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11.
Marković Gordana Marinović-Cincović Milena Vodnik Vesna Radovanović Blaga Budinski-Simendić Jaroslava Veljković Olivera 《Journal of Thermal Analysis and Calorimetry》2009,97(3):999-1006
The properties of chlorosulphonated polyethylene (CSM) rubber, acrylonitrile rubber (NBR) and their blend (50/50 w/w) were
studied. Fourier transform infrared (FTIR) studies supported that CSM/NBR rubber blend is self curable, when cross-linking
takes place between acrylonitrile groups of NBR and –SO2Cl groups or in situ generated allyl chloride moieties of CSM. The thermal stability of vulcanizates was analyzed in nitrogen
by thermogravimetry. It was found that the initial degradation temperature of elastomer based on CSM rubber is lower than
of pure NBR rubber. By adding NBR to CSM rubbers, the degradation temperature of crosslinked material increased, indicating
higher thermal stability. The activation energy for the degradation are determined using the Arrhenius equation The activation
energies for the rubber blends are higher than for elastomers based on pure rubbers. It was found that the mass loss of the
blends at any temperature was between those of the pure rubbers. The differential scanning calorimetry (DSC) was used for
the glass transition temperature determination. It is estimated thermodynamic immiscibility of NBR/CSM blend based on noticed
two different glass transition temperatures, corresponding to CSM and NBR rubbers. 相似文献
12.
Jan Moncol Jaroslava Maroszova Milan Melník Marian Koman 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(3):m114-m116
The title compound, [Cu3(C3H5O2)6(C6H7NO)4]n, is composed of polymeric chains formed by alternating centrosymmetric Cu2(μ‐CH3CH2CO2)4 and Cu(C3H5O2)2(C6H7NO)2 units. These elemental units are linked by two bridging 3‐pyridylmethanol (3PM) ligands. The Cu2(μ‐CH3CH2CO2)4 group presents a centrosymmetric tetrabridged structure with four syn–syn bridging propionate ligands to which two 3PM molecules are bonded (through N), occupying the apical positions of each square‐pyramidal polyhedron around the CuII ions. The remaining mononuclear group is centred around a third CuII ion, which lies on a symmetry centre and is bound to two monodentate propionate groups (through O), two monodentate 3PM molecules (through N) and two bridging 3PM molecules (through O), thus completing a square‐bipyramidal CuO2N2O2 coordination. 相似文献
13.
Carbon‐Based Electrodes for Sensitive Electroanalytical Determination of Aminonaphthalenes 下载免费PDF全文
Jaroslava Zavazalova Mariana Emilia Ghica Karolina Schwarzova‐Peckova Jiri Barek Christopher M. A. Brett 《Electroanalysis》2015,27(7):1556-1564
The electroanalytical performance of bare glassy carbon electrodes (GCE) for the determination of 1‐aminonaphthalene (1‐AN) and 2‐aminonaphthalene (2‐AN) was compared with GCE modified by a Nafion permselective membrane or multiwalled carbon nanotubes and with other types of carbon‐based materials, carbon film and boron doped diamond. Nafion‐modified GCE gave the highest sensitivity and lowest detection limit (0.4 µmol L?1) for differential pulse voltammetric determination of 1‐AN. Electrochemical impedance spectroscopy gave information about the processes at the electrode surface. Simultaneous determination of 1‐AN and 2‐AN in a mixture at GCE and their determination in model samples of river water is presented. 相似文献
14.
The objective of this study was to compare different z-score calculation for the results from proficiency testing programmes. The comparison was carried out on the data from proficiency tests for four different matrices and for all analytes included in the proficiency testing programmes organised by UKZUZ institute from the year 2005 to 2007. It represented 99 samples (three periods per year and eleven samples distributed in each period); the number of determined analytes was 108 in each period. The total number of investigated data sets was 953. Three different approaches to z-score calculation were compared. The results gave reasonably comparable evaluation in most cases but sometimes UKZUZ method proved to be rather strict. The procedure using the robust average and robust standard deviation calculated according to Algorithm A described in ISO 13528 was found to be the most suitable for matrices and level of measurands in UKZUZ proficiency tests. 相似文献
15.
The reaction of iron(II) acetate with the tetradentate Schiff base like ligand H2L [(E,E)‐[{diethyl 2,2’‐[4,5‐dihydroxy‐1,2‐phenylenebis(iminomethylidyne)]bis3‐oxobutanato}]) leads to the formation of the octahedral N2O4 coordinated complex [FeL(MeOH)2] · MeOH ( 1 ). Conversion of 1 with N‐methylimidazole (N‐meim) leads to the N4O2 coordinated complex [FeL(N‐meim)2] · MeOH ( 2 ). Both complexes are pure HS compounds that were characterised using magnetic measurements and X‐ray crystallography. A special attention was given to the role of the two hydroxyl groups at the phenyl ring on the formation of a hydrogen bond network and the influence of this network on the magnetic properties. 相似文献
16.
Vapour-liquid equilibrium in the title system was measured with special regard to concentration limits. The data of both regions were fitted to six different equations for the determination of the best values of limiting activity coefficients (11.53 and 5.58 for acetone and water, respectively). The densities of solutions at 25°C were determined in both boundary regions. 相似文献
17.
Jiři Votinský Jaroslava Kalousová Ludvík Beneš Iveta Baudyšová Vítězslav Zima 《Journal of inclusion phenomena and macrocyclic chemistry》1993,15(1):71-78
A new experimental method is suggested for the kinetic measurements of intercalation reactions in systems formed by a polycrystalline layered host and a liquid molecular guest. The method is based on the fact that the molecular guest decreases its molar volume on entering the space between the host layers. Hence the volume of the system in which an intercalation process takes place is measurably decreased. The time course of the intercalation process can thus be monitored by measuring the volume change of the system. The method has been used to obtain kinetic data about heterogeneous intercalations of some liquid aliphatic compounds into layered structures of anhydrous vanadyl phosphate and sulfate. 相似文献
18.
Tubular and Microcylindrical Platinum Electrodes for Amperometric Detection of Aminobiphenyls and Aminonaphthalenes in HPLC 下载免费PDF全文
Platinum electrodes in microcylindrical and tubular arrangements were compared as working electrodes for amperometric detection of 2‐aminobiphenyl, 4‐aminobiphenyl, 1‐aminonaphthalene, and 2‐aminonaphthalene in HPLC. Factors influencing separation efficiency are favourable for microcylindrical arrangement while tubular arrangement exhibits higher sensitivities and lower limits of detection. These are in the range of 0.0078–0.027 µmol L?1 for tubular, and 0.11–0.42 µmol L?1 for microcylindrical arrangement. Further, a new method with nanomolar detection limits was proposed for determination of tested compounds in urine using solid phase extraction for preliminary separation and preconcentration of the analytes. 相似文献
19.
Zdena Křesinová Lucie Hostačná Jaroslava Medková Monika Čvančarová Tatiana Stella 《International journal of environmental analytical chemistry》2013,93(8):822-836
Chlorobenzoic acids (CBAs) are the major metabolite of aerobic bacterial degradation of polychlorinated biphenyls (PCBs). A rapid and simple simultaneous derivatisation method has been developed for gas chromatography-mass spectrometry determination in historically PCB-contaminated soils for 15 isomers of mono-, di-, tri-, tetra-, and pentachlorobenzoic acids in CBA mixtures. Two derivatisation agents (diazomethane and methyl chloroformate) and various conditions were evaluated (temperature, time, solvents, catalysts) in terms of efficiency. The optimised derivatisation method with diazomethane and 1% methanol running 1 hour at 5°C was used for derivatisation of extracts of soils and river sediment from historically PCB-contaminated sites; the extracts were prepared using accelerated solvent extraction by a previously described method. Methylated CBAs were separated by gas chromatography using a system with two different common columns, DB-5 and DB-200, in series-coupled (tandem) arrangement and detected by EI-MS. A clean-up with a gel permeation chromatography was carried out to remove soil interfering matrix compounds as well as major portion of PCBs. The limits of quantification ranged between 1 and 10 ng g?1 of individual CBA in the soil. The procedure was applied to various soil samples from Lhenice (Czech Republic) highly contaminated with PCBs. CBAs were found in all tested soils and also in the river sediment. The most contaminated soil contained all CBAs representatives under the study with a total concentration of 3.1 µg g?1 of dry soil. 相似文献
20.
Kaewta Kaewtatip Varaporn Tanrattanakul Katalin Mészáros Szécsényi Jelena Pavličević Jaroslava Budinski-Simendić 《Journal of Thermal Analysis and Calorimetry》2010,102(3):1035-1041
The interest in replacing synthetic polymers by biodegradable materials from renewable resources is steadily increasing. In
this work, cassava starch grafted with different content of polystyrene (PS) was synthesized via free-radical polymerization
using suspension polymerization technique. Thermal data of pure starch and the grafted starch with different content of PS
were collected by simultaneous thermogravimetric (TG)–differential scanning calorimetry (DSC) setup in open alumina pans.
Separately, typical DSC measurements were conducted in standard aluminum pans with lid. The data obtained by different methods
are correlated and discussed. Morphology of cryogenic fracture surface of starch sample was studied by scanning electron microscopy.
In order to obtain more reliable data about the processes taking place during the thermal treatment, the changes of surface
morphology of starch treated at different temperatures are observed. 相似文献