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Abstract

This study contains mathematical modelling and numerical analysis of heat transfer in laser beam welding process. The temperature field was obtained on the basis of numerical solution into unsteady heat transfer equation with convective term and volumetric heat sources taken into account. Volumetric heat source model describing laser beam power distribution in combined truncated cone–cylinder volume was developed. Due to the wide range of temperatures appearing in the process latent heat of fusion, evaporation as well as latent heat of phase transformations in solid state were taken into account in the solution algorithm. On the basis of developed numerical algorithms an analysis of heat transfer in laser butt-welded steel sheets as a three-dimensional initial-boundary problem was performed.

Open access

Abstract

New Y(III) and La(III) complexes with 4-bpy (4,4′-bipyridine) and trichloro- or dibromoacetates with the formulae: Y(4-bpy)2(CCl3COO)3·H2O I, La(4-bpy)1.5(CCl3COO)3·2H2O II, Y(4-bpy)1.5(CHBr2COO)3·3H2O III, and La(4-bpy)(CHBr2COO)3·H2O IV were prepared and characterized by chemical, elemental analysis, and IR spectroscopy. Conductivity studies (in methanol, dimethyloformamide, and dimethylsulfoxide) were also described. They are small, crystalline substances. The way of metal–ligand coordination was discussed. The thermal properties of complexes in the solid state were studied by TG-DTG techniques under dynamic flowing air atmosphere. TG-FTIR system was used to analyze principal volatile thermal decomposition and fragmentation products evolved during pyrolysis in dynamic flowing argon atmosphere for La(III) compounds.

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Abstract

This paper presents the effect of halloysite intercalated with a base or modified montmorillonite on the thermal properties and flammability of peroxide and sulfur vulcanizates of styrene–butadiene rubber (SBR). Based on the test results obtained by means of thermal analyses (DTA, TG, DTG, and DSC), oxygen index and microcalorimeter (FAA) it has been found that the thermal stability and flammability of the nanocomposites investigated depend on the spatial network structure as well as the content and type of nanoadditive in the vulcanizate obtained. The nanofillers used considerably reduce the flammability and fire hazard of the cross-linked SBR.

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Abstract

The kinetics of the oxidation of imipramine and opipramol using peroxydisulfate salts in the presence of a large excess of dibenzoazepine derivative (TCA) in acidic sulfate media was studied using UV–vis spectroscopy. The reaction between imipramine and S2O8 2− proceeds via the formation of two intermediates: a free organic radical and a dimeric dication. Further reaction of the intermediate dimeric dication leads to a positively charged radical dimer as one final product. Simultaneously, two other substituent cleavage degradation processes occur, leading to two dimeric derivatives. The first product, the positively charged radical dimer, and the next main product, a radical dimer without one alkyl substituent, were identified by EPR measurements. The measured kinetic trace is not first order and revealed a sigmoid shape with a characteristic induction time. The rate constants were determined by numerical analysis based on ordinary differential equations (ODEs). The reaction between opipramol and S2O8 2− proceeds by a two consecutive reaction scheme. The kinetics of the first degradation step were studied independently of the slower degradation reactions. Linear dependences, with zero intercept, of the pseudo-first-order rate constants (k obs) on [TCA] were determined for the first degradation process of opipramol.

Open access

A highly scalable and efficient flow-system has been developed to perform the catalyzed acetylation of alcohols and phenols, such as salicylic acid, at room temperature in excellent yield. The volumetric throughput and the amount of product can be increased simply by increasing the diameter of a versatile catalytic 12-tungstosilicic acid-supported, silica monolith can be used to increase the quantity of product produced without having to changeing the optimal operatingreaction conditions.

Open access

In this section of the journal, the continuous flow chemistry literature of the preceding months is presented. Included are articles published in January and February 2012 and some articles from 2011 which received page numbers only in the beginning of 2012. Some key examples are highlighted in the form of graphical abstracts. The remaining publications in the field are then listed ordered by journal name, with review articles grouped at the end.

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Positron emission tomography (PET) is a very powerful diagnostic technique routinely used in a variety of medical applications. This review article summarises the developments of using microreactor technology for the radiochemical synthesis of PETagents. The advantages of manufacturing these imaging drugs using microreactors are described, and a review of reactions conducted to date is outlined.

Open access

We present and validate simple mesofluidic devices for producing monodisperse droplets and materials. The significance of this work is a demonstration that simple and complex droplet formulations can be prepared uniformly using off-the-shelf small-diameter tubing, barbed tubing adapters, and needles. With these simple tools, multiple droplet-forming devices and a new particle concentrator were produced and validated. We demonstrate that the droplet-forming devices could produce low-dispersity particles from 25 to 1200 Km and that these results are similar to results from more complicated devices. Through a study of the fluid dynamics and a dimensional analysis of the data, we have correlated droplet size with two dimensionless groups, capillary number and viscosity ratio. The flowfocusing device is more sensitive to both parameters than the T-junction geometry. The modular character of our mesofluidic devices allowed us to rapidly assemble compound devices that use flow-focusing and T-junction devices in series to create complex droplet-in-microcapsule materials. This work demonstrates that flow chemistry does not require complicated tools, and an inexpensive tool-kit can allow anyone with interest to enter the field.

Open access

Photooxygenation of 1,5-dihydroxynaphthalene to Juglone was studied in a falling film microreactor. Moderate conversion rates of up to 31% were achieved after just 160 s of exposure to visible light. In contrast, batch reactions gave much lower conversions of up to 14% after a prolonged time period of 10 min. The difference in performance is explained by the superior light penetration in the microfilm and the large gas-liquid contact area.

Open access
Journal of Flow Chemistry
Authors: Ana Cukalovic, Jean-Christophe M. Monbaliu, Geraldine J. Heynderickx and Christian V. Stevens

The Kiliani reaction, i.e. the elongation of the carbon chain by means of cyanide addition to the carbonyl group of carbohydrate derivatives, is studied on lower C3-, C4- and C6-ketoses under continuous flow conditions. Depending on the process parameters, the corresponding cyanohydrins or α-hydroxycarboxylic acids are obtained. A simple on-line purification of the effluent is studied using cation exchange resins. Reactions provide high yields and selectivity within short residence times, emphasizing the assets of the continuous flow process versus the batch process.

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Abstract

New branched polymethylvinylborosiloxanes (PMVBSs) with random structures were prepared, and their chemical structures were studied by spectroscopic methods (FTIR, 1H-, 29Si-, and 11B-NMR) and elemental analysis (% C, % H, % Si, and % B). Average molecular weights M w and M n were determined by a size exclusion chromatography (SEC), and dynamic viscosities were measured in Brookfield cone–plate reoviscometer HBDV-II+cP. Thermal properties of PMVBSs were studied under air and under nitrogen atmosphere. Thermal curves were interpreted from the point of view of physical and chemical transitions, taking place during the heating process of PMVBSs. Parameters of their thermal stabilities and glass transition temperatures (T g) were determined. The synthesized PMVBSs are characterized by low glass transition temperatures (T g: from −122 to −137 °C) which depend on their chemical structures. It was concluded that gaseous products (such as volatile siloxanes, silanes, CO2, H2O, CH2O, methanol, and formic acid), which could be liberated during the heating process of PMVBSs, promote ceramization processes, leading to the formation of the ceramics of a type SiBCO—a borosilicate glass and silica.

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Abstract

The work considers the methods and techniques, allowing the assignment of the kinetic mechanisms to the chemical reactions evaluated from signals of thermoanalytical measurements. It describes which information about the kinetic mechanisms can be found from either model-free or model-based methods. The work considers the applicability of both methods and compares their results. The multiple-step reactions with well-separated peaks can be equally analyzed by both methods, but for overlapping peaks or for simultaneously running parallel reactions the model-free methods provide irrelevant results.

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Abstract

The paper reports the decomposition of saccharides derivatives in comparison to commercial substances during the process of binder removal from ceramic samples. The saccharides derivatives are polymers synthesized from glucose and fructose with acryloyl group in the sugar molecule. The synthesized compounds played the role of binder in the shaping of ceramic powders by gelcasting method. The method belongs to colloidal processes and allows to produce ceramic elements of complicated geometry. As ceramic powder Al2O3 was used. The thermal analysis have been done on apparatus coupled with mass spectrometer. MS analysis showed what types of gasses are released to the atmosphere during the thermal decomposition of polymers. The obtained results showed important differences in decomposition of polymers obtained from commercial acrylamide, 2-hydroxyethyl acrylate and N,N′-methylenebisacrylamide in comparison to synthesized glucose and fructose derivatives. The measurements allowed to establish the sintering program of the green ceramic samples and evaluate whether harmful NOx gases are released to the atmosphere.

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Abstract  

The article presents the measurement results of the volumetric activity (VA) of artificial radionuclides 90Sr and 137Cs in the coastal waters of the Baltic Sea near the Curonian Peninsula in 2005–2009. The annual average values for this period of time were 12 Bq/m3 (90Sr) and 40 Bq/m3 (137Cs). Considerable variations in the VA of the radionuclide in individual measurements compared to the average results were observed. The extreme values were 6 and 16 Bq/m3 for 90Sr and for 137Cs—27 and 75 Bq/m3. It is proposed to allow such variations under the influence of a variety of external factors such as hydro meteorological situations, inflowing rivers and bays, storm activity and etc. Besides, a possibility of penetration of radionuclides into the sea waters from the additional radioactive sources is not excluded.

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Abstract

Nucleation ability of native and modified rapeseed straw during the polypropylene crystallization from the melt was investigated by the DSC method. Composites were made from isotactic polypropylene and lignocellulosic material using extrusion and injection moulding techniques. They were obtained using polypropylenes differing with respect to melt flow rates and different varieties of rapeseed straw. Chemical modification was carried out in two stages: through mercerisation and treatment with acetic acid anhydride. In the course of investigations, it was found that both native and modified rapeseed straw acted as an active nucleant of polypropylene crystallisation characterised by low values of MFR indices. It was found that for polypropylenes with high MFR values, the values of crystallization temperatures and crystallization half-time in composites were identical when compared with non-filled polymers. The investigations demonstrated that there were insignificant differences among composites containing straw from different varieties of rapeseed. The analysis of crystallization temperatures confirmed that rapeseed straw modification failed to change this parameter of the crystallization process. A similar tendency was observed in the case of changes of the half-time crystallization process. Moreover, the analysis of the crystallization temperature and crystallization half-time showed that the presence in composites of lignified rapeseed straw particles played an important role in the crystallization conditions.

Open access

Abstract

In this study, the calorimeter was applied to follow the hydration of special cement mixtures exhibiting expansion or shrinkage compensation. The shrinkage-less and expansive binders were produced by mixing of Portland cement with an expansive additive produced by sintering and composed of calcium sulfoaluminate (yeelimite), calcium sulfate (anhydrite) and lime. The studies were focused on the synthesis of this aluminate—sulfate—lime additive (temperature of burning process as a parameter controlling the relative activity of components) from the materials being the by products and subsequently on the mixture proportions to ensure the hydration process resulting in non-shrinkage or expansion effect. In the experiments the proportions of expansive mixture and cementitious materials were variable. The investigations with aim to find the relationship between the volume changes and composition of initial mixtures in cement pastes and mortars (with sand) were also carried out. The phase composition and microstructure of products were characterized. The expansive additive in the environment of hydrating cement transforms into ettringite and gives an increase of volume when the plastic material transforms to the more rigid matter but before the ultimate hardening takes place. Proper, moderate setting and hardening in strongly modified mixtures is achieved when the calorimetric curve corresponding to the heat evolution on hydration is analogous to that for the basic Portland cement. The rate of heat evolution data are well compatible with the other results related to the other methods of hydration kinetics assessment (e.g. chemical shrinkage) and discussed in terms of the phase composition of hydration products.

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Abstract

The evaluation of the possibilities to use coal-tar pitch modified with waste poly(ethylene terephthalate) or phenol–formaldehyde resin for the preparation of activated carbons was carried out. The measurement of thermal analysis (DSC), softening point, coking value, content of components insoluble in toluene and quinoline of pitch-polymer compositions were carried out. Coal-tar pitch and pitch-polymer compositions were carbonized and activated with steam at 800 °C to 50 % burn-off. For the obtained activated carbons the determination of thermal analysis (DSC), BET surface area on the basis of volumetric low-temperature adsorption of nitrogen, mesopore, and micropore volume from benzene adsorption/desorption isotherms (gravimetric McBain-Bakr method) were carried out.

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Abstract

Thermoporosimetry, i.e., DSC measurements of melting point depression of water and heptane confined in mesopores, has been used for determination the pore size distribution of several mesoporous silicas synthesized with the use of micelle templates. Porosity of these materials was additionally characterized by low-temperature nitrogen adsorption and quasi-equilibrated thermodesorption of nonane. The pore size distributions obtained using the water thermoporosimetry were similar to those determined using the other methods, but the pore size values found for the narrow pore materials were underestimated by ca 1 nm. Too large pore sizes obtained for the wide pore silica from heptane thermoporosimetry were attributed to nonlinear dependence of the melting point depression on the reciprocal of the pore size.

Open access

Abstract

The aim of the research was obtaining and application of smectic clay modifying agent. The organophilic clay is used as nanofiller in polymer nanocomposites []. A microwave-assisted reaction led to obtaining N-heptaquinolinum, which is amphiphilic compound, containing both hydrophobic (alkyl and aromatic) and hydrophilic sections in its structure []. N-heptaquinolinum was used as a montmorillonite clay modifying agent. Modification was carried out in formulated way [, ]. Modification efficiency was determined by X-ray diffraction (XRD) analysis and elementary analysis. Organophilic clay (Ch7) was introduced, using the extrusion method, into polyethylene matrix in different mass relations (1.5, 3 and 5 %) []. The structure of obtained materials was studied by means of XRD and SEM. To evaluate potential applications thermal properties of received nanocomposites were tested with thermogravimetric analysis and differential scanning calorimetry. The thermal stability of PE/clay composites can be improved in the case of loading 1.5 and 5 mass%.

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Abstract  

A study was conducted on three macroalgae species: Polysiphonia fucoides and Furcellaria lumbricalis, the species of the red algae division, and Cladophora glomerata, representing the green algae division, as well as Zostera marina, representing vascular plants. The main aim of the study was to recognize the level of 137Cs concentrations in the plants, which could be used as a measurement of bioaccumulation efficiency in the selected macrophytes at varying depths, and in the seasonal resolution of the vegetation period: spring–summer and autumnal. The plants’ biomass clearly showed seasonal variability, as did the 137Cs concentrations in the plants. Cesium activity also changed with depth. Seasonal variability in radionuclide content in the plants, as well as the differences in its activity determined along the depth profile, were related mainly to the plant biomass and the dilution effect caused by the biomass increment and reflected the growth dynamics. P. fucoides showed much greater bioaccumulation ability at each depth as compared to C. glomerata, a green algae. Lower concentrations of 137Cs were also identified in F. lumbricalis and in Z. marina, mostly as a result of differences in morphology and physiology. P. fucoides can be recommended as a bioindicator for the monitoring of 137Cs contamination due to the high efficiency of bioaccumulation and the available biomass along the depth profile, as well as the occurrence throughout the entire vegetation season.

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Abstract

A new method for the measurement of solid fuel reactivity towards carbon dioxide has been developed. This new method takes into account high-pressure and temperature effects. Three devolatilized carbonaceous materials have been used in experiments: chars derived from lignite, bituminous coal and blast furnace coke. Processes were carried out at temperatures of 800, 850 and 900 °C and pressures of 1.52, 2.5 and 3.4 MPa. Analysis of the product gas composition was carried out with the maximum degree of conversion of CO2m) proposed as a representative reactivity parameter. Arrhenius and Eyring relationships have been analyzed, and values of the activation energy and activation volume have been calculated.

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Abstract

Glass transformation effect of mixed SiO2–P2O5–K2O–MgO–CaO–CuO glasses was studied by DSC, XRD, SEM, and Raman spectroscopy methods. The relationship between the parameters characterizing glass transformation effect and an amount of phosphorous and copper forming the glassy structure was discussed. It was shown that an increasing content of phosphorous increased solubility of copper in the structure of the studied glasses which was the result of P–O–Cu bonds formation. Degree of changes of T g, Δc p, and time of relaxation values were higher in glasses with higher content of P2O5 and CuO. The observed relations were explained on the basis of the local atomic interactions in the structure of glass.

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Abstract

In this study, it was shown that a possible explanation of increasing photocatalytic activity with temperature may be the fact that with increasing water temperature, the amount of hydroxyl radicals in water also increases, because the ionic product of water increases with an increase in temperature. For measurements of the amount of hydroxyl radicals, the fluorescence technique was used. Terephthalic acid was used as a hydroxyl radical scavenger. After inducing of TiO2, positive holes in the valance band may react with OH ions and produce OH radicals, a strong oxidizing agent.

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Abstract

This article presents the studies on the thermal and viscoelastic properties of novel epoxy-dicyclopentadiene-terminated polyesters-styrene copolymers. The novel materials were prepared during a three step process including the addition reaction of maleic acid to norbonenyl double bond of dicyclopentadiene; polycondensation of acidic ester of dicyclopentadiene, cyclohex-4-ene-dicarboxylic anhydride, maleic anhydride, and suitable glycol: ethylene, diethylene, or triethylene glycol; and the epoxidation process of prepared polyesters. It allowed obtaining novel epoxy-dicyclopentadiene-terminated polyesters which were successfully used as a component of different styrene content (10–80 mass%) copolymers. The influence of the structures of polyester and styrene content on the cross-linking density (v e), tgδ max, tgδ max height, storage modulus (E′ 20 °C), FWHM values as well as the thermal stability of copolymers was evaluated by TG, DSC, and DMA analyses and discussed.

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Abstract  

The significant differences in the activities of 210Pb, 210Bi, 210Po and cosmogenic 7Be and 22Na radionuclides in the urban aerosol samples collected in the summers 2010 and 2011 in the Lodz city of Poland were observed. Simultaneous measurement of these radionuclides, after a simple modification of the one compartment model, allows us to calculate both: the corrected aerosol residence times in the troposphere (1 ÷ 25 days) and in the lower stratosphere (103 ÷ 205 days). The relative input of the additional sources (beside of the 222Rn decay in the air) to the total activity concentrations of 210Pb, 210Bi and 210Po radionuclides in the urban air, plays a substantial role (up to 97% of the total activity) only in the case of 210Po.

Open access

Abstract

The aim of this study was to investigate the self-assembly process for m-8-m gemini surfactants, for m = 8 and 12, in water, using the microcalorimetric titration method within the temperature range of 283.15–343.15 K. The enthalpy of micellization (ΔH mic) and critical micelle concentration (c.m.c.) have been calculated by using modified sigmoidal Boltzmann equation. Other thermodynamic parameters ΔG mic, ΔS mic, and ΔC p,mic, associated with micellization process were determined on the basis of the calorimetric results by applying the pseudo-phase separation model. The c.m.c. and ΔH mic values strongly depend on the temperature and the alkyl chain length. The enthalpy of micellization decreases and then changes its sign and becomes negative when temperature increases. The temperature dependence of the c.m.c. for the surfactants investigated exhibits typical U-shape. The results obtained are compared with literature data for other gemini cationic surfactants with a different alkyl chain length. The differences are analyzed in terms of differences in the hydrophobic interactions between the hydrocarbon chains.

Open access

Abstract

Portland cement paste is a multiphase compound mainly consisting of calcium-silicate-hydrate (CSH) gel, calcium hydroxide (CH) crystal, and unhydrated cement core. When cement paste is exposed to high temperature, the dehydration of cement paste leads to not only the decline in strength, but also the increased pore pressure in the paste. In this article, the dehydration kinetic was characterized in term of the combination of kinetics of CSH and CH. The dehydration kinetics data of cement paste at different heating rates was collected by thermogravimetry. The influence of temperature on the reaction rate is analyzed by Arrhenius equation. The Arrhenius parameters of CSH and CH, activation energy, and pre-exponential factor are determined by isoconversional method. The calculated kinetics parameters were validated by further experimental data finally.

Open access

Abstract

Ceramic–metal composites (cermets) containing 4 mol% yttria-zirconia (4YSZ) and Ni particles as anode materials in solid oxide fuel cells were prepared by two methods. The first method involves nickel oxalate dihydrate precipitation on the 4YSZ powder and decomposition at 360 °C in inert Ar atmosphere. The second method consists of impregnation of the 4YSZ pellets with an aqueous solution of nickel nitrate. The temperature of oxalate decomposition was determined on the basis of TG/DTA experiments. Gaseous products of decomposition were analyzed by mass spectrometry. The structure of the materials was characterized by X-ray diffraction, scanning electron microscopy, porosity studies, and particle size measurements. The thermal expansion coefficient (TEC) was determined by dilathometric method. Electrochemical impedance spectroscopy was used to determine the electrical conductivity. Thus, determined TECs, porosity, and electrical properties were found suitable for anode materials of fuel cells.

Open access

Abstract

A new compound in the Al–Sb–V–O system of the composition AlSbVO6 was successfully synthesized by a solid-state reaction and characterized by powder XRD diffraction. The structural and thermal properties of AlSbVO6 were investigated. The infra-red spectrum of the new phase is presented.

Open access

Abstract

Given the known carcinogenic effects, asbestos minerals are considered as general health hazard. Therefore, the elimination of asbestos materials from the environment is necessary. Asbestos minerals should be entirely transformed to a non-hazardous material. One of these methods is destructing the fibers structure of asbestos minerals by thermal treatment. Asbestos minerals are naturally occurring hydrous silicates, so that they decompose to release water by heating at high temperatures which may lead to changes in crystal structure and the formation of new phases without the dangerous properties. In this article, thermal behavior of asbestos minerals is investigated to observe the disappearance of this hazardous structure and to characterize products obtained by this way. Ten samples of asbestos minerals (six chrysotile samples from different locations, two samples of crocidolite, one amosite, and one tremolite) from different locations were tested. Mineralogical and morphological data (X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy) were obtained before and after differential thermal analysis.

Open access

Abstract

Thermal stability of a compound forming in a binary system MoO3–In2O3 was investigated by DTA/TG, XRD and SEM methods in this study. For the first time, the diagram of phase equilibria established in the whole range of concentrations of this system's components has been constructed. The temperature and concentration ranges of the components of MoO3–In2O3 system in which the compound In2(MoO4)3 co-exists in solid state with MoO3 or In2O3 or with the liquid were determined. The composition and melting point of the eutectic mixture consisting of In2(MoO4)3 and MoO3 were found.

Open access

Abstract

The binary Zn2FeV3O11–Mg2FeV3O11 system has been studied by XRD, DTA, IR, and SEM methods. A new continuous substitution solid solution with the formula Zn2−xMgxFeV3O11 has been obtained by high-temperature synthesis. The DTA investigations were used to choose the heating temperatures as well as for determination of thermal stability of the new triclinic phase. The influence of the degree of Mg2+ ion incorporation on the unit cell volume as well as on the position of the IR absorption bands of the solid solution have been determined. The morphology of crystals of the new phase is presented.

Open access

Abstract

Various Pd amounts (5 and 20 %wt) were chemically deposited on two different carbon materials (activated carbon and carbon black). Support materials were characterized using low-temperature N2 adsorption and FTIR spectroscopy. SEM images and X-ray diffraction patterns were obtained for the samples tested. Cyclic voltammetric curves in 0.1 M H2SO4 were recorded over a variable sweep potential range for carbon materials with and without Pd. For comparison, the same electrochemical measurements were performed for powdered palladium. The hydrogen electro-oxidation potential decreased and the removal of adsorbed hydrogen by activated carbon-supported palladium was facilitated, which enables these systems to be used as anodes in hydrogen–oxygen fuel cells.

Open access

Abstract

The subsolidus phase relations of the ternary system CoO–In2O3–V2O5 were investigated by differential thermal analysis and X-ray diffraction techniques. It has been shown that the system consists of seven subsidiary systems in which three solid phases coexist in equilibrium. The melting temperatures of these subsystems have also been determined.

Open access

Abstract

Phase equilibria up to solidus line in CuO–In2O3 system have been investigated using XRD and DTA/TG methods. According to the results, only one compound of the formula Cu2In2O5 formed in the system studied. Its thermal stability was determined in the air and argon proving that the compound did not melt but underwent decomposition. The decomposition of Cu2In2O5 in the air atmosphere began at 1080 °C, while in argon at 835 °C. Additional studies were undertaken to determine the hitherto unknown colour properties of samples representing the CuO–In2O3 system in the equilibrium state.

Open access

Abstract

The chemical reaction of the formation of compounds within the structure of solid as a reaction medium—internal reactions—is the subject of the article. The mechanism of these reactions on the example silicate mineral structure and nanocrystallization of oxide glasses is considered. Local atoms interaction analysis based on the electronegativity of and ionicity of the chemical bonds values helps to understand this mechanism and predict course of intrastructural thermal processes.

Open access
Journal of Thermal Analysis and Calorimetry
Authors: Barbara Barszcz, Joanna Masternak, Maciej Hodorowicz and Agnieszka Jabłońska-Wawrzycka

Abstract

The synthesis and characterization of cadmium(II) and calcium(II) complexes with N,O-bidentate ligands derived from pyrazinecarboxylic acid (3-hydroxy-2-quinoxalinecarboxylic acid HL1, pyrazine-2-carboxylic acid HL2) are reported. Obtained compounds [Cd(L1)2(H2O)2](H2O)2 (1), [Cd(L2)2]n (2) and [Ca(L2)2(H2O)4] (3) were studied by elemental analyses, IR, Raman spectroscopy and thermogravimetric methods (TG, DTG, DSC). In addition, the molecular structure of complex 1 has been determined by X-ray single crystal diffraction. Thermal analysis reveals a decomposition process of 1, 3 complexes in multiple stages. The data obtained from TG and DSC curves for 1, 3 confirm not only the presence but also the nature of water (crystallization and coordination) and the stoichiometry of the studied metal complexes. The results of thermal studies are in good agreement with their crystal structures. Thermal behavior of complex 2 indicates a single complete decomposition process of the sample. In addition, complex 2 as a coordination polymer is the most stable all of them and the thermal stability of the obtained complexes can be ordered in the following sequence: 1 < 32.

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Abstract

The phase equilibria in the solid state in the system FeVO4–Cu3V2O8 and FeVO4–CuO have been determined. Based on the obtained DTA and XRD analysis results and some additional research, a phase diagram in the whole subsolidus area of the system CuO–V2O5–Fe2O3 has been worked out. Eighteen subsidiary subsystems can be distinguished in this ternary system. Basic properties of the obtained phases with howardevansite- and lyonsite-type structure have been investigated by DTA, IR, and SEM methods.

Open access

Abstract

Mechanical alloying processes are carried out usually with addition of some lubricants, referred to also as a process control agents (PCA). About 1–2 wt% of a PCA (usually stearic acid) is normally added to prevent excessive cold welding amongst the powder particles, especially when powders of ductile metals are milled. However, lubricants (maybe disintegrated after MA process) must be removed in the early stages of heating during the sintering process. The aim of the present study was to determine the effect of the MA process especially (i) milling time and (ii) influence of lubricant addition on thermal effects during heating of iron powder (Astaloy CrM) with the addition of 1 wt% stearic acid measured by differential scanning calorimeter (DSC) and thermogravimetry (TG) techniques. Removal of the lubricants during heating of the blended powders and exhaust gases from the furnace were monitored by quadruple mass spectrometry (QMS). Determination of the physical and technological properties of the powder mixture obtained from MA was performed with a laser particle sizer. Distribution of particle sizes, flow and apparent density were also measured. Furthermore, the shape and morphology of the powders were characterised by a light optical microscope (LOM) and scanning electron microscope (SEM).

Open access

Thermal transformation of polyacrylonitrile deposited on SBA-15 type silica

Effect on adsorption capacity of methyl–ethyl ketone vapor

Journal of Thermal Analysis and Calorimetry
Authors: Rafał Janus, Piotr Natkański, Anna Wach, Marek Drozdek, Zofia Piwowarska, Pegie Cool and Piotr Kuśtrowski

Abstract

Thermogravimetry, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used for the studying of thermally induced structural changes of polyacrylonitrile (PAN) deposited on the surface of SBA-15 type mesoporous silica. Polymer was introduced onto the support by the precipitation polymerization of acrylonitrile in aqueous suspension of SBA-15. Low temperature transformation (to 723 K) of the deposited PAN was analyzed. It was found that at about 523 K, exothermic cyclization of polymer chains to the so-called ladder form of PAN occurred. However, the total cyclization of PAN required higher carbonization temperatures, at which gradual dehydrogenation followed by graphitization was initiated. XPS revealed that the cyclic form of PAN and a relatively large amount of carbonyl species, formed during the carbonization of the PAN/SBA-15 composite at 623 K, were responsible for the high sorption capacity in the methyl–ethyl ketone (MEK) vapor elimination. The efficiency in the MEK adsorption was also influenced by the content of PAN-derived carbon deposited on the SBA-15 surface.

Open access

Abstract  

Two types of ammonium uranyl nitrate (NH4)2UO2(NO3)4·2H2O and NH4UO2(NO3)3, were thermally decomposed and reduced in a TG-DTA unit in nitrogen, air, and hydrogen atmospheres. Various intermediate phases produced by the thermal decomposition and reduction process were investigated by an X-ray diffraction analysis and a TG/DTA analysis. Both (NH4)2UO2(NO3)4·2H2O and NH4UO2(NO3)3 decomposed to amorphous UO3 regardless of the atmosphere used. The amorphous UO3 from (NH4)2UO2(NO3)4·2H2O was crystallized to γ-UO3 regardless of the atmosphere used without a change in weight. The amorphous UO3 obtained from decomposition of NH4UO2(NO3)3 was crystallized to α-UO3 under a nitrogen and air atmosphere, and to β-UO3 under a hydrogen atmosphere without a change in weight. Under each atmosphere, the reaction paths of (NH4)2UO2(NO3)4·2H2O and NH4UO2(NO3)3 were as follows: under a nitrogen atmosphere: (NH4)2UO2(NO3)4·2H2O → (NH4)2UO2(NO3)4·H2O → (NH4)2UO2(NO3)4 → NH4UO2(NO3)3 → A-UO3 → γ-UO3 → U3O8, NH4UO2(NO3)3 → A-UO3 → α-UO3 → U3O8; under an air atmosphere: (NH4)2UO2(NO3)4·2H2O → (NH4)2UO2(NO3)4·H2O → (NH4)2UO2(NO3)4 → NH4UO2(NO3)3 → A-UO3 → γ-UO3 → U3O8, NH4UO2(NO3)3 → A-UO3 → α-UO3 → U3O8; and under a hydrogen atmosphere: (NH4)2UO2(NO3)4·2H2O → (NH4)2UO2(NO3)4·H2O → (NH4)2UO2(NO3)4 → NH4UO2(NO3)3 → A-UO3 → γ-UO3 → α-U3O8 → UO2, NH4 UO2(NO3)3 → A-UO3 → β-UO3 → α-U3O8 → UO2.

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Abstract  

137Cs activity concentrations were determined in samples of macrophytes Polysiphonia fucoides (red algae) and Zostera marina (vascular plant) collected during the entire vegetation season in the Gulf of Gdańsk in the southern Baltic Sea. The measurements showed considerable seasonality of 137Cs activity in both species; an increase of cesium concentrations was observed from spring to autumn with maximal levels 49.1 ± 1.4 Bq kgd.w. −1 (P. fucoides) and 14.5 ± 1.0 Bq kgd.w. −1 (Z. marina) in late autumn. 137Cs concentrations observed in a given season are the result of a number of processes, the intensity of which can differ depending on external environmental conditions. The effects of these processes can differ and their directions can frequently be opposite to one another. The examined macrophytobenthic plant species could serve as bioindicators of radionuclide pollution for monitoring purposes on condition that the samples of plants are taken within a strictly defined period of the year to give comparable results and to supply realistic information about pollution levels.

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Abstract  

The activity concentrations of 234U and 238U in thermal groundwater, deep well water and river water samples from Central Poland were determined. Concentration of 234U and 238U in the examined waters varied from <0.013 (LLD) to 16.8 mBq/dm3 and from <0.013 (LLD) to 45.5 mBq/dm3 respectively. The highest uranium activity concentrations were measured in the thermal groundwater from Mszczonow and Cieplice, while the lowest were observed in thermal ground water from Uniejow and Poddebice. In thermal groundwater from Skierniewice, uranium activity concentrations were below lower limit of detection (0.013 mBq/dm3). The 234U/238U activity ratio varied from 0.37 (Cieplice) to 1.30 (Poddebice well water).

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Abstract  

This paper relates the quantum–mechanical equilibrium isotopic fractionation correction to the radiocarbon dating method by Eq. 9, and also shows the significant influence of temperature on the method. It is suggested that the correction is a function of the frequencies and temperature of a specific sample and these two variables can be evaluated theoretically by the ab initio quantum calculations and experimentally by analyzing the clumped-isotope ratios in it, respectively. This paper also suggests that the 14C/12C ratio in the atmosphere in geological time can be calculated by Eq. 10.

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Abstract

The twenty-first century started with many downsizing applications. This important trend in the engine technology has been constantly developed. There are questions about limits and on the other hand new solutions in the face of new materials, tribological discovery, lubrication oils, turbo- or supercharging, new control electronic system of the engine run, higher accuracy in designing, etc. Some of parameters of thermodynamics of working cycle and thermal load according to the downsizing engine parameters were considered in this article. The downsizing impacts on fuel economy and emission were analysed, too. The investigations were carried out with own measured data (i.e. pressure inside inlet manifold, temperature of engine wall) as well as data from references (for example material properties) and at the end the simulations were done. The essential achievements of the work are (a) downsizing factor (DSF) was defined first time in this article (nobody before), (b) because of possibility of exceeding thermal load in piston (as an example engine part) the changes of DSF has to be restricted to almost 0.95 giving changes of 0.85 for base cylinder diameter and 0.90 ratio of base volume for stroke, (c) the main goal of downsizing to reduce CO2 emission was results of all tests but it show only 10% benefit, and (d) it is possible to optimise the downsizing technology. So, the next research work will be focused on changes of super- and turbocharging as well as lean mixture combustion for better optimisation of downsizing.

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Abstract

A new compound with the formula Cu13Fe4V10O44 has been obtained as a result of a solid-state reactions occurring during heating the mixtures both of oxides: CuO, V2O5, Fe2O3 and vanadates: Cu5V2O10, Cu3Fe4V6O24. The DTA measurements were used to choose the heating temperatures as well as for determination of thermal stability of the new compound. Cu13Fe4V10O44 melts incongruently at 790 ± 5 °C. The new phase crystallizes in the monoclinic system. The indexing results and the calculated unit cell parameters for Cu13Fe4V10O44 are given. Its infra-red spectrum and image obtained by means of an electron scanning microscope are presented.

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Abstract

The following compounds have been synthesized: (a) hydantoins 5,5-dimethylimidazolidine-2,4-dione (1), 1′,3′-dihydrospiro[imidazolidine-4,2′-indene]-2,5-dione (2), 3′,4′-dihydro-1′H-spiro[imidazolidine-4,2′-naphthalene]-2,5-dione (3); (b) monomers: 5,5-dimethyl-3-(4-vinylbenzyl)imidazolidine-2,4-dione (4), 1-(4-vinylbenzyl)-1′,3′-dihydrospiro[imidazolidine-4,2′-indene]-2,5-dione (5), 1-(4-vinylbenzyl)-3′,4′-dihydro-1′H-spiro[imidazolidine-4,2′-naphthalene]-2,5-dione (6), (two of them are unknown: 5 and 6); (c) macromolecular compounds: poly(chloromethyl-p-styrene) (7), used as reference, and three polymers (two of them are novel) obtained by substitution of hydantoins 13 to poly(methyl-p-styrene) (810). Their thermal properties have been studied by thermogravimetry. It was found that the chemical structure, tautomerization, and intermolecular interaction influence the thermal stability of substrates. The presence of phenyl rings causes the increase of resistance of studied hydantoins. The obtained polymers are characterized by significantly improved thermal stability comparing to poly (chloromethyl-p-styrene). The mechanism of thermal degradation of investigated polymers and explanation of their thermal resistance has been proposed. The relatively high temperatures of glass transition of polymers have been determined by DSC.

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Abstract

Ti-SBA-15, one of the latest titanium silicalite catalysts, has been prepared according to the literature by the direct hydrothermal synthesis using Pluronic 123 as structure-directing agent. The characterization of the catalyst was performed by means of the following methods: XRD, IR, UV–Vis, X-ray microanalysis and SEM. The catalytic properties of the Ti-SBA-15 catalyst have been tested in the epoxidation of allyl alcohol, methallyl alcohol, crotyl alcohol and 1-butene-3-ol with hydrogen peroxide. The process has been described by the following main functions: the selectivity to epoxide compound in relation to allylic compound consumed and the conversion of allylic compound.

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Abstract

The thermal, viscoelastic, and mechanical properties of cured dicyclopentadiene (DCPD)-containing polymers prepared from novel DCPD-modified unsaturated epoxypolyesters and styrene were evaluated. This was accomplished using thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, three-point bending test, and Brinell’s hardness. The thermal, viscoelastic, and mechanical properties of DCPD-containing polymers were strongly dependent on chemical structure. The cross-linking density (υ e) of obtained networks increased with increasing content of carbon–carbon double bonds in the poly(ester) structure. In addition, the introduction of DCPD rings into the poly(ester) structure increased the rigidity of the molecular backbone. It resulted in obtaining polymers which showed great improvement in mechanical properties including remarkably higher storage modulus (), flexural modulus at bending (E mod), hardness, lower extension at maximum force (-F max), as well as higher thermal stability. These good properties make these materials highly promising as potential candidates for structural applications.

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Abstract  

The uranium(VI) accumulation was studied in detail by using the biomass of mangrove endophytic fungus Fusarium sp.#ZZF51 from the South China Sea. The uranium(VI) biosorption process onto the tested fungus powders was optimized at pH 4.0, adsorption time 60 min, and uranium(VI) initial concentration 50 mg L−1 with 61.89% of removal efficiency. According to Fourier transform infrared spectra for the tested fungus before and after loaded with uranium(VI), the results showed that both of hydroxyl and carboxyl groups acted as the important roles in the adsorption process. In addition, the experimental data were analyzed by using parameter and kinetic models, and it was obtained that the Langmuir isotherm model and the pseudo-second-order kinetic model provided better correlation with the experimental data for adsorption of uranium(VI).

Open access
Journal of Thermal Analysis and Calorimetry
Authors: Hieronim Maciejewski, Izabela Dąbek, Ryszard Fiedorow, Michał Dutkiewicz and Mariusz Majchrzak

Abstract

Epoxy functional (poly)siloxanes are one of the most important classes of modified silicones. Due to high reactivity of epoxy group and specific features of siloxane chain, they can make an excellent raw material for synthesis of hybrid materials. Results obtained in this study have shown that both the modification of epoxy resins with epoxy functional disiloxanes as well as the application of polysiloxanes with long polysiloxane chains and a specified content of epoxy groups makes it possible to produce hybrid materials of very good thermal stability. Crosslinking reactions were carried out with use of four diamines of which the best one appeared to be 4,4′-diaminodiphenylmethane. The highest thermal stability was found in the case of hybrid materials obtained from epoxy functional polysiloxanes.

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Abstract  

Phosphogypsum (PG) is a residue of the phosphate fertilizer industry that has relatively high concentrations of harmful radioactive materials. The reduction in concentration of the radionuclides from PG was investigated. The removal process is based on leaching of radionuclides using suitable organic extractants. The studied radionuclides were 226Ra, 210Pb, 238U and 40K. The factors affect the leaching process such as type of leaching materials, contact time, concentration of the desired solvent, liquid to solid ratio, and temperature were studied. Based on the experimental results, about 71.1, 76.4, 62.4, and 75.7% of 226Ra, 210Pb, 238U and 40K respectively were successfully removed from the PG. The reduction in the concentration of radionuclides was accompanied by reduction in the concentration of rare earth elements (∑REE) equals to 69.8%. Using the desired organic extractant under optimum conditions for treatment of the PG waste leads to obtain a decontaminated product that can be safely used in many industrial applications.

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Abstract

The results of calorimetric investigations of electrolyte solutions in the mixtures of water, methanol, N,N-dimethylformamide, and acetonitrile with numerous organic cosolvents are discussed with regard to the intermolecular interactions that occur in the solution. Particular attention is given to answer the questions how and to what extent the properties of the systems examined are modified by the cosolvent added and how much the properties of the cosolvent are revealed in the mixtures with the solvents mentioned above. To this goal, the analysis of the electrolyte dissolution enthalpies, single ionic transfer enthalpies, and enthalpic pair interaction coefficients as well as the preferential solvation (PS) model are applied. The analysis performed shows that in the case of the dissolution enthalpies of simple inorganic electrolytes in water–organic solvent mixtures, the shape of the dependence of the standard dissolution enthalpy on the mixed solvent composition reflects to a large extent the hydrophobic properties of the organic cosolvent. In the mixtures of methanol with organic cosolvents, the ions are preferentially solvated either by methanol molecules or by molecules of the cosolvent, depending on the properties of the mixed solvent components. The behavior of inorganic salts in the mixtures containing N,N-dimethylformamide is mostly influenced by the DMF which is a relatively strongly ion solvating solvent, whereas in acetonitrile mixtures, the thermochemical behavior of electrolyte solutions is influenced to a large extent by the properties of the cosolvent particularly due to the PS of cation by the cosolvent molecules.

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Abstract

The effect of mechanical activation on the structure and thermal reactions of glasses has been studied on the example of Na–Al–Fe phosphate glasses. These glasses are used in nuclear technology for immobilization of radioactive waste. The glasses were activated by grinding in a planetary mill. Mechanical activation causes a decrease of the T g temperature as well as of the glass crystallization temperature. The type of crystalline phases formed and the quantitative proportions between them are changing. Analysis of inter-atomic interactions in the structure of glass was applied to explain the observed regularities governing the crystallization of the activated glasses.

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Abstract

Ceramic composites are widely used in various technologies such as tool production, aerospace technology, and nuclear power engineering. Their key features are considerable hardness and resistance to wear and corrosion at high temperature. Because many ceramic nanocomposites are designed to work at high temperature, it is important to determine their high temperature corrosion resistance. The subject of the investigation in this study were nanocomposite MMC (metal matrix composite) materials. As matrix the 316L stainless steel was used and the filler (nanoparticles) was nc-TiC. Using carbonized and purified nc-TiC particles the technology of the production of the nanocomposite structures based on the selective laser melting (SLM) technology was worked out. The MCP HEK Realizer II device was applied. The particles have been depicted by TEM method, whereas characterization of structure and particles size was performed by XRD method. The results of investigations on oxidation process of the steel/ncTiC nanocomposites in dry air have been presented. TG-DSC measurements were carried out under non-isothermal conditions at linear change of samples temperature in time and under isothermal conditions. MS method was used to determine evolved gaseous products.

Open access

Abstract

In this study, new series of lanthanide 4,4′-oxybis(benzoates) of the general formula Ln2oba3·nH2O, where Ln = lanthanides from La(III) to Lu(III), oba = C12H8O(COO)2 2− and n = 3–6, has been prepared under hydrothermal conditions. The compounds were characterized by elemental analysis, infrared spectroscopy, X-ray diffraction patterns measurements and different methods of thermal analysis (TG, DSC, and TG-FTIR). In addition, photoluminescence properties of the selected complexes have been investigated. Crystalline compounds are isostructural in the whole series. Both carboxylate groups are deprotonated and engaged in the coordination of Ln(III) ions. Heating of the complexes leads to the dehydration and next decomposition processes. Although of the same structure, the removal of water molecules proceeds in different ways. In the nitrogen atmosphere, they decompose releasing water, carbon oxides and phenol molecules. The complexes of Eu(III), Tb(III) and Dy(III) exhibit photoluminescence in the visible range, whereas the compounds of Nd(III) and Yb(III) in the near-infrared region upon excitation by UV light.

Open access

SBA-15 silicas containing sucrose

Chemical, structural, and thermal studies

Journal of Thermal Analysis and Calorimetry
Authors: M. Barczak, M. Oszust-Cieniuch, P. Borowski, Z. Fekner and E. Zięba

Abstract

Mesoporous silicas were synthesized by condensation of tetraethoxysilane (TEOS) in the presence of Pluronic P123 as a structure-forming agent, and sucrose as an auxiliary agent, to investigate the effect of sucrose and aging temperature on the final properties, particularly structure-adsorption characteristics. Obtained materials have been characterized by XRD, nitrogen sorption measurements SEM-EDX, TEM, thermogravimetry, and FT-IR. The obtained materials have well-developed porous structure—values of the specific surface area (S BET) are in the range of 300–950 m2/g and the sizes of primary mesopores are in the range of 9–11 nm. It was established that S BET and ordering significantly decreases with an increasing content of sucrose in the initial mixture.

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Abstract  

In situ gamma-ray measurements were taken at six locations in the Modane Underground Laboratory. Count rates for gamma radiation within the energy range of 7–2734 keV varied from 15 to 108 γs−1. The arithmetic mean was 79 γs−1 for measurements taken without a collimator. The metamorphic rocks surrounding the Lab are characterized by low activity concentrations of uranium and thorium equal to 12 and 10 Bq kg−1, respectively.

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Abstract

Vitrification is currently considered to be an effective method for immobilization of radioactive waste. It is based on the enclosing of harmful elements in the structure of the glass. This work presents the results of studies on the thermal properties of glasses from P2O5–Al2O3–Na2O and P2O5–Al2O3–Fe2O3–Na2O systems for rendering nuclear waste in the form of salts such as sulfates, halides, and phosphates with high sodium content. These substances are not accepted by borosilicate glass, commonly used up to now for nuclear waste immobilization. Formation of sinters of glass-waste mixtures was selected as the method for immobilization, and the thermal chemistry of this process was studied. CaCl2 was used as the model chloride waste substance. The process of immobilization consists of its sintering with Na, Al, Fe-phosphate glasses containing more than 50 wt% P2O5 as the amorphous matrix. Thermal analysis showed that all glasses exhibit an ability for crystallization, with that the intensiveness of this process is determined by the chemical composition of these glasses. The addition of Fe2O3 to the glass intensified crystallization process. Leaching of components of sinters tests established that glass containing Fe2O3 in its composition most effectively binds waste in comparison to Al2O3 containing phosphate glass. The test results allow for the statement that the waste substance in the form of chloride salts such as CaCl2 is stable bound in the glass–crystalline sinters, which ensures its effective immobilization.

Open access
Journal of Thermal Analysis and Calorimetry
Authors: Dariusz Szychowski, Barbara Pacewska, Grzegorz Makomaski, Janusz Zieliński, Wiesława Ciesińska and Tatiana Brzozowska

Abstract

The purpose of this study was to determine the possibility of producing hydrophobic mesoporous mineral–carbon sorbents from aluminum hydroxide and compositions of coal tar pitch–polymers on carbonization at 600 °C in a nitrogen atmosphere. Blends of the products of co-precipitation of aluminum hydroxide in the carbonaceous substances medium were subjected to carbonization process. The extent of porous structure development was evaluated using low temperature nitrogen adsorption, adsorption of benzene vapors, and adsorption of iodine from aqueous solution. The highest value of BET surface area of about 370 m2/g was achieved for the carbonization product obtained from co-precipitated raw components with 10 wt% compositions coal tar pitch–polymer. These materials demonstrated high capacity to reduce organic pollutions from sewage. Pitch–polymer composition containing poly(ethylene terephthalate) or phenol–formaldehyde resin was studied by the means of DSC method in order to determine the high-temperature transformations taking place under the conditions of carbonization. DSC method enables to determine i.a. the decomposition temperatures of carbonizates produced from pitch–polymer compositions and the evaluation of their sorption abilities. The additive of poly(ethylene terephthalate) and phenol–formaldehyde resin caused the increase of thermal resistance of the pitch expressed by higher decomposition temperatures.

Open access
Journal of Thermal Analysis and Calorimetry
Authors: V. Sydorchuk, W. Janusz, S. Khalameida, E. Skwarek, J. Skubiszewska-Zięba, R. Leboda and V. Zazhigalov

Abstract

Deposited zirconium phosphate samples on the base of silica and titania have been prepared using the sol–gel and mechanochemical methods. Porous structure, phase composition, and electrokinetic parameters have been studied by means of nitrogen adsorption–desorption, XRD, DTA-TG, FTIR, electrophoresis, and potentiometric titration. The compositions possess varied parameters of porous structure, structure of deposited phase, and electrokinetic properties depending on support nature and synthesis conditions.

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Journal of Thermal Analysis and Calorimetry
Authors: G. Janowska, A. Kucharska-Jastrzabek, W. M. Rzymski and A. Pajak

Abstract

The article describes the measurements results of the thermal properties of cross-linked blends of butadiene–acrylonitrile rubber (XNBR, Krynac X.7.50) and chlorosulfonated polyethylene containing different quantity of combined chlorine (CSM24—Hypalon 48, CSM29—Hypalon 20, CSM35—Hypalon 40, and CSM43—Hypalon 30) under inert gas (DSC) and in air (derivatography). The blends were non-conventionally cross linked at a temperature of 150 °C by means of MgO in the presence of stearic acid. The thermal curves obtained were interpreted from the point of view of phase transitions and chemical reactions of the macromolecular components used. It has been found that the elastomers investigated show a good compatibility brought about by the formation of both interpolymeric covalent bonds and interpolymeric and intrapolymeric ionic bridges, which play the role of a chemical compatibilizer. The results of the examinations performed show that the non-conventional cross-linked XNBR/CSM blends prove very good mechanical properties and are self-extinguished in air. Their flammability defined with the value of OI and combustion time in air clearly depends on the type of CSM.

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