Comparative investigations of new regenerated cellulosic fibers, bamboo viscose fiber and Tencel, together with conventional
viscose fibers have been carried out to explain the similarity and difference in their molecular and fine structure. The analyses
jointly using SEM, XRD and IR reveal that all the three fibers belong to cellulose II. Tencel consists of longer molecules
and has a greater degree of crystallinity, while bamboo viscose fiber has a lower degree of crystallinty. TG-DTG-DSC study
shows three fibers resemble in thermal behavior with a two-step decomposition mode. The first step is associated to water
desorption, suggesting that bamboo viscose fiber holds better water retention and release ability, the second a depolymerization
and decomposition of regenerated cellulose, indicating that Tencel is more thermally stable in this process than bamboo and
conventional viscose fiber.
Authors:Cui -Mei Yin, Yang -Hui Kong, Zi -Ru Liu, Cheng -Yun Wu, De -Hou Ren, Ming -An He, and Hong -Fu Xue
Thermal dissociation reactions and mechanism of complexes of rare earth(iii) nitrates with the crown ether benzo-15-crown-5 were investigated by means of TG-DTG, DSC, DTA and IR technique. The results have shown that the dissociation processes of the complexes consist of several steps, one of which is a fast decomposition reaction. The fast decomposition peak temperatures (DSC) of all the complexes of the lanthanides (except Pm and Tm) decrease regularly with increasing atomic number. Moreover, values of the enthalpy change of desolvation, fast and the fourth step of decomposition and the apparent activation energies of fast and the fourth step of decomposition were obtained.
Authors:J. KŐmives, K. Tomor, J. Sztatisz, L. Lassu, and S. Gál
Changes in the water content of aluminium sulphate hydrate were investigated gravimetrically at room temperature in air with different relative humidities. The samples conditioned in this way were characterized by thermoanalytical (TG, DTG, DSC) and X-ray diffraction measurements. Industrial aluminium sulphate hydrate obtained by freezing the melt has a partly crystalline structure. After grinding, this material crystallizes during storage. This process requires a humid atmosphere; increasing relative humidity brings about more intensive crystallization.
Authors:E. Segal, L. Maistriau, E. Derouane, and Z. Gabelica
The dehydration of a series of VPI-5 and H3 samples, synthesized under various conditions, as well as the solid state transformation
of VPI-5 to AlPO4-8 have been investigated using combined TG-DTG-DSC and high-resolution solid state31P-NMR. The TG curves show a quasi-continuous release of water, the total loss being characteristic for each sample. Complete
dehydration is achieved when the samples are heated from 20°C to about 150°C at various beating rates. Besides the main dehydration
effect, several weak endothermic peaks are observed. These generally non-reproducible modulated peaks, recorded at high heating
rates, are presumably due to the interactions of the water molecules leaving the channels of VPI-5 with the randomly positioned
fragments stemming from the destruction of the water triple helix assemblage.
The non-isothermal kinetic parameters of the dehydration have been evaluated from the TG and DTG curves recorded at low heating
Thermal decomposition of sodium tris(maleato)ferrate(III) hexahydrate, Na3[Fe(C4H2O4)3]·6H2O and sodium tris(fumarato)ferrate(III) heptahydrate, Na3[Fe(C4H2O4)3]·7H2O has been studied upto 973 K in static air atmosphere employing TG, DTG, DSC, XRD, Mössbauer and infrared spectroscopic techniques.
Dehydration of the maleate complex is complete at 455 K and the anhydrous complex immediately undergoes decomposition till
α-Fe2O3 and sodium carbonate are formed at 618 K. In the final stage of remixing of cations, a solid state reaction between α-Fe2O3 and sodium carbonate leads to the formation of α-NaFeO2 at a temperature (773 K) much lower than for ceramic method. Almost similar mode of decomposition has been observed for the
fumarate complex. A comparison of the thermal stability shows that the fumarate precursor decomposes at a higher temperature
than the maleate complex due to the trans geometry of the former.
Authors:L. Sobrados, S. Goni, J. L. Sagrera, and M. J. Martinez
Reactivity of solid mixtures of crystalline V2O5 and basic compounds strongly increases at room temperature by means of water molecules adsorption process from a saturated atmosphere (100% RH). This is due, firstly, to a crystalline-amorphous V2O5 transformation and secondly to the formation of strongly acid V2O5 gels. In the present paper the evolution with time of the CaCO3-V2O5 (1∶1) mixture in the aforementioned conditions was studied by thermal analysis (TG, DTG and DSC), X-ray diffraction (XRD) and infrared spectroscopy (IR). The results confirmed the V2O5 gels formation which decomposed the basic CaCC3 at room temperature through an acid-base mechanism reaction. A new crystalline compound was obtained which corresponded to a hydrated calcium metavanadate.
The thermal behaviors of [1,1,1-trifluro-3-(2-thenoyl)-acetonato]copper(II) Cu(TTA)2 and its adducts with pyridine Cu(TTA)2(Py)2, 2,2'-bipyridine Cu(TTA)2(Bpy), quinoline Cu(TTA)2(Ql)2, and dimethyl sulfoxide Cu(TTA)2(DMS) in a nitrogen atmosphere were studied under the non-isothermal conditions by simultaneous TG-DTG-DSC technique. The
results showed that the evolution of the solvent molecules generally proceeded before the release of TTA in different ways
according to their structures. The Cu(TTA)2(Bpy) exhibited a unique decomposition pattern due to its distinctive structure. The dependences of activation energy on extent
of reaction for all the stage of each compound were determined by using an isoconversional method, Flynn-Wall-Ozawa equation,
which show E values varied with reaction progress, indicating the complexity of these decomposition reactions. In addition,
the values of activation energy E for TTA molecules evolution are generally higher than that for the solvent molecules release.
Thermal analysis of alkaline earth metal ferrisuccinate precursors, M3[Fe(C4H4O4)3]2�xH2O (M=Mg, Ca) has been studied isothermally and non-isothermally employing simultaneous TG-DTG-DSC, XRD, IR and M�ssbauer spectroscopy
to characterize the intermediates/end products. After dehydration, the anhydrous complexes decompose to yield an iron(II)
oxalate intermediate, Fe(II)C2O4 in the temperature range 180–250�C. Decomposition of this iron(II) species leads to the formation of α-Fe2O3 and respective alkaline earth metal oxide/carbonate in the temperature range 250–300�C. Finally, ferrites of the stoichiometry,
MgFe2O4 and Ca2Fe2O5 are formed as a result of solid-state reaction between α-Fe2O3 and MO/MCO3. A special feature of the precursor method, adopted by us, is that the formation of ferrites occurs at much lower temperature
than that of conventional ceramic method.
The nitrate complexes of copper, nickel and zinc with diethylenetriamine (dien) i.e. [Cu(dien)2](NO3)2, [Ni(dien)2](NO3)22H2O and [Zn(dien)2](NO3)2 have been prepared and characterised. Thermal studies were undertaken using TG-DTG, DSC, ignition delay (tid) and ignition temperature (IT) measurements. Impact sensitivity was measured using drop mass technique. The kinetic parameters for both non-isothermal
and isothermal decomposition of the complexes were evaluated by employing Coats-Redfern (C-R) method and Avrami-Erofeev (A-E)
equations (n=2 and 3), respectively. The kinetic analysis, using isothermal TG data, was also made on the basis of model free isoconversional
method and plausible mechanistic pathways for their decomposition are proposed. Rapid process was assessed by ignition delay
measurements. All these complexes were found to be insensitive towards impact of 2 kg mass hammer up to the height limit (110
cm) of the instrument used. The heat of reaction (?H) for each stage of decomposition was determined using DSC.
The thermo-oxidative degradation of a parchment recent manufactured from a goat skin has been investigated by TG/DTG, DSC
simultaneous analysis performed in static air atmosphere, at six heating rates in the range 3–15 K min−1. At the progressive heating in air atmosphere, the investigated material exhibits three main successive processes occurring
with formation of volatile products, namely the dehydration followed by two thermo-oxidative processes. The processing of
the non-isothermal data corresponding to the first process of thermo-oxidation was performed by using Netzsch Thermokinetics—a
Software Module for Kinetic Analysis. The dependence of activation energy, evaluated by isoconversional methods suggested
by Friedman, and Ozawa, Flynn and Wall, on the conversion degree and the relative high standard deviations of this quantity
show that the investigated process is a complex one. The mechanism and the corresponding kinetic parameters were determined
by Multivariate Non-linear Regression program. Three mechanisms, one consisting in four successive steps and two others in
five successive steps, exhibit the best F-test Fit Quality for TG curves. It was also used the previously suggested criterion, according to which the most probable
process mechanism correspond to the best agreement between EFR = EFR (α) (EFR is the activation energy evaluated by isoconversional method suggested by Friedman; α is the conversion degree) obtained
from non-isothermal experimental data and activation energy values, Eiso, obtained by applying the differential method to isothermal data simulated using non-isothermal kinetic parameters. According
to this last criterion, the most probable mechanism of parchment oxidation consists in four successive steps. The contribution
of the thermo-oxidation process in the parchment damage by natural aging is discussed.