Authors:Ana Santos, I. Basílio, F. de Souza, A. Medeiros, Márcia Pinto, D. de Santana, and R. Macêdo
Thermal analysis is an essential analytical tool in development of new formulations as well as to study the interaction between
drugs and excipients. This work aims to investigate the possible interactions between metformin and excipients as microcrystalline
cellulose (Microcel MC101®), starch sodium glycolate (Explosol®), sodium croscarmellose (Explosel®), PVP K30, magnesium stearate,
starch and lactose, usually employed in pharmaceutical products. TG, DSC and DTA techniques were used for the thermal characterization
to track if the thermal properties of the drug substance were modified in the mixture. Disregard of the starch and lactose
systems, no changes in thermal behavior of mixtures were found. Thermogravimetric studies (TG) of metformin and its binary
mixtures showed different thermal behavior.
Authors:J. Orewczyk, S. Jasieńska, A. Łedzki, and S. Iwanczenko
The aim of this work was to investigate the application of mixtures of high-basicity sinters and acidic pellets in blast furnace
The ratio of high-basicity sinter and pellets depends on the nature and basicity of the latter, and is established in order
to secure desired properties of the slag and sufficient reducibility and mechanical strength of the furnace charge. Such a
composition of the charge leads to a considerable cost decrease related to coke saving, the elimination of fluxes and a decrease
in air pollution.
Examinations of phase composition and physicochemical properties of the sinters and pellets as separate materials were carried
out. The effect of the mineral composition of sinters with a basicity of 1.7–2.0 on the reducibility was determined.
Sinters of different basicities (CaO/SiO2=1.7; 2.0) mixed with pellets from Poltawawere reduced in a CO/CO2 gas mixture. The reduction process was followed by thermal analysis.
The formation at high temperatures of phases such as β′,X, and O′-sialon by carbothermal reduction of clays has been studied using simultaneous thermal analysis (STA) and thermomechanical
analysis (TMA). Two reducing agents, silicon carbide and carbon, were used, with either kaolinite or bentonite. The progress
of reaction was followed by interrupted and continuous thermal analysis procedures using STA and TMA and the changes correlated
with the phases observed by X-ray diffraction at different stages. The conversion of kaolinite to β′-sialon is characterised
by the dehydration and transformation of kaolinite independent of the nitriding atmosphere below 1400°C. At higher temperatures
nitriding commences. Similar behaviour is observed with bentonite transforming to lower substitution sialon phases. The weight
changes are correlated with oxidation/reduction reactions and mechanisms are suggested to explain the observed phenomena.
The data obtained will permit the optimization of thermal cycles for batch production of sialon powders from natural minerals.
The programmed heating of montmorillonite samples is accompanied by their dehydration and dehydroxilation, this being registered by means of Derivatograph. The form of the endothermal effects within the 80–250°C interval can be of simple or double character depending on the nature of exchange cations. Though this phenomenon has been known for a long time, no satisfactory explanation has been provided so far. The herewith paper contains the results of bound water researches at various forms (Na, Ca, Al, Fe) of montmorillonite by means of thermal analysis as well as other physico-chemical methods. It has been found that the form of dehydration endoeffects depends on the state of the active centers of the mineral. In certain conditions, by means of thermal analysis one can determine corresponding quantities of bound water that are in agreement with various kinds of active centers of the mineral sorbent.
In this review, application of thermal analysis techniques (differential scanning calorimetry, thermogravimetry, differential
thermal analysis, etc.) for fossil fuel characterization and kinetics are reviewed between 2001 and 2006. The results presented
clearly showed that thermal analysis applications are well-established techniques used in fossil fuel research area.
Authors:A. Petrović, D. Petrović, V. Leovac, and M. Budimir
The paper describes the results of differential thermal analysis of the octahedral Fe(III) complexes of the general formula [Fe(HLn)2]Cl and Fe(HL3)L3, as well as of the corresponding ligands H2Ln (H2Ln — tridentate salicylaldehyde semi thiosemi- and S-methylisothiosemi-carabazones with n=1, 2 and 3 respectively). The decomposition of the complexes involving sulphur-containing ligands (H2L2 and H2L3) starts with sulphur elimination. In case of the complexes [Fe(HL2)]Cl and [Fe(HL3)]Cl sulphur evolves independently, whereas with Fe(HL3)L3 it is eliminated within the SCH3 group. In the former case, sulphur elimination takes place at the same temperature for both complexes. The change in the coordination mode, being a consequence of the replacement of O by S, has no essential effect on thermal stability of the coordination polyhedron. The complexes involving ONN coordination, realized with the H2L3 ligand, exhibit a comparatively highest thermal stability of the coordination polyhedron.
Authors:Agnieszka Leszczynska and Krzysztof Pielichowski
Thermal analysis is a useful tool for investigating the properties of polymer/clay nanocomposites and mechanisms of improvement
of thermal properties. This review work presents examples of applications of differential scanning calorimetry (DSC), modulated
temperature differential scanning calorimetry (MT-DSC), dynamic mechanical thermal analysis (DMA), thermal mechanical analysis
(TMA), thermogravimeric analysis (TG) and thermoanalytical methods i.e. TG coupled with Fourier transformation infrared spectroscopy
(TG-FTIR) and mass spectroscopy (TG-MS) in characterization of nanocomposite materials. Complex behavior of different polymeric
matrices upon modification with montmorillonite is briefly discussed.
Authors:T. Streibel, A. Fendt, R. Geißler, E. Kaisersberger, T. Denner, and R. Zimmermann
The combined analytical methods of thermal analysis and mass spectrometry have been applied in form of a newly developed prototype
of a thermogravimetry — single photon ionisation time-of-flight mass spectrometer coupling (TG-SPI-TOFMS) to investigate the
molecular patterns of evolved gases from several biomass samples as well as a crude oil sample. Single photon ionization (SPI)
was conducted by means of a novel electron beam pumped argon excimer lamp (EBEL) as photon source. With SPI-TOFMS various
lignin decomposition products such as guaiacol, syringol and coniferyl alcohol could be monitored. Furthermore, SPI allows
the detection of aliphatic hydrocarbons, mainly alkenes, carbonylic compounds such as acetone, and furan derivatives such
as furfuryl alcohol and hydroxymethylfurfural. More alkaline biomass such as coarse colza meal show intense signals from nitrogen
containing substances such as (iso-)propylamine and pyrrole. Thermal degradation of crude oil takes place in two steps, evaporation
of volatile components and pyrolysis of larger molecular structures at higher temperatures. Due to the soft ionisation, homologue
rows of alkanes and alkenes could be detected on basis of their molecular ions.
The obtained information from the thermal analysis/photo ionisation mass spectrometry experiments can be drawn on in comparison
to the investigation of the primary products from flash pyrolysis of biomass for production of biofuels and chemicals.
Authors:G. Parkes, P. Barnes, E. Charsley, and G. Bond
This paper describes a new instrument for performing thermal analysis using microwaves both as a form of heating and as a
novel means of detecting thermally induced transformations in materials. Results are presented for a selection of processes
including decompositions, dehydrations and phase changes. The capability of the instrument to be coupled with ancillary techniques
such as EGA is also demonstrated.