Physical-mechanical Characteristics Research Articles

Encapsulated lemon oil and metal nanoparticles in biopolymer for multifunctional finishing of cotton and wool fabrics

This study examined the utilization of different metal nanoparticles encapsulated in biopolymer material in the presence or absence of lemon oil to cellulosic and proteinic fabrics to obtain textile material with mosquito-repellent, fragrance, and antibacterial Properties. Encapsulation of lemon oil into the biopolymers was performed using the mechanical homogenizing mixing method. several treatments for textile materials using pad-dry-packing procedures were devolved in the presence or absence of metal nanoparticles. the natural polymers were used in various concentrations (3%, 5%, and 10%). For each polymer, varied concentrations with encapsulated oil were utilized. Different methods were used to investigate the finished textile materials in terms of their physical-mechanical characteristics. The treated fabrics with AgNPs (5%) encapsulated in gelatin biopolymer give higher antimicrobial activity; the treated fabrics with TiO2NPs (5%) encapsulated in pectin biopolymer give higher mosquito repellent activity; and the treated fabrics with ZnONPs (5%) encapsulated in gelatin biopolymer give higher UPF values. The physical and mechanical qualities of the treated textiles perform well when compared to untreated cloth.

Combined Sulfur and Peroxide Vulcanization of Filled and Unfilled EPDM-Based Rubber Compounds.

The sulfur curing system, peroxide curing system and their combinations were applied for the cross-linking of unfilled and carbon black-filled rubber formulations based on ethylene-propylenediene-monomer rubber. The results demonstrated that the type of curing system influenced the course and shape of curing isotherms. This resulted in the change of curing kinetics of rubber compounds. The cross-link density of materials cured with combined vulcanization systems was lower than that for vulcanizates cured with the peroxide or sulfur system. Good correlation between the cross-link density as well as the structure of the formed cross-links and physical-mechanical characteristics of the cured materials was established. Both filled and unfilled vulcanizates cured with combined vulcanization systems exhibited a higher tensile strength and elongation at break when compared to their equivalents vulcanized in the presence of the peroxide or sulfur curing system. It can be stated that by proper combination of vulcanization systems, it is possible to modify the tensile behavior of vulcanizates in a targeted manner. On the other side, dynamical-mechanical properties were found not be significantly influenced by the curing system composition.

Technical Feasibility of Sorghum Biomass for Briquettes Production

Vegetable biomass has been widely used for bioenergy generation, including sorghum, which has been the object of research for presenting high biomass productivity in the field in a short period of time and its in natura form is an option in sugar and energy plants during the off-season. The use of raw biomass has a number of disadvantages and its densification, through the production of briquettes, improves its energy and physical-mechanical characteristics. The objective of this study was to characterize the in natura biomass and briquettes of two hybrids of biomass sorghum: the commercially used BRS 716 and CMSXS 7016 still in test phase. The cultivation of the two hybrids was carried out at the experimental station of Embrapa Milho e Sorgo, located in the municipality of Sete Lagoas, in Minas Gerais, Brazil, in the 2016/2017 crop, with conventional cultural management for sorghum. The values found for the two hybrids of sorghum biomass are quite satisfactory compared to the values found in the literature for forest and agricultural species that are normally used for energy purposes, except for the ash content, being a viable alternative for energy production. The in natura biomass of hybrid CMSXS 7016 presents similar characteristics to the commercial hybrid BRS 716, and can be used commercially energetic applications. The briquettes of sorghum hybrids biomass are technically feasible for energetic generation, with energy and physical-mechanical characteristics superior to the biomass in natura, with apparent and energy density about 7-8 times higher.

Low-temperature calcination composite binder from dolomite and its application to facing board materials

The article presents the research to obtain low-temperature calcination binder from dolomitic limestone with a MgO content of less than 20%. The initial dolomite material was calcinated at the following temperature range from 700 to 800 ℃ and firing time 25–45 min. The result of the selection of the optimal firing conditions is semi-calcination product caustic dolomite with a minimum content of residual Mg(CO3)2 and free CaO with bending strength 10–11 MPa. Physical-mechanical characteristics and mineral composition of samples were determined by the use of differential thermal analysis and infrared spectroscopy studies. Preliminary experimental samples of facing composite board materials were prepared and the main physico-chemical parameters were determined: bending strength 4–7.6 MPa, density 800–1400 kg/m3 and water absorption 10–25%. A three-dimensional model for the production of glass dolomite slabs has been developed.

Understanding the influence of physical properties on the mechanical characteristics of Mg-doped GaN thin films

This study investigates the impact of Mg doping concentration in GaN thin films on their physical and mechanical properties, specifically on their conductivity transition, luminescence, hardness, Young's modulus, and creep behavior. Mg-doped GaN layers were grown on sapphire substrates using the MOCVD technique, with trimethylgallium (TMG) and bis(cyclopentadienyl) magnesium (Cp2Mg) as precursors for Ga and Mg, respectively. The TMG flow rate was set at 20 μmol/min, while the Mg flow rate was adjusted by tuning the temperature of the thermostatic bath of Cp2Mg. Three different Cp2Mg flow rates: 2, 7 and 9 μmol/min were utilized to explore their effects on the physical and mechanical properties of the grown epilayers. The results demonstrate that an increase in the Mg concentration leads to a conductivity transition from n-type to p-type, with the highest hole concentration (4.5 ± 0.2) × 1017 cm−3 and blue luminescence attained with Mg concentration equal to 2.1 × 1019 atoms/cm3. Moreover, the hardness, Young's modulus and the intensity of compressive stress increase with the Cp2Mg flow rate due to the evolution of pre-existing dislocation density and point defects incorporation. Additionally, this study evaluates the creep behavior of the Mg-doped GaN thin films. It shows that both the creep stress exponent and the maximal creep depth decrease with the increase of the Cp2Mg flow rate. This is attributed to dislocation glides and climbs governing the creep mechanism. Accordingly, this investigation highlights the importance of understanding the relationship between physical properties and mechanical characteristics of Mg-doped GaN thin films, which have potential implications for various technological applications.

Petrographic properties and physical-mechanical characteristics of Salang marbles located in Parwan province, Afghanistan

This research examines Salang marble's petrographic properties and physical-mechanical characteristics in Parwan province, Afghanistan. Situated in the western Hindu Kush zone, these marbles are part of the Afghanistan-North Pamir Folded Region, surrounded by faulted structural units. Despite the lack of detailed information from the Afghanistan Geological Survey, including maps and reserve estimates, there has yet to be a comprehensive evaluation of the marble's quality, physical-mechanical properties, or material composition. Furthermore, research and exploration efforts in this area have been limited. The paper aims to discuss and provide conclusions and suggestions regarding petrographic properties, mineral paragenesis, and physical-mechanical characteristics. The marbles predominantly comprise calcite, constituting around 99% of the composition. Spectrometry analysis reveals the presence of elements and oxides such as calcium, aluminum, iron, magnesium, sodium, silicon, and strontium. The physical-mechanical properties of the Salang marbles, including specific gravity (2.70), bulk density (2.69 g/cm3), marble durability index (98.52 MPa), and resistance to impact value (16.38 GPa) of marble aggregates, are analyzed. This research involves collecting specimens from the mine area and conducting mechanical tests and petrographic studies following established norms and standards. The findings contribute to a better understanding of the Salang marbles and can inform future exploration and utilization of these valuable resources.

Railway ballast aggregate characterization through a new strength index: Preliminary suitability evaluation of an industrial by-product for a railway application

Ballast is a layer of the railway infrastructure that ensures the correct geometric position of track equipment, distributing vertical loads on the underlying layers. Ballast is composed by aggregate grains of adequate grading, containing a consistent number of voids and a medium–low fine content.The aggregates of ballast must be tested in the laboratory to ascertain the suitability for their use under construction or maintenance. In this work, the physical–mechanical characteristics of different types of aggregate (natural and “artificial”) were evaluated to verify their acceptability as ballast under the Italian specifications. All the aggregates came from Italian production plants. One “artificial” aggregate (steel slag) was used to assess if it can be used instead of the natural aggregate on a railway line in Italy. A mixture of natural and artificial aggregates was also tested for comparison purposes. An index from Point Load Test was also assessed to predict the main physical–mechanical characteristics provided by the laboratory tests.The artificial aggregate shows excellent physical–mechanical properties, compared to the natural one, indicating that the tested by-product can replace the natural aggregate. The mixture of natural and artificial aggregates can guarantee the preservation of natural resources and solve supply difficulties of by-products, maintaining very good physical–mechanical characteristics.In general, the Los Angeles index (both before and after the freeze-thawing cycles) shows a good correlation with the Point Load Strength Index for the tested ballast aggregates. Starting from this result, the Point Load Test could be used to characterize ballast aggregates. A statistical analysis was also performed on the other physical–mechanical parameters: a good correlation was found in some cases, indicating that the Point Load Strength Index can provide a first indication of the other physical–mechanical characteristics of ballast aggregates.

Компьютерные модели биоматериалов, применяемых для изготовления створчатого аппарата протезов клапанов сердца

The physical-mechanical characteristics of materials-components of bioprostheses of heart valves presented in clinical practice in Russia, with subsequent adaptation of properties for numerical modeling tasks, have been obtained and generalized. It is shown that all the studied materials have a pronounced nonlinearity and can be represented only in the form of polynomial models. Comparison of the results of computer modeling based on the obtained coefficients of materials showed no differences with the data of full-scale bench tests, which made possible to verify computer models.

Study of the physical-mechanical characteristics of concrete in a concrete-PET mixture

In the field of construction materials, concrete is today one of the most accepted mixtures of materials by the community. Cement is one of the most used products in the world, although large cities are already full of large buildings, cement is still requested in large works. One of the materials widely used as primary packaging are the thermoplastic polymers of the so-called PET (Polyethylene Terephthalate). These materials are currently very polluting mainly in oceans, seas and rivers. The properties of polymers could be exploited to reinforce the properties of concrete and at the same time reuse the polymer to reduce its contamination on the planet. For this research project the experimental methodology was applied consisting of establishing combinations of concrete-PET materials in different ratio. The results obtained from the different mixtures that were prepared from the Flexural Effort tests, it is observed that both in the mixture containing 0.5% PET and in the one containing 1.0%, the results of Flexural Effort are higher compared with the pure mixture.

Влияние фосфорсодержащих антипиренов на показатели пожарной опасности газонаполненных полимеров на основе реакционноспособных олигомеров

Introduc tion. The reduction of flammability of gas-filled polymers prone to carbonization is based on the use of phosphorus- and boron-containing compounds that reduce the formation of combustible volatile pyrolysis products and increase the yield of coke residue. This reduces the rate of heat release, heat and mass transfer between the material and the flame. In the scientific literature the data about the influence of phosphorus-containing flame retardants on thermal stability, combustibility and smokeability of foams are given, but there are no data about the influence of phosphorus concentration on fire danger indicators of foams. The aim of this paper is the development of effective methods of production of casting foams based on reactive oligomers with low fire hazard and high-performance. Objectives: to reveal the influence of phosphorus concentration on the technological and physical-mechanical characteristics, thermal resistance and fire hazard indices of foams and to develop fire-proof thermal insulation materials possessing high performance. Methods. Physical-mechanical properties and fire hazard indices of gas-filled polymers were determined according to current GOST. Thermal properties and composition of combustion products of foams have been studied with thermoanalytical complex DuPONT-9900 and chromatography-mass spectrometry. Results and discussion. The concentration of phosphorus in the synthesis of rigid polyurethane foams with reduced flammability and high performance should exceed 2.1 % wt. The low-combustible urea foams have been obtained at a phosphorus concentration of 0.2–0.3 % wt. For the production of non-flammable, low-­flammable resin foams, the phosphorus concentration is 0.6–0.7 % wt. At the same time, organophosphorus flame retardants containing reactive groups are highly effective. Conclusion s. As a result of experimental studies the influence of phosphorus concentration and content of organophosphorus-containing flame retardants on physical-mechanical properties, thermal stability and fire hazard of foams based on reactive oligomers was revealed, the pouring foams with lowered fire hazard and high performance were developed.

The Role of High Carbon Additives on Physical–Mechanical Characteristics and Microstructure of Cement-Based Composites

Traditional supplementary cementitious materials (SCMs) have been proven to reduce the negative impact of Portland cement production on the environment. However, the availability of SCMs becomes limited due to their extensive usage. For this reason, our work aimed to investigate the effect of partial substitution of ordinary Portland cement (OPC) with two different types of carbon-rich waste powders—biochar (BC) and coal dust (CD), dosed separately up to 10 wt.% of OPC, on the physical, microstructural and mechanical properties of hardened specimens. Obtained data pointed out that replacing OPC with small amounts of BC and CD (not exceeding 5.0 wt.% and 2.5% wt.%, respectively) initiated an increment in mechanical strengths due to a decrease in total open porosity and enhanced formation of hydration products of such composites compared with the reference. Overall, both examined alternatives, if added in appropriate amounts, have the perspective to be effectively applied in cement manufacturing and concrete production, and thus to importantly contribute to the long-term sustainability of the construction industry in view of energy savings, reduced releasing of the greenhouse gasses and mitigating of global climate changes.

Optimizing microencapsulated PCM ratios of sustainable cement mortar for energy savings in buildings

Energy efficiency improvement techniques for buildings are among the fundamental challenges to sustainable buildings. PCMs incorporation in mortar is one of the efficient techniques for improving the energy efficiency of buildings. However, the low integration ratio of PCMs into cement mortar significantly decreases its effectiveness. Using PCMs as a replacement for sand has a negative effect that leads to the deterioration of the mechanical properties of mortar. This study aims to extend using PCMs in mortar eco-friendly and study the impact PCMs up to 50% as additions of cement content with ceramic fine aggregate waste as a replacement for sand on thermal energy storage ability improvement and enhance its physicomechanical properties. Twelve specimens were prepared, four mixtures of mortars with 0%, 12.5%, 25%, and 50% PCMs, as additions to the cement content with 100% natural sand. Eight mixtures were prepared with different ceramic fine aggregate contents with 25%, 50%, 75%, and 100% as replacements from sand content with integrated 25% and 50% PCMs, respectively. SEM, thermal performance, and physical–mechanical characteristics of the mortar-integrated PCM were performed. The results showed no chemical interactions between the PCM and the cementitious components during hydration. The compressive strength and thermal performance results showed enhancement when using ceramic as a replacement for sand by increasing about 37.1% for compressive strength, with the decreased temperatures to 9.5 °C and phase peaks shifting ahead by 115 min for a mix of 50% PCM + 100CFA, compared to 7.0 °C with phase peaks shifting by 85 min for a mix of 50 %PCM + 100NS.

Evaluation of the effect of enrichment of slag aggregate for pavement subbase by grains density on its physical and mechanical characteristics

The article presents the results of a laboratory evaluation of the influence of the enrichment of the slag aggregate (size 20–40 mm) for road construction, obtained from the air-cooled blast furnace slag, on the grains density, on its water absorption, freeze-thaw resistance and resistance to crushing. The results of quantitative and qualitative evaluation of the obtained empirical dependences, performed using the methods of correlation analysis and approximation, are presented. Enrichment of the slag aggregate in terms of grains density makes it possible to reduce its water absorption from 4.9-6.8% to 2.19–3.13%, increase the number of repeated freeze-thaw cycles maintained without significant destruction, from 150 to 300–400, and reduce crushing value from 30-31% to 20–21%. The resulting approximation equations make it possible to predict the change in physical-mechanical characteristics with further enrichment of the slag aggregate in terms of grains density. Laboratory tests showed that the slag aggregate, pre-enriched in grain density, when used as aggregate for pavement subbase operated in continental climates with frequent natural repetition of freeze-thaw cycles, will resist the temperature fluctuations much more effectively than the high-porosity slag aggregate used without enrichment.

Additive Manufacturing and Physicomechanical Characteristics of PEGDA Hydrogels: Recent Advances and Perspective for Tissue Engineering.

In this brief review, we discuss the recent advancements in using poly(ethylene glycol) diacrylate (PEGDA) hydrogels for tissue engineering applications. PEGDA hydrogels are highly attractive in biomedical and biotechnology fields due to their soft and hydrated properties that can replicate living tissues. These hydrogels can be manipulated using light, heat, and cross-linkers to achieve desirable functionalities. Unlike previous reviews that focused solely on material design and fabrication of bioactive hydrogels and their cell viability and interactions with the extracellular matrix (ECM), we compare the traditional bulk photo-crosslinking method with the latest three-dimensional (3D) printing of PEGDA hydrogels. We present detailed evidence combining the physical, chemical, bulk, and localized mechanical characteristics, including their composition, fabrication methods, experimental conditions, and reported mechanical properties of bulk and 3D printed PEGDA hydrogels. Furthermore, we highlight the current state of biomedical applications of 3D PEGDA hydrogels in tissue engineering and organ-on-chip devices over the last 20 years. Finally, we delve into the current obstacles and future possibilities in the field of engineering 3D layer-by-layer (LbL) PEGDA hydrogels for tissue engineering and organ-on-chip devices.

Hydrogels Based on Chitosan and Sodium Alginate with Shape Memory Effect

Hydrogels based on chitosan derivatives, sodium alginate with acrylamide and acrylic acid were obtained by free radical solution copolymerization method in the presence of ammonium persulfate as initiator and urotropin and N,N methylene bisacrylamide as crosslinking agents. The formation of hydrogels was proved by extraction and IR spectroscopy. It is shown that hydrogels are able to fix the temporary form in iron (III) chloride solutions and reclaim it in solutions of ascorbic acid in less than 2 hours. Hydrogels based on sodium alginate have the best physical-mechanical characteristics compared with chitosan-based - the strength reaches 0.7 MPa and 0.11 MPa, the elasticity modulus is 1.02 MPa and 0.17 MPa at 65% deformation, correspondingly.

Modeling Electrochemical Performance of Reinforced Concrete in Natural Marine Airborne-Exposure Environments: DURACON Project,10-Year Evaluation

This research evaluation consisted of a detailed statistical analysis of the recorded data in 72 reinforced concrete specimens, from 12 natural test sites (in nine countries) located in chloride-laden environments (marine airborne-exposure test sites located between 50 m and 250 m from seashore), during a natural exposure period of 10 y. The parameters evaluated included the concrete physical-mechanical characteristics; meteorochemical information; natural reinforcing steel’s instantaneous corrosion current density (icorr) and cumulative icorr; and concrete chloride concentration; surface crack width and rebar cross-section loss correlations. This statistical analysis resulted in empirical instantaneous icorr predictions as a function of the exposure microclimates, through linear multiple regressions. These models showed a high linear dependence of the cumulative icorr with the concrete capillary absorption as well as with the meteorochemical parameters. Results obtained in this investigation showed higher corrosion aggressiveness in tropical environments when compared to nontropical ones. The cumulative icorr proved to be an effective tool to indicate the corrosive likelihood and differentiate the stages of Tuutti’s service life model.

Dynamic tensile mechanical properties of water-saturated and frozen sandstone after freeze-thaw fatigue damage treatment

To study the physical properties and dynamic mechanical response characteristics of rock materials in seasonally frozen regions, density, P-wave velocity, nuclear magnetic resonance, and dynamics Brazilian disc tests were carried out on sandstones treated with different numbers of freeze-thaw cycles. The experimental results show that the water-saturated density and P-wave velocity of sandstone decrease and the Nuclear magnetic resonance porosity increases as the number of freeze-thaw cycles increases. Under a certain loading rate, the dynamic tensile strength of water-saturated sandstone gradually decreases and that of frozen sandstone gradually increases as the number of freeze-thaw cycles increases; at the same time, the dynamic tensile strength of both water-saturated and frozen sandstone increases as the loading rate increases under the same number of freeze-thaw cycles. The reason for the variability of dynamic tensile strength between water-saturated and frozen sandstones with the increase in the number of freeze-thaw cycles can be attributed to the change in porosity. On this basis, the concept of relative dynamic tensile strength of sandstones was introduced and regression analysis was carried out with the increase ratio of porosity, and it was found that the correlation between the relative dynamic tensile strength and the increase ratio of porosity was strong. The relative dynamic tensile strength of water-saturated sandstone decreases exponentially with the increase ratio of porosity; the relative dynamic tensile strength of frozen sandstone increases exponentially with the increase ratio of porosity.

Characteristics of biodegradable plastic from mulu bebe banana peel starch with the addition of chitosan and glycerol plasticizer

Bioplastics are a solution to the food packaging problem, which generally uses synthetic petroleum packaging, which is increasingly limited, difficult to degrade by nature and a food safety solution for health. However, this packaging needs to be strengthened in its mechanical properties by adding chitosan and glycerol. This study aimed to investigate the effect of adding chitosan and glycerol on the physical dan mechanical characteristics of the bioplastics and the physical and mechanical characteristics of bioplastics resulting from adding different chitosan and glycerol. Design experiment using the factorial Completely Randomized Design (CRD) method with 2 (two) treatment factors and 3 (three) replications. The two treatment variables were chitosan concentration (0%, 1%, 2%) and glycerol concentration (1%, 2%, 3%) with three replications. There are 27 experimental units in total. The data obtained were analyzed using analysis of variance with a factorial Completely Randomized Design (CRD) model. If it has a significant effect, a further test with the least significant difference test at the 5% level is carried out. The addition of different chitosan and glycerol affected all parameters. Biodegradable plastic from Mulu Bebe banana peel starch with the addition of chitosan and glycerol plasticizer has the characteristics of water content 13.389-19.621%, density 0.047-0.112 gr/cm3, tensile strength 0.983-4.790 Mpa, elongation 1.402-13.317%, and water absorption 12.407-82.194%.

The Influence of Blast Furnace Slag on Cement Concrete Road by Microstructure Characterization and Assessment of Physical-Mechanical Resistances at 150/480 Days.

The results presented in this paper on the appropriateness of using of blast furnace slag (BFS) in the composition of roads make an original contribution to the development of sustainable materials with the aim to reduce the carbon footprint and the consumption of natural resources. The novelty of this work consists of determining the optimal percentage of BSF in road concrete, in order to: increase mechanical resistances, reduce contractions in the hardening process, and ensure increased corrosion resistances, even superior to classic cement-based mixtures. Thus, the physical-mechanical characteristics and the microstructure of some road concretes were studied in the laboratory for three different recipes. We kept the same amount of ground granulated blast furnace slag (GGBS) as a substitute for Portland cement, respectively three percentages of 20%, 40%, 60% air-cooled blast furnace slag (ACBFS) and crushed as sand substitute from now on called S54/20, S54/40, S54/60. Drying shrinkage, mechanical resistances, carbonation-induced corrosion, microstructure characterization of hardened concretes, and degree of crystallinity by SEM and XRD measurements were analyzed after a longer curing period of 150/480 days. The obtained results on the three BSF mixtures indicated a reduction of drying shrinkage and implicitly increased the tensile resistance by bending to 150 days well above the level of the blank composition. The degree of crystallinity and the content of the majority phases of the mineralogical compounds, albites, quartz, and tobermorite out of the three BSF samples justifies the increase in the compressive strengths at the age of 480 days in comparison with the test samples. Scanning electron microscope (SEM) and X-ray diffraction measurements showed the highest compactness and lowest portlandite crystal content for the S54/20 slag composite. Future research concerns are the realization of experimental sections in situ, the study of the influence of BFS on the elasticity module of road concrete, and the opportunity to use other green materials that can contribute to the reduction of the carbon footprint, keeping the physical and mechanical properties of road concrete at a high level.

Experimental study on physical-mechanical characteristics of steel fiber reinforced concrete with worn rope fibers

This study examined the physical-mechanical properties of steel fiber reinforced concrete with different fiber orientations and vibration times. The concrete mixtures contained crushed stone, sand, Portland cement, Rheobuild 181A plasticizer, and 5 cm steel fibers with 2% reinforcement. Using steel fibers from worn ropes from Innotech LLP (Almaty, Kazakhstan) increased the average strength of concrete and improved its ductility, allowing for plastic failure instead of brittle failure. Joint mixing of steel fiber-reinforced concrete with randomly oriented fibers made from used cables increased the mean value of flexural strength. The concrete mixtures with a vibration time of 9 seconds showed the highest flexural strength, which was 2.1 times higher than that of concrete samples without fiber. These findings demonstrate the potential of steel fiber reinforcement to improve the mechanical properties of concrete, especially in applications requiring flexural strength.