Thermal Stability of N-Heterocycle-Stabilized Iodanes – A Systematic Investigation

2019 ◽  
Author(s):  
Andreas Boelke ◽  
Yulia A. Vlasenko ◽  
Mekhman S. Yusubov ◽  
Boris Nachtsheim ◽  
Pavel Postnikov

<p>The thermal stability of pseudocyclic and cyclic <i>N</i>-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-l<sup>3</sup>-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. NHIs bearing <i>N</i>-heterocycles with a high N/C-ratio such as triazoles show among the lowest descomposition temperatures and the highest decomposition energies. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation. </p>

2019 ◽  
Vol 15 ◽  
pp. 2311-2318 ◽  
Author(s):  
Andreas Boelke ◽  
Yulia A Vlasenko ◽  
Mekhman S Yusubov ◽  
Boris J Nachtsheim ◽  
Pavel S Postnikov

The thermal stability of pseudocyclic and cyclic N-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-λ3-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. Peak decomposition temperatures (T peak) were observed within a wide range between 120 and 270 °C. Decomposition enthalpies (ΔH dec) varied from −29.81 to 141.13 kJ/mol. A direct comparison between pseudocyclic and cyclic NHIs revealed high T peak but also higher ΔH dec values for the latter ones. NHIs bearing N-heterocycles with a high N/C-ratio such as triazoles show among the lowest T peak and the highest ΔH dec values. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation.


2019 ◽  
Author(s):  
Andreas Boelke ◽  
Yulia A. Vlasenko ◽  
Mekhman S. Yusubov ◽  
Boris Nachtsheim ◽  
Pavel Postnikov

<p>The thermal stability of pseudocyclic and cyclic <i>N</i>-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-l<sup>3</sup>-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. NHIs bearing <i>N</i>-heterocycles with a high N/C-ratio such as triazoles show among the lowest descomposition temperatures and the highest decomposition energies. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation. </p>


1992 ◽  
Vol 4 (2) ◽  
pp. 67-71
Author(s):  
N. R. Patel ◽  
N. Z. Patel ◽  
R. M. Patel

Unsaturated polyamides were prepared by condensing /3(4-ethoxyphenyl) glutaconic acid with various aromatic diamines. The polycondensates were characterized by IR spectroscopy, vapor phase osmometry, thermogravimetric analysis, differential scanning calorimetry and elemental analysis. All resins were found to decompose in the range '-210-600 °C. The kinetics of decomposition were studied. The results indicated that the resins possess reasonably good thermal stability.


1997 ◽  
Vol 9 (3) ◽  
pp. 263-279 ◽  
Author(s):  
J A Campbell ◽  
A A Goodwin ◽  
F W Mercer ◽  
V Reddy

Blends of polyimides XU-218 and PEI were investigated using differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis and adhesive bond testing. The thermal stability of the blends increased as the proportion of PEI increased while the α-relaxation of the blends occurred at a slower rate and was broader and more cooperative in some blends, compared with the pure polymers. Physical aging of the pure polymers and blends in the glass state revealed changes in relaxation rate and lost enthalpy that were also consistent with blends not behaving as simple mixtures. The dynamic mechanical and physical aging behaviour was attributed to an increase in density on blending which decreased the unoccupied volume and increased the constraints on molecular mobility, as well as to the presence of concentration fluctuations. The adhesive properties of the blends were also investigated and bond strength was found to vary with blend composition and test temperature.


2021 ◽  
Vol 287 ◽  
pp. 02014
Author(s):  
Amin Abbasi ◽  
Mohamed Mahmoud Nasef ◽  
Wan Zaireen Nisa Yahya ◽  
Muhammad Moniruzzaman

The conversion of palm oil into a sulfur-based polymer by copolymerization with sulfur powder at its molten state is herein reported. The obtained sulfur-containing polymer was characterized using Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) to demonstrate the successful conversion. The disappearance of the peaks related to vinylic groups of oil together with the appearance of a peak representing C-H rocking vibrations in the vicinity of C-S bonds confirmed the copolymerization of sulfur with oil. TGA revealed that the polymers have thermal stability up to 230°C under nitrogen and the polymers leave 10% sulfur-rich ash. DSC proved that a small amount of elemental sulfur remained unreacted in the polymer, which showed amorphous and heavily crosslinked structure resembling thermosets. These copolymers are an environmental-friendly polymeric material promoting the utilization of the abundant sulfur while also adding value to palm oil.


2018 ◽  
Vol 39 (4) ◽  
pp. 21
Author(s):  
Gilbert Bannach ◽  
Rafael R. Almeida ◽  
Luis G. Lacerda ◽  
Egon Schnitzler ◽  
Massao Ionashiro

Several papers have been described on the thermal stability of the sweetener, C12H19Cl3O8 (Sucralose). Nevertheless no study using thermoanalytical techniques was found in the literature. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC) and infrared spectroscopy, have been used to study the thermal stability and thermal decomposition of sweetener.


2018 ◽  
Vol 6 (41) ◽  
pp. 20383-20392 ◽  
Author(s):  
Yongho Lee ◽  
Hyojun Lim ◽  
Sang-Ok Kim ◽  
Hyung-Seok Kim ◽  
Ki Jae Kim ◽  
...  

The thermal behavior of fully lithiated and sodiated Sn electrodes cycled in a MePF6 (Me = Li or Na)-based electrolyte was studied using differential scanning calorimetry (DSC).


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