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The current work concerned the thermal characteristic of Se0.75−xTe0.25Agx (0 ≤ x ≤ 0.1) chalcogenide glasses. Under non-isothermal conditions, differential scanning calorimetry has been used to evaluate the thermal stability of these compositions throughout the temperature identification of the glass transition, Tg, the initial crystallization temperature, Tin, the peak crystallization rate, Tp, and the melting temperature, Tm. Also, the kinetic factor Kr(T) is specified as a further indication of thermal stability. It was found that the Se0.71Te0.25Ag0.04 has the greatest capacity to form glass and the greatest glass thermal stability between these compositions. These findings have been explained using the average coordination numbers of the tested compositions. Also, in this work, we studied the crystallization kinetic of Se0.75−xTe0.25Agx (0 ≤ x ≤ 0.1) thick films via measuring the sheet resistance, Rs whose thickness is 1000 nm at heating rate 5 K min−1, in the 300–630 K temperature range. Two significant regions might be detected in the sheet resistance curve using this range and by considering how sheet resistance is derived according to temperature, one crystallization area is clearly present for the investigated films. The Avrami index was measured for both alloys and thick films. [ABSTRACT FROM AUTHOR]

To evaluate thermal properties and promote the application of novel N-oxide amphoteric energetic compound 4,6-diamino-3-hydroxy-2-oxo-2,3-dihydro-1,3,5-triazine-1-oxide (DAOTO), thermal behaviors of DAOTO were studied systematically by differential scanning calorimeter (DSC), thermogravimetric analyzer (TG/DTG) and thermogravimetric-mass-infrared spectrometry (TG-MS-FTIR) techniques. Results showed that DAOTO has only an obvious exothermic decomposition process during the range of 250 ~ 350 °C with an extrapolated starting point temperature (Te) of 291.6 °C, a peak temperature (Tp) of 320.6 °C, a heat release of 1317 J g−1 and a corresponding mass loss of ~ 17%, at a heating rate of 10 °C min−1, and the kinetic equation of thermal decomposition process was obtained. The main thermal decomposition gas products of DAOTO are H2O, NH3 and CO, and the possible thermal decomposition process was analyzed. Besides, the specific heat capacity of DAOTO at 298.15 K was determined as 1.14 J g−1 K−1, and adiabatic time-to-explosion was calculated to be a certain value between 100 and 105 s. This work proved DAOTO having a good thermal stability and provided theoretical support for the application of DAOTO. [ABSTRACT FROM AUTHOR]

Vanadium-doped quaternary bioactive glass systems 46 SiO2, (24–x/2) Na2O, (24–x/2) CaO, 6P2O5, xV, where x = 0, 0.5, 2.5, 2.8, and 5 mass% of vanadium through the use of V2O5 oxide, were successfully synthesized by the melt-quenching technique. Several physicochemical methods were employed to study the effects of vanadium on the physical, structural, and thermal properties of all doped bioactive glasses 46S6-xV. Density (ρg), molar volume (Vm), oxygen molar volume (VO), and oxygen packing density (OPD) variations were correlated with the decrease in compactness of the vitreous network upon the introduction of 2.8 mass% vanadium. Investigations revealed that the bioactive glass network is less polymerized with an increase in vanadium content up to 2.8 mass%. The thermal characteristics and excess entropy ΔSex of doped bioactive glasses were determined. Calculated thermal stability factors show the high forming ability of elaborated bioactive glass. The obtained results show that the introduction of 2.8 mass% of vanadium on the glass matrix induces a significant decrease in ∆Tg (49 K) and ∆Tf (250 K). Increases in excess entropy confirm that the presence of vanadium leads to a more disordered 46S6 glass matrix. The studied 46S6 glass exhibits better thermal properties when vanadium is incorporated, making it more useful for various industrial and technological applications. [ABSTRACT FROM AUTHOR]

The thermoelectric materials community has made significant progress on nanostructured and processable materials to improve efficiency and flexibility, reducing manufacturing costs. Selenide compounds, such as Ag2Se and Cu2Se, have received a lot of attention because of their promising capabilities in thermoelectric applications. Additionally, Se is significantly more abundant than Te, with approximately ten times higher availability. High-energy ball milling (HEBM) process is a powerful solid-state synthesis/powder mechanical alloying method. The objective of this work is to form selenide compounds at different milling times (1–20 h) by HEBM process. The structural characterization of the compounds was studied by X-ray Diffraction and X-ray Photoelectron Spectroscopy, while the thermal stability of the prepared samples was examined by Thermogravimetric Analysis. The experimental results show that the Ag2Se sample synthesized at 20 h presents lower thermal stability because of the higher specific surface area and the increased porosity as a result of the hardening effect. Additionally, Cu2Se presents Cu2O(SeO3) as the main phase at low temperatures, while at higher temperatures, CuO is the dominant phase. Therefore, as the heating temperature increases, there is a complete evaporation of Se and a conversion of the remaining copper into copper oxide. The present study demonstrates a simple method for the synthesis of Ag2Se and Cu2Se thermoelectric materials with high oxidation resistance. [ABSTRACT FROM AUTHOR]

In this paper, a novel hydrogen-bonded liquid crystalline binary complex system was synthesized from pure mesogenic 4-(octyloxy)benzoic acid (8OBA) and non-mesogenic n-aminobenzoic acid (nABA, n = 3, 4) chemicals. Differential scanning calorimeter (DSC) experiments were performed to investigate the thermal properties of the synthesized samples, and polarized optical microscopy (POM) experiments were performed to investigate the mesogenic phase textures. The DSC and POM results showed that the phase sequence was Cr ↔ SmA ↔ SmC ↔ N ↔ I during continuous heating and cooling cycle. In addition, the thermal stability factor, phase transition entropy, and phase transition activation energy were calculated using DSC data. According to the calculated values, it was concluded that the mesogenic phases of the synthesized complexes occur regularly and the most stable phase is the SmC phase. Moreover, the optical tilt angle value for the SmC phase was measured and it was seen that the value increased up to 29° and 30° for 8OBA/4ABA and 8OBA/3ABA complexes, respectively. The formation of hydrogen bonds between the mesogenic and non-mesogenic molecules in the synthesized mesogenic structure was confirmed by Fourier-transformed infrared spectroscopy (FTIR). Furthermore, XRD results showed that the molecular ordering of the synthesized hydrogen-bonded 8OBA/4ABA and 8OBA/3ABA binary complexes occur in a monoclinic structure in the solid phase. [ABSTRACT FROM AUTHOR]

Synthesis and properties of cerium aluminate catalyst were investigated. The catalyst was prepared via combustion synthesis involving aluminum and cerium nitrates and glycine in the presence of palladium chloride. The obtained material was investigated using X-ray diffraction, Fourier transformed infra-red spectroscopy, differential thermal and thermo-gravimetric analysis, N2 adsorption, Raman spectroscopy, scanning electron microscopy, energy dispersion X-ray spectroscopy and X-ray photoelectron spectroscopy. Catalytic activity was tested for the toluene oxidation process. The direct product of combustion synthesis was CeAlO3 which remained stable even after thermal treatment at 400 °C for 2 h in static air, while temperature treatment at 800 °C for 2 h resulted in the decomposition of CeAlO3 into CeO2 and γ-Al2O3. Both thermal treatment products had sponge-like microstructure, but relatively small specific surface areas. Nevertheless, CeO2 prepared at 800 °C was nanocrystalline. Palladium was present as oxide homogeneously dispersed throughout the catalyst. The prepared catalyst proved to be highly active for the toluene oxidation process. [ABSTRACT FROM AUTHOR]

The use of phase change materials (PCMs) for thermal storage, thermal management, and thermal insulation has been widespread for many years. Thermal storage systems (TES) based on PCMs can be improved and optimized by adding nanoparticles (NPs) to them. Throughout this study, PCM nanocomposites (NCs) based on paraffin wax (PW) loaded by anatase titania (TiO2) NPs were fabricated and characterized to examine their thermal performance as phase change materials. The as-synthesized TiO2 NPs were obtained by hydrolysis technique and showed a well-defined spherical shape with a diameter in the nanoscale range and a crystallite size ~ 22.75 nm. Throughout the used concentrations of TiO2 NPs, 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, and 0.5%, the morphological feature for the PW/TiO2 NCs revealed a good dispersion of NPs in PW. The non-isothermal differential scanning calorimetry (DSC) measurements at a constant heating rate of 10 °C min−1 were used in order to get the melting point (Tm), latent heat of fusion (LH), and latent heat rate (LHR) as a function of TiO2 NP concentrations for the investigated PW/TiO2 NCs. Both LH and LHR values for PW/TiO2 NCs are higher than those obtained for a pure PW sample. The significant enhancement in LH and LHR values for PW/TiO2 NCs was found to be 21.2% and 134.3% in comparison with the pure PW sample, respectively. The thermal stability of the investigated PW/TiO2 NCs was examined using thermal gravimetric (TG) scans. It is found that the thermal stability varies with TiO2 NP concentrations with a non-monotonic trend. At concentrations up to 0.25 mass%, the thermal stability improved. For concentrations over 0.25 mass%, the degradation process became rapid. [ABSTRACT FROM AUTHOR]

During storage, lead styphnate (LS) is affected by different environmental stresses. Especially, the dual stress of temperature and humidity has a synergistic aging effect, which degrades or even completely loses the performance of LS, thus seriously affecting the firing reliability and even leading to misfire. Based on this, an accelerated aging test on LS exploring the aging behavior at high temperature and high humidity conditions was reported in this study. At extreme conditions of temperature and humidity, the color of LS had faded and gradually became lighter with the aging time. According to scanning electron microscope results, it indicated that due to long-term erosion, the surface of LS became rough, cracks and many small micropore. Some crystals were broken, and a large amount of debris appeared. Notably, the intensity of some main X-ray diffraction characteristic peaks decreased significantly or even disappeared with the aging time. On the one hand, the thermal stability of LS decreased slightly. On the other hand, its sensitivity performance gradually degraded after hygrothermal aging. Particularly, the flame sensitivity of LS decreased gradually with the aging time. In a word, our findings provide relevant evidence for the reliability of LS in storage conditions. [ABSTRACT FROM AUTHOR]

The aim of this study is to design viable eco-friendly adsorbents that may be further employed for detoxifying living organisms or decontaminating polluted waters of heavy metal ions. Here are highlighted some results concerning the surface chemistry modification of pectins via oxidation of apple-fruits with ozone in water, concentrated hydrogen peroxide or ozone in hydrogen peroxide. The quality and quantity of carboxylic and phenolic functional groups on intact and chemically-modified pectins were established by using the Boehm titration method, which has shown that these have increased in all cases—especially for three times when using ozone in hydrogen peroxide. Textural changes in the surface of were determined by scanning electron microscopy (SEM) and adsorption–desorption of nitrogen; by oxidation, both the specific surface area and total volume of pores increase, the most significant one being encountered in the case of the sample oxidized with ozone in hydrogen peroxide (three times and, respectively, four times higher). The thermal behaviour and stability of the oxidized pectins versus intact pectins from apple-fruits was studied by thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA) in both inert (nitrogen) and oxidative (air) atmospheres; the thermal behaviour indicates just slight modifications due to the appearance of carboxylic and phenolic functional groups, while the overall stability was basically not affected. The sorption properties of these materials were investigated for the immobilization of Pb2+ and Hg2+ from aqueous solutions, by measuring the adsorption isotherms; the chemical modification of pectins by oxidation has significantly improved the adsorption capacity. [ABSTRACT FROM AUTHOR]

Silica nanoparticles were reported that can improve the fire safety and mechanical properties of polymers simultaneously due to excellent rigidity and physical barrier effect. However, its efficiency was limited by the agglomeration in polymers due to their high specific surface energy. Silica@ polydopamine (SiO2@PDA) was prepared by a facile self-polymerization method to comprehensively improve fire safety, thermal stability, and mechanical properties of plant fiber-reinforced polymer (PFRP) composites. The results of micro-morphology confirmed that the SiO2@PDA nanoparticles exhibit better dispersion state in epoxy matrix. The introduction of SiO2@PDA further increased the thermal decomposition temperature and the yield of graphitized char residue of PFRP composites compared to pure silica nanoparticles. And the fire safety of composites including limiting oxygen index, heat parameters, smoke parameters and mass loss rate was improved effectively. Particularly, the time to ignition of composites was delayed by 30 s, which was beneficial for individuality escape and rescue. Meanwhile, the improvement of storage modulus suggested the SiO2@PDA enhanced the mechanical properties of the PFRP composites. And it was proved that PDA can improve the graphitization degree of char layer and release inert gas including NH3 and CO2 during combustion. The effectiveness of non-toxic PDA in enhancing the quality of char layer and optimizing the interface to improve the dispersion state of nanoparticles appeared promising potential in the field of manufacturing fire-safe polymer-matrix composites. [ABSTRACT FROM AUTHOR]

Sunset Yellow (E110) is an azoic dye synthetized from aromatic hydrocarbons, which is used to improve the physical–chemical properties of food products and their conservation; its chemical formula is C16H10N2Na2O7S2. Here, in order to characterize this azoic dye in powder and solution form, five spectral techniques were employed: Fourier Transform Infrared (FTIR), UV–Vis, Raman, Laser fluorescence and Terahertz (THz) spectroscopy. The Sunset Yellow's morphology, structure and its chemical composition were studied by scanning electron microscopy (SEM), X-ray diffraction and energy-dispersive X-ray spectroscopy (EDXS). The thermal behaviour of Sunset Yellow was studied in correlation with its physical (refractive index, electric susceptivity, optical anisotropy) and chemical (acidity) properties. Thermal analysis effectuated in air indicates the evaporation of absorbed and physically bonded water up to 188 °C, after which the material possesses thermal stability up to 330 °C. The oxidative decomposition takes place in four exothermic steps of which the strongest between 510 and 643 °C develops a heat of 4519.6 J g−1; at 913 °C, a residue of 31.77% is obtained. The study of optical properties of Sunset Yellow shows that the refractive indexes are decreasing when the temperature of the solution increases. The optical anisotropy of Sunset Yellow was studied under polarized light at room temperature. Sunset Yellow exhibits the phenomenon of birefringence on resulted crystallites by drying and crystallization at RT from aqueous solutions with concentrations of 1% and 5%. THz spectroscopy identified the THz spectral "signature" of Sunset Yellow at a few wavelengths. Sunset Yellow has biophysical properties when interacting with proteins (bovine serum albumin (BSA) and collagen). The biological properties of Sunset Yellow were observed through its antioxidant activity and phytotoxicity; while the antioxidant activity is proportional with increasing its concentration, the phytotoxicity study indicates that the Sunset Yellow does not present wheat (Triticum aestivum) growth phytotoxicity at low concentrations (when treating with aqueous solutions of 0.01–0.05%, it could increase its resistance to drought conditions), but at concentrations of 0.25% or higher, there are negative changes in wheat growth. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the aging of poly(ether-ether-ketone) (PEEK) submitted to different media: in air, in water bubbled with nitrogen, in water bubbled with air, and in water at pH 4, for 90 days at temperatures of 120, 140 and 160 °C. The physical, thermal and mechanical properties of PEEK specimens were evaluated before and after aging. The density measurements showed that the aging conditions employed did not promote water absorption or mass loss; thermogravimetric analyses (TGA) showed that all aging media exerted the same effects on the material's thermal stability, with variation in the initial thermal degradation (Tonset) below 5 °C concerning the unaged polymer. The thermal history obtained by differential scanning calorimetry (DSC) did not show significant variations in thermal transition temperatures in the first heating cycle, indicating that the aging conditions did not cause internal degradation in PEEK samples within the studied period. The degree of crystallinity calculated by X-ray diffractometry (XRD) and DSC demonstrated a slight increase over time due to thermal annealing at temperatures above the Tg of the unaged PEEK. The mechanical properties of the aged PEEK showed low variations in Young's modulus and greater variations in the tension at rupture and elongation at rupture, being more drastic in the aqueous media saturated in air and acid solution. [ABSTRACT FROM AUTHOR]

Reinvestigation of the V2O5–SrO system allowed final confirmation of formation of four compounds of the following stoichiometric formulas: Sr(VO3)2, Sr2V2O7, Sr3(VO4)2 and Sr4V2O9. The results presented permitted solving literature controversies regarding low- and high-temperature polymorphs of strontium metavanadate(V), i.e. Sr(VO3)2-I and Sr(VO3)2-II. The polymorphic transformation of both varieties that crystallize in the orthorhombic system was proved to be reversible and take place at 530 °C. Strontium metavanadate(V) was found to melt incongruently at 670 °C with deposition of solid Sr2V2O7. Both polymorphic forms of Sr(VO3)2 were studied by IR and SEM methods. According to the results of tests using the UV-Vis-DRS method, both polymorphs Sr(VO3)2 belong to the semiconductor class. Thermal stabilities of Sr2V2O7, Sr3(VO4)2 and Sr4V2O9 were verified. The powder diffractogram of Sr4V2O9 was indexed. [ABSTRACT FROM AUTHOR]

Polymer/clay-based composites were prepared via solution intercalation method using natural clay and poly (ethylene) glycol (PEG4000) as organic dispersed phase. The present work consists of studying the effect of PEG content on the hybrids surface morphology, thermal stability and thermophysical properties. On the other hand, the TGA data and the measured thermophysical properties are, respectively, fitted with a logistic-like laws and virial expansions for different polymer contents. The results showed that the experimental data agree with the proposed theoretical models. Furthermore, the incorporation of the PEG chains into the clay matrix improves both the thermal stability and thermal characteristics of the raw clay. The thermophysical properties data showed that the elaborated hybrid acts as good thermal insulator for polymer contents higher than 2.5 % . Finally, the resulting clay-based composite showed not only interesting characteristics in terms of insulation, but also satisfies both economic and environmental requirements. [ABSTRACT FROM AUTHOR]

Nowadays, continuous development of soft-electronics and wearable devices opens to the development needs of stretchable and flexible materials able to interface with the human body. In this scenario, biopolymers are particularly intriguing materials given their biocompatibility and biodegradability. For the application in this specific field the material requires several properties such as biological and mechanical performance and thermal stability. In this study, membranes able to fulfill some of these requirements are described. The electrospun membranes, composed of a blend of polycaprolactone (PCL) and gelatin (GN), have been produced in various configurations. The results show how blend or coaxial systems have different effects on both the interactions between the polymers and their thermal and mechanical properties. An important result of the chosen experimental conditions is the narrow dimensional distribution of the nanofiber diameters constituting the electrospun membranes. Thermal and mechanical tests evidenced that, by properly choosing the material composition and the method of the electrospinning process, membranes capable of withstanding high strain values before the failure can be obtained. In particular, optimizing the electrospinning process and using a blend PCL/GN with a mass ratio of 80/20, it is possible to increase the thermal stability up to 310 °C and confer to the sample the ability to reach a percentage of strain up to 350%. [ABSTRACT FROM AUTHOR]

A biodegradable thermoplastic polymer has been formulated by solubilizing Murexide (M) salts in a commercial biodegradable vinyl alcohol copolymer (HVA). The Murexide has been employed as a self-healing filler with the aim to impart the auto-repair ability to the formulated material. Three different percentages (1, 3, and 5 mass%) of filler have been solubilized in HVA to evaluate the effect of the filler concentration on the thermal and self-healing properties of the resulting polymeric materials. The samples have been thermally characterized by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analyses (TGA), while their self-healing ability has been evaluated through the estimation of the storage modulus recovery, measured by Dynamic Mechanical Analysis (DMA). The results of DSC analysis have highlighted that the increase of the amount of Murexide anticipates the thermal events such as glass transition, crystallization and melting. TGA measurements have evidenced that, although there is a reduction of thermal stability of the materials in the presence of a high concentration of M, the polymer still remains stable up to 270 °C. Healing efficiency higher than 80%, at a temperature beyond 60 °C, has been detected for the samples loaded with 3 and 5 mass% of Murexide, thus confirming the efficacy of this compound as an auto-repair agent and the relationship between the self-healing efficiency and its amount. For a temperature lower than 70 °C, the healing tests, carried out at different values of tensile deformation frequency, have highlighted a frequency-dependent healing efficiency. This dependence becomes negligible at higher temperatures for which the healing efficiency approaches the value of 100%. [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]

Polyethylene from renewable resources produced using sugarcane as raw material was modified with phosphonium ionic liquids. Tensile properties and thermal behavior of modified biopolyethylene in air and nitrogen atmosphere were studied. The thermal degradation of ionic liquids and their influence on thermal degradation of polyethylene from renewable resources were studied by thermogravimetric analysis (TGA). In general, modification of biopolyethylene with phosphonium ionic liquids resulted in improvement of tensile properties, i.e., tensile strength and Young's modulus. Thermal degradation of biopolyethylene modified with phosphonium ILs proceeds in one step in the range of 400–500 °C in nitrogen atmosphere. Modification of polyethylene with trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate ionic liquid resulted in increase in DTGpeaks and T10% temperatures toward higher temperature for modified polyethylene in comparison with unfilled PE sample both in air and nitrogen atmosphere. [ABSTRACT FROM AUTHOR]

The N,N′-dimethylformamide (DMF) was used in the microwave-assisted (MW) solvothermal method for the preparation of lanthanide(III) complexes with biphenyl-4,4′-dioxydiacetic acid (H2L) of the formula Ln2L3·xDMF⋅yH2O where Ln = lanthanide(III) ions from La(III) to Lu(III) with the Pm(III) exception x = 1.5–3; y = 2 for Yb and Lu or 0 for the remaining complexes and L = C14H12O2(COO)22−. The obtained complexes were characterized by the elemental analysis, infrared spectroscopy (ATR-FTIR), X-ray diffraction patterns and different methods (TG-DSC and TG-FTIR) of thermal analysis. Crystalline complexes contain N,N′-dimethylformamide molecules in their structures. Additionally, water molecules are present in the structures of Yb(III) and Lu(III) complexes. Coordination of lanthanide ions occurs through carboxylate oxygen atoms from the biphenyl-4,4′-dioxydiacetate ligand and most probably carbonyl oxygen atom from N,N′-dimethylformamide. The investigated compounds exhibit different thermal stability, and removal of solvent molecules takes place in a more complex way in the group of heavy lanthanide complexes. Their desolvated forms are an unstable [except Yb(Lu)2L3 compounds], and their further heating leads to the formation of suitable lanthanide oxides (air atmosphere). Thermal stability of the investigated compounds is higher in nitrogen atmosphere. The TG-FTIR methods allowed to propose way of thermal decomposition of investigated compounds through identification of volatile products such as: DMF, H2O, CO2, CO and CH4 evolved during heating of complexes. The luminescent properties of terbium(III) and europium(III) complexes were also investigated. [ABSTRACT FROM AUTHOR]

Conventional surfactants such as CTAB (cetrimonium bromide), SDS (sodium dodecyl sulphate), SDBS (sodium dodecyl sulphonate) are combined with nanofluids to improve the stability and thermal conductivity of nanofluids. These nanofluids are mainly used for heat transfer applications where heating and cooling are usual courses of action which result in surfactants producing foams and polluting the heat transfer media, affecting the total system performance. Besides, the common surfactant molecules that augment the thermal resistance between the nanoparticles and base fluid also affect the thermophysical properties of the nanofluid. In this paper, [Bmim][Cl] (1-butyl-3-methylimidazolium chloride), a high purity ionic liquid (IL) with higher thermal stability was used to provide a comparative study on the stability and thermal properties with that of the conventional surfactants (CTAB, SDS, SDBS) on multiwalled carbon nanotubes (MWCNT)/propylene glycol (PG) nanofluid. The transient hot-wire based KD2-Pro and zeta potential results demonstrated that the inclusion of ionic liquid improved the thermal conductivity and stability of the formulated nanofluid. However, much like the conventional surfactants, the strong electrostatic repulsive force created by the ionic liquid was found to decrease when the temperature is increased. The outcome demonstrated the most extreme thermal conductivity upgrade of 33.7% at 303 K and maximum dispersion stability of more than one month without any aggregation for the nanofluid containing ionic liquid. [ABSTRACT FROM AUTHOR]

In this work, tea powder was used as a filler to produce low-formaldehyde-emission tea-based melamine-modified urea–formaldehyde resin (TMUF). The thermal stabilities of TMUF and the resin without tea powder (MUF0) were characterized using thermogravimetry. The optimal amount of tea powder m(tea)/m(tea + urea) was equal to 0.15. The formaldehyde emission of the three-layer plywood produced by TMUF was reduced by 75.43%, and the wet bonding strength of the plate was increased by 26.67% as compared with the plywood prepared by MUF0. Compared with MUF0, the thermal degradation peak temperature of TMUF resin was shifted to higher temperature, while the carbon residue was increased. The thermal degradation activation energies of TMUF and MUF0 were similar, while TMUF had a lower pre-exponential A. The Flynn–Wall–Ozawa model-free method is used to estimate various activation energy values at different conversion rates and to predict possible reaction mechanisms. Judging the reaction mechanism according to the slope of the straight line fitted by different models, the best model was based on random nucleation. [ABSTRACT FROM AUTHOR]

In this work, thermal and mechanical properties of cationic cassava starch-g-poly(butyl acrylate-co-methyl methacrylate) films with different amounts of cationic cassava starch (CCS) were studied. The objective of this work was to substitute a portion the monomers (BA/MMA) by CCS in the copolymer and to investigate the consequent effects on the properties of the polymer latex films (e.g., graft percentage, surface tension, thermal and mechanical properties). The results show that the grafting percentage decreased as the concentration of CCS increased. Thermal and mechanical properties of polymer films showed a direct relationship with respect to the content of CCS used and the grafting percentage. Higher grafting percentage led to improvement of the thermal degradation, which indicated better thermal stability than neat poly(BA/MMA). DSC analysis showed that the Tg of the graft copolymers was a little lower as compared to Tg values of un-grafted copolymers. The addition of CCS increases the tensile, elastic modulus and hardness properties of the polymer film, but the elongation at break decreased dramatically. The optimal CCS contents that maximized not only thermal properties, but also mechanical properties, were 7 and 10 mass%, which are directly related to the grafting percentage and CCS content in the formulation. In addition, these results create a new approach for the application of CCS graft-polymer as an adhesive for wood, paper and shoes insole applications. [ABSTRACT FROM AUTHOR]

In this study, different nanofluids synthesized with aluminium oxide (alumina) and titanium dioxide in mass ratios of 1%, 3%, and 5% were tested in an electric oil radiator heater. The base fluid is heat transfer oil, and the nanofluids were synthesized using the two-step method. Simultaneously, optimum ultrasonic mixing times and surfactant amounts were determined to increase the nanofluids' stability values. The stability of the nanofluids produced with alumina and titanium dioxide in mass ratios of 1%, 3%, and 5% was determined by using the sedimentation method. Among the alumina and titanium dioxide nanofluids whose thermal properties were measured, the nanofluids with the highest stability and the best thermal properties were used in heating experiments. The highest thermal improvement rates were 6% for alumina nanofluid and about 9% for titanium dioxide nanofluid, in the 5% mass ratio of nanoparticles. The temperature differences of the alumina and titanium dioxide nanofluids with respect to the base fluid were highest in the first region, at 8% and 10%, respectively, while the highest 11% and 27% temperature differences in the second region were measured, respectively. The stability values of the nanofluids in which significant increases in thermal values were obtained were maintained for long periods. It has been shown that nanofluids can be used in an industrial device. [ABSTRACT FROM AUTHOR]

Nanofluids are considered a promising alternative to the classic fluids used in heat transfer processes. One interesting application of nanofluids is their use as a heat transfer fluid in thermosolar plants, such as those using concentrating solar power (CSP) technology. Therefore, this study presents the preparation of nanofluids based on TiO2 nanoparticles and the most common thermal oil used in CSP plants. The nanofluids were prepared using a one-step method by means of the solvothermal synthesis of TiO2 and also using a two-step method by means of ultrasonic waves and stabilizing the nanoparticles using 1-octadecanethiol as a surfactant. The stability of the nanofluids was analysed using UV–Vis spectroscopy, particle size and ζ potential measurements. The formation of TiO2 nanoparticles in the one-step method was detected using X-ray diffraction, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Thermophysical properties were also measured obtaining an atypical improvement of isobaric specific heat of up to 25.4% for the nanofluids prepared by the two-step method. For the nanofluids prepared by the two-step and one-step methods, thermal conductivity increased by up to 52.7% and 31.4% at higher temperatures, respectively. Finally, enhancements of up to 35.4% of the heat transfer coefficient were estimated, which means these nanofluids are suitable for being used as heat transfer fluids in CSP plants. [ABSTRACT FROM AUTHOR]

Porous microspheres obtained from 2,3-epoxypropyl methacrylate (GMA) and 1,4-di(methacryloyloxymethyl) naphthalene (DMN) were modified by the reaction of active oxirane group with 1-(2-hydroxyethyl)-2-pyrrolidone (HP). Spherical shape of the copolymers was confirmed by scanning electron microscopy whereas low-temperature nitrogen adsorption–desorption method was applied to determine their porous structure. It was found that the modification process did not change noticeably the internal structure of the materials. The specific surface area for both types of materials ranged from 41 to 106 m2g−1 depending on the molar ratio of the monomers. Changes, however, were observed in reference to thermal properties. They were studied using differential scanning calorimetry and thermogravimetry coupled with FTIR in inert and oxidative conditions. The reaction with HP reinforced thermal stability of the modified microspheres in helium atmosphere. Their initial decomposition temperatures (IDTs) increased to 273–281 °C. In air atmosphere, the values of IDTs were at the same level (248–269 °C). The modified beads decomposed in three (helium) or two (air) stages. [ABSTRACT FROM AUTHOR]

Phenolic foam (PF) has excellent performance in fire resistance, thermal insulation and other fields. It has the advantages of lightweight, flame retardant, no dropping and low level of toxic gas emission during combustion. In order to learn the relationships between density and properties, PF samples with density of 40, 50 and 60 kg · m−3 were obtained by adjusting the amount of blowing agent. Their micro-characteristics were analyzed with Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) experiments. Mechanical properties were measured with universal extending machine. Thermal properties and stability were tested by laser thermal conductivity analyzer and thermogravimetry analysis (TG), respectively. FT-IR spectra of samples demonstrate that chemical structure will not be affected by the ratio of foaming agent. Higher density comes with better sealing property of the cell holes and leads to better compressive strength. Changing PF density with foaming agent dosage could affect insulation effect, and the sample with density of 60 kg · m−3 showed poor performance compared with the other foams. TG–DTG curves of the PF samples are similar. Evaporation of water, volatilization of phenols and aldehydes, and pyrolysis of surfactant and curing agents are the main reason for the mass loss. Residues of samples increased with the increase in density at 900 °C. Results of this study can clarify that changing the density of PF with amount of foaming agent will not affect its chemical properties, but the ratio has impact on its physical properties. [ABSTRACT FROM AUTHOR]

Iron phosphate glasses are materials that can have many applications like durable matrixes in waste immobilization techniques, biomaterials, optoelectronic devices, etc. Their possible usage is related to their glass network and thermal properties. The influence of Na2O content on thermal properties and crystallization ability of iron phosphate glass of base composition 30 Fe2O3–70 P2O5 mol% were studied. Increasing the content of Na2O causes a decrease in transformation temperature and increase in ΔCp. Characteristic temperatures, thermal stability and crystallizing phases were determined. Increasing content of sodium causes depolarization of iron phosphate glass network which causes a continuous change in ΔCp and glass transformation temperature. Discontinuous change in some glass properties suggests structure rebuilding about 30 mol% of Na2O. [ABSTRACT FROM AUTHOR]

Layered yttrium hydroxides (LYH)- and graphene oxide (GO)-supported layered yttrium hydroxides (GO–LYH) were synthesized by a co-precipitation route. The additives were characterized by X-ray diffraction and Fourier transform infrared spectra. The LYH were homogeneously dispersed on the GO sheets, demonstrated by the transmission electron microscope analysis. Composites of TPU/LYH and TPU/GO–LYH were prepared by a melt-blending method. The morphologies and structures of the composites, revealed by scanning electron microscope, ascertained that the dispersion of the GO–LYH in the TPU was better because of the strong interaction of the hydrogen bonds between oxygen-containing groups and hydroxyl groups. The fire retardancy of the TPU composites was evaluated using limiting oxygen index (LOI), cone calorimetry and thermogravimetric analysis. The TPU/LYH and TPU/GO–LYH composites, filled with 10 mass% LYH, 9 mass% GO, achieved LOI values of 24.4% and 25.3%, while there was a 67.42% and 70.88% decline of PHRR compared with pure TPU. The improved flame retardancy and smoke suppression were attributed to the physical barrier of GO and the catalytic carbonization of LYH indicated by char analysis. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid composites have received much attention of scientists in the recent years due to the notable improvement of thermal properties without using of organic or inorganic nanoparticles. Hence, we have developed a facile strategy to prepare a 3D hybrid network based on silane materials and novolac resin via sol–gel process. At first step, novolac resin was prepared by general procedure with appropriate thermal properties and then modified with (3-chloropropyl)triethoxysilane (CPTES) to form MNR. In second step, to cure MNR and prepare hybrid composite structures, general amine-cured system and sol–gel process were applied to prepare MNH and MNSG samples, respectively. XRD analysis was used to support the formation of silane networks in hybrid samples. Investigation of thermal properties by DSC and TGA showed that cured samples had much higher thermal stability and char yield with respect to novolac and modified resin (MNR) originated from formation of 3D Si–O–Si network. Presented method limited some disadvantages of using nanoparticles such as aggregation and poor distribution. Such hybrid composites with high thermal stability have potential applications in advanced fields such industrial molds, coatings, adhesives and composites. [ABSTRACT FROM AUTHOR]

A novel composite of SrCO3-microencapsulated palmitic acid (PA) (PA@SrCO3 microcapsules) was prepared an evaluated as a phase-change material through a self-assembly approach. Samples of the material were studied by Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometery (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to determine the composition, crystalloid phase, microstructure, and morphology of the product. Also differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to monitor the thermal behavior of the PA@SrCO3 microcapsules. The data obtained through XRD and FTIR indicated the presence of characteristic peaks of PA and SrCO3, which is only possible when the species do not chemically react with each other. SEM images indicated the PA@SrCO3 microcapsules to be spheres with rough surfaces and average diameters of 1.5–2 µm. TEM images proved the samples as being composed of PA cores encapsulated in a SrCO3 coating. The DSC results showed that the samples had phase-change behaviors, similar to those of pristine PA (melting point = 66.9 °C, latent melting heat = 48.8 J g−1, freezing point = 55.7 °C, latent freezing heat = 43.2 J g−1, at a microencapsulation ratio of 43.92%), and TGA results showed improvements in the thermal stability of PA@SrCO3 microcapsules as opposed to PA, due to the presence of the SrCO3 shell. [ABSTRACT FROM AUTHOR]

The composites were prepared with PVC modified with 3-(dimethylamino)-1-propylamine (aminated PVC) and MWCNT containing 2.5% carboxyl group (oxidized MWCNT) and doped with nanographite in different percentages (1, 5, 8 and 12% by mass). Thermal investigation was performed from DSC and TGA curves. From the DSC curves, it was observed that Tg temperature of aminated PVC increased with the increase in oxidized MWCNT content. At the composite containing 5% MWCNT, Tg temperature of aminated PVC decreased slightly with increasing nanographite, at the composite containing 11% MWCNT increased slightly and at the composite containing 8% MWCNT nearly fixed. While according to initial decomposition temperature doping with nanographite did not affect significantly the thermal stability of composites, the amount of residue at 500 °C increased some with doping. Conductivity was only investigated for aminated PVC/8% oxidized MWCNT/8% nanographite composite. Doping with nanographite significantly increased the conductivity of the composite. (Conductivity increased values from 10−8–10−9 S cm−1 to 10−4 S cm−1). The conductivity increased with increasing temperature at all frequencies. Conductivity-related activation energies were calculated at different frequencies, and while the frequency increased from 630 to 29,500 Hz, the activation energy decreased from 0.0228 to 0.0193 eV. [ABSTRACT FROM AUTHOR]

The effects of three different surfactants were analyzed on the stability and thermal conductivity of GO/de-ionized water nanofluids. One surfactant was cationic, cetyltrimethyl ammonium bromide (CTAB), one was anionic, sodium dodecyl sulfate (SDS), and one was nonionic, TritonX-100 (TX-100). These were added to synthesized graphene oxide (GO) prepared in de-ionized water at different concentrations (0.01, 0.05, 0.1, 0.15, 0.2, and 0.25 mass%). The transient hot-wire technique was employed to measure the thermal conductivity of all nanofluids at 20–40 °C. The stability of the GO/de-ionized water nanofluids without a surfactant was better than that of nanofluids with a surfactant. The stability and dispersion of the nanofluid with SDS were considerably better than nanofluids with the other two surfactants. All nanofluids without a surfactant had higher thermal conductivity than de-ionized water at all temperatures. An increase in the GO concentration from 0.01 to 0.2 mass% improved thermal conductivity by 3.05 and 22.03% at 20 °C, respectively. A further increase to 0.25 mass% caused a 23.73% increase in thermal conductivity. [ABSTRACT FROM AUTHOR]

The influence of cerium oxide on the thermal properties and the glass structure has been studied for the Li2O–(Na2O–K2O)–B2O3–SiO2 system. It has been established that cerium is completely soluble in the quenched glass during the synthesis if addition of CeO2 is 0–10 mol%. The cubic ceria phase is formed in glass either during the synthesis if addition of CeO2 is 20 mol% or after thermal treatment (annealing) if the glass contains 10–20 mol% of CeO2. The studied lithium borosilicate glasses have low thermal stability and demonstrate significant difference in the crystal phase formation for Ce-free and Ce-containing glasses after annealing. The lithium–sodium and lithium–potassium glasses have much higher thermal stability toward crystallization regardless of Ce content. The obtained results are relevant for improving the properties of matrix materials of similar borosilicate systems used for immobilization of radioactive waste. [ABSTRACT FROM AUTHOR]

Two series of new sulfur-containing thermoplastic poly(carbonate-urethane)s (PCURs) were prepared by a one-step melt polyaddition from diphenylethane derivative diol, i.e., 4,4′-(ethane-1,2-diyl)bis(benzenethiohexanol) as a nonconventional chain extender, 1,1′-methanediylbis(4-isocyanatobenzene) (MDI) or 1,6-diisocyanatohexane (HDI) and 20–60 mol% poly(hexane-1,6-diyl carbonate) diol of M ¯ n = 860 g mol−1 as a soft segment. The FTIR and XRD as well as DSC, TG, and TG coupled with FTIR were employed to characterize the PCURs' structure and thermal properties. Their physicochemical, adhesive, and tensile properties as well as Shore A/D hardness were also studied. The amorphous MDI-based PCURs were transparent materials (transmittance at 800 nm: 83–88%), while the HDI-based ones, showing partially crystalline structures (the degree of crystallinity: of 20–28%), were opaque. The polymers derived from HDI exhibited lower glass-transition temperatures than those obtained from MDI (from – 29 to – 12 °C vs. from 14 to 46 °C) as well as a higher degree of microphase separation. In turn, the PCURs based on MDI revealed higher tensile strength (up to 50.8 MPa vs. up to 33.4 MPa) and better thermal stability (e.g., the temperature of 1% mass loss: 294–305 °C vs. 262–278 °C). These sulfur-containing PCURs exhibited better adhesive properties to copper compared with the conventional PCURs synthesized from butane-1,4-diol as a chain extender. [ABSTRACT FROM AUTHOR]

The effects of natural polyphenol-based thermal stabilizer synthesized from tannin, a flavonoid-type natural polyphenol, on the processing, rheological and viscoelastic behaviors of polyvinyl chloride (PVC) were investigated in this work. Rheological properties of PVC were studied via three different types of rheometry techniques: torque by an instrumented batch mixer, dynamic oscillating shear rheometry, and dynamic mechanical thermal analysis (DMTA). In the course of the investigation, rotational melt rheological properties in terms of shear complex viscosity, storage modulus, and loss modulus were studied in order to evaluate the performance of tannin–cadmium complex as bio-based PVC additive and as a thermal stabilizer. Experimental results of this study for all PVC formulations with this derivative at loading percentages of 1, 2, and 3 parts per hundred of PVC resin (phr) reveal that the processing and dynamic thermal stability of PVC monitored by torque curves and rheological tests can be enhanced with the addition of this derivative. Rheological behavior of PVC stabilized with tannin derivative is superior or very close to that of PVC stabilized with trade-grade thermal stabilizer. Additionally, DMTA was carried out to see the effect of tannin–cadmium at 2 phr on the thermo-mechanical properties of PVC. All DMTA-related terms such as storage modulus and damping factor and glass transition region point out that the PVC has good viscoelastic properties compared to that of PVC stabilized with commercial thermal stabilizer. [ABSTRACT FROM AUTHOR]

The new aromatic polyamides containing α-amino phosphonate were synthesized from phosphorus-based dicarboxylic acid 4 and various aromatic diamines by direct polycondensation reaction. Dicarboxylic acid 4 was successfully synthesized from trimethyl phosphite, 4-aminobenzoic acid and terephthaldehyde via a three-component reaction. The polymerization reaction produced the polyamides 6a–f with high yield and desirable inherent viscosities. The thermal properties of the all samples were investigated by thermo-gravimetric analysis (TGA). The TGA results in N2 exhibited the 10% mass loss temperatures (T10) in the ranges of 324–345 °C, while the T10 resulted from thermo-oxidative degradation were higher than those. The main data obtained by microscale combustion calorimetry revealed acceptable combustion properties such as very low peak of heat release rate for the synthesized polyamides 6a–f. The all of the results indicated that these polyamides can be potentially utilized as additive for improvement of thermal resistance and combustion behavior of thermoplastic materials. [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]

Strontium titanate is a promising candidate for applications in thermoelectric, thermal management applications, and modern electronic devices because of its desirable thermal stability, chemical stability, and semiconducting behaviour. However, the absence of its important systematic development, having grain size from several nanometric up to micronic size with evolving thermal diffusivity behaviour, triggers the need for filling up the vacuum. Two different heat treatments have been carried out onto the samples which were with presintering and without presintering. Nanometer-sized compacted powder samples were sintered from 500 to 1400 °C using 100 °C increments. The parallel characterizations of structural, microstructural and thermal diffusivity properties were systematically carried out. Interestingly, three significant value-differentiated groups: weak, moderate, and strong thermal diffusivity were observed, resulting from the influence of different phonon-scattering mechanisms through a systematic development of microstructural properties for both heat treatments. [ABSTRACT FROM AUTHOR]

In the present research, mechanical and thermal properties of high-density polyethylene/wood flour were improved by incorporating nanoclay (Cloisite 30B) and antioxidant (Irganox B225) in the compound. Design of experiments was carried out to optimize composition among nine compounds and to investigate the effect of nanoclay and antioxidant (0–5 phr) and (0–0.4 phr), respectively. The results of mechanical tests showed approximately 24% increase in the tensile strength of compounds containing 2.5 and 5.0 part per hundred (phr) of the nanoclay in the composite compared with the same samples without nanoclay. The tensile modulus of composites increased 7.3% by increasing the level of nanoclay from 0 to 2.5 phr. However, a further increase in the nanoclay content led to a 4.3% decrease in tensile modulus. Evaluation of the thermal oxidation stability of samples confirmed that the thermal oxidation of composites decreased with increasing nanoclay from 0 to 5.0 phr and increased significantly with the addition of the antioxidant. [ABSTRACT FROM AUTHOR]

The coumarilate (coum−) and 1,10-phenanthroline (phen) mixed ligand complexes of Co(II) (1), Ni(II) (2) Cu(II) (3) and Zn(II) (4) were synthesized and structural characterizations were performed by using elemental analysis, magnetic susceptibility, solid-state UV–Vis, FTIR spectra, thermoanalytical TG-DTG/DTA and single-crystal X-ray diffraction methods. The Co(II) and Ni(II) complexes are salt-type compounds, and they have two moles phen ligands bound as bidentate, two moles aqua ligands in coordination sphere and two moles anionic coum− ligand outside of the coordination unit as the counter-ion of the molecular structure. At the same time, the Co(II) and Ni(II) complexes have five moles of aqua ligands as hydrated water outside of the molecules. It was obtained that Cu(II) and Zn(II) complex structures contain one mole of phen ligand, two moles coordinated (coum−) ligand and a one-mole aqua ligand, and the molecules (Cu(II) and Zn(II)) have fivefold structure and obey square pyramidal geometry. Thermal decomposition of each complex started with dehydration (the first removal is the dehydration of complex Co(II) and Ni(II) as removal of hydrate–aqua molecules), and then, the decomposition of organic parts was observed. The thermal dehydration of the complexes takes place in one (Cu(II) and Zn(II)) or two (Co(II) and Co(II)) steps. The decomposition mechanism, thermal decomposition steps and thermal stability of the investigated complexes provide useful data for the interpretation of their structures. The final decomposition products were found to be metal oxides. Some biological applications (antifungal/antibacterial) were performed using structurally characterized compounds. [ABSTRACT FROM AUTHOR]

Products of sorption of uranyl ions on HDTMA-red clay in the presence of phosphates were characterized by thermal analysis. It was established on the basis of DTG curves of the sorption products and FTIR spectra of the gaseous phase of sorption products decomposition that the thermal stability of the mineral increased when P(V) ions were sorbed along with U(VI) ions, i.e., the temperature of defragmentation/oxidation of surfactant increased when going from U(VI)–HDTMA-clay to U(VI)–P(V)–HDTMA-clay to P(V)–HDTMA-clay. The DSC curves of the sorption products showed that defragmentation/oxidation was an exothermic process and dehydration and dehydroxylation had an endothermic character. The investigated sorption system has practical importance, since an evident increase in U(VI) sorption over the entire pH range is observed when going from U(VI)–HDTMA-clay to U(VI)–P(V)–HDTMA-clay. [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 this paper we demonstrate a facile and efficient synthesis of monoalkenylsubstituted POSS compounds, i.e., R7(Si8O12)-alkenyl and R7(Si8O12)(OSiMe2)-alkenyl with a functional alkenyl group of chain length (from vinyl to dec-9-enyl, with or without additional -OSiMe2- spacer between the silsesquioxane core and alkenyl moiety) and with five types of inert groups (Et, iBu, iOc, Cy, Ph) at the POSS core. These compounds constitute a library of monosubstituted POSS systems, including thorough spectroscopic and thermal characteristics. These findings could be especially useful for material chemists applying the compounds as modifiers or comonomers for copolymerization reaction, e.g., with olefins.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC), dilatometry and X-ray diffraction have been used to study thermal behavior and stability of glasses prepared simultaneously in Al2O3 or Pt crucibles in compositional series (40 − x)MgO-xFe2O3-60P2O5 within the concentration range of x = 0-40 mol% Fe2O3. Mössbauer spectra showed that all glasses with Fe2O3 contained both Fe(II) and Fe(III) ions. The contamination glasses from alumina crucibles ranged from 0.3 to 0.9 mol% Al2O3. The replacement of MgO by Fe2O3 resulted in a gradual decrease in glass transition temperature and dilatometric softening temperature, whereas thermal expansion coefficient did not change significantly. The DSC curves showed that all glasses crystallize on heating in the broad temperature range ≈ 560-900 °C. Crystallization temperature decreases with increasing Fe2O3 content. The highest tendency toward crystallization was found for the glass containing 40 mol% Fe2O3. X-ray diffraction measurements showed that the major compounds formed by glass crystallization were Mg(PO3)2, Fe(PO3)3, Fe3(P2O7)2 and FePO4. All thermoanalytical studies showed differences in thermal behavior of glasses prepared in Al2O3 or Pt crucibles. [ABSTRACT FROM AUTHOR]

The thermal features of potato, banana, corn and cassava starches were correlated with structural properties. These starches were characterized by SEM, XRD, FTIR-ATR, DSC and TG. The crystalline index of starches was evaluated, and the banana starch presented the highest. Infrared ratios of amorphous/crystalline regions were close to XRD data for potato and corn starches. The amylose ratio was correlated with Tg and gelatinization measurements by DSC, with some restrictions. TG experiments demonstrated that the crystalline array affects the thermal stability of starches, but the major component is the amylose ratio. [ABSTRACT FROM AUTHOR]

Calorimetric measurements have been performed in quaternary glassy system Se78−xTe20Sn2Cdx (x = 0, 2, 4, and 6) to study the thermally induced glass transition and crystallization phenomena. The characteristics kinetic temperatures (glass transition temperature Tg, onset crystallization temperature To, peak crystallization temperature Tc) and static melting temperature Tm of the quaternary glassy series have been determined using their non-isothermal DSC curves. These temperatures were utilized to calculate the thermal stability S and the Hruby parameter HR for the studied glasses. Both the activation energy of glass transition Et and the activation energy of crystallization Ec for all compositions were evaluated using the well-known Kissinger's relation and the method of Augis–Bennett. Values of the fragility index m and the crystallization rate factor Kp were estimated using the activation energy values Et and Ec, respectively. The compositional dependence of the above-mentioned parameters was discussed on the basis of rigidity models and according to the formation of iono-covalent bonds when our glassy Se–Te–Sn system is doped with a heavy element as Cd. [ABSTRACT FROM AUTHOR]

Industrially relevant nanopowder was synthesised by microwave hydrothermal synthesis to obtain well-controlled composition (ZrO2–AlO(OH) system) which was found to determine a number of physical and thermal characteristics. This study reports variation of particle size, density, specific surface area (SSABET), as well as thermal behaviour of nanopowder mixtures of ZrO2–AlO(OH) in the whole range of compositions. It was found that the onset temperature (Ton) of physically and chemically bounded water desorption depends on the Al3+/or AlO(OH) content. The lower content of Al3+ in the ZrO2–AlO(OH) system, the higher Ton of physically bound water desorption. There are three distinct temperature regions for water decomposition for nanomaterials investigated in air (at approximately 50, 250 and 450 °C). These temperature ranges depend on particle size and chemical composition of ZrO2–AlO(OH) nanopowders. Materials were divided into three groups characterised by different properties: (1) ZrO2 with 2–12% of Al3+, where particle sizes are from 4 to 8 nm, (2) ZrO2 with 30–67% of AlO(OH), where particle sizes are from 10 to 13 nm, and (3) ZrO2 with 80–99% of AlO(OH), where particle sizes are from 13 to 23 nm. AlO(OH) content determines thermal and physico-chemical properties of synthesised ZrO2–AlO(OH) nanopowders. [ABSTRACT FROM AUTHOR]

Five novel bridged heptaphenyl polyhedral oligomeric silsesquioxanes (POSSs), in which two identical silicon cages R7(SiO1.5)8 (with R = Phenyl) are linked to various aliphatic [(CH2)n with n = 2, 6 and 10] and aromatic (Ar–Ar and Ar–O–Ar, where Ar = p-C6H4) bridges, were synthesized. The obtained compounds were characterized by elemental analysis and 1H NMR spectroscopy, and the results were in very good agreement with those of expected products. The synthesized heptaphenyl POSSs were thermally degraded, in dynamic heating conditions (25–700 °C), in both flowing nitrogen and static air atmosphere. The temperatures at 5% mass loss (T5%) and residues at 700 °C were thus determined to evaluate their resistance to thermal degradation, but no substantial difference was found between the values in the two studied environments. The obtained T5% values were much higher than those of the corresponding isobutyl and cyclopentyl POSSs we investigated in the past. Also, the T5% values of the phenyl POSSs with aliphatic bridges decreased quite linearly on increasing the number of bridge carbon atoms (nC). This behaviour was interpreted and attributed to the presence of the external corona formed by voluminous phenyl groups. The residue at 700 °C, which was largely higher than those of the corresponding isobutyl and cyclopentyl POSSs, was a further confirmation of the better thermal stability of the compounds here studied. [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]

Hyperbranched poly(ester)s (HBPE) possess attributes for applications in a number of areas which include platforms for controlled release of actives and as rheology modifiers and coalescent agents in coatings. For the latter applications, properties such as the glass transition temperature and thermal stability are important. A number of HBPEs were produced with varying composition, molecular weight, degree of branching and end-group functionality in order to determine the effect of each on the HBPE thermal and rheological properties. These materials were synthesized from trimethylolpropane and the difunctional acids; adipic, phthalic and terephthalic. The chemical structure of the resulting HBPEs was fully characterized, particularly by SEC and NMR, and the thermal properties by DSC and TG. The glass transition temperature was found to depend primarily on HBPE composition and end-group functionality. The prominent feature of the thermal degradation for the hydroxyl-capped HBPE was dehydrative ether formation while that for carboxyl-capped polymers was decarboxylation. [ABSTRACT FROM AUTHOR]