Papers by Keyword: Physical Properties

Abstract: The present experimental study aims to contribute to the knowledge of the physical-mechanical properties of limestone blocks quarried in the Republic of Moldova. Apparent density, water absorption and compressive strength are examined based on laboratory work. The masonry material - limestone blocks are characterized both in comparison with other types of masonry materials and by comparing the compressive strength with other types of limestones. The analysed limestone samples were taken from 3 limestone quarries located in different areas on the territory of the Republic of Moldova. The results showed that limestone blocks from Moldova have better properties than AAC and some bricks. The materials used in the experimental work were selected to be representative of the mechanical characteristics present in old and existing buildings in Chisinau. This research is significant for the variation of the physical-mechanical properties of Moldovan limestone blocks compared to the same properties of other types of masonry blocks.

Abstract: For the optoelectronics application like (optical waveguides), a nanostructure Lithium Niobate (LiNbO₃) Nano film was produced and placed on a quartz substrate using the pulse laser deposition (PLD) process. The structural, morphological, and optical features of wavelengths od pulsed laser (1064 and 532) nm were investigated for the films of LiNbO₃ Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Ultra-Violet (UV-Vis) spectrophotometer, and Atomic Force Microscopy (AFM) are among the techniques used to describe and evaluate the samples.

Abstract: This manuscript presents the reactive pulsed laser deposition method was used to prepare and deposit the high-quality copper oxide (Cu₂O) Nanofilms using high purity copper metal, Oxygen, and heating at 300 C, at different laser energies rated (800 mj, 1000 mj, and 1200 mj) respectively. The presented results show high ranges of transparent values with the increasing laser energies from 66%-90%. As the laser energies increased the optical energy band gap value was increased from 2.32eV – 2.47eV. Further, the AFM, XRD, I-V, and spectral response tasted and investigated the surface topography, homogeneity, roughness’s, structural and optoelectronic properties for the deposited Cu₂O nanofilms, respectively.

Abstract: Along with the increase in watermelon production, the amount of watermelon rind waste increased. The total mass of fruit rind in a watermelon reaches around 30 percent and this fruit rind can increase the quantity of organic waste in Indonesia. The outer portion of the watermelon rind has a green layer containing a large amount of anthocyanin and a white layer containing flavonoids. In this study, the extract of watermelon rind containing anthocyanins and flavonoids was protected from damaging conditions using the ionic gelation encapsulation method. Chitosan (CN) was used as a natural polymer in this encapsulation method and sodium tripolyphosphate (TPP) was used as an ionic crosslinking agent. The total of flavonols content (TF), microstructure test, in vitro releasing test, and shelf life of microcapsules were observed in the various ratio between watermelon rind and the solvent. From the process, can be concluded that higher watermelon skin levels will produce the most flavonoid microcapsules (70g/35 mL). At 70g/35 mL or 2:1 g/mL watermelon skin levels give the best flavonoid release test results, especially if it will be applied to the pharmaceutical industry, which follows a controlled release method.

Abstract: The results of experimental studies on the effectiveness of insulation of electrical cables with fire-resistant coating are presented. Analysis of methods of cables products using shows a steady trend of increasing their using during the arrangement of premises. Fires and rapid spread of flame are possible during the exploitation of such structures. Statistics of cable products show a low level of safety due to using of combustible insulation, which is highly sensitive to high temperatures and fire. After the test, it is seen that the specimen of the cable without a fire-resistant coating supports self-combustion for more than 30 s, and the damage to the specimen is more than 100 mm. After testing the specimen with a fire-resistant coating, it is seen that the cable specimen doesn’t support self-combustion, and the damage to the specimen isn’t more than 40 mm. Inhibition of the process of ignition and propagation of flame for such specimen is associated with the decomposition of flame retardants under the action of temperature, which occurs with heat absorption and release of non-combustible gases (nitrogen, carbon dioxide), as well as changing the direction of decomposition towards non-combustible gases and flame retardant coke residue. This leads to an increase of the thickness of the coke layer and inhibition of heat transfer of high-temperature flame to the insulation material, which indicates the possibility of transition of combustible insulation of the cable with a fire-resistant coating to non-flammable materials, which aren’t spread a flame.

Abstract: Wood-plastic composites (WPCs) are composites that incorporate plants composed up of wood and non-wood fibres blended with thermosets or thermoplastic polymers to form a composite. Oil palm trunk (OPT) is one of the wastes produced from the oil palm industry known as oil palm biomass (OPB). The OPT was utilized to turn oil palm biomass into a value-added product. In this research, oil palm trunk/polypropylene (OPT/PP) blends composite was produced by extrusion and injection molding techniques. Alkaline treatment was applied to the fibers to improve the interfacial adhesion of fibers. After alkaline treatment, treated OPT (T-OPT) and untreated (UT-OPT) together with PP were blended at 200°C with the speed of 85 rpm in the extruder to form a pellet. Pellets were then injected in injection molding at 200°C to form sample size for mechanical testing; tensile and impact testing. The physical testing conducted was Melt Flow Index (MFI), water absorption test and Thermogravimetric Analysis (TGA). The results show that the mechanical properties of OPT/PP composite were improved by alkaline treatment. In the water absorption test, T-OPT composite demonstrated lower water absorption than that of UT-OPT composite. This indicated that the reduction of water absorption in T-OPT composite is due to alkaline treatment that degraded the lignin and cellulose structure subsequently reducing the OH groups in fibers to absorb water. For TGA, T-OPT composite had slightly higher thermal stability as compared to UT-OPT composite.

Abstract: Weft knitted single jersey (S/J) and lycra single jersey (lycra S/J) fabrics are popular in the textile industry for their lightweight and excellent physical and dimensional properties. However, the property investigation is required to ensure the quality before starting bulk production with any fabrics. The main aim of this study is to compare the physical and dimensional properties of S/J and lycra S/J with considering the manufacturing parameters in order to reduce the manufacturing time as well as cost. The physical properties such as grey GSM (Gram per square meter), finish GSM, bursting strength, color fastness to washing and rubbing; dimensional properties i.e., shrinkage and spirality of S/J and lycra S/J fabric have been investigated and compared while the manufacturing parameters stitch length, machine diameter, machine gauge, number of needles, width etc. and finishing parameters were same. In this current research, the internationally approved methods are performed for example ISO to test fabric GSM, spirality and color fastness to wash; ASTM for bursting strength test; AATCC to measure the shrinkage and color fastness to rubbing or crocking. During the investigation, it is observed that there is a significant difference between grey GSM, finish GSM and bursting strength for both of the fabrics. Moreover, the shrinkage property of lycra S/J fabric is better than S/J fabric. In terms of color fastness to rubbing and spirality, slight differences are found too. However, in case of color fastness to wash, both fabrics exhibited similar behavior.

Abstract: Ti-based composites with advanced properties were fabricated by the explosion of the wires and magnetic-pulsed compaction methods. After the wire explosion the “metal core – oxide (or nitride) shell” structure is formed. Magnetic-pulsed treatment of such poorly conductive powder leads to the destruction of the shells and to the appearance of an electrical conductivity. This conductivity is only 4-7 times higher than that of pure titanium. As a result of the dynamic compaction of 100-150 nm powder the hot-pressed Ti+9TiO₂ composition appeared to have the best combination of mechanical properties: relative density – 95 %, microhardness - 4.2 GPa, reduced modulus of elasticity – 143 GPa, creep under constant load – 105 nm. The coefficients of thermal extension of three materials with different titanium oxide content: 6, 9 and 15 wt. % were measured. The nitride-containing composites were ~30% more porous and had low mechanical properties compared to Ti+TiO₂ compacts.

Abstract: The results of improving physical properties of different types of magnetic cores made of soft magnetic crystalline and amorphous alloys based on siliceous iron are presented. Methods and modes of controlling orientational, dimensional and dynamic parameters of magnetic domains by means of a uniaxially textured complex of thermomagnetic, locally laser, and plane deformation effects have been developed. As a result, in electrical magnetic cores made of anisotropic iron-silicon steels of 3407, 3408 grades a decrease in eddy-current magnetic losses by 25–35% and an increase in magnetic permeability by 1.5–2 times have been achieved.

Abstract: Metal matrix composites based on aluminium reinforced natural waste are a well-known material industry application because they can reduce environmental pollution. This paper presents the hardness and microstructure analysis of recycling milled aluminium (AA7075) at various composition of rice husk silica. Recycling milled AA7075 reinforced with rice husk burned at 1000°C at various composition i.e., 2.5, 5, 7.5, 10 and 12.5 wt.%, were investigated. Metal matrix composites samples were prepared by cold compaction method due to the lower energies consumption and operating cost compared to conventional recycling by casting. The results reveals that the hardness of metal matrix composites samples increased at increasing of rice husk silica up to 5 wt.%. The addition of rice husk silica increased the irregularities of pore shape and it resulted in higher porosity and random pore shapes compared to unreinforced metal matrix composites samples. Based on investigation of metal matrix composites samples, rice husk silica has good potential to improve the material behavior with appropriate composition of rice husk silica to metal matrix composite.