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Journal of Thermal Analysis and Calorimetry: An International Forum for Thermal Studies (v.56, #3)

Thermally Stimulated Current Spectroscopy of Amorphous and Semi-Crystalline Polymers by C. Bacharan; C. Dessaux; A. Bernès; C. Lacabanne (pp. 969-982).
Thermally Stimulated Current (TSC) spectrometry has been applied to the characterization of polymeric materials. The study of a series of amorphous polymers having different physical structures has shown that the compensation parameters are independent of physical aging; contrarily, the activation enthalpy distribution reflects the evolution of the heterogeneity of the amorphous phase.In copolymers, TSC allows us to identify segregated amorphous phases. In semi-crystalline polymers, with semi-rigid chains, we have shown the existence of an amorphous crystalline interphase characterized by a plateau in the temperature distribution of activation enthalpy.

Keywords: amorphous; dielectric relaxation; glass transition; polymer; structural relaxation; TSC spectrometry

The Meaning of the Glass Temperature of Random Copolymers and Miscible Polymer Blends by H. A. Schneider (pp. 983-989).
The glass transition temperature of random copolymers and miscible polymer blends exhibits generally a non-additive composition dependence, showing both positive and negative deviations of additivity predicted by 'Gordon-Taylor' like equations, among which the Fox relation represents the simplest additivity rule for the glass temperature of these polymeric systems. It is shown that the real Tg vs. composition behaviour of both copolymers and polymer blends can be adapted by a parameterized third order Tg vs. composition equation. The fitting parameter, K1, of the square concentration term of this equation accounts essentially for the effect of binary hetero-sequences in copolymers and for specific contact hetero-interactions in polymer blends. The fitting parameter of the third order concentration term, K2, is related exclusively to the effects of heterotriad sequences (copolymers) and conformational entropy changes due to hetero-contact formation (polymer blends), respectively. It is shown that the K1 parameter correlates roughly with the difference between the solubility parameters of the components.

Keywords: fitting and solubility parameters; glass temperature; miscible polymer blends; random copolymers; Tg vs. composition behaviour

Modulated Differential Scanning Calorimetry Analysis of Interphases in Multi-Component Polymer Materials by M. Song; D. J. Hourston; M. Reading; H. M. Pollock; A. Hammiche (pp. 991-1004).
A modulated-temperature differential scanning calorimetry (M-TDSC) method for the analysis of interphases in multi-component polymer materials has been developed further. As examples, interphases in a polybutadiene-natural rubber (50:50 by mass) blend, a poly(methyl methacrylate)-poly(vinyl acetate) (50:50 by mass) structured latex film, a polyepichlorohydrinpoly(vinyl acetate) bilayer film, and polystyrene-polyurethane (40:60 by mass) and poly(ethyl methacrylate)-polyurethane (60:40 by mass) interpenetrating polymer networks were investigated. The mass fraction of interphase and its composition can be calculated quantitatively. These interphases do not exhibit clear separate glass transition temperatures, but occur continually between the glass transition temperatures of the constituent polymers.

Keywords: interfaces; interpenetrating polymer networks; latex; M-TDSC; polymer blends

Simulation of the Glass Transition by J. N. Hay; M. J. Jenkins (pp. 1005-1010).
Enthalpic relaxation has been used to model the development of the glass transition in polymers, using kinetic parameters determined separately. For this purpose the Kohlrausch-Williams-Watt stretched exponential function, relating the extent of relaxation, Φ(t), to time t and an average relaxation time, τa, i.e. $$1 - Phi left( t ight) = exp left( { - t/ta} ight)^{eta }$$ where β is inversely related to the breadth of the relaxation spectrum, has been adopted. The relaxation time dependence on temperature was taken to follow the modified Arrhenius relationship, $$ au _a = Aexp left[ {frac{{XDelta H}}{{RT}} + frac{{left( {1 - X} ight)Delta H}}{{RT'}}} ight]$$ where T is the storage and T′ the fictive temperature, X is the structure factor and ΔH the activation enthalpy. Both have been found to describe the process of enthalpic relaxation in polymer glasses and a direct comparison has been made with the change in specific heat observed with different cooling rates in DSC experiments. The effect of variables, such as activation enthalpies, pre-exponential factors, and the non-linear factors such as X and β on the observed Tgs and the temperature range over which the transition occurred have been determined.

Keywords: DSC; enthalpic relaxation; glass transition; physical ageing

The Application of Modulated Temperature Power Compensation DSC to the Characterisation of Polymer Blends by N. A. Bailey; J. N. Hay (pp. 1011-1016).
A modulated temperature power compensated differential scanning calorimeter, MTDSC, has been built from a standard Perkin-Elmer DSC model-2 such that a computer generated voltage has been applied to induce a sinusoidal change in sample temperature superimposed on a linear heating rate. The effect of amplitude of the temperature fluctuation, modulation period and block temperature on the reversibility has been assessed from the Lissajous diagram of heat flow vs. sample temperature. From their reproducibility and symmetry the most effective conditions for operating the MTDSC has been deduced. The specific heat of sapphire has been measured using these operational conditions for comparison with conventional DSC.Phase separated blends of polycarbonate (PC) and polyethylene terephthalate (PET) have been analysed.

Keywords: crystallisation; glass transition; Lissajous diagrams; modulated temperature power compensation differential scanning calorimetry; polyethylene terephthalate/polycarbonate blends

Adiabatic Calorimetry of a Very Low Density Polyethylene Copolymer by J. C. van Miltenburg; V. B. F. Mathot; P. J. van Ekeren; L. D. Ionescu (pp. 1017-1023).
The heat capacity of a very low-density polyethylene copolymer (VLDPE) was measured between 10 and 410 K. Using two sets of literature data for the fully crystalline and the fully amorphous states, crystallinities were calculated as a function of temperature. During the stabilisation periods in the melting process no equilibrium is reached, because of an exothermic process, which is attributed to (re)crystallization. Values for the enthalpy of melting and for the heat capacity of the liquid are given.

Keywords: calorimetry; crystallinity; polyethylene

Thermal Degradation of Tetrafunctional/Phenol Novalac Epoxy Mixture Cured with a Diamine by L. Barral; J. Cano; J. López; I. López-Bueno; P. Nogueira; C. Ramírez; A. Torres; M. J. Abad (pp. 1025-1032).
The effect of thermal degradation on the mechanical behaviour of a system containing both tetraglycidyl-4-4′-diaminodiphenylmethane (TGDDM) and a multifunctional novolac glycidyl ether (EPN) resins, cured with 4,4′-diaminodiphenylsulphone (DDS) has been studied using dynamic mechanical analysis (DMA) and tensile tests. Different curing paths using the isothermal time-temperature-transformation (TTT) diagram for this system were designed, obtaining thermosetting materials with different conversions. The influences of the degree of cure and of the aging temperature were also studied. The results showed different trends in the dynamic mechanical properties and an increase in the stiffness of the material with increasing aging time. Changes were faster and more intense with the higher temperature.

Keywords: dynamic mechanical tests; epoxy resin; tensile tests; thermal degradation

Cure Kinetics of Amine Cured Tetrafunctional Epoxy Blends with Poly(Styrene-Co-Acrylonitrile) by L. Barral; J. Cano; J. López; I. López-Bueno; P. Nogueira; C. Ramírez; A. Torres; M. J. Abad (pp. 1033-1040).
Cure kinetics using a differential scanning calorimetry (DSC) technique were analyzed for a thermoplastic modified tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) epoxy resin cured with diaminodiphenylsulphone (DDS), an aromatic diamine. The neat resin and its blends with the poly(styrene-co-acrylonitrile) (SAN) of various compositions were studied by applying a phenomenological model proposed by Kamal. Kinetic parameters were determined by fitting experimental data. This model gives a good description of cure kinetics up to the onset of vitrification. Diffusion control was incorporated to describe the cure in the latter stages of cure. The results showed that the addition of SAN did not alter the nature of the reaction, but the reaction rates and final conversions decreased when SAN contents increase, due to reduction of mobility of the reacting species.

Keywords: cure kinetics; DSC; epoxy resin; SAN; thermoplastic blends

Thermoanalytical Studies of Polymeric Membranes for Immunoisolation by E. Rudnik; I. Resiak; C. Wojciechowski (pp. 1041-1046).
Preliminary studies concerning characterization of the structure of polymeric membranes for immunoisolation are reported. Laboratory-made cellulosic and polyurethane membranes for immunoisolation were investigated. Differential scanning calorimetry (DSC) was applied to determine the membrane structure, e.g. the pore diameter. The thermoanalytical measurements were carried out with a Perkin Elmer DSC 7 equipped with a CCA 7 cooling accessory. Diffusive transport across the hollow fiber membrane was evaluated in vitro by using albumin, creatinine and vitamin B12. It was concluded that the DSC method is a useful tool for characterization of polymeric membranes for immunoisolation. Methodology, including experimental conditions, is proposed for capillary membranes.

Keywords: differential scanning calorimetry; immunoisolation; polymeric membranes

Crystallization and Melting of β-Nucleated Isotactic Polypropylene by J. Varga; I. Mudra; G. W. Ehrenstein (pp. 1047-1057).
Ca salts of suberic (Ca-Sub) and pimelic acid (Ca-Pim) were synthesized and used as β-nucleating agents in different grades of isotactic polypropylene (IPP). Propylene homo-, random- and block-copolymers containing these additives crystallize principally in pure β-modification as demonstrated in isothermal and non-isothermal crystallization experiments. Ca-Sub proved the most effective β-nucleating agent known, so far. It broadens the upper crystallization temperature range of pure β-IPP formation up to 140°C. The effect of the additives on the crystallization and melting characteristics of the polymers was studied. The degree of crystallinity of the β-modification was found to be markedly higher than that of α-IPP. High temperature melting peak broadening was first observed and discussed in literary results regarding the same phenomenon for α-IPP.

Keywords: β-nucleating agent; β-polypropylene; crystallization; degree of crystallinity; melt enthalpies; melting; recrystallization

Thermal Dehydration and Miscibility of PHEMA/PMAA Blends by A. Asano; M. Eguchi; T. Kurotu (pp. 1059-1063).
Miscibility and dehydration of poly(2-hydroxyethyl methacrylate) and poly(methacrylic acid) (PHEMA/PMAA) blends were investigated by temperature modulated DSC (TMDSC), TG and solid-state 13C NMR methods. TMDSC spectra and 1H spin-relaxation times showed that the blends are homogeneous on a scale of 5-10 nm for all compositions. From TG and 13C NMR, we elucidated that the mass loss of the blends at 300°C is ascribed to the dehydration between the hydroxyl group of PHEMA and the carboxyl group of PMAA.

Keywords: dehydration; miscibility; NMR; polymer blend; poly(2-hydroxyethyl methacrylate) (PHEMA); poly(methacrylic acid) (PMAA); TG; TMDSC

Thermal Degradation of Polyvinyl Chloride by A. L. Petre; P. Budrugeac; E. Segal (pp. 1065-1070).
The thermal degradation of a sort of polyvinyl chloride was investigated. Complex processes for polyvinyl chloride degradation were evidenced. The kinetic analysis of dehydrochlorination and of subsequent processes was carried out. A change of mechanism was detected when dehydrochlorination goes to completion. The values of non-isothermal kinetic parameters determined by various methods are in a satisfactory agreement. The obtained results allowed some clarifications concerning the thermal degradation steps.

Keywords: non-isothermal kinetic parameters; polyvinyl chloride; thermal degradation

Thermal and Surface Analytical Study of Flame Retarded Polyolefins I. Interaction of Additives and Structure Formation by Gy. Marosi; I. Csontos; I. Ravadits; A. Tohl; P. Anna; F. Sommer; M. Botreau; M. D. Tran (pp. 1071-1080).
Pentaerythritol may react with tetraethoxy-silane and ammonium-polyphosphate in flame retarded polyolefins and an interfacial layer can be formed around the ammonium-polyphosphate particles. It is advantageous to study such systems using methods of thermal and surface analysis together.

Keywords: interfacial layer; phosphorous flame retardants; polypropylene; silicone additive; TOF-SIMS

Thermal Analysis of Crystalline Polymer Blends by M. J. Jenkins; J. N. Hay (pp. 1081-1086).
PEI/PEEK blends have been prepared and analysed by DSC. The blends are compatible over the full composition range in that amorphous samples are transparent and exhibit a single Tg varying with composition between the limits of the two components. The crystallisation kinetics of PEEK from the blend melt has been measured by DSC but the technique is limited to blend compositions above 20% PEEK. The use of a polarised light microscope to measure crystallization kinetics and melting behaviour of blends with compositions as low as 2 and 5% PEEK is discussed. In general, since the extent rather than the rate of crystallization is measured directly, the polarised light microscopy extends the measurement to slower rates and so to a wider temperature range.

Keywords: blends; crystallisation kinetics; hot stage microscopy; polyether ether ketone; polyether imide

The Thermal Degradation of Alkaline Earth Metal Salts of Poly(Itaconic Acid) by D. M. Petrovic-Djakov; J. M. Filipovic (pp. 1087-1092).
The Mg-, Ca- and Ba-salts of poly(itaconic acid) (PIA) were prepared by treating the aqueous solution of the polyacid with the corresponding metal oxide or hydroxide. The resulting polysalts were analysed by FTIR spectroscopy and thermogravimetry. The results indicate that the polysalts are thermally more stable than the parent PIA, they all degrade in a similar manner, the Ba-salt being the most stable.

Keywords: alkaline earth metals; poly(itaconic acid); polysalts; thermal degradation; thermogravimetry

Thermogravimetric Analysis of Aromatic Polyamides with Benzimidazolyl Side Group by H. Abematsu; M. Tsuchiya; Y. Iseri; T. Kojima (pp. 1093-1096).
The TG studies are presented for isomers of benzimidazolyl-substituted polyamides (BIPA). The TG data are compared with those polyamides (PA) of identical backbones without substitution, in view of the mechanism of thermal degradation. The TG mass loss curves divided to three temperature ranges reflect the decomposition reactions in the respective temperature ranges: (1) cleavage of single bonds of nitrogen to aromatic ring, (2) random scission of single bonds, (3) condensation of the remained rings. Liberation of benzimidazole rings occurs in the temperature range (2). The final product, char, contains benzimidazole rings. Terephthaloyl-rich BIPA's retard liberation of benzimidazole from the decomposed polymer.

Keywords: activation energy; aromatic polyamide; benzimidazolyl-substitution; TG; thermal stability

Structure-Dynamic Relationship of Side-Chain Liquid Crystal Polymer with Rigid Backbone by A. Danch (pp. 1097-1105).
To understand better the antagonistic behaviour of the backbone in comparison with the mesogenisity of the pendant side groups in side-chain liquid crystal polymers series of measurements using mechanical spectroscopy as well as DSC were carried out on two disubstituted polynorbornene derivatives.In order to clarify the specific arrangement of chains, the influence of thermal history on the smectic phase stabilisation were studied. By quenching samples from different temperatures, it was possible to obtain the systems which were either in the glassy liquid-crystalline (LC) state or in the glassy isotropic amorphous state. The samples prepared in such ways were used to study the influence of the LC structure on the mobility of chains in amorphous regions. The quality model of the supermolecular structure of the LC polymers is proposed.

Keywords: relaxations; SCLC polymers; supermolecular structure

DSC Analysis of the Induction Period in the Vulcanisation of Rubber Compounds by P. Šimon; A. Kučma (pp. 1107-1113).
Vulcanisation of rubber compounds was studied by DSC under isothermal and non-isothermal conditions. The parameters of an Arrhenius-like equation describing the temperature dependence of induction period have been obtained both from isothermal and non-isothermal measurements. A new method for obtaining the kinetic parameters from non-isothermal measurements, based on the dependence of onset temperature of vulcanisation peak on heating rate, is presented. Also, a procedure for the evaluation of temperature difference between the furnace and sample is proposed. It has been shown that the treatment of non-isothermal DSC measurements gives the kinetic parameters free of systematic errors. The new method can also be used for studying other reactions exhibiting the induction period.

Keywords: differential scanning calorimetry; induction period; kinetics; vulcanisation

Thermal Properties and Morphology of Poly(Ester-Urethanes) Prepared from Polycaprolactone-Diol by B. Bogdanov; V. Toncheva; E. Schacht (pp. 1115-1121).
The soft segment crystallinity and morphology of poly(ester-urethanes) (PEUs) based on poly(ε-caprolactone) (PCL) as a soft segment and an aliphatic diisocyanate in the hard segment were studied. It was found that the restriction of the crystallization of the PCL soft segment depends on the hard segment concentration, the length of the soft segment, and the total molecular mass of the PEUs. The PEU based on a low molecular mass PCL (M=2000) is an amorphous elastic material during a long time after casting from solution or after melt crystallization. A soft-hard segment endothermal mixing transition (Tmix) of about 70-80°C is observed in the DSC curves of this PEU sample.

Keywords: glass transition; mixing transition; poly(ester-urethanes); strain-induced crystallization

Compatibility Testing of Energetic Materials, Which Technique? by W. P. C. de Klerk; M. A. Schrader; A. C. van der Steen (pp. 1123-1131).
Compatibility is an important safety aspect related to the production and storage of energetic materials. To test different combinations of materials a simple test method with clear criteria is advisable. At the last ESTAC the use of microcalorimetry and the vacuum stability test for the compatibility testing of propellants were presented. This paper presents DSC, DTA/TG and (pressure) vacuum stability test results for the same combination. For three polymers (PMMA, PVC and CA) the results for all tests are the same. Only Nylon-6/6 gives a variable result for the different test methods.

Keywords: compatibility; decomposition; energetic materials; peak temperature; polymers; TG

Polymorphism in Polyamide of Dytek®-A and Dodecanedioic Acid by M. Y. Keating; K. H. Gardner; H. Ng; D. N. Marks; W. S. Yung; P. Avakian; H. W. Starkweather Jr. (pp. 1133-1140).
Our X-ray work of Dytek®-A, 2-methyl-pentamethylenediamine, containing polyamides shows polymorphism, whereas the polyamides with linear diamines do not. The polyamide of Dytek®-A and dodecanedioic acid, MPMD-12, is singled out for discussion and compared with the unbranched analogs of polyamides 6,12 and 5,12. Due to the presence of the -CH3 side group in the 2-position of the diamine, the polyamide MPMD-12 exhibits two stable crystal conformations. The new δ polymorph is not seen in linear polyamides 6,12 and 5,12.Studies by DSC polyamide MPMD-12 clearly illustrates at least two crystal forms, γ and δ, coexisting over a wide temperature range, and the isolation of each phase is possible by controlling temperature and time. The DMA modulus in the temperature region between the glass transition (or alpha relaxation) and melting transition shows strong dependence on the thermal history as demonstrated in a study of crystallization kinetics.

Keywords: branched diamine; melting; polyamides; polymorphism; transformation; WXRD

The Influence of Annealing and Heavy Ion Irradiation of Multiple Melting and Crystallization in PBT Films by K. Cieśla (pp. 1141-1146).
The influence of heavy ion-irradiation (Ar 5.5 MeV amu-1, 5·1011 ion cm-2) on the melting and crystallization of two PBT films subjected to different modes of thermal treatment was investigated. Differences were observed between the processes occurring in both initial films, due to differences in crystalline phase content. The course of melting and crystallization in heavy ion-irradiated films during first heating, cooling and second heating differs from that in the initial films. The density data and DSC results indicate a decreased crystalline phase content in the PBT films after irradiation.

Keywords: crystallization; DSC; heavy ion irradiation; melting; PBT films; poly(butyleneterephthalate) films

Dynamical Mechanical Thermoanalysis of High Performance Reinforced Materials Influences and Problems by J. Wolfrum; G. W. Ehrenstein; M. A. Avondet (pp. 1147-1154).
A sensitive method to characterize the thermomechanical behaviour of fiber reinforced composites is the dynamic mechanical thermoanalysis (DMTA) method. A Round-Robin-test with five different institutes was conducted to determine the role of the fiber orientation, processing conditions, test apparatus, the mode of loading, and the matrix materials on the determination of the glass transition temperature (Tg). The result shows that the DMTA is a suitable method to analyze Tg of long fiber composites. However, some major problems have to be taken into consideration:- A direct comparison of results from different DMTA-systems is not possible- The real temperatures in the specimens deviate from the temperatures displayed by the DMTA measuring system- There is no clear and common evaluation method for the glass transition temperature.

Keywords: composites; DMTA; glass transition temperature; Round-Robin-test

Isothermal Crystallisation of PCL Studied by Temperature Modulated Dynamic Mechanical and TMDSC Analysis by A. Wurm; M. Merzlyakov; C. Schick (pp. 1155-1161).
Temperature modulated dynamic mechanical analysis (TMDMA) was performed in the same way as temperature modulated DSC (TMDSC) measurements. As in TMDSC TMDMA allows the investigation of reversible and non-reversible phenomena during crystallisation of polymers. The advantage of TMDMA compared to TMDSC is the high sensitivity for small and slow changes in crystallinity, e.g. during re-crystallisation. The combination of TMDMA and TMDSC yields new information about local processes at the surface of polymer crystallites. It is shown that during and after isothermal crystallisation the surface of the individual crystallites is in equilibrium with the surrounding melt.

Keywords: crystallisation; DMA; DSC; PCL; polymer; temperature modulation

DDSC Studies on POTMG/PMMA Blends and POTMDM-net-PMMA by M. Tsuchiya; M. Ishii; T. Kojima; Y. Oohira (pp. 1163-1166).
Thermal behaviors of POTMDM-net-PMMA and POTMG/PMMA blends were studied by DDSC. Tg of the polymer network was lowered by increasing the POTMDM in feed for copolymerization of POTMDM and MMA. A crystallization peak was observed only when MMA in feed was less than 30%. Tg of POTMG/PMMA was also lowered by decreasing the content of PMMA, however, the change was observed only when PMMA content was more than 70%. These results suggest that thermal transitions of the polymer network are restricted by the mesh size. POTM chains of the polymer network effectively play as a plasticiser.

Keywords: DDSC; glass transition; polymer blend; polymer network; poly(oxytetrametylene)

Thermally Stimulated Processes in a Liquid Crystal Polymer by B. Chowdhury (pp. 1167-1173).
Measurement of voltage-induced thermal depolarization current and calculation of the rate of depolarization as well as the parameters of drift mobility and conductivity of charge carriers for melt-extruded neat unreinforced grade A950 VECTRA® resin - a wholly aromatic copolyester - strongly suggest that an irreversible minor transition centered around 65°C is the primary thermal process related to molecular realignment. Changes in capacitance values with temperature also show this to be the most active temperature region. A major depolarization peak at 100°C having the characteristics of a Tg cannot be justified as due to glass transition but likely to result from molecular motions involving long range intermolecular order. The interpretation for both transitions can be supported by the mechanical response of this polymer. An important outcome of this work is the assertion that contrary to current thinking, it is the number of charge carriers and not viscosity alone that will have to be considered in future development of fast response liquid crystal displays along with the development of newer liquid crystal polymer structures.

Keywords: charge carriers; depolarization rate; liquid crystalline polyester; molecular realignment; thermal depolarization current; viscosity

Thermodynamics of a 24-Mer Triple Helix Formation and Stability by C. Giancola; A. Buono; G. Barone; L. De Napoli; D. Montesarchio; D. Palomba; G. Piccialli (pp. 1177-1184).
In this work we report a thermodynamic characterization of stability and melting behaviour of two 24-mer DNA triplexes. The third strand, that binds the Watson-Crick double helix with Hoogsteen hydrogen bonds, contains 3′-3′ phosphodiester junction that determines the polarity inversion. The target double helix is composed of adjacent and alternate fragments of oligopurine-oligopyrimidine tracts. The two helices differ from the substitution of the cytosine, involved in the junction, with the thymine. Calorimetric data reported here provide a quantitative measure of the influence of pH and base modification on the stability of a DNA triplex.

Keywords: differential scanning calorimetry; DNA triple helix; oligonucleotides; stability

Heat Dissipation of Flying Wax Moths (Galleria Mellonella) Measured by Means of Direct Calorimetry by E. Schmolz; S. Geisenheyner; B. Schricker; I. Lamprecht (pp. 1185-1190).
Heat production rates and flight speed of adult wax moths (Galleria mellonella) were investigated by means of direct calorimetry at TA=20 and 30°C. Specific heat production rates were not significantly different between males and females at TA=20°C (pTH=747±123.7 mW g-1, n=5 for males and pTH=791±169 mW g-1, n=5 for females) even with females having a higher body mass (MB=83.8±21.6 mg, n=9 for males and MB=146.4±25.7 mg, n=11 for females) and wing load. In females, heat production rates were dependent on temperature with higher heat production rates at TA=20°C (pTH=791±169 mW g-1, n=5) than at TA=30°C (pTH=441±74 mW g-1, n=6). Flight speed was also clearly correlated with TA. Both males and females flew more slowly at TA=20 than at 30°C.

Keywords: direct calorimetry; Galleria mellonella; insect flight; metabolic rate

Anaerobic Calorimetry of the Growth of Lactobacillus Helveticus Using a Highly Sensitive Bio-RCl by J.-S. Liu; I. W. Marison; U. von Stockar (pp. 1191-1195).
To meet the need for studies of anaerobic microbial and animal cell cultures involving much lower heat effects as compared to aerobic microbial cultures, a bench scale calorimeter, Bio-RCl, has been improved for achieving a higher long-term sensitivity. This newly improved Bio-RCl was used for heat measurement of anaerobic growth of Lactobacillus helveticus. The results showed that the bench-scale calorimetry has powerful potential for on-line monitoring and control of anaerobic bioprocesses as well as fundamental studies, such as stoichiometry, thermodynamics and kinetics of cellular growth.

Keywords: anaerobic culture; bench scale calorimetry; bio-calorimeter; monitoring

Preliminary Studies Using Differential Scanning Calorimetry of Radiation-Induced Transformations in Starch and Flour by K. Cieśla; E. Svensson; A.-C. Eliasson (pp. 1197-1202).
Differential scanning calorimetry was applied in studies of the effect of gamma irradiation on the potato starch and wheat flour. Essential differences were noticed between endothermal effects observed in concentrated suspensions of the initial and irradiated potato starch and wheat flour heated at a rate of 2.5°C min-1, while only small differences were noticed between gelatinization thermal effects recorded for ca. 20% suspensions of the initial and irradiated potato starch samples heated at a rate 10°C min-1. Moreover, in the case of wheat flour, a decrease of decomposition temperature of the amylose-lipid complex was concluded.

Keywords: amylose-lipid complex transition; differential scanning calorimetry; gamma irradiation; potato starch; starch gelatinization; wheat flour

Effect of Nucleotides on Thermal Transitions of Myosin by D. Lőrinczy; B. Gaszner; F. Könczöl; J. Belágyi (pp. 1203-1209).
The internal dynamics and the thermal stability of myosin in rabbit psoas muscle fibres in different intermediate states of the ATP hydrolysis cycle were studied by differential scanning calorimetry (DSC) and electron paramagnetic resonance (EPR) spectroscopy. Three overlapping endotherms were detected in rigor, in strongly binding and weakly binding state of myosin to actin. The transition at 58.4°C can be assigned to the nucleotide-binding domain. The transition at highest temperature represents the unfolding of the actin and the contributions arising from the actin-myosin interaction. The transition of 54°C reflects the interaction between the subunits of myosin. Nucleotide binding induced shifts of the melting temperatures and produced variations in the calorimetric enthalpy changes. The changes of the EPR parameters indicated local rearrangements of the internal structure in myosin heads.

Keywords: conformation of myosin; DSC; EPR; spin labelling

DSC and Electronmicroscopic Investigation of Dispersion-Type Processed Cheeses Made Without Peptization by B. Schäffer; D. Lőrinczy; J. Belágyi (pp. 1211-1216).
In contrast with the traditional method of cheese processing, where Ca breaks down from the protein chain and protein is peptized, a new technology has been elaborated, during which cheese is dispersed without phosphate-containing processing salt, when the gel is formed by plant hydrocolloids.Raw material of constant composition was processed with a phosphate-containing salt or in the presence of hydrocolloids. Thermodynamic processes occurring during the processing and in the end-products were examined by an ultra-sensitive micro DSC method. The structures of end-products were also investigated by electronmicroscopy.The temperature ranges of the endothermal processes indicating the transformations of protein and hydrocolloids can be distinguished: 81-90°C for peptization processing and 61-72°C for processing without peptization. The differences are less in the end-products: 75-87°C in traditional processed cheese and 68-74°C in processed cheeses made without peptization. In contrast with the spongy structure of traditional processed cheeses consisting of peptized proteins, processed cheeses made without peptization involve structure-forming elements created by the interaction of linear macromolecules of hydrocolloids and cheese proteins.

Keywords: dispersion-type processed cheese; DSC; ELMI

Environmental Research for Art Conservation and Assessment of Indoor Conditions Surrounding Cultural Objects by M. Odlyha; N. S. Cohen; R. Campana; G. M. Foster (pp. 1219-1232).
This paper describes the results and conclusions of research directed towards the development and evaluation of a chemical sensor which would provide information on the quality of indoor environments surrounding cultural objects. In our case these objects were paintings housed in major European galleries and the main objective is their preservation through an improved understanding of their microenvironment. The concept was to prepare and expose test tempera paintings which would behave as dosimeters and integrate the environmental response at these locations. Artificial ageing of similar samples was performed to provide a means of calibrating the test paintings. Samples from the test paintings were compared with artificially aged samples and this enabled the sites to be ranked in terms of their suitability for exposure of cultural objects.Additionally, novel methodology involving piezoelectric sensors was designed for monitoring the relative humidity and temperature of the microenvironment of paintings. Dielectric techniques were also used for measuring the effect of relative humidity fluctuations on artists' materials and novel non-invasive dielectric techniques in the microwave region were used for the determination of their moisture content.

Keywords: environmental monitoring; indoor environments; museums and galleries; risk assessment; tempera paint dosimeters

Microcalorimetric Studies of the Surface Reactivity of Pollutant Gas Atmospheres on Supported SnO2 and Ga2O3 Catalysts by B. Gergely; A. Rédey; C. Guimon; A. Gervasini; A. Auroux (pp. 1233-1241).
The surface properties of gallium oxide and tin dioxide supported on alumina or titania have been studied by adsorption microcalorimetry. The differential heats of adsorption of various pollutant adsorbates such as sulfur dioxide, nitrogen monoxide, nitrogen dioxide and also ammonia were measured on these catalytic surfaces. NH3, SO2, NO2 are strongly adsorbed while NO is only physisorbed. The supported Ga2O3 samples show a slight decrease in acidity as probed by ammonia adsorption, compared to alumina or titania. The addition of SnO2 decreases the number of strong acid sites but creates a few weak and medium strength acid sites on alumina and does not modify the acidity of titania. In all cases, the basicity, probed by SO2 adsorption, is very strongly affected by the deposition of Ga2O3 or SnO2. The differential heats of NO2 adsorption remain nearly constant on all samples. The heats of adsorption are discussed as a function of the coverage and of the amount of guest oxide.

Keywords: adsorption microcalorimetry; Ga2O3 ; NH3 ; NO2 ; SnO2 ; SO2

Emission of Sulphur Dioxide During Thermal Treatment of Fossil Fuels by T. Kaljuvee; R. Kuusik (pp. 1243-1251).
The dynamics of SO2 emission during thermooxidation of Estonian oil shale, its semicoke, different samples of coal and their mixtures, as well as the influence of Estonian oil shale ash addition (for modelling the CFBC process) on the dynamics were studied. The experiments were carried out with thermogravimetric equipment under dynamic heating conditions (5 K min-1) in the atmosphere of dried air, with simultaneous gastitrimetric EGA.It was established that SO2 emission from the fuels started at 200-320°C. Depending on the form of sulphur (organic, pyritic, sulphate), the emission took place in two or three steps, and continued up to 580-650°C, during which 35-75% of the total sulphur was emitted into the gaseous phase. Regulating the mole ratio of free CaO/S in the mixtures of fuels with oil shale ash addition the emission of SO2 ceased abruptly at 460-540°C and it was limited to the level of 7-30%.

Keywords: air pollution; coal; oil shale; semicoke; SO2

Evolved Gas Analysis of Some Solid Fuels by TG-FTIR by I. Pitkänen; J. Huttunen; H. Halttunen; R. Vesterinen (pp. 1253-1259).
FTIR spectrometry combined with TG provides information regarding mass changes in a sample and permits qualitative identification of the gases evolved during thermal degradation. Various fuels were studied: coal, peat, wood chips, bark, reed canary grass and municipal solid waste. The gases evolved in a TG analyser were transferred to the FTIR via a heated teflon line. The spectra and thermoanalytical curves indicated that the major gases evolved were carbon dioxide and water, while there were many minor gases, e.g. carbon monoxide, methane, ethane, methanol, ethanol, formic acid, acetic acid and formaldehyde. Separate evolved gas spectra also revealed the release of ammonia from biomasses and peat. Sulphur dioxide and nitric oxide were found in some cases. The evolution of the minor gases and water parallelled the first step in the TG curve. Solid fuels dried at 100°C mainly lost water and a little ammonia.

Keywords: EGA; fuel; TG-FTIR

Thermal Behaviour of Silica Waste from a Geothermal Power Station and Derived Silica Ceramics by J. Ma. Rincon; M. Romero; C. Díaz; V. Balek; Z. Malek (pp. 1261-1269).
The silica waste originating from a geothermal power plant in Mexico was investigated with the aim of finding its applicability as a raw secondary material for ceramics production. The thermal behaviour of the original silica waste (containing NaCl and KCl from marine brine) and of the purified silica was characterized by means of DTA/TG, emanation thermal analysis (ETA) and thermodilatometry (TD). The reactivity of the purified silica waste mixed with CaCO3 (1.8 mass%) was characterized by means of ETA, DTA and TG. The microstructures and phase compositions of the final products prepared by heating in air were tested by means of X-ray diffraction and of scanning electron microscopy coupled with electron probe X-ray microanalysis. The thermal analysis methods allowed determination of the optimal conditions for thermal treatment of the silica waste in order to obtain partly sintered porous materials for use as refractory bricks.

Keywords: ceramics; emanation thermal analysis; geothermal waste; industrial waste; silica; thermal methods

Prediction of the Behaviour of Biomass Ash in Fluidized Bed Combustors and Gasifiers by S. Arvelakis; C. Sotiriou; A. Moutsatsou; E. G. Koukios (pp. 1271-1278).
Two types of agricultural residues (wheat straw and olive residue) in untreated and pretreated (fractionation, leaching) form were tested as concerns their ash melting behaviour during fluidized bed combustion and gasification by means of thermal analysis techniques. The techniques applied included DSC, simultaneous DSC/TG and TG-MS for the determination of low-temperature ash melts and losses caused by the volatilization of alkali material. In combination with ash elemental analyses on the materials, the applied techniques proved to offer valuable information for prediction of the ash behaviour in fluidized bed reactors.

Keywords: agricultural residues; combustion; gasification; pretreatment; thermal analysis techniques

Kinetic Parameters of Polyethylene Degradation by the Natural Zeolite Chabazite by V. J. Fernandes Jr.; A. S. Araujo; R. A. Medeiros; J. R. Matos; L. P. Mercuri; A. O. Silva; D. M. A. Melo (pp. 1279-1282).
High-density polyethylene (PE) was subjected to thermal degradation alone and in the presence of an ammonium-exchanged zeolite chabazite (CHA/PE). The processes were carried out in a reactor connected online to a gas chromatograph/mass spectrometer in order to analyse the evolved products. Polymer degradation was also evaluated by thermogravimetry, from room temperature up to 800°C, under a dynamic nitrogen atmosphere, with multiple heating rates. From the TG curves, the activation energy relating to the degradation process was calculated by using the Flynn and Wall multiple heating rate kinetic model for pure PE and for CHA/PE. The exchanged chabazite exhibited good selectivity for the catalytic degradation of PE to low molecular mass hydrocarbons.

Keywords: chabazite; Flynn and Wall kinetic model; polyethylene degradation

Thermal Analysis, Microcalorimetry and Combined Techniques for the Study of Pharmaceuticals by D. Giron (pp. 1285-1304).
Modern thermal analysis, microcalorimetry and new emerging combined techniques which deliver calorimetric, microscopic and spectroscopic data offer a powerful analytical battery for the study of pharmaceuticals. These techniques are very useful in all steps of development of new drug products as well as methods for quality control in production. The characterization of raw materials enables to understand the relationships between polymorphs, solvates and hydrates and to choose the proper development of new drug products with very small amount of material in a very short time. Information on stability, purity is valuable for new entities as well as for marketed drug substances from different suppliers. Excipients which vary from single organic or inorganic entity to complexes matrixes or polymers need to be characterized and properly controlled. The thermodynamic phase-diagrams are the basis of the studies of drug-excipients interactions. They are very useful for the development of new delivery systems. A great number of new formulations need proper knowledge of the behaviour of the glass transition temperature of the components. Semi-liquid systems, interactions in aqueous media are also successfully studied by these techniques.

Keywords: amorphous state; combined techniques; drug design; drug product development; drug substance; drug technology; DSC; excipients; failure investigations; hydrates; MDSC; microcalorimetry; pharmaceuticals; polymorphism; polymers; preformulation; process optimization; purity; quality control; solvates; stability; sub-ambient DSC; TG; temperature resolved X-ray diffraction; water interactions; thermal microscopy; water sorption-desorption

A Microcalorimetric Study on the Role of Moisture in Photolysis of Nifedipine Powder by V.-P. Lehto; J. Salonen; E. Laine (pp. 1305-1310).
A well-known photolabile substance, nifedipine, was used as a sample material to test self-constructed irradiation cells and demonstrate their usefulness in photostability studies. The devices were made as accessories for a commercial isothermal microcalorimeter. Several powder samples containing various amounts of moisture were irradiated with monochromatic light as a scan measurement from 700 to 280 nm, and the heat flow evolved in the photodegradation of nifedipine was determined. According to the results, light does not affect the nifedipine molecule directly, but the photodegradation is a result of the combined effects of moisture and light.

Keywords: isothermal microcalorimetry; pharmaceutical substance; photochemistry; photolability

Transient DSC, a Novel and Rapid Method for Assessing Pharmaceutical Powder Compacts by R. Ozao; M. Ochiai; Y. Ichimura; H. Takahashi; T. Takano (pp. 1311-1316).
The previously described method involving the use of transient DSC was applied to pharmaceutical powder compacts and to ceramic powder compacts. The samples were prepared by compressing powders of pentaerythritol tetraacetate and two kinds of alumina powder (differing in particle size distribution) up to a pressure of 20 MPa by using a jig. For pentaerythritol tetraacetate, a linear relationship was obtained between the parameter obtained by DSC and the compaction pressure.

Keywords: alumina; aluminum oxide; compact; DSC; particles; pentaerythritol tetraacetate; pharmaceuticals; powder; thermal resistance; transient state

DSC Screening of Potential Prochlorperazine-Excipient Interactions in Preformulation Studies by M. E. Brown; E. M. Antunes; B. D. Glass; M. Lebete; R. B. Walker (pp. 1317-1322).
Differential scanning calorimetry was used to examine the thermal behaviour of mixtures of the drug prochlorperazine with standard excipients, to assess potential interactions, and of mixtures with cyclodextrins, to investigate inclusion complexation which could increase the photostability of the drug. For most of the excipients (magnesium stearate, stearic acid, Explotab®, Ac-Di-Sol®, Encompress® and Ludipress®, lactose and Starch 1500) disappearance or broadening of the melting endotherm of the drug indicated interactions. Lubritab® was the only 'inert' excipient tested. Mixtures of prochlorperazine and the cyclodextrins gave incomplete inclusion complexation as shown by only partial disappearance of the melting endotherm of the drug.

Keywords: cyclodextrins; drugs; DSC; excipients; prochlorperazine

Application of Thermogravimetry in the Quality Control of Chloramphenicol Tablets by R. O. Macêdo; C. F. S. Aragão; T. G. do Nascimento; A. M. C. Macêdo (pp. 1323-1327).
The stability and thermal behaviour of chloramphenicol and various of its mixtures were investigated. The thermogravimetric and stability constant results showed that the chloramphenicol base is thermally more stable than the tablet in the studied formulation. The reduction in stability was attributed to the presence of starch in the formulation. The thermal decompositions of the chloramphenicol base and the tablet obey first-order kinetics.

Keywords: chloramphenicol; DSC; quality control; TG

Thermoanalytical Study of the Dehydration of Cyclodextrin Inclusion Complexes of Clofibric Acid by M. R. Caira; S. A. Bourne; E. Mvula (pp. 1329-1334).
Hydrated inclusion complexes of the hosts β-CD (CD=cyclodextrin), γ-CD and permethylated β-CD with the guest clofibric acid were analysed by TG and DSC methods to characterise their dehydration behaviours. Activation energies for dehydration of the β- and γ-CD clofibric acid complexes, determined by isothermal thermogravimetry, are significantly lower (∼20-25%) than those for the corresponding uncomplexed hydrated CDs. These data can be reconciled with X-ray structural data which show that H2O molecules in the complexes occupy different crystal sites from those occupied in the parent CDs.

Keywords: cyclodextrin complexes; dehydration; kinetics; TG-DSC

Thermal Behaviour of Perfluoropolyether w/o Percolative Microemulsions by D. Senatra; C. M. C. Gambi; M. Carlà; A. Chittofrati (pp. 1335-1346).
The thermal properties of a perfluoropolyether (PFPE) W/O microemulsion were investigated by Differential Scanning Calorimetry (DSC) both on freezing the liquid samples and upon their melting. PFPE systems as a function of increasing volume fraction (Φ=water+surfactant/total), were studied along a dilution line with a water/surfactant molar ratio W/S=11. The percolative nature of these systems emerged directly from the spreading of the exothermic peaks associated with the freezing of the dispersed phase. This behaviour was found to depend on whether the starting temperature of the DSC measure was at, below or above the percolative threshold temperature of the given sample. A low temperature 'needle-like' peak was found around 143 K, immediately after the glass transition due to the oil continuous phase. The low temperature peak was also present in other percolative, three-component microemulsions. The higher order phase transition at the percolation temperature was also evidenced.

Keywords: DSC of percolative microemulsions; fluorinated compounds; free water; higher order phase transitions by thermal analysis

Thermal Behaviour of Phenol-Formaldehyde (PF) Compounds by L. Y. Tonge; Y. Yazaki; A. S. Blicblau (pp. 1347-1352).
The self-condensation reactions of 2- and 4-mono-methylol phenols (2-MMP and 4-MMP), in the presence of varying concentrations of NaOH, have been studied by differential scanning calorimetry (DSC). The reaction exotherms were analysed to derive the activation energy, Ea, and the heat of reaction, HT, for the condensation reactions. In the case of 2-MMP an increase in NaOH:2-MMP molar ratio caused an increased in Ea and a decrease in HT up to a molar ratio of 0.6:1. However, for 4-MMP, an increase in NaOH concentration caused an increase in Ea up to a molar ratio of 0.3:1 beyond which there appeared to be no further effect. The presence of NaOH had no effect on HT for this compound. The results suggest that in the range of NaOH concentration used the effect of NaOH was substantially greater on 2-MMP compared to 4-MMP.

Keywords: activation energy; differential scanning calorimetry; heat of reaction; 2-mono-methylol phenol; 4-mono-methylol phenol

Thermal Behaviour of Some Terpenoids by R. O. Macêdo; J. M. Barbosa-Filho; E. M. da Costa; A. G. de Souza (pp. 1353-1357).
The terpenoids acetyl sitosterol, lupeol, acetyl diosgenin and stigmasterol were studied. Comparison of the thermogravimetric curves and the activation energies of the terpenoids suggested the following sequence of thermal stability: acetyl sitosterol < acetyl diosgenin < lupeol < stigmasterol. The DSC curves allowed determination of the melting points and the degrees of purity. Comparison of the TG and DSC curves revealed the presence of phase transitions without mass loss that were attributed to rearrangements in the terpenoid molecules.

Keywords: DSC; terpenoids; TG; thermal behaviour

Sorption and Desorption of Inclusion Compound Guests Different Types of Inclusion Compounds by A. Sopková; T. Wadsten; J. Bubanec; M. Reháková (pp. 1359-1366).
The guests present in inclusion compounds participate in bonding with the hosts. The conditions for the sorption and desorption of the guests are decisive for the properties of the inclusion compounds. They are surveyed for many types of inclusion compounds.

Keywords: composites; conditions of sorption and desorption; different guest types; inclusion compounds; thermal behaviour during sorption

The Measurement of Heat Capacity Differences Due to the Change of Water Structure in Aqueous Solutions of Organic Compounds by H. Nakayama; K. Aida (pp. 1367-1373).
In order to observe more directly the structural organization of water molecules around a non-polar molecule in an aqueous solution, heat capacity differences between two kinds of solutions (solution I and II) of quaternary ammonium salts were measured. In the solution I stable water structure was retained as much as possible and in the solution II water structure was destroyed either by heating to high temperatures or by irradiating with ultrasonic waves. It was found that the heat capacity differences ((Cp)II-(Cp)I) were slightly positive and its maximum values corresponded to 7-8 percent of the heat capacity of pure water itself.

Keywords: differential scanning calorimetry; heat capacity; hydrophobic hydration; quaternary ammonium salts

Thermal Behavior of Hexogen Phlegmatized with Montan Waxes by M. Stanković; M. Blagojević; S. Petrović (pp. 1375-1382).
Hexogen can be used pressed only if its crystals are covered by some polymeric material [1], either natural or artificial. Montan waxes, as natural polymeric materials, were used for the phlegmatization. The melting process of seven types of waxes was analyzed by differential scanning calorimetry. The thermal decomposition processes of hexogens and phlegmatized hexogens were investigated by dynamic differential scanning calorimetry and dynamic thermogravimetric analyses. Kinetic parameters of the decomposition processes of hexogens were evaluated by using data obtained from differential scanning calorimetric curves.

Keywords: differential scanning calorimetry; hexogen; kinetic parameters; montan wax; phlegmatization; thermogravimetric analysis

The Thermal Decomposition of Triple-Base Propellants by M. Stanković; V. Kapor; S. Petrović (pp. 1383-1388).
The thermal decompositions of a double-base propellant (DB), five triple-base propellants (TB) and nitroguanidine (NGV) were examined. The kinetic parameters were evaluated using the ASTM, Kissinger, Rogers-Morris, Freeman-Carroll and Borchardt-Daniels methods. The values of the orders of some of the chemical reactions (n), like some values of activation energies (Ea), do not have any physical meaning, but they represent the manner of propellant decomposition and prove that the mechanism of the reaction changes during the decomposition process. As a result of this fact, differences appear in the evaluated kinetic parameters between various methods.

Keywords: ASTM method; Borchardt-Daniels method; double-base propellant; Freeman-Carroll method; kinetic parameters; Kissinger method; nitroguanidine; Rogers-Morris method; triple-base propellant

Thermogravimetric Fourier Transform Infrared Spectroscopy of Hydrocarbon Fuel Residues by A. Zanier (pp. 1389-1396).
Although thermogravimetric analysis (TG) has become an indispensable tool for the analysis and characterization of materials, its scope is limited as no information is obtained about the qualitative aspects of the evolved gases during the thermal decomposition. For processes involving mass loss, a powerful technique to provide this missing information is Fourier transform infrared spectroscopy (FT-IR) in combination with TG. It supplies a comprehensive understanding of thermal events in a reliable and meaningful way as data are obtained from a single sample under the same conditions.The coupling TG/FT-IR is used in fuel analysis for the identification of residual volatiles, to determine their sequence of release and to resolve thermogravimetric curves. In this work, the usefulness of TG/FT-IR for characterizing middle distillate fuel residues is illustrated with some typical examples of recent application. A Bio-Rad FTS 25 FT-IR spectrometer coupled with a TA Instruments TGA 2950 thermogravimetric analyzer was used for data aquisition.The results obtained demonstrate the utility of this combined technique in determining the decomposition pathway of tarry materials at various stages of pyrolysis, thereby allowing new insights into the complex thermal behaviour of hydrocarbon residual systems.

Keywords: FT-IR; fuel; oil; pyrolysis; residue; TG

Introductory Remarks by W. Hemminger (pp. 1399-1400).

Standardisation and Quality Assurance by M. J. Richardson (pp. 1401-1404).
Modern DSC instruments generally give very reproducible results that are ideal for quality assurance work. However, various corrections are needed before quantitative data are obtained. Since the corrections differ from one type of instrument to another, it is important to ensure that they are all properly carried out. Without these corrections, it is fruitless to compare data from different sources. The types of problem, and their solutions, are discussed.

Keywords: calibrants; quality assurance; quantitative data; standard procedures

Quality Assurance in Testing Laboratories by G. Groboth (pp. 1405-1412).
General criteria for the operation of testing laboratories according to standards series EN 45000 and quality assurance under ISO series 9000 are discussed, and other quality management systems too are presented. The important elements of quality assurance as concerns measurements, tests and investigations are pointed out.

Keywords: accreditation; quality assurance

Thermal Analysis as Part of the Quality System within Industrial Laboratories by P. H. Willcocks; N. R. Bosley; A. Broadhurst; I. D. Luscombe (pp. 1413-1418).
The use of thermal analysis as part of a quality system in industry can be effective only if the techniques are made to conform to high standards of quality assurance. Achieving these high standards is not problem free and there remain many issues which require the attention of thermal analysts in industry and academe. Fundamental aspects which have been considered include limitations due to instrument design, problems in computerised control and analysis. A key aim is towards validation of data at international level.

Keywords: quality assurance; standardisation; validation

Eurosolid Session at ESTAC-7 (pp. 1419-1419).

Influence of Operating Conditions on BaSO4 Crystal Size and Morphology in a Continuous Couette Precipitator by S. Pagliolico; D. Marchisio; A. A. Barresi (pp. 1423-1433).
Precipitation of a sparingly soluble salt in the annular gap of a continuous Couette reactor with two unpremixed feeds has been experimentally investigated. Barium chloride and sodium sulphate in stoichiometric ratio are fed at different flow rate in the lower part of the reactor; different feeding modes have been considered. The dependence of precipitation yield, mean crystal size and particle size distribution on rotation speed, axial flow rate and initial supersaturation ratio has been studied. Depending on the operating conditions crystals with different morphologies have been obtained, varying from dentritic tabular crystals to complex pyramidal ones and from single crystals to aggregates.

Keywords: BaSO4 ; Couette reactor; morphology; precipitation

New Method for Catalyst Powder Manufacturing Based on Solvent Combustion by G. Saracco; F. Geobaldo; D. Mazza; G. Baldi (pp. 1435-1442).
A new method for the synthesis of fine catalyst powders is presented. Catalyst precursors are dissolved in an ethanol-water mixture which is burned through a nozzle-type burner. As a result, catalyst powders are formed and removed from flue gases through a filter. LaMnO3 catalysts for the catalytic combustion of methane have been prepared, characterised (TEM, XRD) and compared with a reference manfacturing method (the citrates one) showing promising, though improvable, results.

Keywords: LaMnO3 perovskite catalyst; methane combustion; solvent combustion; spray pyrolysis

CRTA Study of the Reduction of UO2F2 into UO2 by Dry H2 by J. M. Fulconis; F. Morato; F. Rouquerol; R. Fourcade; A. Feugier; J. Rouquerol (pp. 1443-1446).
The reduction of UO2F2 by dry H2 was studied by Controlled Rate EGA, with a special set-up operating under a gas flow under atmospheric pressure. At the constant transformation rate selected, this reduction apparently takes place in one main step, around 450°C (for a total duration of 100 h), followed by a small exothermic step. The final product is a stoichiometric, well crystallized UO2. XRD analysis shows the occurrence of two successive intermediates of which one has a structure close to that of UO2, but with interstitial fluorine atoms.

Keywords: CRTA; Sample Controlled Thermal Analysis; Temperature Programmed Reduction; UO2 ; UO2F2

Constant Rate Thermal Analysis (CRTA) as a Tool for the Synthesis of Materials with Controlled Texture and Structure by M. D. Alcalá; F. J. Gotor; L. A. Pérez-Maqueda; C. Real; M. J. Dianez; J. M. Criado (pp. 1447-1452).
Some examples of the use of the CRTA method for the synthesis of materials with controlled texture and structure are given. BaTiO3 has been obtained from the thermal decomposition of Barium Titanyl Oxalate (BTO) and Barium Titanyl Citrate (BTC) by controlling the reaction temperature in such a way that the partial pressure of the gases generated in the reaction was maintained constant at a value close to 10-2 mbar. It has been shown that this method allows getting BaTiO3 with crystal sizes considerably lower than those obtained by decomposing the same precursors by conventional methods. This small crystal sizes lead to the stabilisation of the metastable cubic phase with regards to the tetragonal phase.It has been also shown that the control of the CO generated in the carbothermal reduction of silica allows tailoring the phase composition of the silicon nitride obtained as final product.

Keywords: CRTA; material synthesis

Calorimetric and Gravimetric Measurements of Hydrocarbon Adsorption on a Granulated Active Carbon by E. Fiani; L. Perier-Camby; G. Thomas; M. Sanalan (pp. 1453-1459).
Adsorption isotherms of n-butane on a granulated activated carbon were measured by two different but complementary experimental methods: calorimetry and gravimetry. Adsorption heats were determined in different ways. For the system studied, the experimental results prove that the adsorbent offers a homogeneous site distribution. Besides, there can be differences between the adsorption heat values which might come from the way they are obtained (by calculation or direct measurements).

Keywords: activated carbon; adsorption; calorimetry; gravimetry; hydrocarbon

Pre-Eutectic Densification of Calcium Carbonate Doped with Lithium Carbonate by F. Tétard; D. Bernache-Assollant; E. Champion (pp. 1461-1473).
Pressureless sintering of CaCO3 was carried out, with Li2CO3 (from 0.5 to 8 wt%) as an additive, under different pressures of CO2. Densification occurs between 600 and 700°C. Sintering above the eutectic temperature (T>662°C) leads to the decomposition of calcium carbonate and the materials become expanded. At 620° under 1 kPa of CO2, a relative density of 96% is reached. Li2CO3 enhances the densification process and grain growth of calcium carbonate. CO2 pressure slows down densification and grain growth kinetics. These results are explained by the influence of carbonate and calcium ion vacancies on the sintering mechanisms.

Keywords: CaCO3 ; densification; kinetics; Li2CO3

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