Physicomechanical Parameters Research Articles

Nanocomposite films based on CMC, okra mucilage and ZnO nanoparticles: Physico mechanical and antibacterial properties

This work examined the physico mechanical parameters and antibacterial activity of CMC/okra mucilage (OM) blend films containing ZnO nanoparticles (NPs). Different proportions of CMC and okra mucilage (100/0; 70/30; 60/40 and 50/50 respectively), were mixed and casted to posterior analysis of formed films. The more colored films were obtained by higher contents of okra mucilage and adding ZnO nanoparticles. The incorporation of ZnO NPs into CMC film decreased the elongation at the break (EB) value of the films and increased the tensile strength (TS) value of the film. With increase in CMC concentration in the films, higher water vapor permeability and higher solubility in water were achieved. Microstructure analysis using SEM showed a smooth and compact surface morphology, homogeneous structure, and a rough surface for CMC, CMC+ZnO, and CMC/OM30%+ZnO, respectively. Nanocomposite films presented antibacterial activity against tested bacteria. Films contained okra mucilage showed more antibacterial activity. The inhibitory activities of resultant films were stronger against S. aureus than E. coli.

Time-Keeping Factor at a Constant Temperature in the Process of Spark Plasma Sintering

The dependence of the effect of time delay at a constant maximum temperature on the physicomechanical parameters of the sintered sample has been considered. Based on the results of the work, it can be concluded that it is necessary to reduce the duration of all sections of the sintering process in order to exclude the recrystallization factor, which worsens the parameters of the ceramics.

SYNTHESIS AND PROPERTIES OF AROMATIC POLYESTERS WHITH CARDED FRAGMENTS

Polyethers are of great interest for various industries due to a complex of valuable properties, such as heat resistance, fire resistance, high strength, etc. Carded polymers occupy a special place among polymers with increased heat resistance, containing in the main polymer chain at least one element that is part of the lateral cyclic grouping. The presence of such fragments increases the glass transition temperature and heat resistance, which allows the copolymers to be operated at higher temperatures without changing the physico-mechanical parameters. For crystalline polymers, the presence of cardo fragments leads to better solubility in organic solvents. One of the promising ways of synthesizing heat-resistant polymeric materials is based on the use of aromatic compounds such as 3,3-bis (4'-hydroxyphenyl) phthalide, 3-chloro-3- (diphenyloxyd-4'-yl) phthalide, 3- chloro-3- (diphenylsulfide-4'-yl) phthalide, 9,9-bis (4'-hydroxyphenyl) fluorene, 9,9-bis (4'-hydroxyphenyl) anthrone-10, 2-phenyl-3,3- Bis (4'-hydroxyphenyl) phthalimidine and the like. At present, the worldwide problem of the release of toxic waste into the environment is aggravated, which causes irreversible climatic changes. To solve this problem, it was proposed to develop solid fuel cells based on polymeric proton-exchange membranes. Thus, polymer membranes must satisfy a number of requirements: to provide minimal ohmic losses, to possess considerable proton conductivity, mechanical strength, thermal stability and to have limited solubility in organic solvents. Polymer membranes with carded fragments in the main chain satisfy all the requirements. In the presented review features of synthesis and properties of copolymers on the basis of polysulfones, polyether ketones, polyetherimides with carded fragments are considered.Forcitation:Shakhmurzova K.T., Kurdanova Zh.I., Zhansitov A.A., Baiykaziev A.E., Khashirova S.Yu., Pakhomov S.I., Ligidov M.Kh.Synthesis and properties of aromatic polyesters whith carded fragments. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 6. P. 28-39.

Research on Similar Materials for Rheological Test of Hard Rock Mass

The analog material, used in the Geo-mechanical model test that is designed to study the unloading rheological behavior and failure characteristics of rock mass, must reflect the physico-mechanical behaviors of the actual rock mass. The surrounding rock of Meng-di-gou hydropower station is in complex geological conditions. With the excavation of the rock mass, the surrounding rock gradually unloading, and the property of the near rock mass. It is necessary to carry out Geo-mechanical model test to study the rheological properties of deep rock mass under complicated geological conditions. So the similar material, comprised of iron powder, barite powder, and quartz sands bound with a solution of alcohol and colophonium, is suggested to be improvable. Firstly, through more than 300 groups of mix proportion tests, the influence of different mix proportions of the ingredients are analyzed to obtain the optimal analog materials; Secondly, more than 1200 specimens are made into size Φ50mm×100mm; Lastly, physico-mechanical tests were conducted by using the specimens to test the mechanical property of the similar material, and the basic physico-mechanical parameters are obtained from the analog material. The results indicates that the property of the similar material matches well with that of the rock mass in site, so the similar material is suitable for the Geo-mechanical model test, and it can be used to test the unloading rheological behavior of rock mass of Meng-di-gou hydropower station.

Analysis of the dependence of the global load on the mechanical parameters of ice under interaction between an ice field and construction

A series of problems concerning interaction between an ice field and a vertically plane construction has been solved numerically using a computing system based on the discontinuous Galerkin method. The results of calculations have been processed, and the maximum global load upon the construction at different physicomechanical parameters of ice has been analyzed based on these data. The chosen parameters were Young’s modulus, the yield stress, tensile stress, and plastic failure strain.

Orientation Processes in Crystalline and Amorphous Regions of Polypropylene During Yarn Spinning

The influence of the spinneret draw ratio and subsequent solid-state stretching of polypropylene multifilament yarns (PMY) on changes in the orientation of crystallites and molecular chains in the polymer amorphous regions was studied using x-ray structure analysis. It was shown that crystallites and molecular chains of amorphous polypropylene (PP) became significantly more oriented already for a yarn spinneret draw ratio of 2400% and changed little if it was increased further. Additional solid-state stretching of yarns at elevated temperature had practically no effect on the orientation of PP crystallites but did halve the misorientation angle of molecular chains in the polymer amorphous regions. This phenomenon suggested that the substantial decrease of the elongation at break and increase of PMY physicomechanical parameters could be attributed to distribution of the applied load onto a larger number of continuous chains.

The Influence of Temperature on Time-Dependent Deformation and Failure in Granite: A Mesoscale Modeling Approach

An understanding of the influence of temperature on brittle creep in granite is important for the management and optimization of granitic nuclear waste repositories and geothermal resources. We propose here a two-dimensional, thermo-mechanical numerical model that describes the time-dependent brittle deformation (brittle creep) of low-porosity granite under different constant temperatures and confining pressures. The mesoscale model accounts for material heterogeneity through a stochastic local failure stress field, and local material degradation using an exponential material softening law. Importantly, the model introduces the concept of a mesoscopic renormalization to capture the co-operative interaction between microcracks in the transition from distributed to localized damage. The mesoscale physico-mechanical parameters for the model were first determined using a trial-and-error method (until the modeled output accurately captured mechanical data from constant strain rate experiments on low-porosity granite at three different confining pressures). The thermo-physical parameters required for the model, such as specific heat capacity, coefficient of linear thermal expansion, and thermal conductivity, were then determined from brittle creep experiments performed on the same low-porosity granite at temperatures of 23, 50, and 90 °C. The good agreement between the modeled output and the experimental data, using a unique set of thermo-physico-mechanical parameters, lends confidence to our numerical approach. Using these parameters, we then explore the influence of temperature, differential stress, confining pressure, and sample homogeneity on brittle creep in low-porosity granite. Our simulations show that increases in temperature and differential stress increase the creep strain rate and therefore reduce time-to-failure, while increases in confining pressure and sample homogeneity decrease creep strain rate and increase time-to-failure. We anticipate that the modeling presented herein will assist in the management and optimization of geotechnical engineering projects within granite.

Analysis of results of interpretation of elastic parameters of solid core of the Earth from the standpoint of current geomechanics

It follows from the basic principles of mechanics of deformable solids relating to the strength, stability and propagation of elastic waves that the inner core of the Earth cannot exist in the form of a spherical structure in the assumed thermobaric conditions and calculation values of physico-mechanical parameters. Pressure level reaches a value that is significantly greater than the theoretical limit of medium strength in the model approximations at the surface of the sphere of the inner core. On the other hand, equilibrium state of the sphere is unstable by the geometric forming at much lower loads under the influence of the dead surface loads. In case of the action of follower loads, the assumed pressure value on the surface of the sphere is comparable with the value of the critical load of internal instability. In these cases, due to the instability of the equilibrium state, propagation of homogeneous deformations becomes uneven in the sphere. Moreover, the elastic waves with actual velocity cannot propagate in such conditions in solid medium. Violation of these fundamental conditions of mechanics needed in determining the physical and mechanical properties of the medium must be taken into account in the integrated interpretations of seismic and laboratory (experimental) data. In this situation, application of linear elasticity theory and elastic waves, despite compliance with the required integral conditions on the mass, moment of inertia and natural oscillations of the Earth, does not ensure the reliability of results on the structure and composition of the Earth's core.

The changes in the microstructure of ion-exchanged clays

Three natural bentonites and their monoionic forms were investigated by the X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). SEM photographs were analysed using the Photoshop CS4 software and the pore parameters were calculated. The parameters were compared to a interplanar spacing d001 value changes between different homoionic forms. The results suggest the connection between the type of exchangeable cation with the structural parameters of the pores and physicomechanical parameters of the soil, therefore the ion exchange method could be used for controlling soil properties corresponding to their suitability for use in the industry.

RETRACTED ARTICLE: Prediction of aggregate modified index (AMI) using geomechanical properties of limestones

Limestone aggregates are considered as construction materials with special suitability for use as a part of base courses, asphalt and Portland cement concrete. The suitability of aggregates for different applications is determined by aggregate parameters including the Los Angeles aggregate abrasion value (LAAV), aggregate impact value (AIV), and aggregate crushing value (ACV). In this paper, a combination of all these parameters is presented as an aggregate index (AI); Hamedan Limestones were classified based on this new index. The physico-mechanical properties of aggregates can also be used to evaluate their suitability for any specific engineering application; therefore, these properties of rock samples were measured. The AI was modified using p-wave velocity parameters, and changed into an aggregate modified index (AI/Vp = AMI). Statistical analyses, including simple and multiple regressions, were applied to offer some rational approaches and identify those physico-mechanical parameters that are more appropriate for prediction of AMI. Consequently, based on these analyses, p-wave velocity, uniaxial compressive strength, dry density and Brazilian tensile strength parameters show significant correlations with AMI at α-level = 0.1.

Assessment of physicomechanical parameters in the Lower Red Unit (LRU) of the Wajid Sandstone, Bir Askar, Najran, Saudi Arabia

The aim of this study is to determine the mechanical and petrophysical properties of sandstone rocks and using P-wave to correlate among these properties as well as the influence of cement which are intrinsic factors controlling the mechanical properties of clastic rocks. The field study included the description of the Lower Red Unit of the Wajid Sandstone outcrop analog section described previously, lithofacies description, identification, and rock sample collection from the subsurface section. Both X-ray diffraction, SEM and petrographic analyses indicate that the red sandstones are composed of predominantly K-feldspar and quartz grains and an illite matrix. In the laboratory work; porosity (n%), permeability (K md), apparent density g/cc, water absorption (Ab%), void index (e%), Schmidt hammer rebound hardness (SHR), uniaxial compressive strength (σc MPa)), Point load index (Pl) and ultrasonic pulse tests (Vp) were carried out. Then, the results were analyzed statistically to find the correlation coefficient between these measured parameters. The results of Vp with the mechanical and physical properties of the rocks were analyzed using the method of least squares regression. In all cases, the weakly to moderately correlation coefficient (R2) was determined for each regression. Relatively high correlation values were seen between Vp index and porosity of R2 0.60. The sandstone in the study can be classified according to the UCS classification for intact rock into very low to low strength (1–20.39MPa) and very low velocity of sound velocity classification.

The New Methodology for Assessing of the Applicability of Elastomeric Materials in the Vibration Isolation Systems of Railway Lines

Abstract The technical requirements for the determination of physical parameters of vibration isolating material have not been standardized in Europe and Poland yet, which significantly hinders the ability to compare vibration isolating materials offered on the market. Therefore, there is a need for establishing a norm that could be applied both for the determination of the physico-mechanical properties of elastic vibration isolation elements in rail transport for domestic and foreign producers as well as in their selection for application in a specific vibration isolation system. The paper presents a proposal to standardize the methodology of the estimation of vibration isolation materials physical parameters authorized for use in vibration isolation systems used in rail transport. Methodology for measuring the physico-mechanical parameters of vibration isolating material presented in the paper forms uniform test procedure developed based on a fragmentary norms for flexible materials testing. The use of the proposed research methodology enables the creation of a unified database of elastic materials which parameters will be easy to compare, and choice between them will become easier for designers of vibration isolation systems used in rail transport.

Elimination of Negative Influence of Fluidized Bed Combustion Fly Ash on Viscosity of Cement Mix

Use of fluidized bed combustion fly ash as an admixture for manufacture of cement based composite materials is not quite common now, however, there are real ways of utilizing its potential. The most important negative feature of this fly ash is its variable chemical composition, which supports formation of new forms growing within the structure with negative impact of durability of the composite material. The morphology of this type of fly ash is also not very favorable as it has negative influence on consistency. Fluidized bed combustion fly ash considerably deteriorates consistency of cement mixture, which results in higher water-cement ratio and consequently worsening of physico-mechanical and durability parameters of the whole composite. Therefore the question arises how to eliminate this negative influence on consistency without the necessity of increasing water cement ratio.

Effect of glycoluril and its derivatives on the flame resistance and physico-mechanical properties of rubber

The effect of bicyclic bisureas (glycolurils) and their derivatives functionalized with hydroxymethyl, halomethyl, and dimethoxyphoshorylmethyl groups on the flame resistance and physico-chemical properties of synthetic isoprene and divinyl rubbers was studied, and the procedures for preparing these agents were suggested. The rubbers with the addition of the synthesized bicyclic bisureas demonstrated satisfactory levels of flame resistance and physico-mechanical parameters.

PLA and PP Composite Nonwoven with Antimicrobial Activity for Filtration Applications

The PLA (50% wt.)/PP (50% wt.), PLA (47.5% wt.)/PP (47.5% wt.)/paraffin (5% wt.), and PLA (47.25% wt.)/PP (47.25% wt.)/paraffin (5% wt.)/CuO·SiO2(0.5% wt.) composite nonwovens were obtained in one-step process by using the melt-blown technique. Thermal properties (by the DSC method), physicomechanical parameters, specific surface area, the structure (by the SEM method), the elemental analysis (by the EDS method), and susceptibility to hydrolytic degradation (in alkaline and neutral media) were studied for all the obtained nonwovens. The antimicrobial properties of the composite nonwovens were determined by using dynamic contact conditions method, with three kinds of microorganisms applied. The DSC analysis of nonwovens revealed that the mixing of PLA and PP caused the decrease in homogeneity of both polymers, as well as a considerable increase in the PLA crystallization enthalpy. The paraffin and CuO·SiO2addition to PLA/PP nonwoven generally improved the filtration properties and downgraded tensile strength. Among all the tested composite nonwovens, the PLA/PP/paraffin/CuO·SiO2was the most and the PLA/PP/paraffin was the least susceptible to hydrolytic degradation in both media used in the study. The PLA/PP/paraffin/CuO·SiO2composite nonwoven revealed strong antibacterial activity and slight activity against the yeast.

The transmission of an acoustic wave through a rectangular plate between barriers

Abstract The problem of the forced vibrations of a rectangular elastic plate hinged to the sides of an opening in an absolutely stiff partition upon the transmission of a monoharmonic acoustic wave through it is considered. It is assumed that the partition is located between two absolutely stiff barriers, one of which forms an acoustic wave that is incident to the plate due to harmonic vibrations with an assigned displacement amplitude, while the other barrier is fixed and has a deformable energy-absorbing coating made from a material with high damping properties. The behaviour of acoustic media in spaces between a deformable plate and barriers is described by classical wave equations based on the model of an ideal compressible fluid, and the mechanics of the deformation of the plate are described by the equations of motion from the classical linear plate theory with consideration of the internal friction of the plate material according to the Thompson–Kelvin–Voigt hysteretic model. To describe the process of the dynamic deformation of an energy-absorbing coating on a fixed barrier, two-dimensional equations of motion based on the use of a model of a transversely soft layer, a linear approximation of the displacement fields in the direction of the thickness of the coating and consideration of the damping properties of its material also according to the hysteretic model are derived. Analytical solutions of the problem are found with and without consideration of the compliance of the supporting elements of the plate. The influence of the physicomechanical parameters of the mechanical system under consideration on the sound reduction parameters of the plate and the sound pressure in the spaces between the plate and the barriers, as well as of the stress-strain state under forced vibrations of the plate as a function of the frequency of the acoustic wave incident to it, is investigated. It is shown that the mechanical behaviour of the plate in the vicinity of resonance frequencies depends practically completely on the aerodynamic damping and that for stiff building materials, which have, as a rule, small values of the logarithmic decrement of the vibrations, taking into account the internal damping has an insignificant influence on the parameters investigated of the system.

Structure-Formation Features in Ultrathin Fibers of Poly(3-Hydroxybutyrate) Modified with Nanoparticles

Supramolecular structure formation of poly(3-hydroxybutyrate) ultrathin fibers prepared by electrospinning and the influence of low concentrations of silicon and TiO2 nanoparticles on the structure, physicomechanical and sorption properties, and resistance to thermal destruction and thermoand photo-oxidative destruction of non-woven fibrous material based on these fibers were studied. It was found that nanoparticles promoted the formation of thinner fibers with enhanced physicomechanical parameters and a structure that was more resistant to thermal and thermo- and photo-oxidative destruction and had a positive effect on the growth dynamics of mesenchymal stem cells.

Cellulose Buccoadhesive Film Bearing Glimepiride: Physicomechanical Characterization and Biophysics of Buccoadhesion.

The present study aimed to develop buccoadhesive film of glimepiride with unique combination of polymers and to investigate its effect(s) on physicomechanical parameters, drug-release, and permeation of films. Drug-polymer interaction was examined by FTIR and DSC analysis. Films were prepared by solvent casting technique and characterized for film strength (320 ± 8.5g, 28.98 ± 2.00mJ), buccoadhesive strength (28.8 ± 1.37g, 3.04 ± 0.32mJ), and tensile strength (260 ± 6.88g, 18.00 ± 0.44mJ) by new instrumental techniques. Increase in polymer concentration augmented zeta potential of polymeric matrix-mucin mixture and exhibited strong buccoadhesion (electrical theory). Buccoadhesion was also influenced by particle size (adsorption theory) and swelling (wetting theory). Erosion behavior of films was observed in swelling and SEM studies. Film GM4 exhibited 98 ± 2% in vitro drug release and 85 ± 8% ex vivo drug permeation in 12h with controlled diffusion mechanism. Films were compatible with oral probiotic microorganisms. Stability studies revealed no significant (P < 0.05) variation in physicomechanical characteristics.

Selectivity of a Singly Permeating Ion in Nonselective NaK Channel: Combined QM and MD Based Investigations

Ion channels, such as potassium channels are known to discriminate ions to achieve remarkable selective transportation of K(+) over Na(+) through the membrane. The recently reported NaK ion channel, on the contrary, seems to be an exception, as it is observed to permeate most of the group IA alkali metal cations and hence is suggested to be nonselective in nature. However, does that correspond to a complete annihilation of selectivity inside the selectivity filter (SF) of the channel? What is the origin of such nonselectivity/selectivity, if any? The present computational study is an extensive multiscale modeling approach to find the probable answers to these intriguing questions. Here, we have used density functional theory (DFT) based calculations using a realistic truncated model of SF from the crystal structures of the NaK ion channel to evaluate the binding of various alkali metal ions (Na(+), K(+) and Cs(+)), free from "contamination" due to the absence any other "rivalry" cations, in its different binding sites. Among all of the possible binding sites, a vestibule is noticed to be nonselective and seen to act as a probable binding site only in the presence of multiple ions. Binding sites S3 and S4 are found to be selective for K(+) and Na(+), respectively. As an important observation, we find that calculations on oversimplified models using an isolated ion binding site may lead to an erroneous selectivity trend as it neglects the synergetics of consecutive binding sites on the final outcome. Energy decomposition analysis revealed ion-dipole electrostatics as the major contributing interaction in metal-bound binding sites. Our investigations find that although NaK is permeable to monovalent alkali metal ions, strongly "site specific" selectivity does exist at the three well-defined noncontiguous binding sites of the SF. Different important physicomechanical parameters (such as ligating environment, synergistic influence of binding sites, and topological constraints) are found to be the determining factor to induce the "site specific" selectivity of ions during translocation. Wherever possible, our computed results are compared with the available experimental findings. We finally conduct a detailed umbrella sampling-corrected metadynamics simulation in order to obtain an ion permeation free energy landscape within the SF that corroborates well with the "site specific" selectivity trend.

Influence of Firing Temperature on the Quality of Fly Ash Body

Nowadays, over 95 % of fly ash is used as construction products in the Czech Republic. However, around 80 % of fly ash is used for renovation of open-pit quarries and areas affected by human activity. Production of artificial aggregate is the way to use over 90 % of energy by-products in the building material industry. It is necessary to find appropriate combination of parameters of input materials and conditions of production to get optimal properties of aggregate. The paper gives an account of the influence of parameters of fly ash and conditions of firing on the quality of ceramic body made from fly ash. Temperatures of 1050 °C, 1150 °C and 1200 °C were examined. The research focused on the structure of the ceramic body as well as its physico-mechanical parameters.