Determination of Activation Energies of Chemical Reactions by Differential Thermal Analysis

Piloyan, G. O.; Ryabchikov, I. D.; Новикова, О. С.

doi:10.1038/2121229a0

Cited by 498 publications

(171 citation statements)

References 6 publications

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“…The torque value at t = 0, at a given curing time t and at the end of the crosslinking reaction were determined and the degree of curing (α) was calculated from Equation (4) reported in the Experimental part. The dependence of α on t and T was investigated by means of three different models [32][33][34][35][36]: induction inflation point [32], exponential [34] and autocatalytic [35,36]. The latter model is the one discussed here, as it gave the best fitting of experimental data (see Figure 1).…”

Section: Elaboration Of Experimental Datamentioning

confidence: 99%

Master curves for the sulphur assisted crosslinking reaction of natural rubber in the presence of nano- and nano-structured sp2 carbon allotropes

Musto¹,

Barbera²,

Cipolletti³

et al. 2017

Express Polym. Lett.

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Abstract. In this paper, master curves are reported for the crosslinking of a diene rubber with a sulphur based system in the presence of either nano-or nano-structured carbon allotropes, such as carbon nanotubes (CNT), a nanosized graphite with high surface area (HSAG) and carbon black (CB). Poly(1,4-cis-isoprene) from Hevea Brasiliensis was the diene rubber and crosslinking was performed in temperatures ranging from 151 to 180°C, with carbon allotropes below and above their percolation threshold. Such carbon allotropes were characterized by different aspect ratio, surface area and pH. However, in the crosslinking reaction, they revealed common behaviour. In fact, the specific interfacial area could be used to correlate crosslinking parameters, such as induction time (t s1 ) and activation energy (E a ) calculated by applying the autocatalytic model. Monotonous decrease of t s1 and increase of E a were observed, with points lying on master curves, regardless of the nature of the carbon allotropes. Remarkable differences were however observed in the structure of the crosslinking network: when the carbon allotrope was above the percolation threshold much larger crosslinking density was obtained in the presence of CNT whereas composites based on HSAG became soluble in hydrocarbon solvent, after the reaction with a thiol. Proposed explanation of these results is based on the reactivity of carbon allotropes with sulphur and sulphur based compounds, demonstrated through the reaction of 1-dodecanethiol and sulphur with CNT and HSAG and with a model substrate such as anthracene.

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Section: Elaboration Of Experimental Datamentioning

confidence: 99%

Master curves for the sulphur assisted crosslinking reaction of natural rubber in the presence of nano- and nano-structured sp2 carbon allotropes

Musto¹,

Barbera²,

Cipolletti³

et al. 2017

Express Polym. Lett.

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“…The values of collision factor, Z, also known as the frequency factor [34] were hand calculated using the relation [36]:…”

Section: Infrared Spectroscopymentioning

confidence: 99%

The Ni(II) Complex of 2-Hydroxy-Pyridine-N-Oxide 2-Isothionate: Synthesis, Characterization, Biological Studies, and X-ray Crystal Structures using (1) Cu Kα Data and (2) Synchrotron Data

Makhyoun¹,

Palmer²,

Soayed³

et al. 2014

Journal of Materials Science and Nanotechnology

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C 12 H 20 N 6 NiO 6 S 2 or NiL 2 (SCN) 2 ](NH 4 ) 2 .2H 2 O, where L is 2-hydroxy-pyridine-N-oxide, has been prepared and characterized using elemental analyses, IR, UV and visible spectrometry, magnetic moment measurements, thermal analyses and single crystal X-ray analyis. The results indicate that the complex reacts as a bidentate ligand and is bound to the metal ion via the two oxygen atoms of the ligand (HL). The activation energies, ∆E*, entropies ∆S*, enthalpies ∆H* and order of reactions have been derived from differential thermogravimetric (DTA) curves. Based on inhibition zone diameter measurements, the complex exhibited significant antibacterial activity against both Staphylococcus aureus and Escherichia coli. It also exhibited significant antifungal activity against Candida albicans, but no activity was found against Aspergillus flavus. The crystal structure of the Ni(II) complex [C 12 H 20 N 6 Ni O 6 S 2 ], Mr = 467.17, was determined from Cu Kα X-ray diffraction data, λ = 1.54178 Å, at 100 K using direct methods. The crystals are monoclinic, space group P2 1 /n with Z = 4 and a = 8.9893(2) Å, b = 17.6680(5) Å, c = 12.5665(3) Å, β = 108.609(1)°. In parallel with this study corresponding results were derived for the crystal structure determined independently from synchrotron X-ray diffraction data, λ = 0.61990 Å, at 100 K. The unit cell parameters derived in this experiment are a = 9.000(2) Å, b = 17.700(4) Å, c = 12.590(3) Å, β = 108.61(3)°. Both studies show 4 O and 2 N atoms coordinating Ni in a distorted octahedral arrangement. Each of the Ni 2-hydroxy-pyridinium-N-oxide moieties is highly planar and the S=C=N-Ni ligands are approximately linear. The crystal structure is characterised by a number of strong hydrogen bonds.

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“…The thermodynamic activation parameters (Table 2) of decomposition processes of the metal (Co(II), Ni(II), Cu(II) and Zn(II)) complexes namely activation energy (E * ), entropy (ΔS * ) and Gibbs free energy change of the decomposition (ΔG * ) were evaluated graphically by employing three methods, Coats-Redfern [19] (CR), Horowitz-Metzger [20] (HM), and Piloyan-Novikova [21] (PN). From the results obtained, the following remarks can be pointed out:…”

Section: Kinetics Of Thermal Decompositionmentioning

confidence: 99%

Synthesis, Spectral Characterization, Cyclic Voltammetry, Molecular Modeling and Catalytic Activity of Sulfa-Drug Divalent Metal Complexes

Abdou¹,

Faheim²,

Alaghaz³

2013

Curr Synthetic Sys Biol

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Complexes of cobalt(II), nickel(II), copper(II), zinc(II) and Hafnium(II) of general composition [M(L)2(Cl)2] [L = 4-(phenylphosphinylideneamino-N-thiazolyl benzene-sulfonamide] have been synthesized. The elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, IR, UV, NMR, SEM, EDX, thermal and EPR spectral studies of the compounds led to the conclusion that the ligand acts as a bidentate manner. The molar conductance of the complexes in fresh solution of DMSO lies in the range of 7.46-9.13 Ω -1 cm 2 mol -1 indicating their non-electrolytic behavior. On the basis of analytical and spectroscopic techniques, octahedral geometry of the complexes was proposed. The ligand binds in a bidentate manner, coordinated through sulfonamide oxygen and thiazole nitrogen atoms. The ligand field parameters were calculated for Co(II), Ni(II) and Cu(II) complexes and their values were found in the range reported for a octahedral structure. The catalytic activities of the divalent metal complexes have been studied in the oxidation of cyclohexane by hydrogen peroxide, an environmental friendly oxidant. The molecular modeling parameters of the ligand and its Co(II) and Hf(II) complexes have been calculated.

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Determination of Activation Energies of Chemical Reactions by Differential Thermal Analysis

Cited by 498 publications

References 6 publications

Master curves for the sulphur assisted crosslinking reaction of natural rubber in the presence of nano- and nano-structured sp2 carbon allotropes

Master curves for the sulphur assisted crosslinking reaction of natural rubber in the presence of nano- and nano-structured sp2 carbon allotropes

The Ni(II) Complex of 2-Hydroxy-Pyridine-N-Oxide 2-Isothionate: Synthesis, Characterization, Biological Studies, and X-ray Crystal Structures using (1) Cu Kα Data and (2) Synchrotron Data

Synthesis, Spectral Characterization, Cyclic Voltammetry, Molecular Modeling and Catalytic Activity of Sulfa-Drug Divalent Metal Complexes

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