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1
Content available Thermal and mechanical properties of polyamide 12/modified carbon nanotubes composites prepared via the in situ ring-opening polymerization
Pełech I., Kwiatkowska M., Jędrzejewska A., Pełech R., Kowalczyk I.
Polimery
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2017
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T. 62, nr 2
101--108
EN
In this study polyamide 12 (PA12) based composites prepared in situ via an ring-opening polymerization of lauryl lactam in the presence of raw and functionalized carbon nanotubes (CNTs) are characterized. This method has been widely applied for thermoplastic based composites, resulting in materials with relatively small amounts and uniform nanofiller distribution. The effect of multi-wall carbon nanotubes chemically modified with hydroxyl or amine groups on PA12 matrix is discussed in terms of the phase structure, thermal, mechanical, and water vapor barrier properties as well as the state of CNTs dispersion in composites. The obtained results confirm, that in general the physical properties of PA12 are noticeably affected by the presence of 0.35 wt % CNTs, whilst the benefits from nanotubes modification are observed in changes of phase transition temperatures and composite mechanical performance, whilst the thermooxidative stability and water absorption the CNTs chemical modification is less pronounced.
PL
Określono właściwości kompozytów na osnowie poliamidu 12 (PA12), napełnionych niemodyfikowanymi lub modyfikowanymi nanorurkami węglowymi (CNTs), otrzymanych in situ w polimeryzacji z otwarciem pierścienia. Metoda ta, szeroko stosowana do wytwarzania kompozytów na osnowie termoplastów, daje możliwość uzyskania materiałów o względnie małej zawartości i jednorodnej dyspersji nanonapełniacza. Omówiono wpływ modyfikacji wielościennych nanorurek węglowych grupami hydroksylowymi lub aminowymi na strukturę fazową, właściwości termiczne, mechaniczne i barierowe osnowy poliamidowej oraz na stopień dyspersji nanocząstek w kompozycie. Wyniki badań potwierdziły wpływ dodatku 0,35 % mas. nanorurek na właściwości fizyczne PA12, przy czym korzyści wynikające z modyfikacji chemicznej obserwowano w wypadku temperatury przemian fazowych oraz wytrzymałości mechanicznej kompozytów, natomiast w odniesieniu do stabilności termooksydacyjnej i właściwości barierowych wpływ funkcjonalizacji był mniejszy.
2
Content available remote Katalizatory kobaltowo-molibdenowe domieszkowane cezem do syntezy amoniaku
Moszyński D., Adamski P., Pełech I., Arabczyk W.
Przemysł Chemiczny
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2015
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T. 94, nr 8
1399-1403
PL
Badano katalizatory kobaltowo-molibdenowe domieszkowane cezem (0,25–3% mas. Cs) w procesie syntezy amoniaku. W katalizatorach tych zidentyfikowano dwie fazy krystaliczne azotków kobaltu i molibdenu: Co₂Mo₃N oraz Co₃Mo₃N. Wykazano, że materiały te charakteryzują się dużą aktywnością w procesie syntezy amoniaku. Optymalną aktywność katalityczną uzyskano dla katalizatorów zawierających 1,7% mas. cezu. Na podstawie testu starzenia termicznego wykazano, że dochodzi do częściowego spiekania krystalitów fazy repeatedly detd. Thermal treatment resulted in sintering of crystallite Co₃Mo₃N phase and decreasing the activity of catalysts.N oraz zmniejszenia powierzchni właściwej. W rezultacie zmniejsza się aktywność katalizatorów.
EN
Co-Mo catalysts contg. Cs (0.25–3.0% by mass) were obtained by redn. of precursors with NH₃ at 700°C. The precursors were derived from aq. solns. of (NH₄)₆Mo₇O₂₄, Co(NO₃)₂ and CsOH. The anal. of catalysts by X-ray diffraction and anal. of the diffraction profiles by Rietveld method showed the presence of Co₂Mo₃N and Co₃Mo₃N phases depending on the content of Cs in the catalyst. Activities of the catalysts were tested under lab. Conditions of the synthesis of NH₃ at 400°C and 10 MPa. The reaction rate const. was detd. by measuring the flow of the reaction gases and NH₃ concns. The highest activity was achieved for the catalyst contg. Cs 1.7% by mass. The catalysts used for the activity detns. were then subjected to aging (650°C, 18 h) and their activity was repeatedly detd. Thermal treatment resulted in sintering of crystallite Co₃Mo₃N phase and decreasing the activity of catalysts.
3
Content available Preparation and characterization of multi-walled carbon nanotubes grown on transition metal catalysts
Pełech I., Narkiewicz U., Kaczmarek A., Jędrzejewska A.
Polish Journal of Chemical Technology
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2014
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Vol. 16, nr 1
117-122
EN
Transition metal catalysts (mainly: iron, cobalt and nickel) on various supports are successfully used in a largescale production of carbon nanotubes (CNTs), but after the synthesis it is necessary to perform very aggressive purification treatments that cause damages of CNTs and are not always effective. In this work a preparation of unsupported catalysts and their application to the multi-walled carbon nanotubes synthesis is presented. Iron, cobalt and bimetallic iron-cobalt catalysts were obtained by co-precipitation of iron and cobalt ions followed by solid state reactions. Although metal particles were not supported on the hard-to-reduce oxides, these catalysts showed nanometric dimensions. The catalysts were used for the growth of multi-walled carbon nanotubes by the chemical vapor deposition method. The syntheses were conducted under ethylene - argon atmosphere at 700°C. The obtained catalysts and carbon materials after the synthesis were characterized using transmission electron microscopy (TEM), X-ray diffraction method (XRD), Raman spectroscopy and thermogravimetric analysis (TG). The effect of the kind of catalyst on the properties of the obtained carbon material has been described.
4
Content available High Pressure Synthesis versus Calcination – Different Approaches to Crystallization of Zirconium Dioxide
Kaszewski J., Yatsunenko S., Pełech I., Mijowska E., Narkiewicz U., Godlewski M.
Polish Journal of Chemical Technology
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2014
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Vol. 16, nr 2
99--105
EN
Calcination and microwave-assisted hydrothermal processing of precipitated zirconium dioxide are compared. Characterization of synthesized products of these two technologies is presented. The infiuence of thermal treatment up to 1200oC on the structural and spectroscopic properties of the so-obtained zirconium dioxide is examined. It was found that initial crystallization of material inhibits the crystal growth up to the 800oC (by means of XRD and TEM techniques), while the material crystallized from amorphous hydroxide precursor at 400oC, exhibits 26 nm sized crystallites already. It was found using the TG technique that the temperature range 100–200oC during the calcination process is equivalent to a microwave hydrothermal process by means of water content. Mass loss is estimated to be about 18%. Based on X-ray investigations it was found that the initial hydroxide precursor is amorphous, however, its luminescence activity suggests the close range ordering in a material.
5
Content available remote Synthesis of nanocrystalline nickel and iron carbides by decomposition of hydrocarbons
Podsiadły M., Pełech I., Narkiewicz U.
Materials Science Poland
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2013
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Vol. 31, No. 1
65-79
EN
Decomposition of hydrocarbons was carried out on nickel and iron catalysts containing small amounts of calcium and aluminum oxides as structural promoters. Decomposition of methane, ethane and ethylene was studied under atmospheric pressure in the temperature range from 500 to 700 °C. The phase composition of the obtained samples was investigated using X-ray diffraction method. The role of nickel and iron carbides in the formation of carbon deposit was discussed.
6
Content available Removal of SO2 from gases on carbon materials
Narkiewicz U., Pietrasz A., Pełech I., Arabczyk W.
Polish Journal of Chemical Technology
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2012
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Vol. 14, nr 1
41-45
EN
The aim of the work is to describe a capability of the active carbon CARBON L-2-4 (AC) and of the nanocarbon (NC) materials containing iron nanoparticles to continuously remove SO2 from air. The carbon nanomaterials (NC) containing iron nanoparticles were synthesised using a chemical vapor deposition method - through catalytic decomposition of ethylene on nanocrystalline iron. The process of SO2 removal was carried out on dry and wet with water carbon catalyst (AC or NC) and was studied for inlet SO2 concentration 0.3 vol.% in the presence of O2, N2 and H2O, in the temperature range of 40-80°C.
7
Content available Preparation of carbon nanotubes using cvd CVD method
Pełech I.
Polish Journal of Chemical Technology
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2010
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Vol. 12, nr 3
45-49
EN
In this work preparation and characteristic of modified nanocarbons is described. These materials were obtained using nanocrystalline iron as a catalyst and ethylene as a carbon source at 700°C. The influence of argon or hydrogen addition to reaction mixture was investigated. After ethylene decomposition samples were hydrogenated at 500°C. As a results iron carbide (Fe3C) in the carbon matrix in the form of multi walled carbon nanotubes was obtained. After a treatment under hydrogen atmosphere iron carbide decomposed to iron and carbon and small iron particles agglomerated into larger ones.
8
Catalytic Decomposition of Ethylene on Iron - the Effect of Process Conditions on the Yield and Morphology of Nanocarbon Products
Narkiewicz U., Pełech I., Arabczyk W., Biedermann K., Tüschner Ch.
Polish Journal of Chemistry
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2008
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Vol. 82, nr 9
1743-1752
EN
The catalytic decomposition of ethylene on nanocrystalline iron was investigated. The processes were carried out in a horizontal tube reactor under atmospheric pressure and in the temperature range of 500-800°C. Various process parameters such as: reaction time, temperature, C2H4:H2 ratio, C2H4:Arratio have been examined to determine the effect of these parameters on both the yield of carbon and the morphology of products. The quality of the products was characterized by means of transmission electron microscopy (TEM). According to the observed results, ethylene can be used as a very effective carbon source for growing multi-walled carbon nanotubes (MWCNTs). The meandiameter of the obtained MWCNTs was 20-30 nm. The length of carbon nanotubes in creased with reaction time. The carbon nanotubes obtained in presence of hydrogen or argon in reaction mixture were straighter and less entangled than carbon nanotubes obtained through de composition of pure ethylene.
9
Content available Utilization of spent iron catalyst for ammonia synthesis
Arabczyk W., Narkiewicz U., Lendzion-Bieluń Z., Moszyński D., Pełech I., Ekiert E., Podsiadły M., Pelka R., Jędrzejewski R., Moszyñska I., Sibera D.
Polish Journal of Chemical Technology
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2007
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Vol. 9, nr 3
108-113
EN
Several methods of the utilization of spent iron catalyst for ammonia synthesis have been presented. The formation of iron nitrides of different stoichiometry by direct nitriding in ammonia in the range of temperatures between 350°C and 450°C has been shown. The preparation methods of carbon nanotubes and nanofibers where iron catalyst catalyse the decomposition of hydrocarbons have been described. The formation of magnetite embedded in a carbon material by direct oxidation of carburized iron catalyst has been also presented.
10
Content available remote Magnetic properties of cementite (Fe3C) nanoparticle agglomerates in a carbon matrix
Lipert K., Kaźmierczak J., Pełech I., Narkiewicz U., Ślawska-Waniewska A., Lachowicz H. K.
Materials Science Poland
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2007
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Vol. 25, No. 2
399--404
EN
Magnetic properties of two FeC samples with different amounts of carbon have been studied. In both cases, the amount of carbon was well above the mass sufficient to transform nanocrystalline iron into iron carbide (cementite). Through the dc magnetic and transmission electron microscopy (TEM) measurements it was shown that cementite nanoparticles formed agglomerates; the size distribution of these nanoparticles was very wide, and superparamagnetic-like behaviour was not observed even at room temperature.
11
Content available remote FMR study of nanocarbon materials obtained by carburisation of nanocrystalline iron
Narkiewicz U., Arabczyk W., Pełech I., Guskos N., Typek J., Maryniak M., Woźniak M. J., Matysiak H., Kurzydłowski K. J.
Materials Science Poland
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2006
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Vol. 24, No. 4
1067--1075
EN
Samples of nanocrystalline iron were carburised with ethylene and next reduced with hydrogen. Both carburisation and reduction were monitored by the thermogravimetry. The obtained samples were characterised using X-ray diffraction, high-resolution transmission electron microscopy and ferromagnetic resonance. The samples after carburisation contained cementite (Fe3C) and carbon deposit (nanofibres and nanotubes). As the result of reduction with hydrogen at 450 or 500 °C cementite was reduced to iron. A major part of carbon was also hydrogenated, only thin carbon nanotubes remained. The FMR spectra of the prepared samples were recorded at room temperature. The sample after carburisation has shown a wide FMR line with weak intensity while the resonance field has been shifted to lower magnetic field. This spectrum has been attributed to the presence of cementite. The FMR lines corresponding to samples after reduction are more intense and are connected with the presence of alfa-Fe nanoparticle conglomerates.
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