A0401 – Thermal transformation of alumina gel spheres
A0405 – Some dn metal complexes with 4,4-bipyridine and trichloroacetates. Preparation, characterization and themal properties
The new mixed ligand complexes with formulae Co(4-bpy)2L22H2O (I), Cu(4-bpy)2L2H2O (II) and Cd(4-bpy)L2H2O (III) (4-bpy=4,4'-bipyridine, L=CCl3COO-) were prepared. Analysis of the IR spectra indicate that 4-bpy is coordinated with metal ions and carboxylates groups bond as bidentate chelating ligands. The electronic spectra are in accordance with pseudo-octahedral environment around the central metal ion in the Co(II) and Cu(II) complexes. The thermal decomposition of the synthesized complexes was studied in air. A coupled TG-MS system was used to analyse the principal volatile thermal decomposition products of Co(II) and Cu(II) complexes. Corresponding metal oxides were identified as a final product of pyrolysis with intermediate formation of metal chlorides.
A0404 – Determination of the oxygen chemical diffusion coefficient in perovskites by a thermogravimetric method
A thermogravimetric method has been used for the determination of the oxygen chemical diffusion coefficients in La(1-x)SrxMnO(3+d); x=0; 0.05; 0.10; 0.15 (LSM).
A temperature range of 700-1000°C was studied.
The chemical diffusion coefficient varies between 1.6.10^(-13) and 1.8.10^(-10) cm2 s-1 for the samples in the temperature range studied. The activation energy for oxygen chemical diffusion was determined to be 190-280 kJ mol-1 for the LSM samples. The magnitude of the chemical diffusion coefficients of the LSM samples does not depend on the strontium site occupation factor.
A0403 – Mise au point d’un couplage thermogravimétrie microchromatographie
A thermogravimetry-microchromatography assembling has been developed and tested for solvent vaporization studies. Cyclodextrine and calcium sulfate dehydrations as well as cobalt carbonate decomposition were studied.
A0408 – Thermal and other properties of new 4,4′-Bipyridine-Trichloroacetato complexes of Mn(II), Ni(II) and Zn(II)
New mixed-ligand complexes of general formulae Mn(4-bpy)(CCl3COO)2.H2O, Ni(4-bpy)2(CCl3COO)2.2H2O and Zn(4-bpy)2(CCl3COO)2.2H2O (where 4-bpy=4,4-bipyridine) were obtained and characterized. The IR spectra, conductivity measurements and other physical properties of these compounds were discussed. The central atoms M(II) form coordinate bonds with title ligands. The thermal behaviour of the synthesized complexes was studied in air. During heating the complexes decompose via different intermediate products to Mn3O4, NiO and ZnO; partial volatilization of ZnCl2 was observed. A coupled TG-MS system was used to the analysis of the principal volatile thermal decomposition products of Mn(II) and Ni(II) complexes. The principal volatile mass fragments correspond to: H2O+, OH+, CO 2 + , HCl+, Cl 2 + , CCl+ and other.
A0407 – Preparation of Cs2ZrO3 & Cs2ThO3 through sol-gel method and their characterization
Cesium zirconate and cesium thorate were prepared by sol-gel method following citrate-nitrate route. The compounds were characterized by X-ray diffraction, chemical analysis and simultaneous TG-DTA. The methods of preparation of Cs2ZrO3 and Cs2ThO3 reported in literature involve difficult steps and require stringent experimental conditions for obtaining the compounds. In this work we report an easier method for the preparation of these compounds at relatively low temperature.
A0406 – FTIR study of the thermal degradation of poly(vinyl alcohol)
The degradation of poly(vinyl alcohol) was investigated using TG analysis and Fourier transform infrared spectroscopy to determine the effect of atmosphere on the process of degradation. In the spectra, four vibrational modes were identified that characterised the major steps of the degradation process. These were the O-H, C-H, C=O and C=C stretching modes. The mechanism observed for degradation in an inert atmosphere was in accordance with the accepted mechanism of elimination followed by pyrolisation. Evidence of conjugated polyenes, however, was not observed. For the air atmosphere, oxidation in both steps of the degradation process was observed.
A0410 – Dégradation thermique et étude vibrationnelle de MII(NH4)4(P3O9)2.4H2O (MII=Cu2+, Ni2+, Co2+)
We have studied the thermal behaviour under atmospheric pressure of isotypictetrahydrate cyclotriphosphates MII(NH4)4(P3O9)24H2O (M II=Cu, Ni and Co), between 25 and 1400°C, by X-ray diffraction, thermal analyses (TG and DTA) and infrared spectrometry. This study shows that the series of the compounds MII(NH4)4(P3O9)24H2O (M II=Cu, Ni and Co) after elimination of water, in two different stages, and ammonia leads, at 400°C to cyclotetraphosphate M2 IIP4O12 crystallized and to a thermal residue with a formula H4P4O12 which undergoes under a thermal degradation by evolving water and pentoxide phosphorus. The kinetic characteristics of the dehydration and elimination of ammonia have been determinated. The vibrational spectra of Cu(NH4)4(P3O9)24H2O were examined and interpreted, in the domain of the valencyfrequencies, on the basis of the crystalline structure of its isotypic compound Co(NH4)4(P3O9)24H2O whose cycle has the site symmetry C1, of our results of the calculation of the IR frequencies and the successive isotopic substitutions of the equivalent atoms (3P, 3Oi and6Oe belonging to the P3Oi3Oe6 ring) of the (P3O9)3- cycle with high symmetry D3h.
A0409 – Elaboration de capteurs de gaz à partir de céramiques conductrices ioniques de type NaSICON
The elaboration of Na+ super-ionic conductor (NaSICON) ceramics is studied in this work. These solid electrolytes can be used as sensor for detection of polluted gases in air. Two sorts of ceramics with different chemical compositions are synthesised by soft chemistry route: a zirconium-based NaSICON and a hafnium-based NaSICON. DTA-TG and temperature depending X-ray diffractometry were used to follow the thermal decomposition of the precursor phases. The electrical properties of these ceramic sodium ionic conductors are investigated by complex impedance spectroscopy (CIS). The substitution of the zirconium by the hafnium increases the ceramic conductivity and decreases the activation energy E a (from 0.29 to 0.12 eV).
A0412 – Thermal behaviour of a TiO2-ZrO2 microcomposite prepared by chemical coating
A systematic study of the effects of bond-coats surface modifications prior to ceramic deposition is presented. TBC systems have been made and tested with most combinations of the following parameters: 1/substrate: IN 100 or AM3 (single crystal) Ni-based superalloys; 2/ bond-coat: VPS NiCoCrAlYTa or CoNiCrAlY, (Ni,Pd)Al, (Ni,Pt)Al; 3/ bond-coat surface finish: as deposited, machined, grit blasted, preoxidized; 4/ top coat: APS or EB-PVD YO stabilized ZrO. The preoxidation treatments of bond-coats were determined from the results of a study (TGA-GIXRD-SEM-SIMS) of their short-term (6 hours) isothermal oxidation behavior as a function of temperature (900 to 1100°C), oxygen partial pressure and heating rate. Under these conditions all bond-coats are alumina formers, but depending on the oxidation conditions, transition aluminas may be formed. The characterization of complete TBC systems was also performed, including isothermal oxidation (TGA), cyclic oxidation at 1100°C, cyclic corrosion at 900°C and thermal shock (fast cooling from 1200°C).
A0411 – Thermal behaviour of TiO2-ZrO2 microcomposite prepared by chemical coating
A microcomposite powder in the system TiO2-ZrO2 as a precursor of zirconium titanate (ZT) materials has been studied by thermal methods (DTA-TG) and X-ray diffraction (XRD). The microcomposite powder has been prepared by chemical processing of crystalline TiO2 (rutile, 10 mass% anatase),as inner core, coated with in situ precipitated amorphous hydrated zirconia gel, asouter core. The morphology and chemical composition of the resultant powders has been examined by SEM-EDX (Scanning electron microscopy-energy dispersive X-ray spectroscopy). Thermal behaviour of the microcomposite powder was reported, showing the dehydration and dehydroxylation of the zirconia gel, the crystallization into metastable cubic/tetragonal zirconia at temperatures 400-470°C, and the feasibility of preparing ZT powder materials by progressive reaction of TiO2 and ZrO2 at higher temperatures (1400°C).
A0416 – Evidence for suppression of the oxidation of a Fe 2.25Cr 1 Mo steel by traces of SO2
A0414 – Role of the microstructure on the high temperature oxidation properties of the intermetallic compound NbAl3
The influence of the NbAl microstructure on its oxidation mechanism was investigated in air under atmospheric pressure over the temperature range 500-1080°C. Different processing techniques as induction melting and mechanically-activated annealing processes (M2AP) were used to produce the intermetallic compound NbAl. A protective external alumina scale grew only on Al-enriched NbAl between 700 and 1080°C. Stoichiometric NbAl exhibited the pesting phenomenon between 550-900°C, whereas a non protective lamellar oxide scale formed above 900°C. The proposed oxidation mechanism explains these observations which are in agreement with the oxidation study of powders with different crystallite sizes.
A0419 – Influence of additives on characterisation and high temperature corrosion of electrodeposited copper and nickel
A0420 – The effect of yttrium on the oxidation of a commercial Fe-Cr-Al alloy at 1173 K
L'étude de l'effet de l'implantation ionique d'yttrium sur l'oxydation isotherme d'un alliage FeCrAl commercial, le Kanthal Al, a été conduite sous air à 1173 K. La cinétique d'oxydation de l'alliage non implanté se caractérise par une prise de masse rapide au cours des six premières heures (étape initiale transitoire) suivie par un régime d'oxydation parabolique. L'implantation modifie le comportement à l'oxydation de l'alliage qui présente alors deux régimes paraboliques consécutifs. La présence de l'élément actif diminue de façon conséquente la vitesse d'oxydation de l'alliage. L'implantation d'yttrium affecte également la composition de la couche d'oxyde. La diffraction, des rayons X in situ montre que l'yttrium supprime la formation des alumines de transition et favorise la croissance d'alumine alpha, ce qui améliore le caractère protecteur de la couche d'oxyde formée.
A0425 – A microscopy study of spalling and growth mechanism of the oxide scale formed on Pd modified nickel aluminum
A0424 – Reactive element (Y,Ce) effect on stresses determined in-situ during iron oxidation at 800°C
A0423 – A phenomenological model for high temperature oxidation of Si3N4-TiN composites
Based on microstructural and chemical analyses, a phenomenological model is proposed in order to describe the high temperature oxidation of SiN-TiN ceramics. The model consists of three steps in the 1000-1200°C temperature range. In a first step, the oxidation of the TiN phase is controlled by the diffusion of Ti through TiO formed at the outer surface, leading to the formation of a porous sub-layer. Simultaneously, the SiN phase oxidation is controlled by oxygen diffusion through SiO. In a second step, the oxidation of inner TiN phase is controlled by the diffusion of oxygen through TiO. The SiN transformation into SiO leads to a high molar volume increase, SiO, which is vitreous in the considered temperature range, creeps in the sub-layer porosity. In a third step, SiO forms a continuous sub-layer, and oxidation is controlled by the diffusion of O through this layer. The kinetic laws proposed from this phenomenological model are in good agreement with thermogravimetric analyses between 1000°C and 1100°C. For higher temperatures, fluctuations in the experimental curves seem to indicate a succession of fracture and crack healing in the oxide layer.
A0428 – Modeling of non-isothermal kinetics of gaseous hydrocarbon adsorption on a granulated active carbon
The adsorption of n-butane on extruded cylindrical activated carbon grains is studied providing two kinds of information: the influence of the temperature and the hydrocarbon partial pressure on the adsorption dynamics (kinetic study) and on the adsorption capacities (thermodynamic study). The thermodynamic aspect could be interpreted by a Langmuir model. From a kinetic point of view, we have experimentally proved that strong temperature variations occur inside the particles during the adsorption. In this paper, a kinetic model including both mass and heat transfer phenomena is proposed. Good agreement is found between the kinetic model predictions and the experimental mass and temperature variations inside the grain during the hydrocarbon adsorption.
A0430 – Encombrement stérique des iso-alcanes lors de l’adsorption sur la zéolithe 5A
A0429 – Chemostratigraphy of late quaternary sediments from lake Albano and central Adriatic Sea cores (Paliclas project)
This paper summarises the results of the geochemical investigations on bulk sediment and
tephra layers from several cores collected, both in Albano and Nemi lakes and in the Middle
Adriatic Sea, within the EU funded PALICLAS Project, aimed at the reconstruction of the environmental
evolution of central Italy within the last climatic cycle (i.e., the last 30,000
years). The main geochemical effects of the transition from Full Glacial to Holocene times,
recorded by lake sediments, are related to changes of organic/inorganic matter ratios, due to
different productivity and terrigenous supply; those found the marine sediments reflect the
values of some major and trace element, testifying to changes in river supply and marine hydrodynamics.
Useful indices for the interpretation of lake palaeoenvironments appeared:
total organic content, biogenic silica and Br for biological matter; Al, Y and Zr/Rb ratio for
terrigenous clastic material; autigenic U and V/Cr for redox conditions. As regards the
Adriatic sediments the more promising geochemical indices of palaeoenvironmental changes
in the late Quaternary appeared Cr, Co, Ni, Sr, and Cr/V, Sr/Ca. The occurrence of tephra
layers interbedded in both lake and sea samples allowed us the determination of some chronostratigraphic
markers for lake-lake, marine-lake and within Adriatic core correlations.
A0434 – Studies on the thermal decomposition of N,N’-ethylenebis(salicylideneiminato) diaquochromium(III) nitrate
A complex of N,N'-ethylenebis(salicylideneiminato)diaquochromium(III) nitrate, [Cr(salen)(H2O)2]NO3 was characterized and its decomposition mechanism was studied by TG. The IR spectrum and X-ray analysis were examined for the complex. The non-isothermal kinetic data were analyzed by means of the Achar method and the Coats-Redfern method. The most probable kinetic model function was suggested by comparison of the kinetic parameters
A0433 – Thermodynamic study of the solid-liquid equilibria in the MPO3-Ce(PO3)3 systems (M=Li, Na, K, Rb, Cs, Ag, Tl)
An equation of the liquidus curve of a stoichiometric phase has been established in a previous publication. In this work, the obtained formula is applied to the phase diagram determination of the MIPO3-Ce(PO3)3 (with MI=Li, Na, K, Rb, Cs, Ag, Tl) systems. The temperature, enthalpy and entropy of fusion are calculated for each solid phase with the exception of lithium and silver polyphosphates, of which crystallization fields were very limited. The enthalpy of fusion of all of these polyphosphates is determined from the DTA curves. The melting enthalpy of Ce(PO3)3, calculated from different binary systems is approximately equal to the measured value. The calculated temperatures and compositions are in good agreement with experimental determinations
A0432 – Simultaneous thermogravimetric-mass spectrometric study on the pyrolysis behaviour of different rank coals
Simultaneous thermogravimetry-mass spectrometry was used to study the pyrolysis behaviour of an anthracite and three bituminous coals of different volatile matter content. This system was optimised by using calcium oxalate as a reference for calibration. A normalisation method that permitted a semiquantitative comparison between the volatile species of the coals was also developed. The instantaneous evolution of the volatile compounds was studied by means of temperature-programmed pyrolysis experiments. The peaks varied in shape, temperature and size, and showed a marked dependence on coal rank. This can be attributed to the varying amounts of the different functional groups in the coals studied. Special attention was paid to the nitric oxide released during pyrolysis, together with its precursor species.
A0431 – Chemical and thermal analysis of the biopolymers in thyme (Thymus vulgaris)
Thyme (Thymus vulgaris) has been known, long time ago, for its aromatic properties. It contains essential oils and polymers such as cellulose (mixture of hemicellulose and cellulose) and lignin. The thyme, studied in this work, was gathered from the same place, in the period from November 1999 to October 2000. The chemical analysis (water, total ash, essential oils, extractive substances, cellulose, holocellulose and lignin) can be used roughly in the characterisation of the four periods that correspond to the four seasons of the year. The cellulose level was found to be more than lignin level in the wet periods (growth of the plant). The opposite was found in the dry periods. The total ash and essential oil levels were found to be high during the period of high pluviometry. The thermal decomposition of cellulose and holocellulose was found to fit well with the first-order kinetics. The activation energy, under air flow, was 185 and 196 kJ mol-1 for cellulose and holocellulose, respectively. The maximum decomposition rate and thermal analysis heating rate of lignin were found to have a direct linear relationship.
A0436 – Thermal behaviour of urea-formaldehyde resins during curing
Urea-formaldehyde (UF) resins are the most widely used polycondensation resins today in manufacturing particleboards. The performance of UF resins in their processing is greatly influenced by curing characteristics. The cure process has been monitored by TG-DTA technique on a Setaram labsys instrument in dynamic heating conditions at different heating rates. Commercial UF resins from different suppliers used in Estonian particleboard factories were selected for TG-DTA measurements. Experiments were carried out without and with catalysts. Ammonium chloride and ammonium sulphate were used. Curing characteristics were evaluated both for fresh and aged resins.
A0435 – Poly(urethane methacrylate) thermosetting resins studied by thermogravimetry and thermomechanical analysis
Two different poly(urethane acrylate) resins (one with a trimer: PUA1, the second with a dimer: PUA2) prepared  by photo curing reaction are investigated by means of thermogravimetry and thermomechanical measurements. The lack of mass loss found up to 300°C for both systems shows their good thermal stability. Beyond this temperature, two mass losses occur consecutively. This mass loss already studied by TG-FTIR coupled measurements for PUA1 resin has been attributed to the degradation of carbonyl groups . The extension to PUA2 and the comparison between the mass loss magnitude and the relative contain in acrylate of the resins leads to attribute the first degradation to the degradation of the acrylate fraction. The degradation of dimer based resin occurs earlier and with a faster kinetic than the trimer based resin. The variations of linear expansion and penetration coefficients measured by thermomechanical analysis (penetration probe) in the glassy state and in the glass transition temperature domain (the onset glass transition temperatures measured by DSC at 20°C min-1 are respectively equal to 111 and 107°C for PUA1 and PUA2, the transitions, not well defined, extending over 30°C), show that despite of a weaker compactness, the trimer based resin is more rigid than the dimer one.
A0438 – Characterisation of the oxidation products of pyrite by thermogravimetric and evolved gas analysis
The identification of the main components of urinary calculi, the knowledge of the true number of water molecules bounded to the calcium oxalate, and the determination of each hydrate in the mixture, are the interests of this memory. The thermal analysis (simultaneous DTA-TG) was applied on thirty-three urinary calculi. The determination of the calcium oxalate hydrates was confirmed by calorimetry (DSC).
A0437 – The use of thermal analysis in determination of some urinary calculi of calcium oxalate
The human urinary calculi are mainly constituted by calcium oxalate, magnesium ammonium phosphate hexahydrate, and uric acid. The ions or molecules are easily characterized by wet chemical methods. The difficulties appear in the differentiation of the hydrates of calcium oxalate (monohydrate COM or Whewellite, and dihydrate COD or Weddelite). A high level of COD in the urinary stones leads, often, inflammation, sharp pain and blood in urine. In the worse cases, they must be extracted by surgical way.
A0439 – High-temperature high-pressure crystallisation and sintering behavior of brookite-free nanostructured titanium oxide : in situ experiments using synchrotron radiation
The formation, stability and physico-chemical properties of TiO2 powders are strongly influenced by the actual synthesis and processing routes employed. Pure and metal-doped nanostructured TiO2 samples were obtained using the sol-gel method. In situ X-ray diffraction (XRD) experiments using synchrotron radiation were performed to explore the high-temperature/high-pressure stability and sintering behavior of these nanomaterials. The present results show a strong decrease of the anatase-to-rutile transition temperatures with increasing applied pressure, thus opening new perspectives for the development of efficient low-temperature sintering procedures.
A0440 – Chemometrics as a tool for the analysis of evolved gas during the thermal treatment of sewage sludge using coupled TG-FTIR
The thermal decomposition of sewage sludge has been investigated using coupled TG-FTIR for long time experiment (10 h). The exploitation of the resulted data from FTIR is performed by the SIMPLe-to-use interactive self-modelling mixture analysis (SIMPLISMA) method and allows to identify some of the evolved gases and to obtain their relative concentration profiles versus time without prior knowledge of constituents. As shown, this method can work properly for mixture with overlapped bands but some compounds remain "invisible" to FTIR analysis. More of that for long time experiment, it is possible to extract a spectrometer baseline contribution, which contributes to minimise noise and time variation.
A0441 – Thermal behaviour of dickite-dimethylsulfoxide intercalation complex
The thermal behaviour of the intercalation complex of a dickite from Tarifa, Spain, with dimethylsulfoxide was studied by high-temperature X-ray diffraction, differential thermal analysis and thermogravimetry, and attenuated total reflectance infrared spectroscopy. The ATR-FTIR study indicated that the heating between room temperature and 75°C produced the elimination of adsorbed molecules. Above this temperature the elimination of intercalated molecules occurs through several stages. Loss of ~6.5% of the intercalated DMSO first causes a slight contraction of the basal spacing at 90°C due to a rearrangement of the DMSO molecules in the interlayers positions. This contraction is followed by the formation of a single layer complex and the restoring of the dickite structure, at 300°C, when the loss of intercalated species have been completed.
A0444 – Burning out of di-n-propylamine template from from MeAPO-31 materials studied by thermal analysis
Conditions for oxidative burning out of template, di-n-propylamine, from MeAPO-31 materials have been studied by means of thermal analysis. The materials were doped with very low amounts of Cu, Cd, Co, Mn, Mg, and Zn, ranging from 0.04 to 0.63 wt.%. These low contents of heteroatoms have significantly determined the observed effects. The same holds for the stability of the microporous ATO (aluminophosphate thirty-one) type structure. Grinding of the crystallites leads to more efficient exchange of atmosphere and the gaseous products and thus results in a tendency to lower calcination temperature. This observation may be useful when considering a lower thermal stability of higher doped microporous MeAPO-31 materials.
A0443 – Low-temperature capacities and thermodynamic properties of crystalline isoproturon
Isoproturon [N-(p-cumenyl)-N,N-dimethylurea] was synthesized, and the low-temperature heat capacities were measured with a small sample precise automatic adiabatic calorimeter over the temperature range from 78 to 342 K. No thermal anomaly or phase transition was observed in this temperature range. The melting and thermal decomposition behavior of isoproturon was investigated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The melting point and decomposition temperature of isoproturon were determined to be 152.4 and 239.0°C. The molar melting enthalpy, and entropy of isoproturon, ?Hm and ?Sm, were determined to be 21.33 and 50.13 J K-1 mol-1, respectively. The fundamental thermodynamic functions of isoproturon relative to standard reference temperature, 298.15 K, were derived from the heat capacity data.
A0442 – Phenoxyalkanoic acid complexes. Part I. Complexes of lead(II), cadmium(II)and copper(II) with 4-chloro-2-methylphenoxyacetic acid (MCPA)
New solid heavy metal complexes with 4-chloro-2-methylphenoxyacetic acid (MCPA) of the general formulae: Pb(MCPA)2.H2O and Cd(MCPA)2.2H2O have been prepared. Diffractometric, IR spectroscopic and thermal analyses of these complexes and the previously described Cu(MCPA)2 have been performed. The complexes have different structures, a low level of crystallinity and exhibit a tendency to form polymers. An attempt has been made to explain the mode of the ligand molecule coordination on the basis of the position of the bands of the characteristic Vasym and Vsym vibrations of the carboxylate group. The course of the TG, DTG and DTA curves indicates that the compounds decompose in two (the copper salt) or three stages. The decomposition of the cadmium complex is preceded by dehydration. The basic gaseous products of decomposition are H2O and CO2. HCOOH, HOCH2COOH, HCl and trace amounts of compounds containing an aromatic ring were also detected. The final solid decomposition product is a metal oxide.
A0445 – Low-temperature heat capacity and thermodynamic properties of crystalline carboxin (C12H12NO2S)
Carboxin was synthesized and its heat capacities were measured with an automated adiabatic calorimeter over the temperature range from 79 to 380 K. The melting point, molar enthalpy (?fusHm) and entropy (?fusSm) of fusion of this compound were determined to be 365.29±0.06 K, 28.193±0.09 kJ mol-1 and 77.180±0.02 J mol-1 K-1, respectively. The purity of the compound was determined to be 99.55 mol% by using the fractional melting technique. The thermodynamic functions relative to the reference temperature (298.15 K) were calculated based on the heat capacity measurements in the temperature range between 80 and 360 K. The thermal stability of the compound was further investigated by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The DSC curve indicates that the sample starts to decompose at ca. 290°C with the peak temperature at 292.7°C. The TG-DTG results demonstrate the maximum mass loss rate occurs at 293°C corresponding to the maximum decomposition rate.
A0446 – Thermodynamic study of ibuprofen by adiabatic calorimetry and thermal analysis
Molar heat capacities of ibuprofen were precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 80 to 400 K. The polynomial functions of Cp,m (J K-1 mol-1) versus T were established on the heat capacity measurements by means of the least fitting square method. The functions are as follows: for solid ibuprofen, at the temperature range of 79.105 K=T=333.297 K, Cp,m=144.27+77.046X+3.5171X2+10.925X3+11.224X4, where X=(T-206.201)/127.096; for liquid ibuprofen, at the temperature range of 353.406 K=T=378.785 K, Cp,m=325.79+8.9696X-1.6073X2-1.5145X3, where X=(T-366.095)/12.690. A fusion transition at T=348.02 K was found from the Cp-T curve. The molar enthalpy and entropy of the fusion transition were determined to be 26.65 kJ mol-1 and 76.58 J mol-1 K-1, respectively. The thermodynamic functions on the base of the reference temperature of 298.15 K, (HT-H298.15) and (ST-S298.15), were derived. Thermal characteristic of ibuprofen was studied by thermo-gravimetric analysis (TG-DTG) and differential scanning calorimeter (DSC). The temperature of fusion, the molar enthalpy and entropy of fusion obtained by DSC were well consistent with those obtained by adiabatic calorimeter. The evaporation process of ibuprofen was investigated further by TG and DTG, and the activation energy of the evaporation process was determined to be 80.3±1.4 kJ mol-1.
A0450 – Thermodynamic studies of monuron
Monuron (C9H11ClN2O; N,N-dimethyl-N'-(4-chlorophenyl) urea, CAS 150-68-5) was synthesized and the heat capacities of the compound were measured in the temperature range from 79 to 385 K with a high precision automated adiabatic calorimeter. No phase transition or thermal anomaly was observed in this range. The enthalpy and entropy data of the compound relative to the reference temperature 298.15 K were derived based on the heat capacity data. The thermodynamic properties of the compound were further investigated through DSC and TG analysis. The melting point, the molar enthalpy, and entropy of fusion were determined to be 447.6±0.1 K, 29.3±0.2 kJ mol-1, and 65.4 J K-1 mol-1, respectively.
A0449 – Heat capacity and thermodynamic properties of crystalline properties of crystalline ornidazole (C7H10ClN3O3)
The molar heat capacities of 1-(2-hydroxy-3-chloropropyl)-2-methyl-5-nitroimidazole (Ornidazole) (C7H10ClN3O3) with purity of 99.72 mol% were measured with an adiabatic calorimeter in the temperature range between 79 and 380 K. The melting-point temperature, molar enthalpy, ?fusHm, and entropy, ?fusSm, of fusion of this compound were determined to be 358.59±0.04 K, 21.38±0.02 kJ mol-1 and 59.61±0.05 J K-1 mol-1, respectively, from fractional melting experiments. The thermodynamic function data relative to the reference temperature (298.15 K) were calculated based on the heat capacities measurements in the temperature range from 80 to 380 K. The thermal stability of the compound was further investigated by DSC and TG. From the DSC curve an intensive exothermic peak assigned to the thermal decomposition of the compound was observed in the range of 445-590 K with the peak temperature of 505 K. Subsequently, a slow exothermic effect appears when the temperature is higher than 590 K, which is probably due to the further decomposition of the compound. The TG curve indicates the mass loss of the sample starts at about 440 K, which corresponds to the decomposition of the sample.
A0447 – Synthesis, characterization, and thermal decomposition of oxamido heterobinuclear Cu(II)-Ln(III) complexes
Three oxamido-bridged copper(II)-lanthanide(III) heterobinuclear complexes described by the overall formula Cu(oxen)Ln(phen)2(ClO4)3 (oxen=N,N'-bis(2-aminoethyl)oxamide, Ln=Eu, Gd, and Er, phen=1,10-phenanthroline), have been synthesized and characterized by the elemental analyses, IR spectroscopy, X-ray analysis and energy dispersive spectrometer (EDS) analysis. The thermal decomposition of the complexes was studied by TG, DTG, and DTA technique under dynamic nitrogen atmosphere. The decompositions of these complexes took place through four stages. The second and third stages were analyzed kinetically by means of the Achar method and the Coats-Redfern method. The activation energies, pre-exponential factors and the most probable kinetic model function were determined for these stages.
A0452 – Assessment of various kinetic models for the pyrolysis of a microgranular cellulose
The kinetics of pyrolysis of a micro-crystalline cellulose in nitrogen were studied from TGA and DTG data, obtained with two different modes of heating: a dynamic mode at constant heating rates between 1 and 11°C/min and an isothermal mode at various temperatures, kept constant between 280 and 320°C. In isothermal mode, it appeared very clearly that the mass depletion shows a sigmoid profile characteristic of an auto-accelerated reaction process. This behaviour is consistent with kinetics of nuclei-growth, well represented by the models of Avrami-Erofeev (A-E) and of Prout-Tompkins (P-T) type. All the other kinetic models commonly applied to the thermal decomposition of solids revealed unsatisfactory. The TGA and DTG data were, thus, found ideally simulated from a reaction scheme consisting in two parallel reactions, termed 1 and 2, each one described by the kinetic law: dx/dt=-A-E/RTxn(1-0.99x)m. Reaction 1 is related to the bulk decomposition of cellulose and is characterised by the set of parameters: E1=202 kJ/mol; n1=1; m1=0.48. Reaction 2 is related to the slower residual decomposition, which takes place over approximately 350°C and affects only 16% by weight of the raw cellulose. With m2 constrained to 1, the optimised parameters of this reaction were: E2=255 kJ/mol; n2=22. Finally, the proposed model allowed to correctly fit not less than to 10 sets of ATG-DTG data, isothermal and dynamic.
A0451 – Investigations of new binary phosphate K4Ce2P4O15
The new potassium cerium(III) phosphate of formula K4Ce2P4O15 in the system Ce2O3-K2O-P2O5 was prepared by solid state reactions and characterized by thermal analysis (DTA, TG, DSC), powder X-ray diffraction and IR spectroscopy. This compound exists only in the solid state (below 880°C) and exhibits a polymorphic transition at 527°C. The low-temperature form ß-K4Ce2P4O15 of this compound crystallizes as a triclinic phase (space group P) with unit cell parameters: a=9.319(7), b=12.129(3), c=9.252(1) Å, alpha=106.875, beta=100.086, gamma=107.202°, V=916.276 Å3.
A0455 – Corrosion behavior and strength degradation of Ti3SiC2 exposed to a eutectic K2CO3 and Li2CO3 mixture
The corrosion of polycrystalline Ti3SiC2 was studied in the eutectic Li2CO3 (68 at.%) and K2CO3 (32 at.%) mixture at 650-850 °C. Ti3SiC2 exhibited better corrosion resistance at 650 °C. However, the mass loss was fast when temperature was above 700 °C. It was demonstrated that the surface chemical reaction-controlled shrinking core model could be applied to describe the relationship between the degree of the corrosion and reaction time for the corrosion of Ti3SiC2 in the 700-850 °C temperature range. The corresponding apparent activation energy was 206 kJ/mol. Corrosion resulted in roughness of specimen surface. The fracture strength of the corroded samples was evaluated by a three-point bending test. The results showed that the degradation of the fracture strength was about 25% of the original values for the corroded specimens up to 10% weight loss. The mechanism of the strength degradation was discussed based on the analysis of the microstructure and composition of the corroded sample.
A0454 – Cyclic oxidation behavior of Ti3SiC2-base material at 1100°C
The cyclic-oxidation behavior of Ti3SiC2-base material was studied at 1100°C in air. Scale spallation and weight loss were not observed in the present tests and the weight gain would just continue if the experiments were not interrupted. The present results demonstrated that the scale growth on Ti3SiC2-base material obeyed a parabolic rate law up to 20 cycles. It then changed to a linear rate with further increasing cycles. The scales formed on the Ti3SiC2-base material were composed of an inward-growing, fine-grain mixture of TiO2+SiO2 and an outward-growing, coarse-grain TiO2. Theoretical calculations show that the mismatch in thermal expansion coefficients between the inner scale and Ti3SiC2-base matrix is small. The outer TiO2 layer was under very low compressive stress, while the inner TiO2+SiO2 layer was under tensile stress during cooling. Scale spallation is, therefore, not expected and the scale formed on Ti3SiC2-base material is adherent and resistant to cyclic oxidation.
A0453 – Oxidation behavior of Ti3AlC2 powders in flowing air
The oxidation behavior of Ti3AlC2 powders has been investigated in air by means of simultaneous TGA-DSC, XRD, Raman spectra, SEM, EDS and BET specific surface measurement to understand the intrinsic oxidation behavior of this newly developed ternary compound. The starting and complete oxidation temperatures determined by simultaneous TGA-DSC were 400 and 1120°C, respectively. These temperatures are higher than those for TiC, suggesting that Ti3AlC2 is more oxidation resistant than TiC. An anomalous oxidation temperature range of 550-650°C in which the final mass gains due to the isothermal oxidation of Ti3AlC2 powders at 550, 600 and 650°C for 2 h are significantly greater than that at a higher temperature of 700°C, was observed. This anomalous oxidation behavior suggests that direct reaction dominated with high oxidation kinetics in this temperature range, which was confirmed by SEM morphology observation and BET specific surface area measurement. The oxidation of Ti3AlC2 powders at temperatures below 700°C resulted in two modifications of TiO2 (anatase and rutile). At temperatures above 800°C the oxidation products consisted of rutile TiO2 and alpha-Al2O3.
A0456 – Cracking behavior of oxide scale formed on Ti3SiC2-based ceramic
The cyclic oxidation and acoustic emission (AE) tests were carried out for studying cracking behavior of oxide scales formed on Ti3SiC2-based ceramic at 1100 °C. A duplex oxide scale with an outer layer of pure TiO2 and an inner layer of a mixture of TiO2 and SiO2 was formed. The oxide scale did not spall from substrate during the cyclic oxidation at 1100 °C for 360 times. However, a great number of micro-cracks penetrating whole inner oxide layer were detected. AE test showed that the oxide scale did not crack during the isothermal oxidation at 1100 °C for 1 h, however, the scale cracked during the cooling stage. Comparing the growth rate and thickness between the oxide layers formed during the isothermal oxidation and cyclic oxidation, respectively, indicated that cracks in the inner oxide layer served as paths mainly for outward diffusion of titanium and for inward diffusion of oxygen, resulting in increased growth rate of the outer oxide layer. Because of entire and compact TiO2 consisted of outer oxide layer, and low thermal stress resulting from small mismatch of thermal expansion coefficients between the oxides and the substrate, Ti3SiC2 exhibited excellent cyclic oxidation resistance at 1100 °C for 360 cycles.
A0457 – High temperature oxidation behavior of Ti3SiC2-based material in air
The oxidation behavior of Ti3SiC2-based material in air has been studied from 900°C to 1200°C. The present work showed that the growth of the oxide scale on Ti3SiC2-based material obeyed a parabolic law from 900°C to 1100°C, while at 1200°C it followed a linear rule. The oxide scale was generally composed of an outer layer of coarse-grained TiO2 (rutile) and an inner layer of fine-grained TiO2 and SiO2 (tridymite) above 1000°C. A discontinuous coarse-grained SiO2 layer was observed within the outer coarse-grained TiO2 layer on the samples oxidized at 1100°C and 1200°C. Marker experiments showed that the oxidation process was controlled by the inward diffusion of oxygen, outward diffusion of titanium and CO or SiO, and that internal oxidation predominated. The TiC content in Ti3SiC2 was deleterious to the oxidation resistance of Ti3SiC2.
A0458 – Oxidation behavior of Ti3AlC2-based ceramic at 900-1300°C in air
The isothermal oxidation behaviour of Ti3SiC2-based ceramic containing 7 wt.% TiC at 900-1300°C in air has been investigated. The growth of the oxide scales on Ti3SiC2 from 900°C to 1100°C obeyed a parabolic law, whereas at 1200°C and 1300°C, it was a two-step parabolic oxidation process. The scale was composed of an outer layer of coarse-grained TiO2 (rutile), an inner layer of a mixture of fine-grained TiO2 and SiO2 (tridymite). Furthermore, the oxide scale at 1100°C contained a discontinuous SiO2 "barrier" sandwiched in the outer TiO2 layer. The scales formed on Ti3SiC2 were dense, adhesive and have good adhesion with the substrate during the cyclic oxidation.
A0459 – Improving the oxidation resistance of Ti3SiC2 by forming a Ti3Si0.9Al0.1C2 solid solution
The oxidation behavior of the Ti3Si0.9Al0.1C2 solid solution in air was investigated at 1000-1350°C. The parabolic rate constants of Ti3Si0.9Al0.1C2 were decreased by 2-4 orders of magnitude compared with those of Ti3SiC2 at 1000-1300°C. At 1000-1100°C, the oxide scales displayed a continuous alpha-Al2O3 inner layer and a discontinuous TiO2 (rutile) outer layer. At 1200-1300°C, the continuous inner layer was still alpha-Al2O3, but the outer layer was a mixture of TiO2 (rutile) and Al2TiO5. The oxide layers were dense, adherent and resistant to thermal cycling. However, the oxidation resistance of Ti3Si0.9Al0.1C2 deteriorated at 1350°C because of the depletion of alpha-Al2O3. This depletion was caused by the extensive reaction between TiO2 (rutile) and alpha-Al2O3 to form Al2TiO5. The high activity and diffusion of Al and the low solubility of oxygen in the solid solution were the key factors for the formation of a continuous alpha-Al2O3 layer during high-temperature oxidation
A0461 – Investigation on the effects of fire retardants on the thermal decomposition of wood-derived rayon fiber in an inert atmosphere by thermogravimetry-mass spectrometry
The effects of three retardants, NH4Cl, (NH4)2SO4 and NH4H2PO4, on the thermal decomposition of wood-derived rayon fiber have been investigated by thermogravimetry-mass spectrometry (TG-MS) analysis. The main thermal decomposition of pure wood-derived rayon fiber, like other cellulosic materials, takes place rapidly over a narrow temperature range. When wood-derived rayon fiber is impregnated with the fire retardants, there is a shift in the temperature of maximum rate of weight loss to the values lower than 300°C, while the amount of char residue formed is increased. The fire retardants have resulted in the increase of the intensity (peak area) of m/z=18 and 28 MS signals, but the decrease of the intensity of m/z=44 MS signals. Furthermore, it appears with a relative decrease of the intensity of m/z=60 and 68 MS signals, which means that low levels of levoglucosan and levoglucosenone are recorded in the presence of the fire retardants. Finally, the relationship between char residue formation and the relative quantity of levoglucosan is determined.
A0460 – Synthesis and thermal characterization of zinc(II) di(o-aminobenzoate) complexes of imidazole and its methyl derivates
Mixed complexes of the type: Zn(Han)2(Him)3, Zn(Han)2(Him)5, Zn(Han)2(4-MeHim)2 and Zn(Han)2(1,2-diMeim)2 (where Han: NH2C6H4COO-, Him: imidazole, 4-MeHim: 4-methylimidazole, 1,2-diMeim-1,2-dimethylimidazole) have been synthesized. The complexes and the corresponding sinters, obtained at temperatures determined on the basis of the thermogravimetric (TG) curves, have been analyzed by chemical, X-ray, infrared (IR) spectroscopy and thermal methods. The compounds with Him and 4-MeHim decompose in two stages, and those with 1,2-diMeim in three stages. Thermal decomposition pathways have been postulated for these complexes.
A0462 – Effect of electrodeposited film containing yttrium on high temperature oxidation behaviour of i base alloy
Thin films containing yttrium were deposited on Ni-20Cr substrate surfaces by an aqueous
electrochemical technique, called cathodic precipitation. After deposition, the samples were
thermally treated to transform the deposited hydroxide into corresponding oxide and to improve the
adhesion of the film to the metallic substrate. The influence of these thin solid films on the
isothermal oxidation behaviour of a Ni-20%Cr-1.5%Si (wt%) alloy was investigated between
800°C and 950°C using several analytical techniques. The influence of silicon is also discussed.
A0464 – High-temperature oxidation behaviour of low-energy high-flux nitrided Ni and Ni-20% Cr substrates
Nitridation at low-energy, high-flux implantation-diffusion has been performed on pure Ni and Ni /20at.% Cr substrates in order
to study their high-temperature oxidation behavior at 700 and 800°C in synthetic air. The nitridation treatment leads to significant
sputtering on pure Ni, but no implanted nitrogen has been detected. However, the Ni /20at.% Cr substrates are able to incorporate
nitrogen, with a very different surface state. Porosity is found on both substrates after the nitridation treatment. No particular
difference is found in the oxidation kinetics of Ni specimens, but in their scales morphology. In contrast, in Ni /20at.% Cr
specimens, oxidation is enhanced mainly upon the first exposure times owing to trapping of chromium by the implanted nitrogen.
Furthermore, the expanded austenite gN layer formed on the nitrided Ni /20at.% Cr samples is stable up to 700°C for 24 h, where
after nitride precipitation sets in.
A0463 – Chronological study of the oxidation of phosphated alpha-iron
In the present work, the morphological evolution of the iron-oxide layers growing at 400°Con alpha-Fe and phosphated alpha-Fe in
artificial air at 1 atm is investigated. The oxidation kinetics of alpha-Fe and phosphated alpha-Fe are firstly presented for various oxidation
times. Then a detailed chronological study is undertaken of the microstructural states in the different stages of the complex
oxidation kinetics. Correlations are established between the morphology of the oxides layers and the successive parabolic oxidation
stages. It is shown that the phosphate conversion layers seem to modify the growth mechanisms of the oxides.
A0465 – Effects of an ion nitriding treatment on the oxidation behaviour of an ODS FeAl alloy
A B2 oxide-dispersion-strengthened (ODS) iron aluminide has been treated at 400°Cwith a high flux and low energy nitrogen
ion beam. The oxidation resistance has been investigated by in situ thermogravimetric experiments and related to structural
changes studied by X-ray diffraction, scanning electron microscopy and chemical analysis of the surface. After the nitriding
process the hexagonal AlN phase is detected, and during the oxidation tests between 800 and 950°Ca hematite layer is formed.
A0466 – Thermal characterization of carbonate rocks
Representative carbonate rock samples collected from the broader area of Kozani (NW Macedonia, Greece) are examined. The participation of constituents in the formations was determined combining three different methods of analysis, atomic absorption spectroscopy (AAS), X-ray diffraction analysis (XRD) and thermogravimetry (TG). The three methods are used in a complimentary way in order to specify the exact composition of the samples. Although the question about the composition can be answered by AAS, the percentage of the included calcite and dolomite can be determined with accuracy, only through TG analysis, under the appropriate conditions, regarding the gas carrier. The results of the analysis lead to a more complete view of the geological conditions that predominated in the studied area.
Sodium zirconium phosphate [NaZr2P3O12], a potential ceramic matrix for fixation of high level nuclear waste, was synthesized by heating the mixture of sodium carbonate [Na2CO3], zirconyl nitrate hydrate [ZrO(NO3)2.5H2O] and ammonium dihydrogen phosphate [NH4H2PO4] in air, in a resistance heated furnace and a microwave heating system respectively in the temperature range 450 to 650°C. The mixture heated for 1 h in a resistance furnace at 450°C yielded a poorly crystalline NaZr2P3O12 [NZP]. Increasing the temperature to 650°C produced a highly crystalline product. The same mixture heated in a microwave oven at 450°C for 1 h however, yielded the most crystalline NZP.
A0468 – Preparation, characterization and standard enthalpy of formation of Sr2CeO4
In an alternate method, the mixture of sodium dihydrogen phosphate (NaH2PO4), zirconium dioxide (ZrO2) and diammonium hydrogen phosphate [(NH4)2HPO4] heated in resistance furnace at 650°C for the same period did not react in air. It also did not yield the pure product at 450°C when heated in microwave assembly for 1 h.
A0469 – Studies on the kinetics of synthesis of TiC by calciothermic reduction of TiO2 in presence of carbon
Reaction kinetics of the formation of TiC by calciothermic reduction of TiO2 in presence of carbon have been investigated using thermal analysis (TG-DTA) of a powder mixture of TiO2, Ca, and C in argon atmosphere at different heating rates. Both the reaction initiation and the peak temperatures are found to increase with heating rates. The appearance of exothermic peaks in the DTA plots after Ca melting indicates the reduction of TiO2 by liquid calcium and formation of TiC by in-situ reaction of Ti with C. The apparent activation energy of the process has been found to be 170.8±0.5 kJ mol-1.
A0472 – Complexes of dicamba with cadmium(II), coper(II), mercury(II), lead(II) and zinc(II) : synthesis and properties
New solid complexes of a herbicide known as dicamba (3,6-dichloro-2-methoxybenzoic acid) with Pb(II), Cd(II), Cu(II) and Hg(II) of the general formula M(dicamba)2.xH2O (M=metal, x=0-2) and Zn2(OH)(dicamba)3.2H2O have been prepared and studied. The complexes have different crystal structures. The carboxylate groups in the lead, cadmium and copper complexes are bidentate, chelating, symmetrical, in Hg(dicamba)2.2H2O - unidentate, and in the zinc salt - bidentate, bridging, symmetrical. The anhydrous compounds decompose in three stages, except for the lead salt whose decomposition proceeds in four stages. The main gaseous decomposition products are CO2, CH3OH, HCl and H2O. Trace amounts of compounds containing an aromatic ring were also detected. The final solid decomposition products are oxychlorides of metals and CuO.
A0471 – TG-MS, TG, DTG and DTA methods in study of thermal decomposition of some d-metal complexes with 4,4′-bpy and propionates
The new mixed ligand complexes with formulae M(4-bpy)(C2H5COO)2.2H2O (where M(II)=Mn, Co, Ni; 4,4-bpy or 4-bpy=4,4-bipyridine) and Cu(4-bpy)0.5(C2H5COO)2.H2O were prepared and characterized by VIS (for solid compounds of Co(II), Ni(II), Cu(II) in Nujol), IR spectroscopy, X-ray powder diffraction and molar conductance in MeOH, DMF or DMSO. Thermal behaviour of complexes was studied under static conditions in air atmosphere. Corresponding metal oxides were identified as final products of pyrolysis. A coupled TG-MS system was used to analysis of principal volatile thermal decomposition and fragmentation products of isolated complexes under dynamic air and argon atmosphere. The principal species correspond to: C+, OH+, H2O+, NO+, CO2 + and other; additionally CO+ in argon atmosphere.
A0475 – Thermal investigation by simultaneous TG/DTG-DTA and IR spectroscopy of new lanthanide complexes with salicylhydroxamic acid
The reaction of a hydrated nitrate salt of lanthanide (Ln=Pr, Nd, Gd, Dy, Er) with the polyfunctional ligand salicylhydroxamic acid (H3sha), in the presence of base, afforded solid compounds, insoluble in common organic solvents and in water. The new complexes characterized by means of elemental analyses (C, H, N, Ln), magnetic moment determinations and spectroscopic data (IR, MS). It is proposed that they are neutral, with a possible polymeric structure of the general type: [Ln2(Hsha)2(H2sha)(DMF)x(CH3O)(H2O)]n.2H2O Their thermal decomposition was studied in nitrogen and/or oxygen atmosphere, between 25-1000°C by using simultaneous TG/DTG-DTA technique. The IR spectroscopy used to determine the intermediates and the final products. The intermediates at 180°C suggest the formation of N-hydroxylactam complex, which upon further heating gives a carbonaceous residue of Ln2O3 at 1000°C in nitrogen, while in oxygen the stable oxides are formed at 600°C.
A0474 – Pyrolysis study of fluorinated Sol-gel silica
Fluorinated silica gels at various fluorine content were prepared via sol-gel by hydrolysis of 3,3,3-trifluoropropyltrimethoxysilane and tetraethoxysilane mixtures. The gels, of nominal stoichiometry Si(CH2CH2CF3)XO(2-X/2)(X=0.1-1), were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS) and N2 adsorption analysis. The thermal stability of the fluorinated samples was investigated by coupling thermogravimetric measurements with mass spectrometric and gas chromatographic analyses of the evolved gaseous species. The chemical reactions occurring in the gel matrices during heating were siloxane chain rearrangements involving condensation between residual hydroxyl and ethoxyl groups in the 100-350°C temperature range, whereas the thermal decomposition of the fluoroalkyl groups were observed at higher temperatures (450-600°C). The release of the fluoroalkyl moieties also involved C-F/Si-O bond exchanges inside the siloxane chains, with gas-phase evolution of different fluorinated silicon units.
A0473 – The coupled TG-MS investigations of lanthanide(III) nitrate complexes with hexamethylenetetramine
New transition metal compounds of the general formula Ln(NO3)3.2[N4(CH2)6].nH2O, where Ln = La, Nd, Sm, Gd, Tb, Dy, Er, Lu, and n = 7-12, were obtained. The compounds and the gases evolved in the course of their thermal decomposition were characterised by thermogravimetric analysis. The measurements were carried out in air and argon environment in order to compare the intermediate products, final products and the mechanism of the thermal decomposition. The combined TG-MS system was used to identify the main volatile products of thermal decomposition and fragmentation processes of the obtained compounds.
A0477 – Thermal analysis of heritage stones
Many of Sydneys heritage buildings and monuments were built as a result of the first European settlement in the 1800s. These buildings not only display the richness of the Australian culture, but also capture the architectural and historical values of its past. Although many of these buildings still appear to be strong and sound, many signs of deterioration have been detected in recent years. Conservators from various disciplines such as science, architecture and engineering are working closely together to develop suitable solutions to stop or at least slow down the degradation process of these precious buildings. This study demonstrates the usefulness of thermal analysis in determining the weathering mechanisms of marble and sandstone taken from two of Sydneys landmarks, the Captain Arthur Phillips Monument at Sydneys Botanic Gardens and Sydneys St Marys Cathedral. This paper reports the findings of the weathering behaviours of both marble and sandstone samples determined using thermal analysis techniques.
A0476 – Pyrolysis study of Sol-gel derived zirconia by TG-GC-MS
A homogeneous ZrO2 gel was obtained by hydrolysis-condensation of zirconium(IV) n-propoxide previously reacted with acetic acid. Dried zirconia powders were characterized by Fourier transformed infra-red (FTIR) and X-ray diffraction (XRD) analyses. Thermogravimetric (TG) and differential thermal analysis (DTA) coupled with mass spectrometric (MS) and gas chromatographic (GC) measurements were carried out in order to identify and quantify the organic products released during the ZrO2 gel pyrolysis. The TG-MS semi-quantitative analysis of the main released species allowed to describe the chemical rearrangement occurring in the solid during heating and to determine the chemical composition of the initial gel.
A0478 – Application of coupled TG-FTIR system in studies of thermal stability of manganese(II) complexes with amino acids
Detailed thermal analysis of manganese(II) complexes with -amino acids were carried out. The thermal degradation is multi-stage. Dehydration of complexes is the first mass loss step. Anhydrous compounds are unstable and decompose to Mn3O4 in air or to MnO in inert atmosphere. The intermediate solid products were identified by TG method and TG/FTIR combined technique. Among others solid residues, the presence of MnSO4, MnBr2 and Mn(CH3COO)Cl was found. In the gaseous products of decomposition of organic ligand H2O, NH3, CO2, CO, aromatic and non-aromatic hydrocarbons and very probably cyanoacetic acid and dimethyl sulfide occurred. Inorganic ions, i.e. Cl-, Br- or So4 2- remain in the solid products of decomposition or are lost as HCl, HBr or SO2.
A0479 – Thermal degradation mechanism of ploy(ethylene succinate) and poly(butylene succinate): comparative study
Two aliphatic polyesters that consisted from succinic acid, ethylene glycol and butylene glycol, -poly(ethylene succinate) (PESu) and poly(butylene succinate) (PBSu)-, were prepared by melt polycondensation process in a glass batch reactor. These polyesters were characterized by DSC, 1H NMR and molecular weight distribution. Their number average molecular weight is almost identical in both polyesters, close to 7000 g/mol, as well as their carboxyl end groups (80 eq/106 g). From TG and Differential TG (DTG) thermograms it was found that the decomposition step appears at a temperature 399°C for PBSu and 413°C for PESu. This is an indication that PESu is more stable than PBSu and that chemical structure plays an important role in the thermal decomposition process. In both polyesters degradation takes place in two stages, the first that corresponds to a very small mass loss, and the second at elevated temperatures being the main degradation stage. The two stages are attributed to different decomposition mechanisms as is verified from the values of activation energy determined with iso-conversional methods of Ozawa, Flyn, Wall and Friedman. The first mechanism that takes place at low temperatures, is auto-catalysis with activation energy E = 128 and E = 182 kJ/mol and reaction order n = 0.75 and 1.84 for PBSu and PESu, respectively. The second mechanism is nth-order reaction with E = 189 and 256 kJ/mol and reaction order n = 0.68 and 0.96 for PBSu and PESu, respectively, as they were calculated from the fitting of experimental results.
A0480 – Influence of atmosphere kind on temperature programmed decomposition of noble metal chlorides
The hydrated chlorides of noble metals located in the 8-10 groups of Periodic System were used in this work: Ru, Rh, Pd, Ir and Pt. The common mechanism of chloride compounds decomposition in oxidative, inert and reductive atmospheres was postulated and mutual similarities and differences were discussed. These compounds play a significant role in heterogeneous catalysis, as starting materials for metal/oxide catalysts, and also in analytical chemistry and industry.
A0481 – Synthesis, spectral and thermal properties of macrocyclic zinc(II) complexes
The new zinc ternary complexes [Zn(cyclen)NO3]ClO4 (I), [Zn2(cyclen)2(m-nic)](ClO4)3 (II), [Zn2(cyclen)2(m-pic)](ClO4)3 (III) (cyclen=1,4,7,10-tetraazacyclododecane; nic=nicotinic acid; pic=picolinic acid) were synthesized and their spectral and thermal properties were investigated. The compounds were characterized by elemental analysis, IR spectroscopy and TG/DTG, DTA methods. Moreover, the way of coordination of pyridinecarboxylate anions was proposed on the basis of the spectral data and consequently proved with results of X-ray structure analysis.
A0483 – Thermal degradation of poly(acrylic acid) containing copper nitrate
A high temperature superconductor (HTSC) precursor containing a polymer and metal nitrates may be processed with relative ease before pyrolysis. This article focuses on the thermal decomposition of poly(acrylic acid) (PAAc) containing copper nitrate (Cu-N) as a first step in the study of an HTSC precursor containing copper, barium and yttrium nitrates. The degradation of PAAc/Cu-N was found to be a complex multi-stage process that was not always directly related to the degradation of the individual components. Adding Cu-N to PAAc causes a dramatic decrease in thermal stability. While the degradation of PAAc in argon yields a carbonaceous residue, no such residue was found for the degradation of PAAc/Cu-N in air. The rate of PAAc/Cu-N degradation is significantly higher in air than in argon. The decomposition mechanisms include polymer chain scission catalysed by copper ions and the formation of terminal macroradicals that generate low molecular weight organic compounds.
A0482 – The effect of dehydroxylation/amorphization on pozzolanic activity of kaolinite
The effect of heat treatment parameters on the dehydroxylation/amorphization process of the kaolinite-based materials such as natural and artificial kaolin clays with different amounts of amorphous phase (metakaolin) was investigated. The procedure for quantitative estimation of amorphous phase in the heat-treated kaolinite materials was developed. The process of dehydroxylation/amorphization of kaolinite was characterized by DTA/TGA with mass-spectrometry and X-ray powder diffraction. The influence of the heat treatment temperature and content of the amorphous phase on pozzolanic activity was studied. Finally, the relationships between the chemical activity, activity strength index and the amorphous phase content were found and discussed. The results obtained are important for an optimization of the process of the metakaolin large scale production and it's use as an active pozzolanic admixture.
A0486 – Calorimetric study and thermal analysis of crystalline nicotinic acid
As one primary component of Vitamin B3, nicotinic acid [pyridine 3-carboxylic acid] was synthesized, and calorimetric study and thermal analysis for this compound were performed. The low-temperature heat capacity of nicotinic acid was measured with a precise automated adiabatic calorimeter over the temperature rang from 79 to 368 K. No thermal anomaly or phase transition was observed in this temperature range. A solid-to-solid transition at T trs=451.4 K, a solid-to-liquid transition at T fus=509.1 K and a thermal decomposition at T d=538.8 K were found through the DSC and TG-DTG techniques. The molar enthalpies of these transitions were determined to be trs H m=0.81 kJ mol-1, fus H m=27.57 kJ mol-1 and d H m=62.38 kJ mol-1, respectively, by the integrals of the peak areas of the DSC curves.
A0485 – Thermal analysis of the binary system Al2O3-SnO2 obtained by sol-gel technique
A series of Al2O3-SnO2 catalysts with Al2O3 to SnO2 molar ratio of 1:1, 1:0.5, 1:0.2 and 1:0.1 were synthesized by sol-gel technique and characterized by thermal analysis and FTIR. In the case of binary gels - addition of tin component leads to better crosslinking than in pure alumina gel and as a result to a much uniform texture structure.
A0484 – Template transformations in preparation of MCM-41 silica
Template transformation in MCM-41 material during thermal treatment under different conditions was investigated on the basis of thermogravimetry (TG-DTA), X-ray diffraction (XRD) and positron annihilation lifetime spectroscopy (PALS). Micelle templated silica was prepared using C18 trimethylammonium bromide. The pore structure of MCM-41 samples obtained after removal of the surfactant in air, argon flow and vacuum was analyzed on the basis of the adsorption isotherms of nitrogen at 77 K and XRD experiments. The TG-DTA experiments confirm the mechanism of the template removal known from literature. However, the sequence of the processes during thermal treatment of as-synthesized sample and temperature of transformations depended strongly on the presence of oxygen and the heating rate. The main template degradation took place below 573 K and was independent of the kind of atmosphere above the sample. Residual carbonaceous species are removed from pores and the external surface of MCM-41 silica upon heating to 823 K by combustion or evaporation. The latter process as well as translocation of liquid-like products of template degradation from the pore interior to external surface was confirmed by PALS experiment in vacuum.
A0487 – Thermal degradation kinetics of Göynük oil shale with polystyrene
Göynük oil shale, polystyrene and several polystyrene-oil shale blends were degraded in a thermobalance apparatus at atmospheric pressure. Experiments were carried out dynamically by increasing the temperature from 298 to 1173 K with heating rates of 10 and 60 K min-1 under an argon atmosphere. Derivative thermogravimetric data were analyzed by a reaction rate model assuming first order kinetics. Effects of blending ratio of oil shale and polystyrene and heating rate on the thermal degradation kinetics were investigated. Kinetic parameters were determined and the results were discussed.
A0488 – TG-FTIR study of gaseous compounds evolved at thermooxidation of oil shale
The combined thermogravimetric (TG) Fourier transform infrared (FTIR) techniques were used for studying the gaseous compounds evolved at thermooxidation of oil shale samples from different deposits (Estonia, Jordan, Israel). In addition to H2O and CO2as the major species, the formation and emission of CO, SO2, HCl and a number of organic species as methane, ethane, ethylene, methanol, formic acid, formaldehyde, chlorobenzene, etc. was determined. Differences in the absorbance of respective bands in FTIR spectra depending on the origin of oil shale and on the heating rate used were established.
A0489 – Infrared and nuclear magnetic resonnance structural studies vs thermal treatment of geopolymers / biphasic calcium phosphates
In biomaterial field, the introduction of new types of composites presents a great interest for orthopaedic surgeons. In this work, geopolymers which are a family of aluminosilicates were synthesised and mixed with biphasic mixture (hydroxyapatite and of tricalcic phosphate). The optimised thermal treatment causes the reduction of pH to 7 units and favours the expansion of composites. Consequently, the increasing of porosity percentage was induced. These properties offer a good opportunity for applied composite as potential osseous biomaterial. To study the consequences of thermal treatment in the initial amorphous structure of composites some physico-chemical techniques like SEM, MAS-NMR and FTIR were employed. These methods permitted to evaluate the porosity, different links in composites and contributions of different groups of Si and Al before and after thermal treatment.
A0490 – New 2,2′-bipyridine-chloroacetato complexes of transition metals(II)
The new mixed-ligand complexes of d-electron metals (M(II)=Mn, Ni, Cu) with 2,2'-bipyridine (2-bpy) and mono- or dichloroacetates were prepared as crystalline solids. The general formulae of the synthetized complexes are: Cu(2-bpy)2(CClH2COO)2.2H2O, Mn(2-bpy)2(CCl2HCOO)2, M(2-bpy)2(CCl2HCOO)2.2H2O (M(II)=Ni, Cu). The compounds were characterized by chemical analysis, IR and VIS spectroscopy. Their magnetic, molar conductivity and thermal properties also were studied. During heating in air complexes decompose via different intermediate products to metal oxides. A coupled TG-MS system was used to analyse the principal volatile thermal decomposition (or fragmentation) products of 2,2'-bipyridine-chloroacetato complexes.
A0492 – Kinetic study of a HGdP2O7.3H2O dehydration step
A kinetic study of the transformation of HGdP2O7.1.5H2O into HGdP2O7.0.5H2O has been achieved by means of isothermal thermogravimetry experiments under controlled water vapour pressure. This pressure was found to have an accelerating effect upon the rate of reaction. The kinetic curves giving the extent of reaction versus time can be described using a Mampel's model. Via this modeling, values of surfacic growth rate and frequency of nucleation have been determined.
A0491 – Nonisothermal reaction kinetics of diasporic bauxite
Thermogravimetric data for the decomposition of diaspore have been obtained under nonisothermal conditions. A model-free isoconversional method is used to yield dependency of the activation energy on the extent of conversion for experiments. Reaction model of the Sestak-Berggren equation is identified by Malek and Mitsuhashi method. The parameter of the model SB(m, n) and the pre-exponential factor (A) are calculated.
A0494 – The effects of procedural variables on the maximum capture efficiency of CO2 using a carbonation/calcination cycle of carbonate rocks
The effect of procedural variables-mass and heating and cooling rate-on the maximum capture efficiency of CO2 is studied, using a carbonation/calcination cycle, for a series of carbonation rocks with different stoichiometries of dolomite and calcite. The extent of carbonation and the cyclability depends particularly on dolomite presence and at the same time seems to be influenced by the existence of impurities. Samples having the highest percentage of calcite and the lowest percentage of impurities seemed to be independent on the above variables. In limestone samples with small quantity of dolomite, impurities or a combination of both of them was observed a very small increase in the extent of carbonation due to the increase in the initial mass of the samples, while these samples in the case of the same initial mass presented an increase in the extent of carbonation due to the decrease in the cooling and the second heating rate.
A0493 – Some physico-chemical alterations caused by mechanochemical treatments in kaolinites of different structural order
Two kaolinites of different structural order designated KGa-2 and KC were milled for variable times (15, 30, 45, 60, 75, 90, 105 and 120 min). The ensuing changes were monitored using particle size distribution (PSD) analyses, pH measurements and thermal methods [thermogravimetric analysis (TGA), and differential thermal analysis (DTA)]. The size mode for the initial particles ranged from 0.31 to 0.36 ?m in KGa-2 and from 6.6 to 7.7 ?m in KC. After 120 min of milling, however, both kaolinites exhibited similar PSD results and modes (26.2-30.5 ?m). Milling caused the transformation of surface charges and produced water molecules. This resulted in a decreased pH in KC and an increased one in KGa-2; however, both tended to converge on pH 6 after several minutes of milling. The new larger particles were formed by bonding between the new water molecules formed. Based on the temperature at which they disappeared, the water molecules were coordinated as zeolitic or interlayer water. The effects of milling became apparent at an earlier stage in the less ordered kaolinite. In well-ordered kaolinites consisting of large particles, the inner-to-inner surface hydroxyl ratio results in a symmetric dehydroxylation effect; thus, milling increased structural disorder and decreased the peak temperature, symmetry and width. Also, Tp - Ton increased by effect of an increased presence of edges and inner surface hydroxyls, whereas Toff - Tp decreased with decreasing proportion of inner hydroxyls relative to other types of OH groups.
A0496 – Thermogravimetric and textural studies of modified carbonaceous materials
Thermoanalytical (TG, DTG) and adsorption methods were applied in investigation of waste agricultural products, e.g. plum stones, which can serve as raw materials for production of active carbon. The study was performed on three series of carbonaceous materials prepared from plum stones. In the first series, the raw material was subjected to ammoxidation by a mixture of NH3/air, carbonisation and activation by steam. In the second series, the material was carbonised, ammoxidised and activated with steam, whereas in the third series, it was carbonised and finally activated. Modification of carbonaceous material by ammoxidation was used in order to obtain carrier material for catalysts with diverse surface properties. The above procedure allows obtaining an active carbon precursor with high density of surface nitrogen sites of Lewis basic character, which may play an important role as active sites in the catalytic processes.
A0495 – Thermal analysis and microscopical characterization of cholesterol in gallstones
Cholesterol constitutes the major component of most gallstones. It was identified and determined in gallstones by thermal analysis technique (DSC and TG-DTA), mainly by the use of the melting temperature (Tonset=145°C and Tmax=149°C) and by DTG peak decomposition (Tmax=364°C). Cholesterol anhydrous (ChA), which showed endothermic polymorphic peak, Tmax=40°C, without mass loss, was differentiated from cholesterol monohydrate (ChH), which showed a broad endothermic peak, Tmax=59°C, attributed to loss of water of crystallization (theoretical 4.45%). Morphological studies of gallstones were performed by optical microscopy and scanning electron microscopy (SEM). The stones consisted of a pigmented core with a variably-sized irregular central cavity, surrounded by a radially arranged deposits of plate-like ChH. The outer part of the stones showed ChA crystal arborescences. X-ray microanalysis gave a typical spectrum rich in C and O, and in some instances the presence of P, which was attributed to the presence of phospholipids. CaCO3 was easily characterized by TG with the use of DTG decomposition peak at 674°C.
A0499 – Strengthening of Ti3AlC2 by incorporation of Si to form Ti3Al(1-x)SixC2 solid solutions
A series of Ti3Al1-xSixC2 (x < 0.25) solid solutions were synthesized using an in situ hot pressing/solid-liquid reaction method. It was
revealed that the lattice parameter c decreased dramatically but a remained almost unchanged with an increase of Si in the Ti3Al1-xSixC2
solid solutions. A relationship between lattice parameter c (in nm) and Si content x, c(x) = 1.8541- (8.5674 . 10^(-2))x, was established. A
significant strengthening effect was observed when x was greater than 0.15 in the Ti3Al1-xSixC2 solid solutions: the Vickers hardness,
flexural strength and compressive strength were enhanced by 26%, 12% and 29%, respectively, for Ti3Al0.75Si0.25C2 solid solution.
The electrical resistivities of Ti3Al1-xSixC2 solid solutions were in the range 0.35-0.37 lX m and increased slightly with an increase
of Si content. The addition of Si to Ti3AlC2 to form solid solutions had no deleterious effect on the oxidation resistance at 1100°C
due to the formation of a continuous Al2O3 layer.
A0497 – A study on the thermal decomposition behavior of derivatives of 1,5-diamino-1H-tetrazole (DAT): A new family of energetic heterocyclic-based salts
The thermal decomposition of the highly energetic 1,5-diamino-4-methyl-1H-tetrazolium nitrate (2b), 1,5-diamino-4-methyl-1H-tetrazolium dinitramide (2c) and 1,5-diamino-4-methyl-1H-tetrazolium azide (2d) were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Mass spectrometry and IR spectroscopy were used to identify the gaseous products. Decomposition appears in the cases of 2c and 2d to be initiated by a proton transfer to form the corresponding acid HN3 and HN3O4 whereas in the case of 2b a methyl group transfer to MeONO2 is observed as initial process. The gaseous products after the exothermic decomposition are comparable and are in agreement of the possible decomposition pathways discussed for the corresponding compounds. For all processes, possible decomposition schemes are presented. The decomposition temperatures of 2b and 2c are significantly higher than that of 2d and were supported by evaluation the values of the activation energy according the method of Ozawa and Kissinger.
A0501 – In Situ Processing and High-Temperature Properties of Ti3Si(Al)C2/SiC Composites
Ti3SiC2 has many salient properties including low density, high strength and modulus, damage tolerance at room temperature,
good machinablity, and being resistant to thermal shock and oxidation below 11001C. However, the low hardness
and poor oxidation resistance above 11001C limit the application of this material. The poor oxidation resistance at temperatures
above 11001C was because of the absence of protective layer in the scale and the presence of TiC impurity phase. TiC
impurity could be eliminated by adding a small amount of Al to form Ti3Si(Al)C2 solid solutions. Although the high-temperature
oxidation resistance was significantly improved for the Ti3Si(Al)C2 solid solutions, the strength at high temperatures
was lost. One important way to enhance the high-temperature strength is to incorporate hard ceramic particles like SiC. In this
article, we describe the in situ synthesis and simultaneous densification of Ti3Si(Al)C2/SiC composites using Ti, Si, Al, and
graphite powders as the initial materials. The effect of SiC content on high-temperature mechanical properties and oxidation
resistance were investigated. The mechanisms for the improved high-temperature properties are discussed.
A0500 – Oxidation behavior of bulk Ti3SiC2 at intermediate temperatures in dry air
The isothermal oxidation behavior of bulk Ti3SiC2 at intermediate temperatures from
500 to 900°C in flowing dry air was investigated. An anomalous oxidation with
higher kinetics at lower temperatures was observed. This phenomenon resulted from
the formation of microcracks in the oxide scales at low temperatures. The generation
of these microcracks was caused by a phase change in the oxide products, i.e., the
transformation of anatase TiO2 to rutile TiO2. This phase transformation resulted in
tensile stress, which provided the driving force for the formation of the microcracks
during oxidation. Despite the existence of microcracks, the intermediate-temperature
oxidation of Ti3SiC2 generally obeyed the parabolic rate law and did not exhibit
catastrophic destruction due to the fact that cracks occurring in the oxide layers were
partially filled with amorphous SiO2. Therefore, further high oxidation kinetics was
A0502 – Thermogravimetric analysis and kinetics modeling of isothermal carbonization of olive wood in inert atmosphere
The kinetics of olive wood carbonization is investigated by means of isothermal thermogravimetric analysis method. Measurements were carried out in a thermobalance for different fixed temperatures between 498 and 648 K. A two-stage semi-global kinetic model consisting of four sequential steps was proposed to derive kinetic parameters. The olive wood is classified in three pseudo-components. For the first two, similar thermal degradation mechanisms take place in a single reaction step. For the third, the thermal degradation takes place in two consecutive steps. The isothermal conditions allow the kinetic constants (activation energy and pre-exponential factors) to be estimated by means of the analytical solution of the mass conservation equations. An overall good agreement was obtained with activation energy values available in the literature.
A0504 – Effect of molecular weight on thermal degradation mechanism of the biodegradable polyester poly(ethylene succinate)
A series of aliphatic polyesters, in particular poly(ethylene succinate), having different molecular weights, were synthesized from succinic acid and ethylene glycol, following the melt polycondensation process. Intrinsic viscosities (IV), GPC, DSC, 1H NMR and carboxylic end group measurements were used for their characterisation. From thermogravimetric analysis, it was concluded that the molecular weight of polyesters achieved during polycondensation are strongly related to thermal stabilities of initial oligomers. In order to synthesise high molecular weight polyesters, the number average molecular weight of oligomers must not be lower than 2300-3000 g/mol, since thermal decomposition begins at temperatures lower than 200°C. However, even in that case, polycondensation temperatures must not exceed 230-240°C. From TGA studies, it was found that sample having different molecular weights could be divided into two groups characterized by different thermal stability. In the first group, belong samples with intrinsic viscosity of IV = 0.08 dL/g and in the second one all the other samples (IV > 15 dL/g). From kinetic analysis of thermal degradation, it was found that degradation of all polyesters takes place in three stages, its one corresponding to a different mechanisms. Degradation of samples with low molecular weight is more complex that that of polyesters having high molecular weights. The values of the activation energy and the exponent n for the two groups of samples-with different molecular weight-are similar, regarding the first two mechanisms, while there is an alteration in the case of the third mechanism.
A0503 – Thermal and crystallization studies of short flax fibre reinforced polypropylene matrix composites: Effect of treatments
The effect of fibre treatments on thermal stability of flax fibre and crystallization of flax fibre/polypropylene composites was investigated. For thermal stability study, flax fibres have been treated using maleic anhydride, maleic anhydride polypropylene copolymer, vinyltrimethoxy silane and alkalization. In order to compare thermal stability of flax fibres thermogravimetry (TG) analysis has been used. Kinetic parameters have been determined by Kissinger method. Results showed that all treatments improved thermal stability of flax fibres. For crystallinity analysis, three different techniques have been used, differential scanning calorimetry analysis (DSC), pressure-volume-temperature (PVT) measurements for analysis of volume shrinkage and polarized optical microscopy (POM). All techniques results showed that addition of flax fibre increased crystallization rate. Besides, depending on fibre surface treatment and crystallization temperature, flax fibre/PP composites can show transcrystallinity.
A0506 – Thermal analysis of quinolinium tetrachloroferrate(III)
Thermal decomposition of a compound consisting of a tetrachloroferrate(III) anion and a quinolinium cation, of general formula [QH][FeCl4], has been studied using TG-FTIR, TG-MS, DTA and DTG techniques. The measurements were carried out in an argon atmosphere over the temperature range 20-800°C. The solid products of the thermal decomposition were identified by IR, FIR and Mössbauer spectroscopy.
A0505 – Synthesis, characterization and thermal analysis of polyaniline/ZrO2 composites
Conducting polyaniline-zirconium dioxide (PANI/ZrO2) composites were synthesized by 'in situ' deposition technique in the presence of hydrochloric acid (HCl) as dopant by adding the fine grade powder (average particle size of approximately 20 nm) of ZrO2 into the polymerization reaction mixture of aniline. The composites obtained were characterized by infrared spectra (IR) and X-ray diffraction (XRD) and thermogravimetric analysis (TGA). TG curves and DTG curves of the composites suggest that the thermal degradation process of PANI/ZrO2 composites proceeds in two-steps and the composites are more thermally stable than that of the pure PANI. The improvement in the thermal stability for the composites is attributed to the interaction between PANI and ZrO2, which restricts the thermal motion of PANI chains and shields the degradation of PANI in the composites.
A0508 – Factors influencing the thermal decomposition of transition metal complexes with 2-OH-aryloximes under nitrogen
The thermal behavior of copper(II), nickel(II) and palladium(II) complexes with two anionic varieties of 2-OH-aryloximes (ox), [M(ox)2] (2-hydroxypropiophenonoxime and 2-hydroxy-4-methoxy-benzophenonoxime) was studied by using simultaneous TG/DTG-DTA technique under nitrogen in the temperature range 40-700°C. The behavior was compared with that in static air, which had been previously studied. It was found that the metal, the substituents on the ligand and the heating rate influenced their thermal decomposition. The thermal stability of the complexes with the same ligand depended on the metallic cation, following the order Pd(II)>Ni(II)>Cu(II). It also depended on the type of ligand, increasing with bulky substituents on the oximic carbon and the benzene ring. The sample mass almost did not affect their decomposition mode. The residues at 700°C of all complexes consisted of a carbonaceous oxide, determined by energy dispersive spectrometry (EDS) and IR spectroscopy
A0507 – Determination of carbonation profiles in non-hydraulic lime mortars using thermogravimetric analysis
The carbonation profile of material taken at various depths in a lime mortar specimen has been determined at different times from manufacture using a novel, high-speed thermogravimetric analysis (TGA) method. While conventional phenolphthalein staining suggests a sharp boundary between carbonated and non-carbonated regions, the new TGA technique shows that up to 15% (w/w) of portlandite remains uncarbonated at the exterior of the mortar and that the extent of carbonation declines linearly over up to 15 mm into the interior. The technique demonstrates the possibility of identifying the presence of Liesegang patterns by measuring variations in the concentration of Ca(OH)2 through the depth profile.
A0510 – Thermal analysis (TG-DTA) and drift spectroscopy applied to investigate the evolution of humic acids in forest soil at different vegetation stages
Humic acids (HAs) extracted from soils developed under two Norwegian spruce (Picea abies, (L.) Karst) subalpine forests of northern Italy were characterized using chemical, thermal (TG-DTA) and spectroscopic (DRIFT) analyses. The samples were taken from five sites which differed in orientation (northern and southern exposure) and vegetal cover at different old age: grassland, regeneration, immature and mature stands. In general, the thermal patterns of HAs were similar (three exothermic reactions appeared around at 300, 400 and 500°C) in both sites in grasslands and regeneration while a considerable modification appeared in HA from stands of different age at northern and southern exposure site. DRIFT spectroscopy confirmed the differences observed through TG-DTA analysis. In particular the main structural changes were ascribed to modification of carbonyl group and of CH stretching in aliphatic components in each HAs from different sites.
A0509 – Application of TG-DTG analysis in the study of the ammoxidised carbon materials
The effect of ammoxidation on thermal stability of carbonaceous materials characterised by degree of coalification other than that of brown coal (Konin mine, Poland) or sub-bituminous coal (So?nica mine, Poland) was studied by thermogravimetric (TG-DTG) method. Analysis of TG-DTG curves has shown that coal samples ammoxidised at the higher temperature show slightly lower thermal stability. It has been established the importance of the sequence in the processes of carbonisation and ammoxidation. Both the amount of nitrogen introduced on the surface of studied carbonaceous materials and the thermal stability of nitrogen groups were affected.
A0512 – Combustion and pyrolysis characteristics of tunçblek lignite
In this study, thermal characteristics and kinetic parameters of cleaned Tunçbilek lignite were determined by using a Setaram Labsys DTA/TG/DSC thermal analysis system both for combustion and pyrolysis reactions. Experiments were performed at a heating rate of 10°C min-1 under reactive (air) and inert (nitrogen) gases up to 1000°C. Non-isothermal heating conditions were applied and reaction intervals were determined for combustion and pyrolysis reactions from obtained curves. The combustion properties were evaluation by considering the burning profile of the lignite sample. Burning temperatures and rate of combustion were determined from TG/DTG curves. Calorific value of the lignite sample was measured by DSC curve and compared with the adiabatic bomb calorimeter result.
In addition to investigation of the combustion properties, pyrolysis characteristics of the lignite sample were investigated based on TG/DTG/DSC curves. Activation energy (E) and pre-exponential factor (A) were calculated from the TG data by using a Coats-Redfern kinetic model both for combustion and pyrolysis reactions of cleaned Tunçbilek lignite.
A0511 – TG/DTA/MS Study of the thermal decomposition of FeSO4.6H2O
The thermal decomposition of FeSO4.6H2O was studied by mass spectroscopy coupled with DTA/TG thermal analysis under inert atmosphere. On the ground of TG measurements, the mechanism of decomposition of FeSO4.6H2O is:
i) three dehydration steps
ii) two decomposition steps
The intermediate compound was identified as Fe2(SO4)3 and the final product as the hematite Fe2O3.