BazTech - Yadda

1

Investigating the effects of alumina nanoparticles on the impact resistance of polycarbonate nano-composites

Alavi Nia Ali, Amirchakhmaghi Saeed

Archive of Mechanical Engineering

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2022

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LXIX, nr 3

431--454

EN

In this project, two types of treated and untreated alumina nanoparticles with different weight percentages (wt%) of 0.5, 1 and 3% were mixed with polycarbonate matrix; then, the impact ballistic properties of the nano-composite targets made from them were investigated. Three types of projectile noses -cylindrical, hemispherical, and conical, each with the same mass of 5.88 gr – were used in the ballistic tests. The results highlighted that ballistic limit velocities were improved by increasing the percentage of alumina nanoparticles and the treatment process; changing the projectile’s nose geometry from conical to blunt nose increases the ballistic limit velocity, and ultimately, by increasing the initial velocity of conical and hemispherical nosed projectiles, the failure mechanism of the targets changed from dishing to petalling; whereas for the cylindrical projectile, the failure mode was always plugging.

2

Modified bentonite-derived materials as catalystsfor selective catalytic reduction of nitrogen oxides

Szymaszek Agnieszka, Kubeł Maciej, Samojeden Bogdan, Motak Monika

Chemical and Process Engineering

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2020

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Vol. 41, nr 1

13–-24

EN

In the last few years, cationic layered clays, including bentonites have been investigated as potentialcatalysts for SCR DeNOxsystems. In this work, bentonite as the representative of layered clays wasmodified in order to obtain an alternative, low-cost NH3–SCR catalyst. Samples of raw clay wereactivated with HCl or HNO3, treated with C2H2O4and subsequently pillared with alumina by the ion-exchange. Afterwards, the modified materials were impregnated with iron and copper. The obtainedcatalysts were characterized by XRD and FT-IR. SCR catalytic tests carried out over analyzed samplesindicated the conversion of NO of approximately 90% for the most active sample. The type of acidused for modification and the type of active phase strongly influenced the catalytic properties of theanalyzed materials.

3

The role of hydrogen gas buble in hydrophobic properties in mixed micro layer (Al2O3+Mg)

Subagyo R., Wardana I. N. G., Widodo A., Siswanto E.

Archives of Materials Science and Engineering

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2020

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Vol. 105, nr 1

5--16

EN

Purpose: To find out more about the role of hydrogen gas bubbles in improving the hydrophobic nature of a layer, especially in the layers of microparticles Alumina (Al2O3) with Magnesium (Mg). Design/methodology/approach: The method used is an experimental method by first conducting the SEM-Edx test, testing the content of the elements in the waxy layer and observing the topographic shape on the surface of the taro leaves. Then prepare a mixture of Alumina micro particles with Magnesium to investigate the hydrophobicity of the taro leaves. The mixed presentations between Alumina and Magnesium are: (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%). Findings: The results of this study found three conditions of the Alumina and Magnesium mix layer when in contact with a droplet, namely: Hydrophobic conditions occur when the surface structure of the rough mixed micro layer forms micro crevices, then bubbles of hydrogen gas fill it to form trapped gases. When droplets come in contact with the surface of the mixed layer the effect of the gas being trapped is very effective at creating hydrophobic properties. While the transition conditions occur when more and more hydrogen gas bubbles along with the increasing percentage of Mg and the opposite occurs in micro particle fissures. Bubbles fill the micro-gap space fully so that the tops of the micro particles are covered by bubbles. This causes the droplet surface tension to weaken, so the droplet contact angle decreases. Furthermore, hydrophilic conditions occur when the micro gap is getting narrower as the percentage of Mg increases and the formation of hydrogen gas bubbles increases. The high level of bubble density in the micro gap closes the peaks of the micro particles, which results in the surface tension of the droplet getting weaker. In this weak surface tension condition, the hydrogen bubble can break through the droplet surface tension and change its hydrophobic nature to hydrophilic. Research limitations/implications: This research is limited to the hydrophobicity of Alumina and Magnesium materials, mainly to investigate the role of hydrogen gas in supporting the hydrophobic nature of taro leaves (Colocasia esculenta). Practical implications: The practical implication in this study is the use of hydrophobic membranes which are widely applied to filtration. Originality/value: Discovered the composition of a membrane mixture of Alumina (Al2O3) and Magnesium (Mg) to create hydrophilic and hydrophobic conditions.

4

Involvement of hybrid materials based on natural clay and poly(vinyl chloride) into extraction of metal cations

Chrayet B., Ammari F., Meganem F.

Polimery

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2017

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T. 62, nr 3

187--192

EN

The solid-liquid extraction is one of the most used methods for protection of the environment against organic and inorganic pollutants. The hybrid materials have been synthesized by a simple method from natural clay and modified poly(vinyl chloride) (PVC). The obtained products were characterized by various techniques, infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The final materials were successfully used for entrapping heavy metal ions (Fe, Cu, Cd, Zn, Pb, Mn, and Co). The quantities of adsorbed metal cations were determined by atomic absorption analysis. It has been revealed that the metals extraction was governed essentially by the affinity between the functional groups of the hybrid material and the investigated metal ion. The cations are extracted in the following decreasing order of effectiveness: Fe3+ > Cu2+ > Co2+ ≈ Mn2+ > Pb2+ > Cd2+ ≈ Zn2+.

PL

Proces ekstrakcji w układzie ciało stałe-ciecz jest najczęściej stosowany w celu ochrony środowiska przed działaniem szkodliwych, organicznych i nieorganicznych zanieczyszczeń. Materiały hybrydowe zsyntetyzowano w prosty sposób z modyfikowanego poli(chlorku winylu) i naturalnej, tunezyjskiej glinki. Otrzymane materiały badano różnymi metodami: spektroskopii w podczerwieni (FT-IR), analizy termograwimetrycznej (TGA) oraz różnicowej analizy termicznej (DTA). Oceniano przydatność otrzymanych materiałów hybrydowych w procesach ekstrakcji kationów metali ciężkich: Fe, Cu, Cd, Zn, Pb, Mn i Co w układzie ciało stałe-ciecz. Ilości zaadsorbowanych kationów oceniano metodą absorpcji atomowej. Wykazano, że ekstrakcja metali jest możliwa dzięki powinowactwu grup funkcyjnych kompozytów hybrydowych z jonami metali. Za pomocą wytworzonych materiałów hybrydowych ekstrahowano badane jony w stopniu określonym następującą kolejnością: Fe3+ > Cu2+ > Co2+ ≈ Mn2+ > Pb2+ > Cd2+ ≈ Zn2+.

5

Manufacturing of ceramic porous preforms by sintering of Al2O3 powder

Kremzer M., Dobrzański L. A., Dziekońska M., Macek M.

Archives of Materials Science and Engineering

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2015

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Vol. 75, nr 2

63--69

EN

Purpose: The aim of the study is to develop a method of manufacturing porous preforms based on ceramic powder Al2O3 used as the strengthening for the production of modern metal composite materials. Design/methodology/approach: Semi-products were produced by sintering of ceramic powders with addition of the pores forming agent. The material of the preform was Al2O3 powder while as a pores and canals forming agent inside the sintered ceramic skeleton coal and charcoal were used. Particle size measurements of Al2O3 powder, charcoal, and coal using laser particle size measurer were made. Preforms were also observed in the scanning electron microscopy (SEM). Findings: The obtained preforms have a volume fraction of ceramic phase in the range of 20-44% due to the differences of sintering temperature and various portion and coal origin used as pores forming agent. Research limitations/implications: The main limitation of presented method is the possibility of obtaining preforms where a porosity are not exceeding 80%. Where, in the case of using ceramic fibers, the pores may be more than 90% volume fraction of the material. Practical implications: Manufactured ceramic preforms are widely used as a reinforcement for production of composite materials by infiltration methods. This method enables the production of metal and locally reinforced composite products with an exact mapping shape. Originality/value: Results indicate the possibility of obtaining new preforms which are a cheaper alternative to semi-finished products based on ceramic fibers. On the other hand, the use of coal and charcoal as a pores forming agent is an economically justified alternative to previously used materials such as fibers carbon and graphite.

6

Properties of Al–Al2O3 composites synthesized by spark plasma sintering method

Garbiec D., Jurczyk M., Levintant-Zayonts N., Mościcki T.

Archives of Civil and Mechanical Engineering

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2015

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Vol. 15, no. 4

933--939

EN

This work presents fabrication and characterization of Al–Al2O3 composite materials with a 5%, 10%, 15% and 20% volume fraction of reinforcing phase particles. The spark plasma sintering method was applied for the purpose of fabricating these materials. The obtained Al–Al2O3 composites were characterized with an porosity from 1.27% to 5.07%. It was proven that as the content of hard ceramic particles increases in the composite, its density, hardness, and compression as well as tensile strength increase. The conducted study showed that a composite with 20% alumina content is characterized by a larger hardness (1355 MPa) and compression strength (247 MPa).

7

Compatibilized ethylene-propylene-diene terpolymer nanocomposites containing different type of organoclays

Malas A., Das C. K.

Polimery

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2013

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T. 58, nr 3

204-211

EN

The simple mixing of non-polar rubber and organically modified nanoclay may not lead to good dispersion of organoclay in the rubber matrix, which is due to the incompatibility between the rubber and the filler. Thus, the application of polar compatibilizer which is compatible with both the gum base and organically modified clay may help to increase the reinforcing efficiency of the organoclay. Oil extended carboxylated styrene-butadiene rubber (XSBR) was used as a compatibilizer for the dispersion of the organically modified clay (Cloisite 15A, Cloisite 20A and Cloisite 30B) in the ethylene-propylene-diene terpolymer (EPDM) matrix. The degree of dispersion of organoclays in non-polar EPDM matrix after application of polar compatibilizer as well as the influence of these organoclays on the properties of nanocomposites based on EPDM were analyzed in this study. The microstructure of the organoclay filled EPDM composites was studied by wide angle X-ray diffraction (WAXD) method and high resolution transmission electron microscopic (HR-TEM) analysis. Dynamic mechanical thermal analysis (DMTA), scanning electron microscopic (SEM) analysis, thermogravimetric analysis (TGA) and curing tests were conducted for each nanocomposite. Cloisite 30B filled EPDM composite showed best thermal, mechanical and dynamic mechanical properties compared to all other investigated nanocomposites.

PL

Proste mieszanie niepolarnej gumy i polarnej organicznie zmodyfikowanej nanoglinki może nie wystarczyć do dobrego rozproszenia tej glinki w matrycy kauczuku. Jest to spowodowane brakiem kompatybilności między gumą i wypełniaczem. Zastosowanie polarnego kompatybilizatora, który jest kompatybilny z gumą bazową jak i z polarną organicznie modyfikowaną glinką, może pomóc w zwiększeniu efektywności wbudowywania w matryce gumowe organiczne modyfikowanych glinek. W tej pracy do wbudowania organicznie modyfikowanych nanoglinek (Cloisite 15A, Cloisite 20A i Cloisite 30B) w matryce niepolarnego terpolimeru etylenowo-propylenowo-dienowego (EPDM) użyto modyfikowanego olejem polarnego karboksylowanego kauczuku butadienowo-styrenowego (XSBR). Zbadano stopień dyspersji nanoglinki w matrycy niepolarnego EPDM po zastosowaniu polarnego kompatybilizatora oraz wpływ rodzaju glinki z kompatybilizatorem na właściwości otrzymanych nanokompozytów na bazie EPDM. Wszystkie nanokompozyty badano metodami szerokokątowej dyfrakcji promieniowania rentgenowskiego (WAXD), wysokorozdzielczej transmisyjnej mikroskopii elektronowej (HR-TEM), dynamicznej analizy termomechanicznej (DMTA), skaningowej mikroskopii elektronowej (SEM) oraz analizy termograwimetrycznej (TGA). Kompozyt EPDM napełniony Cloisite 30B charakteryzował się najlepszymi właściwościami termicznymi, mechanicznymi i dynamicznymi spośród wszystkich badanych nanokompozytów.

8

Rheology of dispersions of plasma-processed fine alumina in epoxy resin

Jakobsons E., Palcevskis E.

International Journal of Applied Mechanics and Engineering

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2005

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Vol. 10, no spec

225-232

EN

The rheological properties (flow curves and the viscoelastic behavior) of the dispersions prepared from plas-ma-processed Al2O3 powders and epoxy wax were investigated on wide ranges of shear rates (from 0.018 to 1350s-1) and frequencies (from 0.063 to 157s-1). Oleic acid and Hypermer LP1 was chosen as dispersants for preparation of the dispersions. It is stated that, at the concentration f ? 15 vol. %, for the composites studied, a spatial particle-particle network structure arise, which is broken at a critical stress s0. The slippage of the sample against the surface of rheometer tools was tested by mutual collation of test records obtained with the cone-plate and cylinder-cylinder equipments. The results showed that the influence of dispersants is the most pronounced if the composite has a spatial particle-particle structure.