Journal of Thermal Analysis and Calorimetry (v.101, #1)

Preface by K. S. Gavrichev; V. A. Drebushchak (3-3).

The influence of heat treatment of a liquid phase on “melting-crystallization” processes of silver thiogallate (AgGaS2) having chalcopyrite structure I $$ ar{4}2{ ext{d}} $$ , has been studied by the method of statistical thermal analysis (STA). It is shown that the melting temperature of solid phase (T m) increases non-monotonic from 970 °C due to rise in the preliminary melt overheating, and T m reaches asymptotically 1010 °C. The equilibrium melting-crystallization temperature ( $$ T_{ ext{m}}^{ ext{o}} $$ ) has been defined as 989.2 °C. It is also found an extreme dependence of the melt supercooling on its overheating. The two curves of irregular dependence of nucleation rate on melt supercooling have been plotted at different melt overheating.
Keywords: Melting temperature; Nucleation; Supercooling; Thermal analysis; Silver thiogallate

Calorimetric investigation of radiation-thermal synthesized lithium pentaferrite by A. P. Surzhikov; A. M. Pritulov; E. N. Lysenko; A. N. Sokolovskiy; V. A. Vlasov; E. A. Vasendina (11-13).
LiFe5O8 solid-phase synthesis at radiation-thermal (RT) annealing of lithium carbonate and iron oxide mechanical mixture was studied using thermal analysis (TG/DSC) and X-ray powder diffraction (XRD) techniques. The RT annealing was proceeded with high-power pulsing beam of 2.4 MeV electrons. It was shown that RT synthesis of the precursors considerably enhances the reactivity of the solid system within temperatures range 600–800 °C. In particular, lithium ferrite can be obtained at lower temperatures than those necessary in the absence of RT annealing.
Keywords: Ferrite; LiFe5O8 formation; TG; DSC; Kinetics; Radiation-thermal synthesis

Calorimetry, densimetry, 1H NMR and UV–vis spectroscopy were used to characterize inclusion complex formation of hydroxypropylated α- and β-cyclodextrins with meta- and para-aminobenzoic acids in aqueous solutions at 298.15 K. Formation of more stable inclusion complexes between para-aminobenzoic acid and cyclodextrins was observed. The binding of aminobenzoic acids with hydroxypropyl-α-cyclodextrin was found to be enthalpy-governed owing to the prevalence of van der Waals interactions and possible H-binding. Complex formation of hydroxypropyl-β-cyclodextrin with both acids is mainly entropy driven. The increased entropy contribution observed in this case is determined by dehydration of solutes occurring during the revealed deeper insertion of aminobenzoic acids into the cavity of hydroxypropyl-β-cyclodextrin. By comparing complex formation of aminobenzoic acids with native and substituted cyclodextrins it was found that the availability of hydroxypropyl groups slightly influenced the thermodynamic parameters and did not change the binding mode or driving forces of interaction.
Keywords: Aminobenzoic acid; Cyclodextrins; Inclusion complex formation; Thermodynamics

Computer models of eutectic-type Txy diagrams with allotropy by V. I. Lutsyk; V. P. Vorob’eva (25-31).
Using the eutectic-type Txy diagram as an example, it can be represented the analysis of its geometrical construction dependence on the temperature of a component two polymorphous modifications which participate in mono- and invariant metatectic and invariant eutectic (eutectoid) transformations above or below (and within) binary eutectics temperature intervals and below a ternary eutectic temperature. Computer models for considered phase diagrams have been designed. Such models help to solve applied tasks like visualization, isopleths and isothermal sections decoding, mass balances calculation and evaluation of phase and conglomerate concentration in microstructure.
Keywords: Allotropy; Phase diagram; Metatectic equilibrium; Phase scheme with phases paths

Joint results of the differential scanning calorimetry (DSC) and thermogravimetry (TG) experiments were the basis for the fusion enthalpy and temperature determination of the biuret (NH2CO)2NH (synthesis by-product of the urea fertilizer (NH2)2CO). Recommended values are Δm H = (26.1 ± 0.5) kJ mol−1, T m = (473.8 ± 0.4) K. The DSC method allowed for the phase diagrams of “water–biuret,” “water–urea,” “urea–biuret” binary systems to be studied; as a result, liquidus and solidus curves were precisely defined. Stoichiometry and decomposition temperature of the biuret hydrate identified, composition of the compound in “urea–biuret” system was suggested.
Keywords: Urea; Biuret; Thermal decomposition; Enthalpy of fusion; Phase diagram; DSC; TG

Thermodynamic characteristics of phase conversion of structural isomers for volatile complex of ruthenium (III) trifluoroacetylacetonate by S. V. Sysoev; T. N. Cheremisina; L. N. Zelenina; S. V. Tkachev; K. V. Zherikova; N. B. Morozova; N. V. Kuratieva (41-44).
The comprehensive analysis of volatile β-diketonate compound—ruthenium(III) trifruoroacetylacetonate (Ru(tfac)3)—was carried out. By means of flow method in quasi-equilibrium conditions and static method the temperature dependencies of saturated vapor pressure have been measured over solid and liquid cis- and trans-modifications of Ru(tfac)3 and isomer mixture. The thermodynamic characteristics of sublimation, evaporation, melting, and phase conversion have been calculated for structural isomers. Also by differential-scanning calorimetry the temperature meanings and the thermodynamic characteristics of melting have been determined for individual isomers of Ru(tfac)3 and their mixtures. By XRD the structures for cis- and trans-modifications have been determined. Both structures consist of neutral molecules arranged in pseudo layers.
Keywords: Vapor pressure measurements; Thermodynamic characteristics; Structural parameters

Thermochemical properties of MnNb2O6 by A. N. Mansurova; R. I. Gulyaeva; V. M. Chumarev; V. P. Mar’evich (45-47).
Homogeneous manganocolumbite (MnNb2O6) was synthesized from Nb2O5 and MnO oxides. Powder sample was orthorhombic with unit cell parameters: α = 0.5766 nm, b = 1.4439 nm, c = 0.5085 nm and V = 0.4234 nm3. Heat capacity over the temperature range of 313–1253 K was measured in an inert atmosphere with combined thermogravimetry and calorimetry using NETZSCH STA 449C Jupiter thermoanalyzer. Melting point was 1767 ± 3 K, enthalpy of melting was 144 ± 4 kJ mol−1. Experimental heat capacity of MnNb2O6 is fitted to polynomial C pm = 221.46 + 3.03 · 10−3 T + −39.79 · 105 T −2 + 40.59 · 10−6 T 2.
Keywords: Heat capacity; Heat of melting; Manganese niobate

The temperature dependence of heat capacity of a natural zinc silicate, hemimorphite Zn4Si2O7(OH)2·H2O, over the temperature range 5–320 K has been investigated by the method of low-temperature adiabatic calorimetry. On the basis of the experimental data on heat capacity over the whole temperature interval, its thermodynamic functions C p (T), S(T) and H(T) − H(0) have been calculated. The existence of a phase transition in the area of 90–105 K determined on the basis of vibrational spectra has been confirmed, and changes of entropy ΔS tr. and enthalpy ΔH tr. of the phase transition have been calculated. Hemimorphite heat capacity has also been determined by the calculation methods according to the valence force field model in LADY program. The values of force constants of valence bonds and angles have been calculated by semi-empirical method PM5. The calculated IR and Raman spectra concordant with the experimental spectra have been obtained. The heat capacity values calculated according to the found vibrational states satisfactorily agree with those experimentally obtained with an accuracy of ±1.7% in the area of 120–200 K, and not more than ±0.8% for the interval of 200–300 K. This fact testifies that the calculation of thermodynamic characteristics is correct.
Keywords: Hemimorphite; Low-temperature adiabatic calorimetry; Thermodynamic functions; Quantum chemical calculation; Valence force field model

Thermodynamic investigation of the systems LnSe2LnSe1.5 (Ln = La, Nd) by L. N. Zelenina; T. P. Chusova; I. G. Vasilyeva (59-62).
A detailed thermodynamic study of the systems LnSe2LnSe1.5 (Ln = La, Nd) was performed by static method of vapour pressure measurement using quartz membrane-gauge manometers within the temperature range 713–1,395 K. The p SeTx dependences obtained in this study have shown that the phase regions in composition intervals studied consist of discrete phases: LnSe1.95 LnSe1.90, LnSe1.85, LnSe1.80 (Ln = La, Nd). The enthalpies and the entropies for the stepwise dissociation process were calculated from the experimental data. The standard enthalpies of formation and the absolute entropies were estimated for the compounds investigated using literature data.
Keywords: Nd- and La-polyselenides; Vapour pressure measurements; Phase diagram; Enthalpy of formation; Absolute entropy

Thermal properties of fossilized mammal bone remnants of the Urals by S. Votyakov; D. Kiseleva; Yu. Shchapova; N. Smirnov; N. Sadykova (63-70).
Late-Quaternary material of various rodent species remnants (lower jaws and teeth) of different depth and age burials from zoogenic deposits in karstic cavities of the Urals (Russia) has been analyzed by thermogravimetry, differential thermal analysis, differential scanning calorimetry, and inductively coupled plasma mass spectrometry. Exothermic peaks position and shape as well as quantitative values of mass loss and heat effects (especially parameters of organic matter combustion at 200–600 °C) were found to vary significantly depending on bone’s age and fossilization conditions. On the basis of correlation between bone organic component and corresponding concentrations of some trace elements, three different types of fossilization had been proposed. The obtained values of the organic contents in the bone remnants of similar type and location were used to identify different age admixtures as well as chronologically systematize large sample collections.
Keywords: Bone; Teeth; Quaternary small mammals; Heat treatment; Thermal analysis

Regular Papers (71-71).

Thermoanalytical studies of silver and lead jarosites and their solid solutions by Ray L. Frost; Sara J. Palmer; János Kristóf; Erzsébet Horváth (73-79).
Dynamic and controlled rate thermal analysis has been used to characterise synthesised jarosites of formula [M(Fe)3(SO4)2(OH)6] where M is Pb, Ag or Pb–Ag mixtures. Thermal decomposition occurs in a series of steps. (a) dehydration, (b) well defined dehydroxylation and (c) desulphation. CRTA offers a better resolution and a more detailed interpretation of water formation processes via approaching equilibrium conditions of decomposition through the elimination of the slow transfer of heat to the sample as a controlling parameter on the process of decomposition. Constant-rate decomposition processes of water formation reveal the subtle nature of dehydration and dehydroxylation. CRTA offers a better resolution and a more detailed interpretation of the decomposition processes via approaching equilibrium conditions of decomposition through the elimination of the slow transfer of heat to the sample as a controlling parameter on the process of decomposition. Constant-rate decomposition processes of non-isothermal nature reveal separation of the dehydroxylation steps, since in these cases a higher energy (higher temperature) is needed to drive out gaseous decomposition products through a decreasing space at a constant, pre-set rate.
Keywords: Jarosite; Thermal analysis; Controlled rate thermal analysis; Thermogravimetry

In this study, the thermal analysis of the ω nanophase transformation from a quenched metastable β Ti–12Mo alloy composition (mass%) was investigated by electrical resistivity and dilatometry measurements. The activation energy was observed to be 121 ± 20 kJ mol−1 (from resistivity measurements) and 114 ± 12 kJ mol−1 (from dilatometry measurements) during the early stage of the transformation process. The kinetic of the ω nanophase transformation was modelized by using the classical Johnson–Mehl–Avrami (JMA) theory and a modified Avrami (MA) analysis. An Avrami exponent close to 1.5 was found at the early stage of the transformation suggesting a pure growth mechanism from pre-existing nucleation sites. Nevertheless, it was observed a decrease of the Avrami exponent to 0.5 at higher transformed fraction demonstrating a dimension loss in the growth mechanism due to the existence of the high misfit strain at the interface β/ω.
Keywords: Titanium alloy; Dilatometry; Electrical resistivity; Activation energy; Kinetic

From the peculiarities of Temperature-programmed reduction (TPR) method and using the Sestak–Berggren conversion function, we describe first the TPR curve simulation procedure. The influence of the Sestak–Berggren exponents on the TPR peak maximum and shape is demonstrated, by analyzing several synthetic TPR profiles. Finally, the kinetic parameters of Au/CeO2 promoted with yttrium as well as those of Au/CeO2–Al2O3 promoted with V2O5 are discussed.
Keywords: Temperature-programmed reduction; Conversion function; Sestak–Berggren exponents; Kinetic parameters

Calorimetric evolution of the early pozzolanic reaction of natural zeolites by R. Snellings; G. Mertens; J. Elsen (97-105).
The pozzolanic reaction between natural zeolite tuffs, portlandite and water was investigated over the course of the early reaction period up to 3 days. Isothermal conduction calorimetry experiments supplemented by TG/DTG and XRD analyses assisted in the elucidation of the sequence of reaction processes taking place. The calorimetry experiments clearly showed the dependence of the pozzolanic reaction rate and associated heat release on the fineness of the zeolite tuff. Higher external surface areas of pozzolans yield higher total heat releases. Also the exchangeable cation content of the zeolites influences the reaction rate. Release of exchangeable alkalis into solution promotes the pozzolanic reaction by raising the pH and zeolite solubility. The appearance of an exotherm after approximately 3 h of reaction is more conspicuous when alkali-rich zeolites are reacted. This exotherm is conceived to be related to a transformation or rupture of initially formed reaction products covering the zeolite grains. The formation of substantial amounts of ‘stable’ calcium silicate hydrate (C–S–H) and calcium aluminate hydrate (C–A–H) reaction took place after an induction period of more than 6 h. The openness of the zeolite framework affects the proneness of the zeolite to dissolution and thus its reactivity. Open framework zeolites such as chabazite were observed to react much more rapidly than closed framework zeolites such as analcime.
Keywords: Pozzolanic reaction; Zeolites; Lime; Conduction calorimetry

The kinetics of the pozzolanic reaction of enriched kaolin from the “Senovo” deposit (Bulgaria) with lime is the object of this article. The kaolin contains kaolinite as a major clay mineral as well as admixtures of quartz and illite. The experimental data of pozzolanic activity at temperatures of 100 and 23 °C are obtained for different reaction times. The reaction degrees of kaolinite and lime at 100 °C are determined from the pozzolanic activity data using a powder X-ray diffraction analysis. The kinetic analysis is performed by joint presentation of theoretical and experimental data in dimensionless coordinates having in mind the influence of particle size distribution on the reaction rate. It is found by the kinetic analysis that the rate of entire reaction is limited by the rate of chemical reaction on the reaction surface up to degree of reaction near to 0.4. The rate of penetration of the chemical reaction into the kaolinite particles for this area—from the beginning to degree of reaction 0.4, is determined to be equal to 2.10−11 m/s.
Keywords: Kinetics; Lime–kaolinite reaction; Pozzolanic reaction

The thermal conductivities enhancement of mono ethylene glycol and paraffin fluids by adding β-SiC nanoparticles by S. Masoud Hosseini; A. R. Moghadassi; D. Henneke; Ali Elkamel (113-118).
Changes in the thermal conductivities of paraffin and mono ethylene glycol (MEG) as a function of β-SiC nanoparticle concentration and size was studied. An enhancement in the effective thermal conductivity was found for both fluids (i.e., both paraffin and MEG) upon the addition of nanoparticles. Although an enhancement in thermal conductivity was found, the degree of enhancement depended on the nanoparticle concentration in a complex way. An increase in particle-to-particle interactions is thought to be the cause of the enhancement. However, the enhancement became muted at higher particle concentrations compared to lower ones. This phenomenon can be related to nanoparticles interactions. An improvement in the thermal conductivities for both fluids was also found as the nanoparticle size shrank. It is believed that the larger Brownian motion for smaller particles causes more particle-to-particle interactions, which, in turn, improves the thermal conductivity. The role that the base-fluid plays in the enhancement is complex. Lower fluid viscosities are believed to contribute to greater enhancement, but a second effect, the interaction of the fluid with the nanoparticle surface, can be even more important. Nanoparticle-liquid suspensions generate a shell of organized liquid molecules on the particle surface. These organized molecules more efficiently transmit energy, via phonons, to the bulk of the fluid. The efficient energy transmission results in enhanced thermal conductivity. The experimentally measured thermal conductivities of the suspensions were compared to a variety of models. None of the models proved to adequately predict the thermal conductivities of the nanoparticle suspensions.
Keywords: Nanofluid; Base fluid; Thermal conductivity; Concentration; Particles interaction; Size of nanoparticle; Brownian motion; Interfacial shell

To use flue gas desulfurization (FGD) gypsum and limestone as supplement of cement, conduction calorimetry was applied to investigate the early hydration of ternary binder of calcium aluminate cement (CAC), Portland-limestone cement (PLC), and FGD gypsum, supplemented with the determination of setting times and X-ray diffraction (XRD) analysis. Different exothermal profiles were presented in two groups of pastes, in which one group (group A) sets the mass ratio of FGD gypsum/CAC at 0.25 and the other group (group B) sets the mass ratio of PLC/CAC at 0.25. Besides the two common exothermal peaks in cement hydration, a third exothermal peak appears in the pastes with 5–15% FGD gypsum after gypsum is depleted. It is found that not PLC but FGD gypsum plays the key role in such ternary binder where the reaction of ettringite formation dominates the hydration process. PLC accelerates the hydration of ternary binder, which mainly attributes to the nucleating effect of fine limestone particles and PC clinker. The modified hydration process and mechanism in this case is well visualized by the means of calorimetry and it helps us to optimize such design of ternary cementitious material.
Keywords: Calcium aluminate cement; Calorimetry; FGD gypsum; Hydration; Portland-limestone cement

Ternary complexes of Co(II), Ni(II), Cu(II), and Zn(II) with nitrilotriacetic acid as a primary ligand and alanine or phenylalanine as secondary ligand were prepared in slightly acidic medium. The structures of the complexes were elucidated using elemental, IR, molar conductance, magnetic moment, UV–Vis spectrophotometry, and thermal analyses. The ternary complexes were isolated in 1:1:1 (M:HNTA:alaH) ratios, and the molecular structures were found to be [M(HNTA)(alaH)(H2O)2]. Thermogravimetric analysis confirmed this structure and that the water present is coordinated to the central metal atom. UV–Vis spectra showed that the complexes have octahedral symmetry.
Keywords: Alanine; Mixed-ligand complexes; Nitrilotriacetic acid; Phenylalanine ternary complexes; Thermal analyses

Cation distribution in manganese cobaltite spinels Co3−x Mn x O4 (0 ≤ x ≤ 1) determined by thermal analysis by H. Bordeneuve; A. Rousset; C. Tenailleau; S. Guillemet-Fritsch (137-142).
Thermogravimetric analysis was used in order to study the reduction in air of submicronic powders of Co3−x Mn x O4 spinels, with 0 ≤ x ≤ 1. For x = 0 (i.e. Co3O4), cation reduction occurred in a single step. It involved the CoIII ions at the octahedral sites, which were reduced to Co2+ on producing CoO. For 0 < x ≤ 1, the reduction occurred in two stages at increasing temperature with increasing amounts of manganese. The first step corresponded to the reduction of octahedral CoIII ions and the second was attributed to the reduction of octahedral Mn4+ ions to Mn3+. From the individual weight losses and the electrical neutrality of the lattice, the CoIII and Mn4+ ion concentrations were calculated. The distribution of cobalt and manganese ions present on each crystallographic site of the spinel was determined. In contrast to most previous studies that took into account either CoIII and Mn3+ or Co2+, CoIII and Mn4+ only, our thermal analysis study showed that Co2+/CoIII and Mn3+/Mn4+ pairs occupy the octahedral sites. These results were used to explain the resistivity measurements carried out on dense ceramics prepared from our powders sintered at low temperature (700–750 °C) in a Spark Plasma Sintering apparatus.
Keywords: Thermogravimetric analysis; Cobalt and manganese oxides; Spinels; Cation distribution

Nonisothermal crystallization kinetics and microstructure evolution of calcium lanthanum metaborate glass by Kaushik Biswas; Atul D. Sontakke; M. Majumder; K. Annapurna (143-151).
This paper reports results on the crystallization kinetics of 35.5CaO–7.25La2O3–57.25B2O3 glass under nonisothermal conditions based on the studies carried out from the differential thermal analysis upon using various well-established models. The crystalline phases formed during the optimized ceramization process have been confirmed from the X-ray diffraction. The activation energies of the first (formation of CaLaB7O13) and second (formation of LaBO3) crystallization events have been estimated using the conventional methods of Kissinger, Augis–Bennett, Ozawa, and Matusita, and the results are found to be in good agreement with each other. The Avrami exponents that are determined by these models for the crystallization of CaLaB7O13 and LaBO3 are found to be in the range of (1.81–2.35) and (4.03–4.65), respectively. This indicates that the formation of CaLaB7O13 is dominated by a surface crystallization, whereas LaBO3 is formed by three-dimensional bulk crystallization with an increased rate of nucleation. This observation is further validated by microstructural investigation, which shows the formation of CaLaB7O13 phase as a surface layer and a bulk crystallization of LaBO3 in optimally ceramized samples.
Keywords: Crystallization kinetics; Differential thermal analysis; Calcium lanthanum metaborate glass; Glass–ceramic; Activation energy; 82.20.Pm; 65.60. +a; 64.70 dg

Thermal decomposition of silylated layered double hydroxides by Qi Tao; Hongping He; Ray L. Frost; Peng Yuan; Jianxi Zhu (153-159).
Anionic surfactant and silane modified layered double hydroxides (LDHs) were synthesized through an in situ coprecipitation method. The structure and morphology were characterized by XRD and TEM techniques, and their thermal decomposition processes were investigated using infrared emission spectroscopy (IES) combined with thermogravimetry (TG). The surfactant modified LDHs (H-DS) shows three diffractions located at 1–7° (2θ), while there is only one broad reflection for silane grafted LDHs (H–Si) in this region. The morphologies of the H-DS and H–Si show fibrous exfoliated layers and curved sheets, respectively. The IES spectra and TG curves indicate that alkyl chain combustion and dehydroxylation are overlapped with each other during heating from 373 to 723 K in H-DS and to 873 K in H–Si. Sulfate anion transformation process occurs at 473 K in H-DS and 523 K in H–Si. The derivant of sulfate can exist even above 1073 K. After further decomposition, the metal oxides and the new type of Si–O compounds are formed beginning at around 923 K in silane modified sample.
Keywords: Anionic surfactant; IES; Layered double hydroxides; Silylation; TG

Influence of organic surfactants on structural stability of mechanochemically treated bentonite by Jana Hrachová; Peter Billik; Vladimír Štefan Fajnor (161-168).
The aim of this work was to compare the influence of organocations with different length of alkylammonium chain on the structural stability of clays towards mechanochemical treatment. An industrial product JP A030 (Envigeo, Inc., Slovakia) based on Jelšový Potok bentonite (Slovakia) and three organoclays prepared from this material via ion exchange with tetramethylammonium, octyltrimethylammonium and octadecyltrimethylammonium cations (TMA-JP A030, OTMA-JP A030 and ODTMA-JP A030, respectively) were ground for 1–20 min in a high-energy planetary mill. The products were investigated by X-ray diffraction analysis, thermal analysis, scanning electron microscopy and energy dispersive X-ray analysis. The long-chain organic cations apparently enhance the structural stability of bentonite during high-energy grinding.
Keywords: Bentonite; Mechanochemical treatment; Organoclay; Thermal analysis

Thermal expansion and heat capacity of dysprosium hafnate by G. Panneerselvam; R. Venkata Krishnan; K. Nagarajan; M. P. Antony (169-173).
Dysprosium hafnate is a candidate material for as control rods in nuclear reactor because dysprosium (Dy) and hafnium (Hf) have very high absorption cross-sections for neutrons. Dysprosium hafnate (Dy2O3·2HfO2-fluorite phase solid solution) was prepared by solid-state as well as wet chemical routes. The fluorite phase of the compound was characterized by using X-ray diffraction (XRD). Thermal expansion characteristics were studied using high temperature X-ray diffraction (HTXRD) in the temperature range 298–1973 K. Heat capacity measurements of dysprosium hafnate were carried out using differential scanning calorimetry (DSC) in the temperature range 298–800 K. The room temperature lattice parameter and the coefficient of thermal expansion are 0.5194 nm and 7.69 × 10−6 K−1, respectively. The heat capacity value at 298 K is 232 J mol−1 K−1.
Keywords: Dysprosium hafnate; Control rod; Heat capacity; Thermal expansion; HTXRD

Sodium zirconium phosphate (NZP) composition Na1−x Li x Zr2(PO4)3, x = 0.00–0.75 has been synthesized by method of solid state reaction method from Na2CO3·H2O, Li2CO3, ZrO2, and NH4H2PO4, sintering at 1050–1250 °C for 8 h only in other to determine the effect on thermal properties, such as the phase formation of the compound. The materials have been characterized by TGA and DTA thermal analysis methods from room temperature to 1000 °C. It was observed that the increase in lithium content of the samples increased thermal stability of the samples and the DTA peaks shifted towards higher temperatures with increase in lithium content. The thermal stability regions for all the sample was observed to be from 640 °C. The sample with the highest lithium content, x = 0.75, exhibited the greatest thermal stability over the temperature range.
Keywords: Thermal analysis; Sodium zirconium phosphate; NASICON

Thermal analysis of two types of dextran-coated magnetite by Oana Carp; Luminita Patron; Daniela C. Culita; Petru Budrugeac; Marcel Feder; Lucian Diamandescu (181-187).
The thermal stability of two kinds of dextran-coated magnetite (dextran with molecular weight of 40,000 (Dex40) and 70,000 (Dex70)), obtained by dextran adsorption onto the magnetite surface is investigated in comparison with free dextran in air and argon atmosphere. The thermal behavior of the two free dextran types and corresponding coated magnetites is similar, but atmosphere dependent. The magnetite catalyzes the thermal decomposition of dextran, the adsorbed dextran displaying lower initial decomposition temperatures comparative with the free one in both working atmospheres. The dextran adsorbed onto the magnetite surface decomposes in air through a strong sharp exothermic process up to ~450 °C while in argon atmosphere two endothermic stages are identified, one in the temperature range 160–450 °C and the other at 530–800 °C.
Keywords: Dextran-coated magnetite; Thermal analysis; X-Ray diffraction (XRD); FTIR spectoscopy

New features of the glass transition revealed by the StepScan® DSC by Marek Liška; Zdenek Černošek; Mária Chromčíková; Jana Holubová; Eva Černošková; Libor Vozár (189-194).
The results of StepScan DSC obtained for various oxides, chalcogenides, and organic glasses are discussed in connection with the commonly accepted theory of the glass transition. The new experimental features supporting the apparent idea of a reversible equilibrium being a part of the glass transition that is commonly interpreted as purely kinetic-relaxation phenomenon are discussed. Two alternative methods of the description of the reversible part of StepScan DSC record are compared:the empirical one using the exponential-power function [1 − exp(T/T g) n ], and the second one based on the van’t Hoff’s equation describing the temperature dependence of equilibrium constant in terms of reaction enthalpy, ΔH. The adequacy of the empirical description is rationalized in the framework of the Tool–Narayanaswamy–Moynihan’s relaxation theory.
Keywords: Glass; Glass transition; Enthalpy relaxation; SpepScan; DSC

Synthesis and thermal stability of hydrotalcites based upon gallium by Laure-Marie Grand; Sara J. Palmer; Ray L. Frost (195-198).
Hydrotalcites based upon gallium as a replacement for aluminium in hydrotalcite over a Mg/Al ratio of 2:1 to 4:1 were synthesised. The d(003) spacing varied from 7.83 Å for the 2:1 hydrotalcite to 8.15 Å for the 3:1 gallium containing hydrotalcite. A comparison is made with the Mg/Al hydrotalcite in which the d(003) spacing for the Mg/Al hydrotalcite varied from 7.62 Å for the 2:1 Mg hydrotalcite to 7.98 Å for the 4:1 hydrotalcite. The thermal stability of the gallium containing hydrotalcite was determined using thermogravimetric analysis. Four mass loss steps at 77, 263–280, 485 and 828 °C with mass losses of 10.23, 21.55, 5.20 and 7.58% are attributed to dehydration, dehydroxylation and decarbonation. The thermal stability of the gallium containing hydrotalcite is slightly less than the aluminium hydrotalcite.
Keywords: Hydrotalcite; Hydrocalumite; Gallium; Synthesis; Thermal stability

Trifluoromethoxy functionalized copper(II) Schiff base complexes N,N′-bis(5-trifluoromethoxysalicylaldehyde)cyclohexanediiminatodiaquacopper(II) and N,N′-bis(5-trifluoromethoxysalicylaldehyde)phenylenediiminatocopper(II) were synthesized and characterized. Thermal decompositions of the synthesized complexes were studied by thermogravimetry in order to evaluate their thermal stability and thermal decomposition pathways. Three similar decomposition steps occurred for the two copper complexes. Mass losses and evolved gasses were characterized by TG/DTA-MS. Kinetic parameters were calculated and the results showed that the values obtained are comparable.
Keywords: Schiff base; Salen; Copper(II) complexes; Thermal decomposition; Coupled TG/DTA-MS

Synthesis, crystal structure, and thermal decomposition kinetics of complex [Nd(BA)3bipy]2 by H. M. Ye; N. Ren; H. Li; J. J. Zhang; S. J. Sun; L. Tian (205-211).
The complex of [Nd(BA)3bipy]2 (BA = benzoic acid; bipy = 2,2′-bipyridine) has been synthesized and characterized by elemental analysis, IR spectra, single crystal X-ray diffraction, and TG/DTG techniques. The crystal is monoclinic with space group P2(1)/n. The two–eight coordinated Nd3+ ions are linked together by four bridged BA ligands and each Nd3+ ion is further bonded to one chelated bidentate BA ligand and one 2,2′-bipyridine molecule. The thermal decomposition process of the title complex was discussed by TG/DTG and IR techniques. The non-isothermal kinetics was investigated by using double equal-double step method. The kinetic equation for the first stage can be expressed as dα/dt = A exp(−E/RT)(1 − α). The thermodynamic parameters (ΔH , ΔG , and ΔS ) and kinetic parameters (activation energy E and pre-exponential factor A) were also calculated.
Keywords: Benzoic acid; Crystal structure; TG/DTG; Non-isothermal kinetics

Structural and thermal properties of rare earth complexes with 2,2′-biphenyldicarboxylic acid by Z. Rzączyńska; J. Sienkiewicz-Gromiuk; H. Głuchowska (213-219).
Rare earth complexes with 2,2′-biphenyldicarboxylic acid (diphenic acid = H2dpa) were obtained as hydrated precipitates of the general formula Ln2(C14H8O4)3nH2O, where n = 3 for the of Y(III) and Ce(III)–Er(III) and n = 6 for La(III), Tm(III), Yb(III) and Lu(III) complexes. On heating in air atmosphere complexes lose all water molecules in the temperature range 30–210 °C in one step and form anhydrous compounds, which are stable up to 315–370 °C. During further heating they decompose to oxides. The trihydrated compounds are crystalline powders whereas the hexahydrated are amorphous solids. The trihydrated complexes crystallize in the monoclinic (Pr(III) and Ce(III) complexes) and triclinic (Y(III) and Nd(III)–Er(III) complexes) crystal systems.
Keywords: 2,2-biphenyldicarboxylates; Thermal analysis; X-ray powder diffraction analysis

Thermal decomposition of linear tetranuclear copper(II) complexes including μ-azido bridges by S. Öz; M. Kunduracı; R. Kurtaran; Ü. Ergun; C. Arıcı; M. A. Akay; O. Atakol; K. C. Emregül; D. Ülkü (221-227).
In the first instance, mononuclear Cu(II) complexes are prepared with bis-N,N′(salicylidene)-1.3-propanediamine and derivatives. After that, these mononuclear complexes are combined with μ-bridges, by the help of azide ions, to obtain the tetranuclear complexes. Prepared complexes are characterised using IR spectroscopy, elemental analysis, and X-Ray techniques. In addition, the complexes are further analysed via TG and DSC. Molecular models of two of the nine prepared complexes are determined using X-Ray diffraction methods. The two terminal copper ions are observed to be in square pyramide coordination sphere between two oxygens of the organic ligand, two iminic nitrogens and an oxygen of the solvent while the other two cupper ions are observed to be in square pyramide coordination sphere between the fenolic oxygens of the organic ligand and the nitrogen donors of the three azide ions. It is found that the fenolic oxygens form μ-bridge and two azide ions are monodentate coordinated. In the TG analyses, the complexes are observed to decompose in a highly exothermic manner at about 200 °C. This thermal reaction is partially similar to that of explosive molecules and the data from DSC proved that the liberated heat is at explosive material levels.
Keywords: Azide containing complexes; Explosives; Molecular structure; TG

Thermal properties of amphiphilic biodegradable triblock copolymer of l,l-lactide and ethylene glycol by C. G. Mothé; A. D. Azevedo; W. S. Drumond; S. H. Wang (229-233).
Samples of poly(l,l-lactide)-block-poly(ethylene glycol)-block-poly(l,l-lactide) (PLLA-PEG-PLLA) were synthesized from l,l-lactide polymerization using stannous 2-ethylhexanoate, Sn(Oct)2 as initiator and di-hydroxy-terminated poly(ethylene glycol) (PEG) (M n  = 4000 g mol−1) as co-initiator. The chemical linkage between the PEG segment and the PLA segments was characterized by Fourier transform infrared spectroscopy (FTIR). Thermogravimetry analysis (TG) revealed the copolymers composition and was capable to show the deleterious effect of an excess of Sn(Oct)2 in the polymer thermal stability, while Differential Scanning Calorimetry (DSC) allowed the observation of the miscibility between the PLLA and PEG segments in the different copolymers.
Keywords: PLLA-PEG-PLLA; Drug delivery systems; Amphiphilic copolymer; Thermal properties

In this article, synthesis, characterization, and thermal properties of diacrylic/divinylbenzene copolymers based on the new aromatic tetrafunctional acrylate monomers are presented. The new monomers were generated by treatment of epoxides derived from various aromatic diols: naphthalene-2,3-diol (NAF), biphenyl-4,4′-diol (BIF), bis(4-hydroxyphenyl)methanone (BEP) or 4,4′-thiodiphenol (BES), and epichlorohydrin with acrylic acid. The addition reaction was carried out by a ratio of 0.5 mol of suitable epoxy derivative and 1 mol of acrylic acid in the presence of 0.7 wt% of triethylbenzylammonia chloride (TEBAC) as a catalyst and 0.045 wt% of hydroquinone as a polymerization inhibitor. The chemical structure of the prepared acrylate monomers was confirmed by 13C NMR and GC MS spectra. The emulsion–suspension polymerization of acrylate monomers with divinylbenzene (DVB) in the presence of pore-forming diluents (toluene + decan-1-ol) allowed obtaining microspheres containing pendant functional groups (hydroxyl groups). This process was carried out at constant mol ratio of acrylate monomers: DVB (1:1), and constant volume ratio of pore-forming diluents to monomers (1:1). The different concentrations of toluene in the mixture with decan-1-ol were used for qualifying the effect of the diluents on the microsphere characteristics. The influence of synthesis’s parameters on the properties of copolymer beads, e.g., pore size and surface area by BET method, the surface texture by AFM, swelling behavior in polar and non-polar solvents as well as thermal stability by differential scanning calorimetry (DSC), and thermogravimetric analysis (TG) was studied and discussed.
Keywords: Emulsion–suspension polymerization; Multifunctional acrylate monomers; Copolymers; Porous microspheres

Non-isothermal melt crystallization kinetics for ethylene–acrylic acid copolymer in diluents via thermally induced phase separation by Jun Zhang; Shuangjun Chen; Jing Jin; Xuming Shi; Xiaolin Wang; Zhongzi Xu (243-254).
Non-isothermal crystallization kinetics of the ethylene–acrylic acid copolymer (EAA) in diluents during thermally induced phase separation (TIPS) process was investigated via differential scanning calorimetry (DSC). Dioctyl phthalate (DOP), diphenyl ester (DPE), and peanut oil were used as diluents. Kinetic models, such as Jeziorny theory, Ozawa theory, and Mo’s approach, were utilized for description. The effective activation energy of EAA component in mixture was calculated by Friedman’s method. In the results, the Jeziorny theory and Mo’s approach could obtain good linear fitting relationship with the primary crystallization behavior of EAA, but the Ozawa theory failed to get a suitable result. The homogeneous nucleation of EAA proceeded at the end of liquid–liquid phase separation, while the non-isothermal crystallization developed within a solid–liquid phase separation environment. In the mixtures, the molecular weight, polar groups, and conformation of the diluent molecules would affect the nucleation of EAA, and its growth rate. Comparing with the non-isothermal crystallization of neat EAA, EAA in diluents obtained a higher Avrami index n, and comparatively lower crystallization rate. Peanut oil facilitated the homogeneous nucleation of EAA, leading to a higher melting peak temperature of EAA in the subsequent melting endotherms. The largest EAA’s Avrami index obtained in peanut oil also indicated a higher crystal growth dimensional geometry. The crystallization rate and crystallinity of EAA during the non-isothermal process decreased in the sequence: EAA/DPE > EAA/DOP > EAA/peanut oil.
Keywords: Non-isothermal crystallization; Ethylene–acrylic acid copolymer; Diluents; Crystallization kinetic parameters

In our present study, the reprocessability of a self-reinforced PP composites (SRPPC) prepared by compression molding was studied. The composite materials (handled separately, based on the related matrix material) were ground, then extruded five times and injection molded after the first and fifth cycle in order to investigate the behaviour of the material during reprocessing. As a reference, the matrices of the composites were also reprocessed and injection molded similarly to the composites. On the manufactured specimens, static (tensile and flexural) and dynamic mechanical tests (Charpy) were performed. The melting and crystalline characteristics were studied by Differential Scanning Calorimetry (DSC). The probable decomposition caused by multiple extrusions was followed by the Melt Volume Rate (MVR). The results indicated that in case of commercial materials there is no significant degradation even after multiple reprocessing cycles; therefore, the reprocessability of SRPPC products has no hindrance. The presence of α-iPP reinforcement in the rPP-based composites after reprocessing results in increased inclination for crystallization and consequently leads to improved mechanical stiffness compared to rPP neat matrices.
Keywords: iPP; Reprocessing; Self-reinforced composite; β-PP

Coir-fiber-based fire retardant nano filler for epoxy composites by Akhil Kumar Sen; Sandeep Kumar (265-271).
Coir-fiber-based fire retardant nano filler has been developed for epoxy resin (ER). At first, the coir fiber was brominated with saturated bromine water and then treated with stannous chloride solution. After drying, it was grinded to nano dimension and mix well with ER for composites preparations. FTIR, DSC, and TG techniques were used to characterize the brominated coir fiber. Gravimetric analysis shows only 10% by mass of bromination on coir fiber. Bromination decreases the thermal stability of the coir fiber, but it does not affect the final stability of the composites. This study concentrates on the thermal, fire retardant, and morphological properties of nanocomposites prepared by direct mixing. The fire retardancy properties (smoke density and limiting oxygen index) of coir–epoxy nanocomposites have increased significantly.
Keywords: Coir fiber; Bromination; Epoxy; Thermal; Fire retardant

Thermal behavior of partially hydrogenated polydienes by p-toluenesulfonylhydrazide by C. K. Santin; M. M. Jacobi; R. H. Schuster; M. Santoso (273-279).
The hydrogenation of natural rubber (NR), polybutadiene (BR), and styrene-butadiene (SBR) rubbers with different microstructures was performed by a diimide hydrogenation agent generated in situ by a non-catalytic method [1–3]. Many properties of the material depend considerably on variables such as degree of hydrogenation and proportions of vinyl or phenyl units. The mobility of the hydrogenated chain was investigated by differential scanning calorimetry (DSC) and the results confirm the relationship between the degree of hydrogenation and chain flexibility. The flexibility of a high cis-1,4 BR hydrogenated sample, was significantly changed and a melting point (T m) was detected after a certain degree of hydrogenation. Thermal stability was investigated by thermogravimetric analysis (TG) and an increase was found, but, the thermal resistance was influenced by the presence of the byproduct p-toluenesulfinic acid. Oxidation stability was investigated by chemiluminescence analysis and it improved with hydrogenation.
Keywords: Hydrogenation; Polydiene rubbers; p-Toluenesulfonylhydrazide; Thermal properties

Synthesis and thermal properties of spiro phosphorus compounds by Chinnaswamy Thangavel Vijayakumar; Nagarajan David Mathan; Vijayakumar Sarasvathy; Thangamani Rajkumar; Arunachalam Thamaraichelvan; Durairaj Ponraju (281-287).
Intumescent materials, 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro-[5,5]-undecane-3,9-dioxide and 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro-[5,5]-undecane having the capacity to produce dehydrating agent, blowing agent, and undergo carbonization during burning have been synthesized. The thermal behavior of the synthesized materials was investigated using differential thermal analysis, thermal volatilization analysis, programmed vacuum pyrolysis–mass spectrometry, flash pyrolysis–mass spectrometry and off-line pyrolysis–gas chromatography–mass spectrometry. The materials show exothermic degradation after 250 °C. Monitoring the release of hydrogen chloride and water, the blowing agents for the production of carbon foam, clearly indicated the superior performance of the pentavalent phosphorus compound over the trivalent phosphorus compound. The major gaseous degradation products released during pyrolysis showed the presence of sufficient quantities of several alkyl-substituted benzenes and fused aromatics. Suitable degradation mechanism has been proposed and discussed to explain the formation of various organics during thermal degradation.
Keywords: Spiro phosphorus compounds; Intumescence; Thermal analysis; Flash pyrolysis–mass spectrometry; Off-line pyrolysis–GC–MS

Thermal decomposition and glass transition of industrial hydrolysis lignin by H. Hatakeyama; Y. Tsujimoto; M. Ja. Zarubin; S. M. Krutov; T. Hatakeyama (289-295).
Thermal properties of industrial hydrolysis lignin (HL) obtained from bio-ethanol production plants were investigated by thermogravimetry and differential scanning calorimetry. Thermal decomposition of HL was observed in two stages suggesting coexisting carbohydrates. Glass transition temperature (T g) was observed in a temperature range from 248 to 363 K. T g values were lower than that of other industrial lignins, such as kraft lignin or lignosulfate. Enthalpy relaxation was observed as sub-T g, which is not as prominent as other industrial or laboratory scale isolated lignins. T g of HL decreased in the presence of water and saturated at water content (W c) of 0.18 (mass of water/mass of dry HL). The amount of bound water calculated from melting enthalpy of water and W c was ca. 0.18. Thermal decomposition and molecular motion of as obtained industrial HL are affected by coexisting carbohydrates.
Keywords: Hydrolysis lignin; Bio-ethanol; Glass transition; Enthalpy relaxation; Water

In order to enhance the thermal conductivity of MWCNT filled poly(dimethyl siloxane) (PDMS) composites, the MWCNT was coated with silica layer by three step reactions. The composites filled with raw and silica-coated MWCNTs were prepared and the properties were investigated in terms of the curing characteristics, mechanical properties, and thermal conductivity. Due to the poor compatibility between raw MWCNT and PDMS, raw MWCNT showed poor dispersion uniformity and wettability in PDMS. On the other hand, due to the chemical affinity between silica/MWCNT and PDMS throughout the hydrogen bonding, the silica-coated MWCNT filled PDMS showed improved mechanical properties in terms of tensile strength and 100% modulus, and good interfacial compatibility than raw MWCNT incorporated PDMS. Finally, the good wettability of silica/MWCNT in PDMS resulted in higher thermal conductivity caused from the facile phonon movement at the interface even with the smaller MWCNT contents.
Keywords: PDMS; Thermal conductivity; Carbon nanotube; Silica

Thermal catalytic conversion of the used isobutyl isoprene rubber into valuable hydrocarbons by M. Rasul Jan; Farah Jabeen; Jasmin Shah; Fazal Mabood (303-308).
An environment friendly method, thermal catalytic pyrolysis of used isobutyl isoprene rubber was investigated. In this method, the used inner butyl tube rubbers were catalytically pyrolyzed into valuable hydrocarbons and carbon black. In this method, the tube rubber was pyrolyzed both thermally (with out catalyst) and catalytically in a batch reactor under atmospheric pressure. The effect of temperature, the amount of catalyst, and the reaction time on the yields of the pyrolyzed products were investigated. Char yield decreased with increase of pyrolysis temperature while total gas and liquid yields increased. The liquid fraction was obtained with boiling point up to 478 K. At optimum conditions, the liquid product was collected and analyzed for different fuel properties. Typical analysis of the used isobutyl isoprene rubber oil for both the cases of parent and refluxed oil has been performed. Phenols and carbonyls were quantitatively determined by spectrophotometric methods using folin-denis and phenyl hydrazine reagents, respectively. The distillation data showed that ~100% of oil has boiling point <473 K which is the boiling point for 80% of distilled product in commercial kerosene. Its specific gravity, viscosity, freezing point, Cetane number, and diesel index were also within the limits of kerosene.
Keywords: Thermal and catalytic pyrolysis; Isobutyl isoprene rubber (inner butyl tube); Liquid fuel; Zinc oxide

Thermal degradation of poly(alkyl methacrylates) by Zbigniew Czech; Robert Pełech (309-313).
The thermal degradation of selected poly(alkyl methacrylates) at temperatures between 300 and 800 °C was investigated by pyrolysis gas chromatography. Quantitative characterization of the pyrolysis products yields insights into the mechanism for thermal degradation of poly(alkyl methacrylates) under these conditions. Unsaturated monomeric alkyl methacrylates, carbon dioxide, carbon monoxide, methane, ethane, methanol, ethanol, and propanol were formed during thermal degradation of poly(alkyl methacrylates).
Keywords: Poly(alkyl methacrylates); Solvent-borne polymerization; Thermal degradation; Pyrolysis; Breakdown products

Thermally stimulated current and differential scanning calorimetry spectroscopy for the study of polymer nanocomposites by Mulayam Singh Gaur; Bhupendra Singh Rathore; Pramod Kumar Singh; Ajaypal Indolia; Anand Mohan Awasthi; Suresh Bhardwaj (315-321).
The thermally stimulated discharge current (TSC) and differential scanning calorimetry (DSC) spectroscopy have been recorded in 25 μm thick samples of pristine polycarbonate (PC) and zinc oxide nano particle-filled polycarbonate. Polycarbonate (PC)/zinc oxide (ZnO) nanocomposites of different mass ratio (e.g., 1, 3, and 5%) were prepared by sol–gel method, followed by film casting. The glass transition temperature of nanocomposite samples increases with increase in concentration of ZnO nano fillers. It is due to the strong interaction between inorganic and organic components. The TSC peaks of nanocomposite and pristine PC indicate the multiple relaxation process. It has been observed that the magnitude of TSC decreases with increase in concentration of nanofillers. The TSC characteristics of 5% filled nanocomposites shows exponential increase of current at higher temperature region. This increase in current is caused by formation of charge-transfer complex between inorganic phase (e.g., ZnO) and organic phase (e.g., PC). Thus, the nano material like zinc oxide transfers the charge carriers from inorganic phase to organic phase rapidly and resultant current increases exponentially. This current is known as leakage current or breakdown current. TSC peak height is observed as a function of the polarizing field. The height of TSC peak increases as the field increases in pristine PC, while TSC peak height is suppressed in nanocomposite samples. This indicates the amount of space charge is smaller in the nanocomposites with a proper addition of ZnO nano fillers than in the pristine PC.
Keywords: TSDC; Nanofillers; ZnO; Activation energy; Secondary relaxation

Thermal properties of new composites based on nanoclay, polyethylene and polypropylene by Ewa Olewnik; Krzysztof Garman; Wojciech Czerwiński (323-329).
The results presented by a number of researchers indicate that the introduction of montmorillonite into polymer matrix results in an increase of thermal stability of polymer nanocomposites. The main purpose of this study was to evaluate the effect of the organoclay on the thermal degradation of polyolefins (polyethylene and polypropylene). Polyolefin-clay nanocomposites were prepared by melt compounding of polyolefins and montmorillonite clay organically modified with 4,4′-methylenebisaniline (MBA) (from 1.5 to 5 wt%). Changes in the surface of montmorillonite and the dispersion of organoclay in the polymer matrix were evaluated using X-ray diffraction (XRD) and elemental analysis. The thermal stability of the clay and nanocomposites were analysed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The XRD results show that almost complete exfoliation of the silicate layers took place and nanocomposite structure was obtained for all new materials. The thermal stability of the PE and PP/clay nanocomposites can be improved in the case of loading above 5 wt%.
Keywords: Thermal degradation; Nanocomposites; Nanofillers; Montmorillonite; Polyolefins

The thermal behaviour of a new kind of hybrid system based on silanized poly(ether-urethanes) (SPURs) has been analyzed by thermogravimetric analysis (TG). The influence of the chemical nature of employed alkoxysilanes, polyether diol molecular weight and the physical state of the obtained hybrids (cured and non-cured) has been studied. The results show that in the non-cured state, aminosilane-based systems present a higher stability compared with those based on isocyanatesilane. However, in the cured state, both types of hybrids present a similar thermal stability, but much higher than their corresponding partners before the curing process. The presence of the inorganic silica network improves the thermal stability of all the systems studied.
Keywords: Organic–inorganic hybrid; Thermal properties; Thermogravimetric analysis (TG)

The aim of this study was to correlate the results of experimental data using DTA method and predictions of artificial neural network (ANN) and multivariate linear regression (MLR). Thermal decomposition of polymers was analyzed by simultaneous DTA method, and kinetic parameters (critical points, the change of enthalpy and entropy) of polymers were investigated. A computer model based on multilayer feed forwarding back propagation and multilayer linear regression model were used for the prediction of critical points, phase transitions of low-density polyethylene (LDPE) and mid-density polyethylene. As a result of our study, we concluded that ANN model is more suitable than MLR about prediction of experimental data.
Keywords: Differential thermal analysis (DTA); Artificial neural networks (ANN); Multivariate linear regression (MLR); LDPE and MDPE; Phase transitions; Enthalpy; Entropy; Melting Point

Experimental data of excess molar enthalpy (H m E ) of binary liquid mixtures containing (methanol or ethanol or 1-propanol, or 1-butanol) + n-butylamine mixtures have been determined as a function of composition at temperatures 288.15 and 308.15 K, at atmospheric pressure, using a modified 1455 PARR mixture calorimeter. The H m E values are negative for both systems over the whole composition range. The applicability of the ERAS Model to correlate H m E of mixtures studied is tested, and the agreement between experimental and theoretical results is satisfactory. The model results are discussed in terms of the cross-association interactions with temperature variation as well as in terms of the variation of the carbon chain in the alcohols presents in the mixtures.
Keywords: Alcohols; Amines; Excess molar enthalpy; ERAS Model

The molality dependence of specific conductivity of pentadecyl bromide, cetylpyridinium bromide and cetylpiridinium chloride in aqueous solutions has been studied in the temperature range of 30–45 °C. The critical micelle concentration (cmc) and ionization degree of the micelles, β, were determined directly from the experimental data. Thermal parameters, such as standard Gibbs free energy $$ Updelta G_{m}^{0} , $$ enthalpy $$ Updelta H_{m}^{0} $$ and entropy $$ Updelta S_{m}^{0} , $$ of micellization were estimated by assuming that the system conforms to the pseudo-phase separation model. The change in heat capacity on micellization $$ Updelta C_{p} , $$ was estimated from the temperature dependence of $$ Updelta H_{m}^{0} . $$ An enthalpy–entropy compensation phenomenon for the studied system has been found.
Keywords: Pentadecylpyridinim bromide; Cetylpyridinium bromide; Cetylpyridinium chloride; Conductivity; Critical micelle concentration; Enthalpy, entropy and standard Gibbs free energy of micellization; Heat capacity; Temperature dependence

Heat capacities and thermodynamic properties of MgBTC by Li-Fang Song; Chun-Hong Jiang; Jian Zhang; Li-Xian Sun; Fen Xu; Yun-Qi Tian; Wan-Sheng You; Zhong Cao; Ling Zhang; Dao-Wu Yang (365-370).
A novel two-dimensional metal organic framework MgBTC [MgBTC(OCN)2·2H2O, where BTC = 1,3,5-benzenetricarboxylate] has been synthesized solvothermally and characterized by single crystal XRD, powder XRD, FT-IR spectra. The low-temperature molar heat capacities of MgBTC were measured by temperature modulated differential scanning calorimetry (TMDSC) over the temperature range from 190 to 350 K for the first time. No phase transition or thermal anomaly was observed in the experimental temperature range. The thermodynamic parameters of MgBTC such as entropy and enthalpy relative to reference temperature of 298.15 K were derived based on the above molar heat capacities data. Moreover, the thermal stability and decomposition of MgBTC was further investigated through thermogravimetry (TG)-mass spectrometer (MS). Four stages of mass loss were observed in the TG curve. TG-MS curve indicated that the products of oxidative degradation of MgBTC are H2O, N2, CO2 and CO. The powder XRD showed that the mixture after TG contains MgO and graphite.
Keywords: Magnesium; MDSC; Metal organic frameworks; Molar heat capacity; TG

Heat capacity and thermal expansion coefficient of rare earth uranates RE6UO12 (RE = Nd, Gd and Eu) by R. Venkata Krishnan; Hrudananda Jena; K. V. Govindan Kutty; K. Nagarajan (371-377).
Rare earth uranates Nd6UO12, Gd6UO12 and Eu6UO12 were prepared by combustion synthesis and characterized by XRD. Single-phase rhombohedral structure was observed for all the above compounds. Heat capacity measurements were carried out on Nd6UO12 and Gd6UO12 with differential scanning calorimetry in the temperature range 298–800 K. Enthalpy, entropy and Gibbs energy functions were computed. Heat capacity values of Nd6UO12 and Gd6UO12 at 298 K are 436 and 400 J K−1 mol−1, respectively. Thermal expansion characteristics were studied using high temperature X-ray diffraction (HTXRD) in the temperature range 298–873 K. The coefficients of thermal expansion measured for Eu6UO12 are 10.5 × 10−6 and 7.3 × 10−6 K−1 along a- and c-axis, respectively. Similarly, the coefficients of thermal expansion of Gd6UO12 along a-axis are 10.0 × 10−6 K−1 and along c-axis is 9.7 × 10−6 K−1.
Keywords: Heat capacity; Rare earths; Uranates; Rare earth uranates; Thermal expansion

A thermodynamic study on the interaction of nickel ion with myelin basic protein by isothermal titration calorimetry by G. Rezaei Behbehani; A. A. Saboury; L. Barzegar; O. Zarean; J. Abedini; M. Payehghdr (379-384).
The interaction of myelin basic protein (MBP) from the bovine central nervous system with divalent nickel ion was studied by isothermal titration calorimetry at 37 and 47 °C in Tris buffer solution at pH = 7. The new solvation model was used to reproduce the heats of MBP + Ni2+ interaction over the whole Ni2+ concentrations. It was found that MBP has three identical and independent binding sites for Ni2+ ions. The intrinsic dissociation equilibrium constant and the molar enthalpy of binding are 89.953 μM, −14.403 kJ mol−1 and 106.978 μM, −14.026 kJ mol−1 at 37 and 47 °C, respectively. The binding parameters recovered from the new solvation model were correlated to the structural changes of MBP due to its interaction with nickel ion interaction. It was found that in the low and high concentrations of the nickel ions, the MBP structure was destabilized.
Keywords: Myelin basic protein; Nickel; Isothermal titration calorimetry; Binding parameters

Thermal conductivity enhancement of Ag nanowires on an organic phase change material by J. L. Zeng; Z. Cao; D. W. Yang; L. X. Sun; L. Zhang (385-389).
One of the greatest challenges in the application of organic phase change materials (PCMs) is to increase their thermal conductivity while maintaining high phase change enthalpy. 1-Tetradecanol/Ag nanowires composite PCM containing 62.73 wt% (about 11.8 vol%) of Ag nanowires showed remarkably high thermal conductivity (1.46 W m−1 K−1) and reasonably high phase change enthalpy (76.5 J g−1). This behavior was attributed to the high aspect ratio of Ag nanowires, few thermal conduct interfaces, and high interface thermal conductivity of Ag nanowires in the composite PCM. These results indicated that Ag nanowires might be strong candidates for thermal conductivity enhancement of organic PCMs.
Keywords: Silver nanowires; Composites materials; Nanocomposites; Thermal conductivity; Phase change materials

We modified a commercially available thermogravimetric analyzer to introduce helium alone or with steam, oxygen or both, atmosphere of which was controllable to be similar to that in a fixed-bed or an entrained-flow type gasifier, for studying basic properties of biomass gasification. We also connected it to a gas chromatograph-mass selective detector for identifying materials produced during the thermogravimetric analyses. Thermogravimetric analyses of Japanese cedar wood and identifications of the produced materials at around 365 °C were measured as demonstrations.
Keywords: Thermogravimetric analysis in steam–oxygen; Gas chromatograph mass spectrometry; Biomass gasification

Photopyroelectric calorimetry of solids by D. Dadarlat; M. Streza; M. N. Pop; V. Tosa; S. Delenclos; S. Longuemart; A. Hadj Sahraoui (397-402).
An alternative photopyroelectric (PPE) technique that combines the front detection configuration (FPPE) with the thermal wave resonator cavity (TWRC) method is proposed. The theoretical analysis of the FPPE signal indicates that the configuration also offers information about both fluid sample and backing solid material. It is demonstrated that the normalized phase of the FPPE signal has an oscillating dependence as a function of the sample’s thickness. In the thermally thin regime for the sensor and liquid sample, the method can be used for direct measurement of backing thermal effusivity. This article presents experimental results on solid materials, with various values of thermal effusivity (Cu, brass, steel, glass, bakelite, and wood), used as backings in the detection cell. A study of the sensitivity of the technique for different liquid/backing effusivity ratios is performed. The main result of this article is the possibility of deriving the thermal effusivity of a solid sample (backing material) by monitoring the thickness of a fluid with well-known properties. In such a way, the so-called coupling fluid is not anymore a disturbing factor; however, its properties can be used to obtain the value of the thermal effusivity of a solid. The method proved to be suitable especially for thermal effusivity investigations of low thermal conductors. An application on polymer composites with different liquid/powder content is presented.
Keywords: PPE technique; Thermal effusivity; Thermal waves; TWRC method

The physical–chemical properties and fatty acid composition of sheep subcutaneous, tallow, intestinal, and tail fats were determined. Sheep fat types contained C16:0, C18:0, and C18:1 as the major components of fatty acid composition (19.56–23.40, 20.77–29.50, 32.07–38.30%, respectively). Differential scanning calorimetry (DSC) study revealed that two characteristic peaks were detected in both crystallization and melting curves. Major peaks (T peak) of tallow and intestinal fats were similar and determined as 31.25–24.69 and 7.44–3.90 °C, respectively, for crystallization peaks and 15.36–13.44 and 45.98–44.60 °C, respectively, for melting peaks in DSC curves; but those of tail fat (18.29 and −2.13 °C for crystallization peaks and 6.56 and 33.46 °C for melting peaks) differed remarkably from those of other fat types.
Keywords: Sheep fats; Fatty acids profile; Differential scanning calorimetry (DSC)

Events (411-411).