulated complex of PMP of PE and PE-CNT includes elastic modulus, Poisson's ratio, bulk modulus, shear modulus, yield strength, mass isobaric heat capacity, and coefficient of linear thermal expansion (CLTE). The results verification of the PE molecular model showed the obtained MD simulation data either coincide with available literature data or are close to them. The results justify the use of the same algorithms to obtaine reliable data on the PMP of PE-CNT. Comparing the complex PMP of molecular models of pure PE and PE-CNT, it was established the elastic modulus of PE-CNT α=1.4 % increases by 10.4% at 300 K and by 29.3% at 320 K. The yield strength of PE-CNT α=1.4 % also increases by 33.2 % at a strain rate of 109 s−1 and a temperature of 300 K compared to PE. Meanwhile, mass isobaric heat capacity and CLTE decrease with increasing temperature: mass isobaric heat capacity decreases by 1.3 % at 300 K and by 4.4 % at 320 K; CLTE decreases by 20.2 % at 300 K and by 22.6 % at 320 K. Nonlinear two-parameter dependencies of the PMP of PE-CNT obtained in the temperature range (280–320) K and the volume fraction of fillers (0–1.5) %. These results allow to develop of new composite materials without conducting sufficiently complex and time-consuming numerical experiments based on MD simulation. The obtained data on the complex PMP are necessary for modeling the thermo-elastic-plastic state of products made of PE-CNT under operational conditions in a continuum approximation.

ОЦІНКА ПАРАМЕТРІВ ЗОНИ РОЗВАНТАЖЕННЯ ТА ЇЇ ВИКОРИСТАННЯ ДЛЯ БЕЗПЕЧНОГО ВІДПРАЦЮВАННЯ ВИКИДОНЕБЕЗПЕЧНИХ ВУГІЛЬНИХ ПЛАСТІВ

Meta. The purpose of the research is to substantiate the main characteristics of the unloading zone in the bottom-hole part of the seam and to clarify the parameters of its use for the safe mining of outburst-hazardous coal seams. Research methodology. The article analyzes the results of determining the size of the unloading zone by various methods of monitoring the effectiveness of the measures taken and the danger of coal mining in this zone. Results. The definition of the unloading zone as some degassed part of the mountain massif with destroyed or extracted coal is formulated, when discussing the obtained results. It has been established that in this zone there is a possibility of excavation coal to a given depth without anti-emission measures with the possibility of adjusting the amount of excavation by the depth of the unloading zone, taking into account non-reducing advance. The size of the unloading zone is determined by the time bottomhole sludge, taking into account: SSS (stress-strain state), PMP (physical and mechanical properties), geological factors and technology of destruction of the array. Scientific novelty. The size of the unloading zone may vary depending on the technological factor (excavation technology). For example, with a fast plow cut, the zone does not have time to form, i.e. when a plow (combine) either takes out a strip along the entire length of the lava or can be cut forward by 2-3 m. Practical significance. The performed studies established the fact of the formation of an unloaded zone in the bottom-hole part of the formation. The time interval for the formation of an unloading zone is from 1 to 3 hours for mechanized coal mining and up to 24 hours for explosive breaking of coal, which is practically used in regulating the duration of technological processes. The unloading zone on outburst-prone formations varies from the minimum dimensions close to zero to several meters.

Physical and Mechanical Properties of Selected Fruit-bearing and Underutilized Tree Species in the Philippines

To help augment the raw material supply of the wood-based industries, the study evaluated the physical and mechanical properties (PMP) of six selected timber species in the Philippines – four fruit-bearing and two underutilized tree species. The fruit-bearing species were “nangka” (Artocarpus heterophyllus Lamk.), “santol” [Sandoricum koetjape (Burm. F.)], “durian” (Durio zibethinus Murray), and “marang” [Litsea perrottetti (Blume) F. Vill.] collected from Bislig, Surigao del Sur (Caraga Region, Mindanao), while the underutilized tree species were “antipolo” [Artocarpus blancoi (Elmer) Merr] and “batino” (Alstonia macrophylla G. Donn) collected from Batangas City and Quezon Province (Region IV, Luzon), respectively. Physical properties included relative density (RD), moisture content (MC), and shrinkage. Mechanical properties covered modulus of rupture, stress at proportional limit, and modulus of elasticity in static bending; compression parallel-and perpendicular-to-grain; shear; hardness; and toughness. Standard testing procedures (ASTM-D143) were followed. Variations on the six species’ PMP were statistically analyzed, including the effect of individual trees and height levels. Among the six species, batino exhibited the highest RD (0.60), followed by nangka (0.49), antipolo (0.47), santol (0.46), marang (0.36), and durian (0.34). The MCs of nangka, santol, durian, antipolo, batino, and marang were 111.07, 121.21, 183.7, 152.68, 85.77, and 189.97% while the volumetric shrinkages (VSs) were 6.67, 6.86, 6.96, 9.07, 12.23, and 9.39%, respectively. The RD of batino was classified moderately high; those of nangka, santol, and antipolo were moderately low; and those of marang and durian were low. There was an inverse relationship between RD and MC in the six species. The VS values of nangka, durian, and santol were classified low; those of batino were medium; and those of antipolo and marang were moderately low. Overall, the mechanical properties of batino were moderately high; those of nangka, santol, and antipolo were moderately low; and those of durian and marang were low. The mechanical properties of the six species were compared with those of the “Philippine mahogany” species traditionally used for construction.

INVESTIGATION OF THE INFLUENCE OF MICROWAVE RADIATION ON THE PROPERTIES OF GRANULAR HEAT INSULATION MATERIALS BASED ON LIQUID GLASS

The main methods of improving the performance of granular thermal insulationmaterials based on liquid glass are chemical methods of their modification, which are based onchanging their structure through the use of special ingredients. At the same time, there is a need to introduce often a large number of components and individual technological operations, which is notalways technological. One of the promising methods of changing the physical state of substancesunder the action of an electromagnetic field is non-thermal treatment of microwave radiation. Theadvantages of using microwave radiation in comparison with the generally accepted methods ofmodification of materials are the transformation of their structure without significant changes in thetechnological process and the need to use additional components. Due to volumetric heating and themechanism of non-thermal action of microwave radiation on processing objects the duration of theirheating considerably decreases. When microwave heating of a liquid glass composition part of theenergy of electromagnetic radiation is converted into heat, which contributes to the intense swellingof the material, and the other part is aimed at structural changes in the material, which improve itsproperties due to the non-thermal effect of microwave radiation. Studies show that the best set ofperformance properties have granular materials obtained under the action of microwave radiationat a power of 650 W, which corresponds to a temperature of 110-120 0C. The required duration ofsuch heat treatment is 6-7 minutes. The closest to them in terms of coefficient of swelling are materialsobtained by convective heating at a temperature of 200 0C for 1 hour, but their physical andmechanical properties are much lower. Thus, it can be noted that the use of microwave radiationallows to obtain granular thermal insulation materials with a better set of performance properties atlower energy costs for their production.

Мелкозернистый бетон на основе техногенного сырья для дорожных покрытий .

On the basis of technogenic raw materials – ash and slag waste and burnt rocks of mine dumps – the compositions of fine-grained concrete were selected. The developed compositions have been tested in the manufacture of pilot batches of paving slabs. The introduction of fly ash and crushing screenings of burnt rocks into the composition of concrete improves the physical and mechanical properties of products with significant savings in cement. The applicability of the investigated technogenic raw materials in fine-grained concrete, intended for the manufacture of paving slabs and road paving elements, has been proved. Products have high indicators of physical and mechanical properties and quality.

Express ultra-jet diagnostics of defect resistance for surface layer of a material

In the manufacture of products of modern technology, such technologies of waterjet processing as water jet cutting are successfully used for cutting materials. However, the physical and energy basis of ultrajet technology predetermines a much broader scope of its practical applications. Most of modern technical products are made of composite materials. Moreover, some of them were obtained by innovative methods, for instance, selective laser fusion, which complicates their diagnostics. This article proposes an innovative method for determining a new informative parameter characterizing the defect resistance of various materials. This technique is based on the process of hydro-erosive destruction in the process of ultrajet exposure to a high-energy jet on the surface of the material being diagnosed. Ultra-jet diagnostics (UJD) is based on the analysis of the dependence of the characteristics of local hydro-erosion of the diagnosed area of the surface of the object under analysis (OA) on the parameters of its quality. Surface quality parameters include physical and mechanical properties (PMP) and the degree of operational and technological damage. In this article a new formula has been developed that numerically determines the degree of defect resistance of materials. Experimental testing of this technique on some types of modern materials confirms its reliability. The directions of the future development of the research results are formulated.

Applied Research on Prediction Methods of Properties of Particleboard Based on Data-Driven Methods

As a kind of wood-based panel, particleboard is widely used in production and daily life. The physical and mechanical properties (PMPs) of particleboard play a decisive role in its practical application. At present, destructive methods are primarily used to measure the actual properties of particleboard on the production line, which is a waste of resources and time-consuming method. In order to solve these problems, this paper uses several data-driven methods to predict the PMPs of particleboard. Firstly, the data set is constructed based on the parameters of particleboard production process. Secondly, seven commonly used data-driven methods are used to build models to predict the PMPs. Finally, three different assessment indexes are used to determine the most suitable method for property prediction. The results showed that the random forest method is better for predicting the PMPs of particleboard.

Miscanthus x giganteus as a building material - lightweight concrete

A perennial plant Miscanthus x giganteus has found its habitat and multiple applications in Europe, despite the fact that it originates from Asia. This study presents the potential use of this plant in new lightweight concrete materials so-called bio-concretes. The above-ground part of the plant was harvested, dried, crushed, and mixed with binders in different proportions. After casting and drying, the samples were characterized physical and mechanical properties. The results have shown that the sample with a higher content of binders while smaller miscanthus granulation and casted in molds under higher pressure exhibited the highest values of the compressive strength and density. In specific, the density was in the order of magnitude of that reported for other types of lightweight concrete with organic fillers, such as sawdust-based concrete ("Durisol"), which further justifies the use of miscanthus for these purposes.

New technology for production of leather for gloves and fancy goods

The results of the development of chromium saving method for obtaining of glove-haberdashery leather, allowing to improve the quality of leather and to provide the ecological safety of production, are presented in the paper. Leather tanning with ecologically harmless tannages under proper parameters and consumption of chemical materials has been carried out in semi-production conditions. The improvement of glove-haberdashery leather quality had been achieved by partial replacement of chromium by complex compounds, containing titanium and aluminum. Physical and mechanical properties of glove-haberdashery ecologically harmless leathers corresponded the standard norms and can be recommended for production of men’s and women’s gloves.

BLAST-WAVE IMPULSE COMPACTION OF THE VISCOELASTOPLASTIC MOLDING SAND

This article examines the compaction process in the green molding sand by the explosive impulse ofcombustion gas. The study was taken on a testing device based on the semi-automatic molding machine. Thedependence of mold density on impulse power and physical and mechanical properties of the sand has been found.An explosion pressure wave drives the sand column in a flask. The sand moves gradually by layers. Each layer firstaccelerates, then moves uniformly, decelerates and eventually stops. Here, the layer is compacted due to the kineticenergy of its movement. The higher the velocity of the molding sand is, the higher its kinetic energy and thecompressive stress gained during the compaction, are. Fluidity of the molding sand depends on its physical andmechanical properties, particularly on its viscosity. The behavior of viscous, elastic and plastic properties of themolding sand during the compaction process has been researched using the self-designed device. During thecompaction process, the parameters interchange, while the value of the sum is constant. During the accelerationphase, the molding sand has minimal elastic properties, the viscous properties recede and plastic properties enhance.During the uniform motion of the sand, its viscous properties are minimal, while the plastic properties enhance to themaximum. Then till the end of the process, viscous properties keep enhancing up to 80…90 %, while plasticproperties recede almost to zero. Elastic properties slightly enhance almost linearly during the whole process.

SPATIAL VARIABILITY OF PHYSICAL AND MECHANICAL PROPERTIES OF ROCK MASS IN CENTRAL KAZAKHSTAN

The efficiency and quality of drilling and blasting operations in the development of mineral deposits largely depend on the variability of the properties of the rock mass. With a detailed study of various geological objectsmineral deposits or structural elements of the earth’s crust of any order, up to a single layer or block, it is possible to create three-dimensional digital models. The article considers the possibility of spatial variability of rock mass properties in Central Kazakhstan by means of mathematical modeling using data from the drilling process control file of the Aquila system of a DH-M drilling rig. To assess the structure and condition of the rock mass, it was constructed two-dimensional sections digital model, which shows the spatial variability of physical and mechanical properties. A pseudolinear approximation between the file vectors is chosen as a method for constructing twodimensional sections. The application of the mathematical method of pseudo-linear interpolation is shown, which allows with a sufficient degree of reliability to evaluate the physical and mechanical properties (PMP) of the rocks in the inter-well and inter-interval space of the rock mass. Based on the results of the study, the software was developed that provides an operational and effective assessment of the physical and mechanical properties of the rock mass with the visualization of the result. The developed approach and software can be used to improve the efficiency of drilling and blasting operations of existing mining enterprises, as well as in the implementation of scientific and industrial research on mathematical modeling of state of the rock mass.

Impact of epoxy resin modification on their strength parameters

Modifications of polymer composites are one of the fastest developing fields of technology. Research is focused on two directions: obtaining new composites or modifying existing materials. The first group of tests uses methods for preparing new chemical formulas of polymers containing, as the main structural element: carbon (organic polymers) or silicon (inorganic polymers). In the second group, the research consists in seeking methods to modify the properties of polymers. In building construction, among the others types, the glues (adhesive polymers) are used. They are exerted to connect materials with different physical andmechanical properties. Under the influence of the factor initiating the crosslinking reaction (hardener or temperature), the polymers obtain a solid form. The strength of the glued joint depends on the initial parameters of the glue resin and the target substrate of its application.The glued surface is usually the weakest element in this connection in terms of the possibility of damage due to the effects of loads, therefore methods to improve the strength parameters of adhesives are sought. The study presents the results of own research on methods of modification of a selected epoxy resin used in the technique as a glue. In order to ensure effective mixing of the adhesive with the fillers, ultrasound energy was used. After the resin had hardened, tests were carried out to determine the hardness and tensile strength of the obtained composites. Based on the results, SEM analysis and observation of the effect of ultrasound, the phenomena affecting the changes in the above mechanical properties were explained.

A Review on the Application of the Solid Waste for Building Material

The present study is an attempt to take an overview on the application of the solid waste for building material such as concrete, cement, tiles, roof, brick and geopolymer. According to the Global Environment Centre (GEC), 23,000 tons of wastes were produce every day, expected rise to 30,000 tons by 2020 and only 5% have been recycled in Malaysia. Increasing of population, rapid urbanization and industrialization affected the increasing of the number of solid waste produced. Based on Department of Statistic Malaysia (DOSM), the population growth rate of 1.1% at 2018 with estimated 32.4 million populations compared to 2017 with 32.0 million populations and estimation of the waste increase by 2020 will occur. This review discusses the incorporation of the solid waste such as fly ash, polystyrene, plastic, sludge, glass and timber dust affect the physical and mechanical properties of the building materials. In addition, this paper reviews the recycling and reusing method of the different solid waste that can be applied to building materials. Most of the building materials such as concrete and bricks mix with the different solid waste show the positive effect by producing the lightweight materials, increased in water absorption, compressive strength, the plasticity of the materials and increasing of energy saving based on various research reviews. The findings and the potential application of the different solid waste in building material may help increasing the sustainable development.

Ultrasonic method of quality control for textile materials

Purpose: The ultrasonic amplitude method for controlling the surface texture density of textile materials was first studied and used. Design/methodology/approach: For the first time, the surface texture density has been determined. The research was conducted using the ultrasonic method, rather than by mathematical calculations, which made it possible to invent a new approach to contactless quality control of textile materials. In order to identify the functionality of bicomponent textile material, formed from raw materials with opposite hygroscopic properties, two-layer knitted fabrics were chosen to protect the human respiratory organs. As a hydrophilic type of raw material used yarn with composition is as follows – cotton 34%, flax 33%, viscose 33%, and in the function of a hydrophobic raw material, polypropylene multifilament yarn. Using the ultrasonic method, studies of a new type of knitwear were carried out, the values of the surface density of the material were obtained. Products from this composition provide respiratory protection from dust and comfortable work in the area of road repairs up to 8 hours. Findings: The combination of natural and synthetic materials for individual masks allowed them to be used under different operating conditions. The problem of structure and design of materials was resolved through the use of computer technology and computer-aided design of textiles, and the possibility of applying the ultrasonic amplitude method to control the surface density of textile materials was substantiated. During the analysis of the results of experimental studies, it was found necessary to ensure the uniformity of the physical and mechanical properties of textile materials in the production process. Using the ultrasonic method, the thickness gauge was used to determine the surface density of various materials for the manufacture of personal protective equipment for road maintenance workers. Research limitations/implications: The method of measurement has been tested and has no limitations. However, the study was conducted on samples of textile materials that were manufactured in Ukraine and according to patents of authors. Practical implications: Individual masks for the protection of human respiratory organs are recommended for use by road workers and cyclists. Originality/value: The originality of the results of the article is the experimental data of studies on the content of textile materials and the accuracy of measuring their surface density by an ultrasonic contactless device.

Farklı Sıcaklık Türünün Genleştirilmiş Perlit Agregalı Betonlar Üzerindeki Etkilerinin Araştırılması

This study was carried out to investigate the effect of high temperature by using fire and oven on the physical and mechanical properties of three different concrete classes that are C16/20, C20/25 and C40/50 also, concrete samples are manufactured as containing expanded perlite aggregate (EPA) and not containing perlite aggregate. The reference temperatures are specified as 22 ºC, 100 ºC, 300 ºC, 500 ºC in the oven and the case of fire. These temperatures are applied to a sample having 100x100x100 mm3 dimensions. The tests made on each concrete type are weight per unit volume, compressive strength, and ultrasonic pulse velocity. Consequently, the test results come out statistically different of the concrete samples affected by high temperature according to if the heat is applied by the oven or fire, the compressive strength of the samples decreases as the high-temperature degree increases in a compressive strength test. Besides that, while the loss of compressive strength of oven samples at 500 ºC comes out approximately 60 %, for samples applied fire is approximately 10%.

Stability analysis of slopes along roads in bio-reinforced soil conditions

Root system has ability to stabilize slopes, improving physical and mechanical properties of soil on which it develops. Morphology and tendency of root system to compose soil particles into one monolithic mass, which we call bio-reinforced soil, contribute to increasing the resistance of soil to shearing. In this paper, is presents a comparative analysis of slope stability along roads without and with the influence of root system. The analyzes were made for the needs of defense of roads, finding most optimal types of root system as an alternative solution for stabilization of the slopes along roads. ?n the slope model was simulated influence of four groups of vegetation, based on morphology of root system (plate, heart, tap and undefined). For each selected species, value of root cohesion (cr) has been adopted. Software for geotechnical numerical modeling-GeoStudio 2007, was used for all slope stability analyzes. Analyzing stability of the slope model without influence of vegetation, slope is unstable. By calculating stability of slope model with vegetation groups, an increase in stability of the slope model is achieved. The greatest influence on stability of the slope model has group 2.- vegetation with a tap root system, followed by group 1. - with a heart root, while group 3, plate root, and group 4, undefined types of root system, gave at least the values. The results from this paper, represent a contribution to choice of solutions for stabilization of slopes along roads and the prevention of erosion processes.

Effect of Freezing and Thawing on Physical and Mechanical Properties of Sedimentary Rock

Rocks have been used as a building material throughout the history. The EngineeringProperties of rocks mainly depends on mineralogical composition and texture of therock type. Weathering processes influence the rock porosity in cold climate area. Thispaper studies the effect of weathering (freezing thawing cycles) on physical andmechanical properties of specific types of rock (sedimentary rocks). Freeze–thawcycles is one of the most important phenomena affecting the engineering propertiesof rocks. This study was conducted based on literature data to analyze the durabilityand stability of rocks throughout the physical and mechanical properties such as(density, porosity, Brazilian tensile strength, unconfined compressive strength andpoint load Index) of sedimentary rock specimens exposed to excessive amountfreezing-thawing cycles. Key factors that affecting the strength of frozen rocks wereanalyzed. Results showed that porosity and the intensity of freezing-thawing cyclesinfluenced Engineering properties of sedimentary rocks significantly. The loss inunconfined compressive strength is an important indicator for rock strength anddurability However, this test is extremely expensive and tedious. Therefore, differentcorrelations and Statistical models were developed using multiple regression analysesto predict the mechanical properties of rocks such as unconfined compressivestrength and tensile strength from other physical properties and corresponding tospecified number of F-T cycles. The models are very reliable with R 2 = 95% and can be used to predetermination of unconfined compressive strength and tensile strengthof sedimentary rocks.

Scope of Dry Wood and Wood Composite Alternate to Stone in Case of Acid Wash on Denim Fabric

For the betterment of comfort ability, to impart decent fading effect and to make more exquisite, denim fabric is examined with different washing techniques. Usually, Acid wash is used to fade the color of denim to a higher degree and therefore this wash has a significant effect on the physical and mechanical properties of the denim. In this paper, we worked on to find out the comparison among stone, waste wood and wood composite in case of acid wash on denim fabric dyed with indigo dye. Denim garments were processed using some parameters such as temperature 30 °C, time 30 min as well as acid concentration (H3PO4) 1 ml/L, (KMnO4) 4 gm/l. This study was focused on the physical and mechanical properties like strength, weight loss, shrinkage, EPI and PPI, absorbency, color fading, GSM, wash, rubbing and perspiration fastness test and monitored the comparison of each treated and untreated fabric samples. It was noticeable that, a significant difference was found in case of Waste wood washed and wood composite washed garments in almost all properties than stone washed garments but the desired fading effects were achieved by acid washing with wood composite on denim fabric.

FORECASTING THE CONDITION OF PETROLEUM IMPREGNATED LOAD-BEARING CONCRETE AND REINFORCED CONCRETE STRUCTURES

Petroleum products (PP) used in industrial processes systematically fall on the load-bearing CRC structures and gradually impregnate therein. Currently, available guidelines for the assessment of technical condition and reliability of load-bearing CRC structures do not fully take into account the effect of viscosity of PP that impregnated therein. Our study was performed on the basis of analyzing, generalizing and evaluations of experimental data on the effect of PP of different viscosities on the physical and mechanical properties (PMP) of concrete using the methods of probability theory and mathematical statistics. The obtained results allow to constitute a scientifically substantiated forecast of changes in PMP of PP impregnated load-bearing CRC structures and to provide a quantitative characterization of their technical condition.

Sand Cement Brick Containing Recycled Concrete Aggregate as Fine-Aggregate Replacement

Nowadays, the usage amount of the concrete is increasing drastically. The construction industry is a huge consumer of natural consumer. It is also producing the huge wastage products. The usage of concrete has been charged to be not environmentally friendly due to depletion of reserve natural resources, high energy consumption and disposal issues. The conservation of natural resources and reduction of disposal site by reuse and recycling waste material was interest possibilites. The aim of this study is to determine the physical and mechanical properties of sand cement brick containing recycled concrete aggregate and to determine the optimum mix ratio containing recycled concrete aggregate. An experiment done by comparing the result of control specimen using 100% natural sand with recycled concrete aggregate replacement specimen by weight for 55%, 65%, and 75%. The sample was tested under density, compressive strength, flexural strength and water absorption to study the effect of using recycled concrete aggregate on the physical and mechanical properties of bricks. The result shows that the replacement of natural sand by recycled concrete aggregate at the level of 55% provide the highest compressive and flexural strength compared to other percentage and control specimen. However, if the replacement higher than 55%, the strength of brick was decreased for compressive and flexural strength, respectively. The relationship of compressive-flexural strength is determined from statistical analysis and the predicted result can be obtained by using equation ff,RCA = 0.5375 (fc)0.3272.