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This paper reports the synthesis of exfoliated structure of Poly-methylmethacrylate/organomontmorillonite nanocomposites by in situ polymerization of Methylmethacrylate monomer as a cost-effective adsorbent for ultrahigh removal of azo dye pollutant from aqueous media. The obtained nanocomposites with different organoclay loading (1–7 mass%) were characterized by XRD, FTIR, DTA, TGA, TEM and SEM. In the XRD results, the observation of small pick shoulders (d001) and almost no reflection in the X-ray diffractrograms indicated, respectively, the establishment of intercalated/exfoliated structures and major exfoliation of OMMT clay into polymer. This observation was supported by TEM microscopy. TGA results revealed improved thermal properties in comparison with the pure polymer. Adsorption parameters such as pH-value, contact time and initial dye concentration were investigated to assess optimum adsorption activity. The adsorption experiments showed that the equilibrium time of adsorption was reached very rapidly. According to the kinetic study, the adsorption process followed pseudo-second-order model. The adsorption capacity is unaffected by variation of solution pH. The high maximum adsorption capacity of PMMA/OMT nanocomposite toward dye was found to be 309.6 mg g−1. Langmuir isotherm was more suitable model to describe the adsorption of dye than Freundlich and Dubinin–Radushkevich models. Thermodynamic study showed that the removal of the azo dye from aqueous solution by PMMA/OMT nanocomposite is endothermic nature, spontaneous and physisorption process. Under three adsorption–desorption cycles, PMMA/OMT nanocomposite had good re-adsorption effect. Thus, PMMA/OMT nanocomposite can be an efficient and recyclable adsorbent for azo dyes. [ABSTRACT FROM AUTHOR]

Bio-based interpenetrating polymer networks (IPNs) with tunable thermal and mechanical properties were prepared by bio-based polyurethane (PU) and epoxy resin (EP) derived from plant oils. The cure reaction, dynamic mechanical properties, thermal stability, mechanical performance and morphology of bio-based PU/EP IPNs were characterized by Fourier transform infrared spectroscopy, dynamic mechanical analysis, thermogravimetry, universal test machine and scanning electron microscopy. Dynamic modulus, glass transition temperature, thermal stability and tensile strength of bio-based EP/PU IPNs decreased in the content of soybean oil-based PU prepolymers. However, the damping properties of bio-based EP/PU IPNs increased in the content of soybean oil-based PU prepolymers. The elongation at break of bio-based EP/PU IPNs was greatly higher than that of the plant oil-based EP. The elongation at break of the bio-based EP/PU IPN containing 20% soybean oil-based PU prepolymer was fourfold higher than that of the plant oil-based EP. Soybean oil-based PU prepolymer significantly improved the damping properties and the elongation at break of the plant oil-based EP. By adjusting the mass ratio of the plant oil-based EP to the soybean oil-based PU, the glass transition temperature, damping and mechanical properties of bio-based PU/EP IPNs can be optimized. [ABSTRACT FROM AUTHOR]

The composite powders of nanoscale aluminum (n-Al) and iron fluoride (FeF3) were prepared by an ultrasonic mixing method. The microscopic morphology was examined by scanning electron microscopy, the crystalline phase structure was analyzed by X-ray diffractometer, and extensive thermal analysis of the single components and composites was carried out, focusing on the thermal reaction properties of n-Al/FeF3. The reaction process and pre-ignition reaction of the complexes were investigated by characterizing the reaction products of n-Al/FeF3 and Al2O3/FeF3 at certain temperatures. Finally, the apparent activation energy of the thermite reaction of n-Al/FeF3 was determined using the Ozawa method, the Flynn method, and the Starink method. Under an Ar environment, n-Al/FeF3 could react at a lower temperature (613.8 ℃) and give off more heat (1097.0 J g−1) compared with n-Al/Fe2O3. In the air environment, n-Al/FeF3 also showed a lower reaction temperature (509.7 ℃). N-Al could be totally oxidized at a lower temperature with a higher degree of reaction, although the reaction heat release (1477.6 J g−1) was lower than that of n-Al/Fe2O3 (2692.5 J g−1). A pre-ignition reaction occurred before the main reaction of n-Al/FeF3, but no evident exothermic peaks were found in the thermal analysis. The activation energies of exothermic peaks 1 and 2 for n-Al/FeF3 were 113.79 kJ mol−1 and 185.45 kJ mol−1, respectively, slightly higher than those of n-Al/Fe2O3. The study results reported in this work provide a certain reference for the in-depth research and application of the n-Al/fluoride thermite system, as well as fresh ideas for the development of novel nanothermite materials. [ABSTRACT FROM AUTHOR]

The aim of this work was to improve mechanical properties of a biocomposite of polylactic acid (PLA) reinforcing with fibrillated methacrylate-silanized hemp fibre. The effect of hemp fibre on photo-oxidation and hydrolytic degradation of PLA was evaluated through a QUV accelerated weathering test. Incorporation of 20 mass% fibre filler into neat PLA matrix resulted in increased tensile and flexural modulus for 150% and 200%, respectively. The outdoor degradation of neat PLA and PLA biocomposites was simulated in a 30 days of QUV accelerated weathering test in accordance with ISO 11507 method B. Glass transition temperature (Tg) was periodically recorded to measure the rate of degradation. Differential scanning calorimetry (DSC) analysis indicated that the degradation rate of the PLA matrix of the biocomposites tended to decrease proportionally to exposure time. The statistical regression method revealed a linear relationship between ln(Mn) and lnTg (R2 = 0.96). The 20 mass% hemp/PLA biocomposite was mostly destroyed over neat PLA after 30 days. The rate of degradation tended to have a linear proportion with hemp content. The results of FTIR 13C-NMR analysis confirmed that the substantial degradation of hemp/PLA biocomposites was due to the lignin content of the hemp fibre. The sensitivity of the PLA biocomposite to UVB light and moisture absorption accelerated photo-oxidation and hydrolytic degradation to the lowest molecular weight of PLA. [ABSTRACT FROM AUTHOR]

The knowledge of the thermal properties of textiles is important with regard to their vast applications in most industries. Thermal properties, as one of the physical features of a textile, are influenced by its structural parameters such as thickness, density, and so on. In this study, a new structural model is developed to predict the effective thermal conductivity in knitted spacer fabrics. In the first step, a spacer fabric was considered as a three-layer set. The thermal conductivity of each layer was calculated separately, and then the effective thermal conductivity of fabric was determined based on its structural parameters. The performance of the proposed model was evaluated using spacer fabrics, and the results were compared with those of other models. The results of the new model and the experimental method showed that the most effective parameters involved in thermal conductivity are thickness, porosity and density. A good agreement (with R2 = 0.91) was found between the results of the proposed model and the experimental values. [ABSTRACT FROM AUTHOR]

Cuban and Mexican zeolites are of particular interest from economic outlook because of their exceptional properties and abundance. Here, we present the results of the comparative study of the elemental, structural, morphological, thermal and textural properties of natural zeolites: clinoptilolite, mordenite and erionite from various deposits. Despite a complex phase and element compositions of the studied materials, some general features were detected. The observed dehydration steps are related to water desorption from porosity of different size ranges: mesopores, main and small zeolite voids. This dehydration pattern interferes with the exchangeable cation composition that also affects the general trends. Thermochemical properties of samples are influenced by the geographical location of the deposits. Depending on the origin of the sample, the dehydration enthalpy varies in quite a wide range, which is a function of both zeolite framework structure and exchangeable cation composition. The study of meso- and macropore systems reveals that all the samples exhibit multimodal pore size distribution and possess significant amounts of mesoporosity and even macroporosity. Among the studied samples, the mordenite from Palmarito de Cauto, the clinoptilolite from Etla and the erionite from Agua Prieta (Sonora) have a significant number of pores with average size of about 3 nm. All the samples, except erionite from Agua Prieta, show macroporosity with rather well-defined pore size between 0.3 and 2 μm. The porosity over mass does not change noticeably from one sample to other and varies from 0.32 to 0.65 cm3 g−1. [ABSTRACT FROM AUTHOR]

The crystal structures and thermal characteristics of two polymorphs of methylethanolammonium 2-chloro-4-nitrobenzoate were investigated by a combined experimental and computational approach. The main attention was paid to the synthesis of polymorphs, structural characterization associated with computational studies on the nature of intermolecular interactions, and thermodynamic stability relationship between the polymorphs and thermal decomposition kinetics. Analysis of the polymorphs structure revealed distinct crystal packing arrangements and different numbers of independent molecules pairs in the asymmetric crystal unit. Depending on the conformation of cations, polymorphs α and β exhibit the formation of different charge-assisted and normal hydrogen bonds, while in β, non-covalent interactions of halogens are also manifested. The calculated values of the lattice energies indicated that α has a more stable lattice than β at high temperatures. The thermodynamic stability relationship between the polymorphs pair is monotropic and is determined by measuring melting points and heats of fusion. The kinetics of thermal decomposition processes has been comparatively studied by two different kinetic methods. The results showed higher activation energies for α compared to β. According to the modified nonparametric kinetic method, the decomposition mechanism revealed two distinct stages in both polymorphs, indicating one predominant chemical degradation process followed by a physical transformation process. [ABSTRACT FROM AUTHOR]

MnO2 particles were prepared by a hydrothermal method and characterized via the SEM imaging, XRD and FTIR analyses, showing that the individual particles were spherical and less than 1.0 μm in diameter but were clustered in α type crystal. The particles were then added into the n-octadecane to form a new class of phase-change energy storage composites. After that, the composite powder was wrapped into polyethylene by the suspension polymerization, forming microcapsules with an average size 4.9–5.6 μm in diameter. Eventually the morphology and thermal properties of the microcapsules were analyzed. No forming of chemical bond between the core material and the shell material was found during the microcapsule synthesis process. The latent heat and encapsulation efficiency of the microcapsules with addition of 0.5 mass% MnO2 particles in the n-octadecane were measured at 107.5 ± 1.3 J g−1 and 95.3 ± 1.2%, respectively, which are higher than the microcapsules with pure n-octadecane, measured at 84.9 ± 1.2 J g−1 and 75.3 ± 1.4%, respectively. The thermal conductivity of the n-octadecane microcapsules modified with 0.5 mass% MnO2 was enhanced by about 103.3% at 15.0 °C compared with the microcapsules without MnO2. Thermogravimetric and thermal cycling studies showed that the modified new microcapsules had good thermal stability. Such a modification provided an effective way to prepare phase-change energy storage microcapsules with better thermal properties and higher encapsulation efficiency. [ABSTRACT FROM AUTHOR]

The effects of the microwave treatment (MWT) and mechanochemical treatment (MChT) on the structure and physicochemical properties of precipitated zirconium oxide were investigated. The obtained materials were characterized using the N2 adsorption/desorption, thermogravimetry (TG, DTG, DTA), XRD and UV–Vis/DRS methods. Photocatalytic properties of the samples were also studied as regards the rhodamine B (RhB) degradation in the aqueous solution. The results show that the microwave and MChT, differing in mill rotation speed, temperature or treatment media, causes significant changes in the porous structure of the obtained samples. In most samples, the specific surface area increase was observed. The DTA and XRD results showed the formation of crystalline structure during MWT. As follows from the investigations, each way of modification results in the shift of the absorption edge toward higher wavelength values and causes photocatalytic degradation of RhB under UV irradiation and makes the obtained materials effective photocatalysts in the visible region. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) were used to examine the thermal decomposition of benzoyl peroxide (BPO). The interruption rescanning method was adopted to examine the effect of thermal history on the autocatalysis and thermal decomposition of BPO. Autocatalysis of BPO was verified through isothermal experiments. According to the DSC linear temperature rise data of BPO, mathematical methods were used to decouple and divide the peaks. Kinetic analysis using both the Kissinger and Friedman methods was performed. The initial decomposition temperature of the decoupled BPO ranged between 101.4 and 104.6 °C. The peak temperature was 110.9–126.2 °C, and the decomposition enthalpy was 229.7–524.2 J g–1. The apparent activation energy was higher in the coupling state than after decoupling one. The thermal history and isothermal experiments demonstrated that BPO possessed autocatalytic properties. Results revealed that initial decomposition temperature tended to decrease with the increase in interruption temperature. In addition, the apparent activation energy of BPO decreased following the thermal history analysis because of the formation of intermediate products from BPO in the thermal history experiments, which further promoted BPO's thermal decomposition. This effect led to a decrease in BPO's initial decomposition temperature. [ABSTRACT FROM AUTHOR]

Buckwheat starch is an alternative source to supply the high global demand for starch. The properties of starch can be modified through chemical and physical methods; one of them is the milling process, which can be considered as green method according with the green chemistry principles. Thus, this work aims to use the milling process and study its effects on thermal and crystalline properties of starch extracted from common buckwheat (Fagopyrum esculentum). It was observed in differential scanning calorimetry and X-ray powder diffraction that after the milling process, the starch losted its crystallinity and was pre-gelatinized. Nevertheless, the samples showed similar decomposition, dehydration and oxidation profiles, as observed by thermogravimetry and differential thermal analysis curves. The thermal stability did not show considerable difference (less than 5 °C) after the milling process. Moreover, the medium infrared spectroscopy showed that the milling process did not change the functional groups of starch. The morphology of the starch granules, as observed by scanning electron microscope presented surface roughness, and also the decrease of the average diameter of the modified starch was observed. [ABSTRACT FROM AUTHOR]

Purple taro tubers (Colocasia esculenta B. Tini) were used in extraction of starch by aqueous methodology. After isolation, the starch was characterised and subjected to physical modification by ultrasound technique, using different amplitudes (40, 50 and 60%). Starch characterisation was performed by thermal analysis, pasting properties, X-ray powder diffractometry and high-resolution scanning electron microscopy. The root presented high carbohydrate content and low protein and lipid content. The apparent amylose content obtained from native starch was 26.45%. From thermal analysis, three major mass loss events were observed for all samples, and due the modification, an increase in thermal stability was achieved. There was a decrease in transition temperatures during the gelatinisation process after sonicated samples. The degree of relative crystallinity was lower for modified starches. An increase in peak and final viscosities was observed for physically modified samples, accompanied by a decrease in pasting temperature. The size of the granules showed a slight decrease, and agglomerations were not observed in this studied amplitude range. [ABSTRACT FROM AUTHOR]

Silver, silver alloys, and composites with silver matrix are used mainly as electric contacts, circuit-breakers, and slide bearings. Contacts working conditions require as high as possible thermal and electrical conductivity, wear resistance during electric arc work, low susceptibility to tacking, and chemical stability. Unreinforced silver alloys do not meet those expectations, hence increasing interest in metal matrix composites. Reinforcing with ceramic particles improves tribological wear resistance and minimizes formability of silver alloys. At the same time, introduction of ceramic particles decreases thermal and electrical conductivity. In this paper, manufacturing method of silver-based composites reinforced with particles Al2O3, SiC, and glassy carbon was described. Composites were subjected to differential thermal analysis. Furthermore, thermal diffusivity measurements using laser flash method, as well as measurements of linear thermal expansion coefficient using dilatometric method were performed in order to determine heat conductivity of the prepared composites. [ABSTRACT FROM AUTHOR]

Thermal energy storage (TES) has been identified as a breakthrough concept in development of renewable technologies. However, the main challenges are related to the development of competitive heat storage materials. Despite the number of studies on heat storage materials, the determination of new alternatives for next generation technologies is still open. In this regard, this paper presents the results of an experimental study of the physical, thermal and mechanical properties of SiC-doped ceramics as potential materials for TES applications. Two kinds of SiC additives (high and low densities) were incorporated with different percentages into the clay matrix in order to produce ceramics via the extrusion process. The addition of low-density SiC (true density 3.16 g cm−3) led to the increasing of porosity with large pore sizes and the decreasing of bulk density. Therefore, the thermal and mechanical properties are decreased up to − 50% for flexural strength and − 15% for thermal conductivity when 20 mass% of low-density SiC was used. On the other hand, when high-density SiC (true density 3.42 g cm−3) was used, properties of the clay ceramic were strongly improved: i.e., increase in the bulk density, decrease in the porosity, increase in the thermal conductivity and increase in the flexural strength. The best material was found with the addition of 20 mass% of high-density SiC which had a thermal conductivity of 1 W m−1 K−1, a specific heat capacity of 0.62 kJ kg−1 K−1 and a mechanical strength of 19.6 MPa. It also showed a high thermal stability after 20 successive heating/cooling cycles. Hence, this study provided a useful insight into how the SiC modified the microstructure and properties of fired clay ceramics. Thus, the current results suggest that clay ceramics with high-density SiC addition are promising materials for thermal energy storage applications. [ABSTRACT FROM AUTHOR]

The building sector has been showing great interest in incorporating technologically advanced materials with lightweight, ecofriendly, high strength, and stiffness properties in flooring, roofing, and partition walls, etc. In addition to the mechanical properties, these materials should have good thermal properties as well. In response to these requirements, an attempt has been made to study the thermal behavior of green composite sandwich made of flax and agglomerated cork. Composite sandwiches were fabricated by using flax as skin reinforcement and agglomerated cork as core with different densities as 240, 280, and 340 kg m−3 using vacuum bagging method. Glass was also used as skin reinforcement for manufacturing composite sandwiches for comparison purpose. Experiments were conducted to predict thermal properties, viz. thermal conductivity, thermal expansion, flammability, and thermal stability. The experimental results show that the lowest thermal conductivity of 0.03 W m−1 K−1 was observed in flax-based composite sandwich having core density of 240 kg m−3; the lowest thermal expansion of 29.2 × 10−5 °C−1 was observed in glass-based composite sandwich having core density of 340 kg m−3; the highest value of time to ignition was 12 s, and minimum propagation rate was 0.25 mm s−1 in flax-based composite sandwich having core density of 340 kg m−3; The highest initial degradation temperature was 362 °C for glass-based skin and 263 °C for cork having density of 240 kg m−3. [ABSTRACT FROM AUTHOR]

This work aims to determine the nickel selenate hexahydrate thermal behavior by simultaneous thermogravimetry–differential thermal analysis and differential scanning calorimetry and characterize its thermal intermediates decomposition. Moreover, at 25 °C, this material is a green-colored compound; however, with the temperature increase (until 420 °C), a color change from yellowish green to yellowish orange and finally to yellow was observed. This characteristic is due to the water molecules release, changing the ultraviolet–visible/near-infrared spectroscopy analysis absorption spectra and consequently modifying the crystal structure, as confirmed by X-ray powder diffraction, and resulting in visual changes in photo-DSC. The new data are essential to determine the better conditions to use this material as a precursor in synthesis and also to use it in future applications. [ABSTRACT FROM AUTHOR]

Fly ash recycling reduces the amount of waste to be treated or disposed in landfills, allowing both to decrease the environmental damage and to save the costs of transport and disposal of waste. Systems with different percentages in mass of fly ash (20, 50 and 70 mass%) and the remaining part of pure metakaolin were synthesized. The effect of fly ash on the mechanical and thermal properties of a new geopolymer has been investigated in this paper. Fourier transform infrared spectroscopy has allowed us to verify the bonds formation between the geopolymeric matrix and the fly ash. The consolidation of the materials has been confirmed by pH and conductivity at up to 28 days of hardening. Dynamic mechanical analysis, differential scanning calorimetry and thermogravimetric analysis were performed in order to evaluate the thermo-mechanical performance of this new geopolymer in comparison with its counterpart pure geopolymer. [ABSTRACT FROM AUTHOR]

The aim of the present work is to study the influence of graphite particles on the molecular structure of the hydrogel composed of amylopectin/poly(vinyl alcohol) hybrid matrix by thermogravimetric analysis, differential scanning calorimetry and dynamic mechanical thermal analysis techniques. Hybrid amylopectin/PVA hydrogels were prepared with and without particles, and their properties were measured. The results of the analyses showed that the presence of particles in the reaction medium decreased the formation of cross-links among macromolecular chain segments, modifying thermal and mechanical properties of hydrogel. Raman spectroscopy confirmed the obtaining of graphitic carbon particles. Besides, optical microscopy and atomic force microscopy showed a large distribution in particles dimensions. [ABSTRACT FROM AUTHOR]

Different types of phosphorus containing halogen-free flame retardants (FRs) were added to an epoxy-dicyandiamide resin formulation in order to study to which extent they affect its glass transition temperature (Tg), tensile properties, thermal stability and burning behavior of the resin. For this purpose, an additive-type FR (ammonium polyphosphate encapsulated in melamine resin, MAPP) and two reactive-type FRs i) a commercial epoxy resin pre-reacted with 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide, (DOPO), and ii) a phosphorus containing hardener (poly(m-phenylene methylphosphonate), (PMP) were used. It was observed that the addition of additive-type FR did not affect in great extent the Tg and provided a V-0 rating in UL94 test at low loadings. The addition of reactive-type FRs (DOPO and/or PMP), however, modified the structure of the chain network resulting in lower crosslink density as a consequence of their higher equivalent mass, but achieving also with low PMP content V-0 rating. [ABSTRACT FROM AUTHOR]

The thermal behavior of new and aged low-density polyethylene (LDPE) insulations was investigated using an SDT Q600 thermal analyzer. The activation energy and pyrolysis reaction model were estimated using the non-isothermal and masterplots methods. The thermal degradation processes present different behaviors of the LDPE insulations before and after thermal aging. The thermogravimetric curves shift to the direction of higher temperature, for the aged LDPE insulation. The values of activation energy evaluated using the Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) methods are almost same. However, the activation energy values estimated by the Friedman method were slightly higher than those obtained using the KAS and FWO methods. The suitable pyrolysis reaction models of the new and aged LDPE insulations were attributed to the "Contracting area" (R2) model, which was determined using the generalized masterplots method. In addition, the pre-exponential factor and compensation effect are discussed. Finally, it should be stressed that the aged LDPE insulation generally pyrolyzes more weakly and with more difficulty than the new insulation, i.e., the ignition and flame spread of aged wire in old buildings are not relatively easy. [ABSTRACT FROM AUTHOR]

A series of quaternary hybrid kenaf (K) flour-PP nanocomposites, such as PP/KF/MAPP/GNP/MgOH (K-GNP-MgOH), PP/KF/MAPP/GNP/APP (K-GNP-APP) and PP/KF/MAPP/GNP/MgO (K-GNP-MgO) filled with exfoliated graphene nanoplatelets (GNP)-3 phr acting as adjuvant in combination with mineral flame retardants, 20 mass/% magnesium hydroxide (Mg (OH)2) and 20 mass/% magnesium oxide (MgO), and 20 mass/% intumescent ammonium polyphosphate (APP), respectively, were prepared through melt extrusion using co-rotating twin screw extruder. The resulting quaternary nanocomposites were characterized in terms of flame retardancy, thermomechanical, thermal conductivity, thermal behavior, heat deflection temperature (HDT), and mechanical, morphological and structural properties. Mass loss calorimeter data revealed a significant reduction of peak heat release rate, total heat release, effective heat of combustion, mass loss rate and delayed time to ignition due to GNP-MgOH, GNP-MgO and GNP-APP synergistic mechanism in hybrid nanocomposites, respectively. The effective thermal conductivities and HDT of quaternary nanocomposites were found to significantly increase. DSC results revealed enhanced crystallization temperatures with reduced degree of crystallinity, while melting points remained stable. [ABSTRACT FROM AUTHOR]

In this work, polyethylene glycol nanocomposites containing different nanofillers (namely hydrotalcites or boehmites, at 5 mass% loading) were prepared by melt compounding. Their morphology and microstructure were assessed by means of SEM and XRD analyses. The interactions between the different nanofillers and the polymer matrix were evaluated by performing rheological, differential scanning calorimetry and thermogravimetric analyses. The two types of nanofillers were found to differently interact with the polymer matrix. In particular, the rheological tests performed on the systems containing hydrotalcites revealed that the presence of nanofillers affects the relaxation dynamics of the macromolecular chains, in a remarkable way. Conversely, the crystallinity degree of the polymer was influenced by the presence of boehmites only, whose nucleating capability was found to depend on their average size. Finally, the thermo-oxidative stability of the polymer matrix was generally improved by the selected nanofillers, with the only exception of the organo-modified hydrotalcite that significantly anticipated the polymer degradation. [ABSTRACT FROM AUTHOR]

Although gypsum belongs to the low-energy environmentally friendly binders, its wider applications in building constructions are limited due to the negative effect of moisture on its mechanical properties. When calcined gypsum (CaSO4·1/2H2O) transforms into its hydrated form (CaSO4·2H2O), it is partially soluble in water and it has a relatively low strength. This problem can be resolved when gypsum is used as a part of binary or ternary binders. In this paper, a system consisting of calcined gypsum, lime, and silica fume is presented as a functional solution for a wider utilization of gypsum in wet environments. For this purpose, the newly designed materials were stored in different environments (laboratory conditions in air or water) up to 182 days. The effect of silica fume on the hydration process and the growth of the main products is evaluated by using differential scanning calorimetry and thermogravimetry in the temperature range from 25 to 1000 °C with a heating rate of 5 °C min−1 in an argon atmosphere. The carbonation level of studied materials is also evaluated. Besides this, the information about the thermal stability of studied materials is provided. These results are supported by evolved gas analysis, X-ray diffraction, and scanning electron microscopy. The basic physical and mechanical properties are determined to provide more detailed information about the behavior of the designed materials under various conditions at selected days of hydration. The addition of silica fume to the gypsum-lime system activates the pozzolanic reaction of the analyzed pastes, which is proved by the presence of the CSH phase and by the consumption of portlandite in the mixtures. Wet environment speeds up the hydration processes and prevents samples from carbonation. [ABSTRACT FROM AUTHOR]

The increasing numbers of used tyres constitute a serious threat to the natural environment. The progress made in recent years in the management of polymer wastes has meant that used tyres are starting to be perceived as a potential source of valuable raw materials. The objective of this research was to study the burning characteristics of various used tyres. Waste tyres of seven producers have been tested. In order to understand thermal properties, three different assessment methods were used to study the behaviour of the material: (1) determination of ash content, (2) flame propagation test and (3) thermal analysis. The ash content test can be used to analyse how many percentage of the tyre leaves in the form of smoke or gas. The flame propagation test gives information on the duration of the combustion and the degree of smoke generation. Results of thermal analysis (TG/DTG/DTA) show the degree and speed of the mass changes of the different tyre types, the enthalpy change and the temperature of the reactions during heating. By combustion tests, it was modelled how the tyres behave when they are burning in incineration plant. In terms of recycling, those tyres are better, which have low decomposition temperature and smaller residual mass. This also means that maximum combustion heat can be recovered. After burning, the samples showed the greatest difference in loss of mass; however, all are different in flammability, afterglow time and their thermal stability. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, silver nanoparticles were coated on different coir fibers to see their improvements in thermal behavior against the raw coir fiber. The fibers taken for the study are raw coir, parent coir (PC), modified coir-1 (MC1), modified coir-2 (MC2), silver nanoparticles (AgNPs)-coated PC and MC fibers. All the fibers were subjected to FESEM along with line scans of EDS, thermo gravimetry, differential thermal gravimetry and differential scanning calorimetry (DSC) analyses to observe the size of AgNPs and their responses to thermal behaviors, respectively. FESEM along with line scans of EDS shows the size of AgNPs varies from 40 to 210 nm in the coated fiber. The temperature of degradation (Tf (°C)) of AgNPs-coated coir increases significantly compared to PC and MCs. DTA and DSC analyses indicate higher thermal stability of silver-coated fibers over PC and MCs. In general, all the fibers show higher thermal stability over raw fiber and when coated fibers were compared, the thermal stabilities follow the order MC2 > MC1 > PC. It was also found that increase in the concentration of silver during coating further increases the thermal stability in all the cases without changing the order.Graphical Abstract: [ABSTRACT FROM AUTHOR]

This study aims to assess the thermal properties of mixtures of sugarcane bagasse and iron(III) nitrate in the following proportions (mass/mass): 1/2, 1/1, and 2/1, using thermogravimetry/differential thermogravimetry and differential thermal analysis. These thermoanalytic techniques were performed to assess the best temperatures for the heat treatment of the mixtures for the subsequent production of the carbonaceous material/iron oxide composites and their behavior at different temperatures. According to thermal analysis, the decomposition profile of the mixture depends on the ratio of sugarcane bagasse to iron nitrate (BC/NF). The synthesized composites were characterized by X-ray diffraction, proving the formation of phases established from thermal analyses performed at 400, 500, and 600 °C. It was concluded that composites of the precursor mixtures may be produced to have different and interesting properties according to their application in sewage treatment processes such as adsorption. [ABSTRACT FROM AUTHOR]

Computer-aided cooling curve thermal analysis technique was used to investigate microstructure and phase evolutions in Mg-5Zn alloy containing 0-1.5 mass% yttrium (Y) solidified at 0.7 °C s cooling rate. Optical and field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction analysis were performed to characterise microstructure of the cast alloys. The observations revealed that a considerable refinement, calculated as over 74%, was occurred in the alloys with increasing Y content to 1.5 mass%. The first derivative curves revealed two peaks corresponding to α-Mg and MgZn for the binary Mg-5Zn alloy. The results also showed the evolution of three peaks related to the α-Mg, W-phase (MgZnY) and I-phase (MgZnY) in the Mg-5Zn- xY alloys. The nucleation temperature of both α-Mg and I-phase decreased slightly by increasing Y content. In addition, the solidification range and total solidification time increased by 44.4 and 50% with increasing Y content. [ABSTRACT FROM AUTHOR]

Thermal and rheological properties of plant-based natural filler-reinforced polyethylene bio-composites applying various filler loadings as well as the impacts of the different compatibilizers were investigated by means of differential scanning calorimetry and dynamic mechanical thermal analysis (DMTA). As lignocellulosic materials, such as rice-husk flour and wood flour, are eco-friendly biomaterials and a thermoplastic polymer, for example, high-density polyethylene, has good physico-mechanical and thermal properties, therefore their bio-composites can combine and utilize these two advantages at the same time. The temperature of the α-relaxation ( T ) slightly increased and melting temperatures ( T ) of the matrix polymer in the case of the studied bio-composites did not shift significantly as the filler loading changed, because the rigid interphase hinders the motion of polymer segments resulting in the increase in T and only weak interactions developed at the interface between the matrix polymer and the reinforcement in the case of non-compatibilized composites. However, compatibility between the reinforcement and the matrix polymer was enhanced by incorporating compatibilizers, which further improved stiffness. From the DMTA experiment, the reinforcements result in composite samples having higher storage modulus ( E′) than the neat polymer sample, indicating that incorporating lignocellulosic filler increased their stiffness. [ABSTRACT FROM AUTHOR]

Several polypropylene (PP) reactor blends were synthesized using homogenous binary metallocene catalytic systems composed of isospecific (I): rac-MeSi(2-Me-4-Ph In)ZrCl and oscillating (II): (2-Ph In)ZrCl catalysts. The reactor blends were analyzed using gel permeation chromatography and differential scanning calorimetry. All the blends showed bimodal molecular weight distribution, and the MWs were shifted toward higher values compared with PPs synthesized with each of individual catalysts showing some probable interactions between the two active sites. Self-nucleation and annealing treatment on hexane-insoluble-heptane-soluble parts of the PP reactor blends showed that as the II/I molar ratio increases from 0 to 40 in the binary system, multiplicity of the endotherm peaks increases from 1 to 7, which is indicative of the presence of various lamellar thicknesses in the samples. Wide-angle X-ray scattering studies on the PP reactor blends confirmed that the blends have isotacticities and crystallinities between those of polymers obtained by the individual catalysts. [ABSTRACT FROM AUTHOR]

Films based on blends with different gelatin (GEL) and chitosan (CH) (GEL100, GEL75:CH25, GEL50:CH50 and CH100) ratios, with and without ethanolic extracts (boldo of Chile, guarana, cinnamon and rosemary), were prepared by casting technique. The thermal behavior of all films was studied by DSC analysis, and glass transition ( T ) temperature, melting temperature ( T ) and melting enthalpy (Δ H ) were determined. In addition, crystallinity ( X) was calculated. In the first scan, GEL100 presented higher T (81.9 ± 0.5 °C), Δ H (22.6 ± 0.2 J g) and X (36.4 ± 0.3%) values than CH100 ( p ≥ 0.05). In the second scan, the T of GEL100 films dislocated a lower temperature (28.2 ± 1.1 °C). Films based on blends (GEL75:CH25 and GEL50:CH50) without extracts exhibited a T of around 50 °C and intermediate T and X values in the first scan, which significantly decreased as CH increased (GEL50:CH50: T = 74.3 ± 1.0 °C, Δ H = 16.6 ± 0.1 J g and X = 15.7 ± 0.1%) ( p ≥ 0.05), showing good compatibility among these biopolymers. Furthermore, ethanolic extracts addition decreased significantly the Δ H and X of films based on blends with 50% of chitosan polymer in the formulation ( p ≥ 0.05), showing intermediate values between pure biopolymers. [ABSTRACT FROM AUTHOR]

In this work, the structure and thermal properties of aluminosilicate fritted glazes in SiO-AlO-CaO-MgO-NaO-KO-ZnO system with (4.0 mol%) and without addition of ZnO were examined by GIXRD, FTIR, MAS-NMR and thermal methods (DTA, DIL). It has been found that the all experimental glazes are amorphous material (transparent glazes). On the base of spectroscopic investigations, it was found that zinc ions exist in the network glazes in the octahedral coordination-Zn ions play a network modifier role in structure of glazes. An analysis of the data obtained from thermal tests showed that addition of ZnO into chemical composition results in decrease in glass transition temperature value ( T ) for all glazes (DTA, DIL). The coefficient of thermal expansion ( α) is decreased as the whole measurement range for one series of fritted glazes. [ABSTRACT FROM AUTHOR]

Phase relationships in the Tb-Al-Si system have been established and experimentally studied at 500 °C. The main experimental techniques used were scanning electron microscopy, electron microprobe analysis and X-ray powder diffraction. Some samples have been analyzed by differential thermal analysis. Six ternary compounds form in the system: the five ternary structures τ-TbAlSi, τ-TbAlSi, τ-TbAlSi, τ-TbAlSi and τ-TbAlSi have been confirmed, while the compound τ (TbAlSi, crystal structure oI10-WCoB) was not previously known in the literature for the Tb-Al-Si system, but its formation was known in other R-Al-Si (R: Dy,Ho,Er,Tm) systems. The two ternary phases τ-TbAlSi and τ-TbAlSi show a homogeneity range, at constant Tb content. A number of boundary binary phases dissolve the third element, at 500 °C, forming ternary solid solutions extending into the ternary field: Tb(AlSi) (0 ≤ x ≤ 0.13), Tb(AlSi) (0 ≤ x ≤ 0.02), Tb(AlSi) (0 ≤ x ≤ 0.08), Tb(AlSi) (0 ≤ x ≤ 0.10), Tb(AlSi) (0 ≤ x ≤ 0.10), Tb(AlSi) (0 ≤ x ≤ 0.24) and Tb(AlSi) (0 ≤ x ≤ 0.15). The Al and Si richest part of the system is characterized by the coexistence of three phases (Al), (Si) and TbAlSi (τ); this behavior is common to all the known R-Al-Si phase diagrams. The phases are involved in the ternary eutectic equilibrium L ⇄ (Al) + (Si) + TbAlSi close to the binary eutectic point of the Al-Si binary system. Experimental measurements confirm the ternary eutectic reaction at a temperature of 565 °C. [ABSTRACT FROM AUTHOR]

We investigated the effect of three different quenching medias on martensitic transformation, thermodynamic parameters, phase equilibria, microstructural properties and microhardness values of high-temperature Cu-13.2Al-5.1Fe-1.2Ti (mass%) shape memory alloy by means of differential scanning calorimetry, X-ray diffraction, optical microscopy, scanning electron microscopy and Vicker's microhardness measurements. Thermal analysis indicated that the transformation temperatures and thermodynamic parameters of the alloy changed depending on quenching conditions and the transformation temperature range was proportional to the cooling rate. It was found that the step-quenching treatment improved the operation temperature of alloy. Structural analysis showed that the phase components of the alloy were not affected significantly by the quenching conditions, but elemental analysis also revealed that high cooling rate leads to very significant changes on chemical compositions of the phase components. From microstructural investigations, it was found that the microstructure of alloy included a great number of voids having different sizes and forms and also different precipitates grow in these voids. In particular, it was seen that the step-quenching process caused the formation of new voids in the microstructure. Vicker's microhardness measurements revealed that the microhardness value of the alloy was not influenced markedly by the quenching treatments. [ABSTRACT FROM AUTHOR]

The effects of tannin-cadmium complex on the thermal and oxidation stability of PVC were investigated. Tannin-cadmium complex has been successfully synthesized and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray analysis techniques. Thermal degradation and thermal oxidation-degradation behaviors of PVC formulations obtained by thermal mixing method were evaluated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) under inert and oxidizing atmospheres, respectively. The obtained results such as the onset, maximum and final degradation temperatures as well as the degradation rates from TG and DTG curves revealed that the tannin-cadmium has significant impact on the thermal stability of PVC. The experimental data of PVC thermal degradation obtained by DSC studies also clearly showed that the stabilizing efficiency of tannin-cadmium is superior to that of synthetic thermal stabilizer applied as reference. Due to the HCl scavenging and antioxidation activities of tannin-cadmium, the global thermal and morphological properties of PVC stabilized by this product proved the best in morphology and stabilization properties both against thermal and thermal oxidation-degradations. Graphical abstract: [ABSTRACT FROM AUTHOR]

In this study, silica sol (SiO sol) and KCO were used as flame retardants for wood. The synergistic effect of SiO sol and KCO on the flame retardancy, leaching resistance, and thermal properties of wood was investigated. The limiting oxygen index results revealed a significant improvement in the flame retardancy and leaching resistance of the wood sample treated with KCO and SiO sol using the double bath technique. The thermal analysis results showed that the synergistic effect of KCO and the SiO sol effectively prolonged the degradation of the wood sample during the charring stage and improved the stability of the char residue. The thermogravimetry-mass spectrometry analysis and scanning electron microscopy results showed that KCO catalyzed the degradation reaction of the wood sample at lower temperatures resulting in an increase in the water and carbon dioxide output, and the SiO sol formed a compact and melted barrier on the surface of the char residue, which hindered the transfer of heat and combustible gases in the condensed phase. Thus, the combination of KCO and SiO sol proves to be a promising flame-retardant system for wood. [ABSTRACT FROM AUTHOR]

In this study, 2,4,6-trichlorophenyl methacrylate (TClPhMA) was synthesized by the reaction of methacryloyl chloride with 2,4,6-trichlorophenol in the ice bath condition. The obtained monomer was extracted by chloroform and purified on a chromatography column. In order to confirm the chemical structure of the new compound, spectroscopic studies (ATR-FTIR, H NMR, C NMR and GC-MS) were undertaken. The obtained TClPhMA was copolymerized with commercially available monomers such as methyl methacrylate, styrene, 1,4-divinylbenzene and 2-hydroxymethyl methacrylate. The copolymers were obtained by bulk polymerization in which benzoyl peroxide was used as a free radical initiator. The thermal properties of the copolymers were investigated by differential scanning calorimetry and thermogravimetry. [ABSTRACT FROM AUTHOR]

This study comes to complete the initial investigation of the liquid crystalline properties of 4-[(4-chlorobenzyl)oxy]-3,4′-dichloroazobenzene (CODA). Here, the thermal analysis of CODA dye was performed in air flow and nitrogen flow atmospheres by means of simultaneous thermogravimetry TG, derivative thermogravimetry DTG, differential thermal analysis DTA and differential scanning calorimetry DSC; differences between the two steps of the thermal degradation of CODA related to the two experimental atmospheres were observed. Drops cast and spin coating techniques were used for nanostructuring CODA on platinum (Pt) substrates; the deposited materials were characterised by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Exotic crystalline nanowires of CODA were obtained as function of used deposition technique, while the deposition time decisively influenced their features. The present results advocate for employing these materials as template matrices for producing high-aspect-ratio inorganic nanomaterials (i.e. Au) in the form of nanotubes, nanowires, nanorods or nanoparticles with enhanced functional properties. [ABSTRACT FROM AUTHOR]

Leuco dye-developer-solvent composites with thermochromic properties were studied. The applied 1-dodecanol solvent shows β crystalline, α solid (rotator) and liquid phases. The inclusion of the crystal violet lactone dye increases transition temperatures of all phases and strengthens the α phase. The benzyl 4-hydroxybenzoate developer causes opposite effects and prevents the appearance of the α phase. These consequences combine in ternary composites, where lower transition temperatures were obtained as in the solvent, but the α phase is formed more likely as expected due to the presence of the developer. The hydration of the composite strengthens its crystalline network, but makes α phase more unstable. The thermal properties were related to the temperature-dependent colour. Composites with well-resolved α and β phases at cooling show a typical colour hysteresis. If only weak α phase or none at all was found in DSC curves, the colour hysteresis has an unusual shape with heating and cooling curves crossing each other. The hydration of the composite changes the colorimetric properties in accordance with the relation found for anhydrous composite. More conclusions and interrelations between the two properties require application of other analytical methods. [ABSTRACT FROM AUTHOR]

Borophosphate glasses of the BaO-BO-PO ternary system were prepared and studied within the large glass-forming region of the system. Fourteen investigated glass samples of barium borophosphate glasses were discussed for a comparison of the compositional trends in their properties in four compositional series such as A: (100 − x)Ba(PO)- xBO, B: 40BaO- yBO-(60 − y)PO, C: (50 − z)BaO- zBO-50PO, and D: (60 − w)BaO- wBO-40PO. Changes in glass density and molar volume primarily depend on the BaO content in the glasses. The thermal properties were studied with a differential thermal analysis, hot-stage microscopy, and dilatometry. Glass transition temperature increases with a rising BO content most rapidly in the glass series A and B. It reaches its maximum in these series for the glasses containing 20-30 mol%, where the glass network represents a 3D structure interlinked with P-O-B, P-O-P, and B-O-B bridges. The thermal expansion coefficient decreases, in contrast, with the increasing BO content in these ternary glasses as well as their chemical durability. The crystallization of these glasses, in the samples with a low BO content, results in the formation of barium metaphosphate BaPO. Certain crystallized samples also contain a small amount of BPO, and diffraction lines of ternary compounds BaBPO and BaB(PO) were revealed in a number of samples. A new compound of the composition BaBPO was identified in the crystallized glass 50BaO-10BO-40PO. [ABSTRACT FROM AUTHOR]

A characterization study of the samples of hair and animal keratin was performed to enhance the understanding of the thermal properties of the hair of the main ethnic groups. The mechanical, physicochemical and thermal properties of Caucasian, Oriental and African-ethnic hair have been widely described; however, this research adds knowledge about the thermal and analytical properties of these types of hair. To achieve such objective, thermogravimetry (TG), differential scanning calorimetry (DSC) and elemental analysis techniques were employed. To estimate the thermal stability of the hair samples, TG carried out a non-isothermal TG method kinetic study. The results obtained of TG/DTG showed similarity between the samples of hair and animal keratin, for all the events of thermal decomposition involved with mass loss. African-ethnic hair sample presented the lower thermal stability. This fact can be related to the data literature that showed that this type of ethnicity has the less tensile strength and breaks more easily than others types of the hair. Oriental hair sample showed to be, from the non-isothermal TG method kinetic study, more thermally stable than the other samples. DSC results showed that the hair samples presented melting/denaturation of the crystalline phase; however, animal keratin sample did not present such. [ABSTRACT FROM AUTHOR]

The comprehension of the thermal phenomena of milk powders is still object of investigation, being the result of complex interactions among their components as affected by composition, storage conditions and manufacturing. For a better understanding of the above-mentioned phenomena, the effect of the single milk component (proteins, casein, whey proteins and lactose) on the thermal behavior of whole and skim milk powders was investigated by means of DSC during heating. Whole milk powders exhibited two endothermic transitions related to the fat crystal melting at temperatures between 276 and 325 K. Glass transitions of lactose (309 K) and caseins (347-358 K) with their enthalpy relaxation phenomena were observed in the milk derivatives, being instead highly influenced from a and composition in the dried milk. At higher temperature (353-473 K), different exothermic events, such as lactose crystallization, Maillard reaction and/or decomposition of carbohydrates and proteins, were recognized in the curves of milk and protein derivatives powders. A good explanation of the thermal properties of the milk powders was obtained from the comparison with the heating curves of the single components. Lactose resulted the key component of many thermal events, being the molecule more influenced by the environmental conditions. These results can lead to a better comprehension of the physical properties of the milk powders, fundamental for their functional and commercial quality. [ABSTRACT FROM AUTHOR]

Three new complexes of nickel(II) prepared from azo-containing salicylaldimine ligands with nickel(II) acetate. The prepared complexes were characterized by IR, UV-Vis, elemental analysis, fluorescence and H NMR spectroscopy. Thermal properties and decomposition possibilities of nickel(II) complexes are suggested. The interpretation of all thermal decomposition stages has been evaluated. Electronic structure of the complexes indicated that the absorption between 450 and 528 nm, which were the lowest energy transfers in the complexes, was attributed to the metal-ligand charge-transfer transitions. The redox behavior of nickel(II) complexes studied by cyclic voltammetry. All the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. [ABSTRACT FROM AUTHOR]

In this paper synthesis, spectroscopic and thermal characterization of the new monomer: 2,7-di(methacyloyloxy)naphthalene (2,7-NAF.M) is presented. Its structure was confirmed by the spectroscopic methods: H NMR, C NMR, ATR-FTIR and GC-MS. The resulting compound was copolymerized with the commonly used, commercial vinyl monomers: styrene, methyl methacrylate, 1,4-divinylbenzene, N-vinyl-2-pyrrolidone and 2-hydroxyethyl methacrylate. For comparison, the homopolymer (2,7-NAF.M-HOMO) was also prepared. Dibenzoyl peroxide as a thermoinitiator was used in the copolymerization process. Thermal properties of 2,7-NAF.M, and their copolymers were determined by differential scanning calorimetry and thermogravimetric analysis for both inert and oxidative atmospheres. The influence of vinyl monomers on the physicochemical properties of the obtained copolymers was discussed. Additionally, photoluminescent properties of the obtained monomer were examined. [ABSTRACT FROM AUTHOR]

In this study, the adsorption of methane (CH) on zeolite from Sivas-Yavu region of Turkey and on forms treated with 1 M heavy metal nitrate solutions (AgYZ, Cu YZ and FeYZ) and 1, 3 and 5 M HCl solutions (HYZ, 3HYZ and 5HYZ) was investigated. Adsorption isotherms of methane by zeolite minerals were obtained using volumetric apparatus at 0 and 25 °C up to 100 kPa. Natural and modified samples were characterized by X-ray fluorescence, X-ray diffraction (XRD), thermogravimetric/differential thermal analysis and nitrogen adsorption methods. Quantitative XRD analysis showed that the major components of the natural zeolite were clinoptilolite and mordenite, together with minor amounts of quartz, feldspar and clay mineral. Among all the modified forms, Fe-form of zeolite sample exhibited the highest adsorption capacity for CH at both temperatures. The adsorption capacity of CH on FeYZ increased from 0.597 to 0.796 mmol g as the temperature decreased from 25 to 0 °C. In addition, uptake of CH on the adsorbents decreased with increasing acid concentrations. [ABSTRACT FROM AUTHOR]

Vitrification is the most effective method of hazardous waste immobilization. Toxic elements are incorporated into a glass structure. Iron alumino-phosphate glasses are presently being considered as a matrix for storage of a radioactive waste which cannot be vitrified using conventional borosilicate waste glasses. Influence of NaSO as a one of components such the waste on thermal properties and crystallization ability of 60PO-20FeO-20AlO glass was studied. It was observed that NaSO decreases transformation temperature and increases Δ C. The glass characteristic temperatures, glass crystallization ability and crystallizing phases were determined. NaSO increases the glass crystallization ability which could be related with Δ C heat capacity accompanying glass transition changes. The glass internal structure rebuilding accompanying the sodium content increase is considered. The obtained results were compared with structural model previously developed for 60PO-40FeO glass and showed the structural similarity between these glasses. [ABSTRACT FROM AUTHOR]

New zinc(II) 2-aminobenzoate complexes with general formula Zn(2-NHbenz)(L) (where 2-NHbenz is 2-aminobenzoate, and L is phenazone, N-methylnicotinamide, nicotinamide and isonicotinamide) were prepared and characterized by elemental analysis and by FTIR spectroscopy. The stability and thermal behaviour of the compounds were studied by thermal analysis techniques (TG/DTG, DTA), and the decomposition reactions were proposed. The decomposition of the studied compounds is always a multistep process, when after the release of the bioactive ligand, 2-aminobenzenecarbaldehyde, 2-aminobenzene and carbon dioxide were evolved. The solid intermediate compounds were confirmed by FTIR spectroscopy, and the volatile products were identified by mass spectrometry. The final solid product of thermal decompositions was zinc oxide, which was confirmed by XRD and FTIR analysis. The non-isothermal kinetic investigation of Zn(2-NH2benz)(mnad) decomposition in air was performed by means of isoconversional methods, for a better understanding of the undergoing processes. The antimicrobial assay was carried out comparatively for the investigated compounds; they have higher biological activity towards Staphylococcus aureus, Escherichia coli and Candida albicans in comparison with zinc(II) 4-bromobenzoates. [ABSTRACT FROM AUTHOR]

The thermodynamic analysis of the thermal decomposition reaction of carbonates showed that the temperatures of thermal stability of dolomite and magnesium carbonate are very similar. Kinetics of isothermal and non-isothermal decompositions of natural dolomite in air atmosphere were investigated. Under the examined conditions, dolomite decomposed in a one-stage process. The final solid products of dolomite's decomposition were calcium and magnesium oxides. The average value of isoconversional apparent activation energy of non-isothermal decomposition was 205.60 kJ mol. The kinetics of decomposition can be described by the power-law model P2/3 with ln( A) = 20.98 for the extent of reaction α < 0.77 and by two-dimensional diffusion model D2 with ln( A) = 21.12 for α > 0.77. [ABSTRACT FROM AUTHOR]

The synthesis and thermal research of a pyridine-containing polyimide were reported in this work. The corresponding diamine monomer, 2,6-bis(4-(4-aminophenoxy)phenyl)-4-phenyl pyridine (BApPP), was synthesized through combining the nucleophilic aromatic substitution with modified Chichibabin reaction and hydrazine monohydrate reduction. Fourier transform infrared spectroscopy (FT-IR), H nuclear magnetic resonance spectroscopy (H-NMR), and elemental analysis were used for chemical structural characterization, the results identified the chemical structures of the monomer and polymer. The melting behavior of the diamine monomer was studied by differential scanning calorimetry (DSC). The thermal properties of the resulting polyimide were investigated from DSC and thermo gravimetric analysis together. The results indicated the resulting polyimide exhibited excellent thermal stability, with the glass transition temperature around 275.0 °C and the initial mass loss of sample beyond 487.5 °C. The thermal decomposition process was analysed by combining the Avrami-Erofeev dynamic model and Ozawa-Flynn-Wall method. The coefficients of the thermal decomposition kinetics equation were calculated, and the final equation was obtained by polynomial fitting method. [ABSTRACT FROM AUTHOR]

Hydrazinated nickel cobalt zinc ferrous fumarate precursor has been synthesized and decomposed autocatalytically to NiCoZnFeO. The thermal decomposition behavior of the precursor has been investigated by thermogravimetric (TG) and differential thermal analysis (DTA). The chemical composition was assigned to precursor based on chemical analysis, TG-DTA, infrared (IR), isothermal mass loss, and total mass loss studies. The X-ray powder diffraction of the decomposed precursor confirms the formation of monophasic nickel cobalt zinc ferrite, and IR spectrum exhibits two peaks in the region of 340-420 and 550-660 cm characteristic of spinel ferrites. The average grain size evaluated by TEM is found to be 15-20 nm. The electrical DC resistivity measurement was carried out with respect to temperature using two-probe method and dielectric properties as a function of frequency. The high dielectric constant values found at lower frequencies were due to nanosize nature of the 'as prepared' ferrite. The Curie temperature of the 'as-prepared' NiCoZnFeO determined by alternating current susceptibility measurements was found to be 380 °C. [ABSTRACT FROM AUTHOR]

Nowadays, there is the widespread use of clay minerals as fillers in polymeric materials. One of the most widely used mineral is montmorillonite belonging to the smectite. We have prepared organically modified clays using two different types of accelerators TP and ZDT for sulfur vulcanization. Intercalation of these accelerators into the interlayer of clays was performed using a gas reaction at room temperature. They were examined (characterized) by thermal analysis (DTA, TG), X-ray analysis, and infrared spectroscopy (FTIR). [ABSTRACT FROM AUTHOR]