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1

Thermal Decomposition Behaviour of Bis(4-Nitrophenol)-2,4,6-Triamino-1,3,5-Triazine Monohydrate

100%

Kanagathara N., Marchewka M., Anbalagan G.

Acta Physica Polonica A

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2016

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vol. 129

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issue 6

1235-1241

EN

Thermal decomposition behavior of bis (4-nitrophenol)-2,4,6-triamino-1,3,5-triazine monohydrate (BNPM) has been studied by means of thermogravimetric analysis at three different heating rates 10, 15 and 20°C min¯¹. Non-isothermal studies of BNPM have revealed that the decomposition occurs in three stages involving dehydration and decomposition. The values of effective activation energy (E_{a}), pre-exponential factor (A) of each stage of thermal decomposition for all heating rates were calculated by model free methods: Arrhenius, Flynn-Wall, Friedman, Kissinger and Kim-Park method. A significant variation of effective activation energy (E_{a}) with conversion (α) indicates that the process is kinetically complex. The linear relationship between the A and E_{a} values was well established (compensation effect). Dehydration stage was governed by the Avrami-Erofeev model (A2) and decomposition stages were governed by the Avrami-Erofeev model (A4).

2

Vibrational Spectroscopic and Computational Studies on Bis(2-aminopyridinium)fumarate - Fumaric Acid (1:1) Complex

100%

Kanagathara N., Pawlus K., Marchewka M.

Acta Physica Polonica A

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2018

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vol. 133

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issue 1

45-56

EN

The new vibrational and computational studies on bis(2-aminopiridinium) fumarate - fumaric acid (1:1) complex have been made. The molecular geometry, vibrational frequencies and intensities of vibrational bands have been interpreted with the aid of structure optimization based on density functional theory (B3LYP) method with 6-311++G(d,p) basis set. The highly occupied-lowly unoccupied molecular orbital energies and chemical reactivity of the molecule have been calculated with time-dependent density functional theory approach. Stability energies of the molecule have been studied using natural bond orbital analysis. The predicted nonlinear optical properties of the title compound are much greater that those of urea. In addition, the molecular electrostatic potential surfaces and thermodynamic properties were calculated.

3

Kinetics and Mechanical Studies of Melaminium bis(trichloroacetate) dihydrate

100%

Kanagathara N., Marchewka M., Gunasekaran S., Anbalagan G.

Acta Physica Polonica A

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2014

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vol. 126

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issue 3

827-832

EN

The thermal decomposition kinetics of melaminium bis(trichloroacetate) dihydrate (MTCA) has been studied by thermogravimetry and derivative thermogravimetry techniques using non-isothermal experiments at three different heating rates 10, 15, and 20°C min^{-1}. Non-isothermal studies of MTCA revealed that the decomposition occurs in three stages involving dehydration and decomposition. The apparent activation energy (E_{a}) and the pre-exponential factor (ln A) of each stage of thermal decomposition at various linear heating rates are calculated using Flynn-Wall, Friedman, Kissinger, and Kim-Park method. A significant variation of effective activation energy (E_{a}) with conversion (α) indicates that the process is kinetically complex. The linear relationship between the A and E_{a} values is well established (compensation effect). Isothermal kinetics of thermal decomposition of MTCA was found to obey Avrami-Erofeev's (A4) and power law (P3) equations. In addition to the above, mechanical properties have been estimated by Vicker's microhardness test for the grown crystal.

4

Specific Heat of (NH_{2}(CH_{3})_{2})_{3}Bi_{2}I_{9}

88%

Plackowski T., Włosewicz D., Tomaszewski P., Baran J., Marchewka M.

Acta Physica Polonica A

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1995

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vol. 87

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issue 3

635-641

EN

The specific heat of title compound was measured by adiabatic calorimeter in the temperature range 80-315 K. The phase transitions at about 304, 285 and 235 K were confirmed. A new structural phase transition at about 125 K was observed as well as new anomaly on differential scanning calorimetry (DSC) curve at about 318 K. The peculiar multiple character of C, anomalies may be explained in terms of phase transitions or intermediate phases induced by impurities. The specific heat data are in agreement with the independent DSC measurements and with preliminary X-ray studies.

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Thermal Decomposition Behaviour of Bis(4-Nitrophenol)-2,4,6-Triamino-1,3,5-Triazine Monohydrate

Vibrational Spectroscopic and Computational Studies on Bis(2-aminopyridinium)fumarate - Fumaric Acid (1:1) Complex

Kinetics and Mechanical Studies of Melaminium bis(trichloroacetate) dihydrate

Specific Heat of (NH_{2}(CH_{3})_{2})_{3}Bi_{2}I_{9}