Authors:Burcu Alver, Meryem Sakizci, and Ertuğrul Yörükoğullari
Turkey clinoptilolite-rich tuffs from Gördes and Bigadiç regions of western of Anatolia and their exchanged forms (K+, Na+, Mg2+ and Ca2+) were characterized by TG/DTG-DTA, DSC and XRF methods and the surface areas were also determined for both tuffs. TG-DTG
and DTA curves of all clinoptilolite samples were measured in the temperature range 30–1000 °C. All clinoptilolite samples
had major, rapid mass losses between 30 and 200 °C, with slower and less significant mass losses at higher temperatures. The
mass loss of the Natural-G is 9.54% while that of the Natural-B sample is 10.50%. Water content increases in the order of
K < Na < Ca < Mg for Bigadiç clinoptilolite samples and in the following sequence K < Na < Mg < Ca for Gördes clinoptilolite
samples. One mass loss step for all clinoptilolite samples was observed using differential scanning calorimeter (DSC) in the
range of 30–550 °C.
Non-isothermal dehydration of copper chloride dihydrate and nickel chloride hexahydrate were studied by using TG, DTG, DTA
and DSC measurements. The copper chloride salt loses its two water molecules in one step while nickel chloride salt dehydrates
in three consecutive steps. The first two steps involve the loss of 4 water molecules in two overlapped steps while the third
step involves the dehydration of the dihydrate salt to give the anhydrous NiCl2.
Activation energies (ΔE) and the frequency factor (A) were calculated from DTG and DTA results. We have also calculated the different thermodynamic parameters, e.g. enthalpy
change (ΔH), heat capacity (Cp) and the entropy change (ΔS) from DSC measurements for both reactants.
The isothermal rehydration of the completely dehydrated salts was studied in air and under saturated vapour pressure of water.
Anhydrous nickel chloride was found to rehydrate in three consecutive steps while the copper salt rehydrated in one step.
Authors:J. Goworek, A. Kierys, M. Iwan, and W. Stefaniak
Mesoporous materials MCM-41 with the hexagonal arrangement of pores
were obtained using dodecyltrimethylammonium bromide and octadecyltrimethylammonium
bromide as templating surfactants. Adsorption of toluene and propan-1-ol on
the as-synthesized MCM-41 silica samples was investigated using the TG-DTG,
DTA and DSC techniques. The sorption mechanism of used adsorptives is discussed
in terms of hydrophobicity of pore interior filled with template as well as
Authors:A. Rotaru, Anca Moanţă, P. Rotaru, and E. Segal
Thermal analysis of 4-[(4-chlorobenzyl)oxy]-4′-chloro-azobenzene dye, exhibiting liquid crystalline properties, was performed
in dynamic air atmosphere. The compound behavior was investigated using TG, DTG, DTA and DSC techniques, under non-isothermal
linear regime. The evolved gases were analyzed by FTIR spectroscopy. Kinetic parameters of the first decomposition step were
obtained by means of multi-heating rates methods, such as isoconversioanl methods, IKP method and Perez-Maqueda et al. criterion.
Authors:Lucinéia de Carvalho, Milena Segato, Ronaldo Nunes, Csaba Novak, and Éder Cavalheiro
The thermal decomposition behavior of acesulfame-K (ACK), aspartame (ASP), sodium cyclamate (SCL), saccharine (SAC), and sodium
saccharine (SSA) were investigated. After re-crystallization of the commercial samples the compounds were characterized by
using elemental analysis, IR spectroscopy and thermoanalytical techniques (TG/DTG, DTA, and DSC). Evidences of hydrate water
loss were observed for SSA and ASP. Melting was detected for SSA and SAC. Each compound decomposed in a characteristics way.
The decomposition of APS and SAC took place completely, while ACK, SCL and SSA resulted in K2SO4, Na2SO4, and Na2SO4, as residues respectively. The Flynn-Wall-Ozawa method for kinetic calculations was applied for the volatilization of saccharine
resulting in Ea = 80 ± 1 kJ mol−1 and log A = 7.36 ± 0.07 min−1.
Authors:A. Rotaru, Anna Kropidłowska, Anca Moanţă, P. Rotaru, and E. Segal
Thermal analysis of three azomonoether dyes, exhibiting liquid-crystalline properties, was performed in dynamic air atmosphere.
Thermal stability studies and the evaluation of the kinetic parameters of each physical or chemical transformations are essential
for a full characterization, before attempting accurate thin films’ depositions of such materials used in non-linear optical
applications. New synthesized dyes with general formula:
where R is a nematogenic group: CN, CF3 or a highly polarizable group: NO2 were investigated using TG, DTG, DTA and DSC techniques, under non-isothermal regime. The evolved gases were analyzed by
FTIR spectroscopy. The activation energies of the first decomposition step were evaluated for each compound, the obtained
results revealing complex mechanisms.
Two bis(bipyridine) polymeric metal nitrate complexes
with 4,4’-bipyridine of simple formula like [M(bipy)2](NO3)2⋅xH2O (where M=Co, Ni and Cu; x=4, 2 and 0, respectively) have been prepared and
characterized. Their thermal decomposition has been undertaken using simultaneous
TG-DTG-DTA and DSC in nitrogen atmosphere and non-isothermal TG in air atmosphere.
Isothermal TG has been performed at decomposition temperature range of the
complexes to evaluate the kinetics of decomposition by applying model-fitting
as well as isoconversional method. Possible mechanistic pathways have also
been proposed for the thermolysis. Ignition delay measurements have been carried
out to investigate the response of these complexes under the condition of
Authors:A. Rotaru, Irina Nicolaescu, P. Rotaru, and C. Neaga
Over the ages, the deposits of dead vegetation buried by rock and mudflows, compacted and compressed out all of the moisture;
it slowly carbonized and became coal.
Humic acids are natural organic acids — brown coloured biological macromolecules, formed in coal by biochemical changes (decomposition,
pyrolysis) of lignocellulosic matter.
From lignite coal bed, the humates were extracted in alkaline medium and isolated from the residual fraction. Humic acids
were obtained by treating humantes’ solutions with HCl.
Thermal analysis (TG, DTG, DTA and DSC) was used in order to establish the decomposition and thermal effects of lignite, humates,
humic acids and residual matter extracted from Rovinari mines in Romania. A non-isothermal linear temperature regime was imposed
to reveal all decomposition steps.
Authors:A. Rotaru, Catalin Constantinescu, P. Rotaru, Anca Moanţâ, M. Dumitru, Margareta Socaciu, Maria Dinescu, and E. Segal
A new synthesized 4CN type azomonoether, exhibiting dying properties, crystalline nature and generating interest as a material
for non-linear optical applications was investigated. Modern devices incorporating liquid crystals tend to use thin films
of such materials because of their special characteristics. Thermal stability studies are indispensable before attempting
any deposition experiment.
We have investigated the thermal behaviour of 4-[(4-chlorobenzyl)oxy]-4′-cyano-azobenzene (TG, DTG, DTA and DSC) in inert
flow atmosphere, under non-isothermal conditions. The phase transitions were studied by repeated heating-cooling regimes,
with intercalated isothermal steps. The thin films were deposited on silicon and quartz substrates by matrix assisted pulsed
laser evaporation (MAPLE) using a Nd:YAG laser working at 266 nm. FTIR spectroscopy of the obtained thin films confirmed the
preservation of the compound’s structure.
Authors:J. H. Levy, W. I. Stuart, and R. N. Whittem
TG, DTG, DTA and DSC methods were used to study the curing reaction of diglycidyl ether of bisphenol A and nadic methyl anhydride in the presence of a reactive diluent. DTG plots were used to identify the various stages of weight loss arising from volatilization of components from the resin formulation and pyrolysis of cured resin. DTA and DSC results established the temperatures at which catalysed and thermally activated cure occurred.