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Crystal structure, thermal stability, and the process of scandium tris-methylcyclopentadienyl Sc(MeCp)3 evaporation are studied. It is shown by XRD that crystals of this compound with the C2/c space group and the following parameters at 150 K are formed from the gas phase and from the solution: a = 7.9568(4) Å, b = 13.7620(6) Å, c = 28.239(2) Å, β = 107.4860(10)°, V = 2949.3(3) Å3, Z = 8, Dcalc = 1.217 g/cm3. The violation of the crystal packing order is manifested as diffuse scattering accompanied by single-crystal Bragg diffraction. The obtained data suggest that the complex has the Sc(η5-MeCp)2(η1-MeCp) structure with Sc–Z distances equal to 2.26-2.37 Å, where Z is the center of the η5-MeCp species or the C atom (for η1-MeCp). The NMR data obtained for the Sc(MeCp)3 samples, which were kept for 7 days at 423 K, 453 K, and 483 K, indicate that the substance undergoes noticeable decomposition only at the highest temperature. Temperature dependences of the saturated vapor pressure of the complex are measured independently by the flow method (transpiration) (392-469 K) and by the static method (441-514 K). As a result of joint processing of the tensimetry data, the following thermodynamic parameters of Sc(MeCp)3 evaporation are determined: ΔevH0(458.5) = 82.5±1.1 kJ/mol, ΔevS0(458.5) = 135±2 J/(mol·K). [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]

Nanocellulose derived from cellulose, the abundant natural polymer, is used in various applications due to its superior chemical, mechanical and thermal properties along with good biocompatibility and biodegradability. This paper reports an investigation of the extraction of nanocellulose from two freely available natural precursors-watermelon rinds and water hyacinth leaves. Cellulose isolation was carried out through chemical methods, including acid and alkali treatments followed by bleaching. The chemical composition, percentage crystallinity and particle size were studied using various characterization techniques. FTIR spectra indicate the removal of hemicelluloses, pectin, and lignin resulting in the effective isolation of cellulose from both precursors. Results of XRD indicate a high concentration of Cellulose Nanocrystals (CNCs) in the treated sample. The FESEM and SEM-EDAX images also confirm the formation of CNCs. TGA and DSC results show excellent thermal stability for both CNCs. Investigations on the properties of a CNC-reinforced epoxy composite are also reported. Results indicate considerable improvement in the mechanical properties, thermal stability and thermal conductivity of the composites compared to the pristine polymer. [ABSTRACT FROM AUTHOR]

Hibiscus vitifolius was found to possess the promising potential required for reinforcing polymer matrices. In this study, Hibiscus vitifolius fibers were immersed in 2, 3, 4, 5, 6, 7, and 8% NaOH solution for 1 hr and the effects of alkali treatment on chemical, mechanical and thermal characteristics of the fiber were evaluated through chemical tests, X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis, tensile tests, and field emission scanning electron microscopy. From the test results, it was inferred that Hibiscus vitifolius fibers treated using 5% NaOH exhibited high crystallinity, tensile strength, and Young's modulus compared to raw fibers. Beyond 5% NaOH treatment, the fibers suffered a decline in crystallinity index and mechanical properties. The morphological analysis of alkali-treated fibers revealed the removal of amorphous constituents and separation of fiber bundles into individual fiber filaments. [ABSTRACT FROM AUTHOR]

The reactions of magnesium nitrate with trans-1,4-cyclohexanedicarboxylic acid (H2Сhdc) in N,N-dimethylformamide (DMF) and N-methylpyrrolidone (NMP) as solvents afford new coordination polymers [Mg3(DMF)4(Chdc)3] (I), [Mg3(DMF)2(NMP)2(Сhdc)3] (II), and [Mg3(NMP)4(Сhdc)3] (III). Coordination polymer [Ca3(NMP)4(Chdc)3] (IV) is synthesized from calcium acetate and H2Chdc in NMP. The reaction of cadmium nitrate with H2Сhdc and urotropine (Ur) in DMF gives coordination polymer [Cd(Ur)(DMF)(Chdc)] (V). The structures of the synthesized compounds are determined by single-crystal X-ray diffraction (XRD) (CIF files CCDC nos. 2120662 (I), 2120666 (II), 2120664 (III), 2120663 (IV), and 2120665 (V)). The coordination polymers of alkaline-earth metals (I–IV) are based on trinuclear carboxylate blocks {M3(OOC)6} linked by the dicarboxylate linkers into trigonal layers. The cadmium compound (V) is built of the mononuclear fragments {Cd(NUr)2(DMF)(OOC)2} linked by bridging trans-1,4-cyclohexanedicarboxylates and urotropine molecules into polymer layers. Compounds I–III are characterized by IR spectroscopy, elemental analysis, and thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

Electrospun Polyvinylidene fluoride (PVdF) membrane is fabricated as a separator for supercapacitor applications. Different weight percentages (5, 10, 15, 20, and 25 wt%) of PVdF were suspended in 50:50 wt% of THF and DMAc solvents, respectively, and electrospinning technique was used to synthesize the polymer separator membranes. The structural morphology was investigated using SEM analysis and thermal stability of the synthesized membranes were determined using TGA and DSC analysis to identify the optimum wt% of PVdF membrane with high porosity, high electrolytic uptake, and lower crystallinity, respectively. It was found that PVdF membrane with 20 wt% exhibited superior properties of lower fiber diameter of about 400 ± 8 nm, high electrolytic uptake of 200 ± 2%, and high porosity of 86.83 ± 2% compared to other synthesized membranes. Further, 20 wt% PVdF membrane was found to be thermally stable up to a temperature of about 450°C. The crystalline nature of the separator membranes were determined using the X-ray diffraction technique. Electrochemical studies (Liner sweep voltammetry) studies revealed that the synthesized PVdF membrane is stable up to 2.5 V. Thus, it was found that PVdF polymer membrane with 20 wt% exhibited superior structural and thermal properties compared to other membranes, making it as a reliable separator membrane for supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Slow evaporation synthesis method at room temperature of (C 6 H 7 N 2 S)NO 3. • Hybrid nitrate salt of 4-pyridinethioamide with a supramolecular crystal structure. • A good thermal stability for a wide range of temperatures. Organic-inorganic hybrid nitrate salt associating the aromatic organic molecule 4-pyridinethioamide with the (C 6 H 7 N 2 S)NO 3 formula was synthesized by slow evaporation method at room temperature. The obtained material is crystallized in the monoclinic system with the centro-symmetric space group P 2 1 / c. The supramolecular crystal structure was built from nitrate anions N O 3 - entities linked to the organic cations (C 6 H 7 N 2 S)+ by hydrogen bonds and weak interactions. Besides, the aromatic pyridinium rings of 4-pyridinethioamide molecules were proven to form chains through π...π interactions. The Hirshfeld analysis results have shown that in all potential molecular contacts, the H...O/O...H constitutes the most important interaction in the crystal with a contribution percentage of 39 %. The thermal behavior studied by thermogravimetric analyses revealed good stability up to 175 °C. Preliminary analyses recorded with infrared and Raman spectroscopy confirmed the existence of vibrational modes corresponding to the formation of the hybrid compound before performing the characterization by X-ray single-crystal diffraction. The optical absorption spectrum exhibits two bands located at 4.82 eV (257 nm) and 3.95 eV (314 nm), which can be even observed with the naked eye at room temperature and is due to exaction emission. [ABSTRACT FROM AUTHOR]

Cu 1.8 S has received a lot of interest as a prospective thermoelectric material with the best performance and abundant resources. While high charge carrier concentration contributes to the high electrical conductivity and power factor values, grain-boundary engineering is required to improve the phonon scattering and thermal stability of Cu 1.8 S. We used a simple process that combined nanoparticles via mechanical alloying and post-annealing to introduce the reduced graphene oxide (rGO) heterointerface into the Cu 1.8 S matrix. A significant enhancement of power factor has been realized that the highest power factor is 721 μWm−1 K−2 at 550 K in the composite Cu 1.8 S/rGO with 10 % rGO, which is higher than the pure Cu 1.8 S. Furthermore, following four cycles of testing from ambient temperature to 550 K, the composite demonstrated excellent repeatability of power factor, confirming its practical application potential. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Single-phase MgFe 2 O 4 nanoparticles (crystallite size ∼ 27 nm) were synthesized via citrate precursor route. • Saturation magnetization increased from ∼ 26.46 emu/g (300 K) to ∼ 34.79 emu/g (100 K). • Low coercivity (92–187 Oe) from 300 K to 100 K indicated soft magnetic behavior. • Observed remanent magnetization of ∼ 5.58 emu/g and remanence ratio of 0.21 at 300 K. • Blocking temperature estimated at ∼ 573 K, coercivity at 0 K at ∼ 249 Oe, and Curie temperature at ∼ 660 K. Low temperature magnetization measurements of citrate precursor-synthesized magnesium ferrite nanoparticles (MFNPs) of ∼ 27 nm were conducted by progressively lowering the temperature from 300 K to 100 K. Hysteresis curves revealed unsaturated magnetization even at ± 15 kOe, attributed to surface spins. Specific saturation magnetization (σ s) and coercivity (H c) experienced an increase from 26.46 emu/g (300 K) to 34.79 emu/g (100 K), and from 92 Oe (300 K) to 187 Oe (100 K), respectively. Specific remanence magnetization (σ r) rose from 5.58 emu/g (300 K) to 10.14 emu/g (100 K), indicating a notable shift in magnetic behavior. Effective anisotropy constant (K eff) showed significant growth from 2474.14 erg/g (300 K) to 6635.04 erg/g (100 K), highlighting low magnetocrystalline anisotropy at room temperature. The rise in magnetic moment (n B) from 0.95 Am2 at 300 K to 1.25 Am2 at 100 K indicates improved magnetic alignment and stability, particularly at lower temperatures. Correlation analysis revealed strong negative curvilinear correlations between magnetic properties and temperature. Extrapolation estimated the blocking temperature (∼573 K), coercivity at 0 K (∼249 Oe), and Curie temperature (∼660 K). These results suggest promising applications in space technology, underscoring the enhanced sensitivity of MFNPs to external magnetic fields in cold environments. [ABSTRACT FROM AUTHOR]

The Al/α-AlH3 was prepared in ether solution with LiAlH4 and AlCl3 with some addition. The crystallization and the morphology of the prepared samples were studied by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The organic elemental analyzer can be used to determine the content of H element. Furthermore, the effects of Al on the thermal stability and security of α-AlH3 were also studied. The thermal stability has been studied by TG curves. The impact sensitivity test, friction sensitivity test and electrostatic spark sensitivity test have been tested. The results shown that the existence of the Al has no impact on the friction sensitivity, impact sensitivity of pure α-AlH3. However, the existence of Al increases the decomposition rate of α-AlH3. [ABSTRACT FROM AUTHOR]

Two new mesogenic compounds having a bicyclic aromatic thiazolo[5,4-d]thiazole linked to four 1,3,4-oxadiazol heterocycles were synthesised and their liquid-crystalline properties were investigated. The compounds exhibit enantiotropic hexagonal columnar mesophase with strong homeotropic orientation induced under confinement, and a wide mesophase range. The molecular packing is preserved at room temperature, especially the π-stacking inside the columns, which is essential for good charge carrier transport. They show high thermal stability, blue photoluminescence in solution, and blue-green in thin film. The morphology of spin-coated films is smooth even after thermal annealing, where large molecular-ordered domains were induced, but preserving the photoluminescence quantum yield. All characteristics suggest that this new class of mesogenic molecules is promising for technological applications. [ABSTRACT FROM AUTHOR]

The present work deals with the development of new metal-based nanocomposites reinforced by multiwall carbon nanotubes (MWCNTs) for nanotechnology field. Samples are prepared in situ and contain a ratio of 4:1 Fe–Cu, with MWCNT additions of 0 vol%, 0.25 vol%, 0.75 vol% and 1 vol%, respectively. The materials are characterized using thermodynamic and structural techniques like dilatometry, DSC, TG, X-ray diffraction and Raman spectrometry (SERS). Dependence of relative variations in elongation has been noted as a function of the temperature range. Among the synthesized materials, the FeCu1%MWCNT nanocomposite seems to be the best configuration. The latter expands the least and presents fewer defects. The Raman study of the FeCu1%MWCNT nanocomposite showed that the MWCNT are in an ordered state. The addition of 1% of MWCNT to FeCu matrix gives the most refined structure with high thermal stability and provides better FeCu ion protection against oxidation. [ABSTRACT FROM AUTHOR]

• New oxyfluoroniobate glasses were synthesized in the ZnNbOF 5 -BaF 2 -InF 3 system. • The thermal properties of the obtained glasses are determined. • The structures of the glass networks in the system studied are revealed. • Glasses in the ZnNbOF 5 -BaF 2 -InF 3 system show luminescence was properties. • In glasses with luminescent properties, nano-objects 9–13 nm in size were found. Glasses in the ZnNbOF 5 –BaF 2 –InF 3 and ZnNbOF 5 -BaF 2 systems were produced using the ZnNbOF 5 •6H 2 O compound. The structure, thermal and luminescent properties of the obtained glasses were studied with IR-, Raman, SAXS, luminescent spectroscopy methods, calorimetry and X-ray diffraction. The highest range of thermal stability and resistance of glass to crystallization has been established for the glass of 20ZnNbOF 5 –40BaF 2 –40InF 3 composition. This value is an order of magnitude higher than in glasses of the same system, but not containing InF 3. Glasses networks are formed from polyhedra of InF 6 , NbO 2 F 4 and NbO 3 F 3. For all glasses containing InF 3 , photoluminescence contribution which depends on the concentration of indium trifluoride in the glass was recorded. This contribution corresponds to the emission levels of 542, 573, 673, 751 nm. Luminescent properties are shown by glasses in which nanoobjects (nanoinhomogeneities) in size of 9-13 nm were detected by SAXS method. [ABSTRACT FROM AUTHOR]

In this work, preparation of thermal barrier coatings based on zirconium oxide is shown. The phased treatment of the copper substrate is proposed in order to obtain a layered thermal barrier oxide coating on it. The sample surface is nanostructured, titanium is deposited layer-by-layer (by the vacuum-arc method) and then zirconium (by the magnetron method), and then zirconium is converted into zirconium dioxide by the microplasma method. The formed oxide-ceramic coatings contain elements from a solution, according to the results of elemental analysis, and zirconium dioxide in tetragonal and monoclinic modifications, according to the results of X-ray diffraction. A study of thermal cyclic stability was carried out. It is revealed that an increase in the time of microplasma treatment to a certain value has a positive effect on the thermal cyclic properties of the obtained layer material and it is able to sustain more than 90 cycles without serious damage to the surface layer. [ABSTRACT FROM AUTHOR]

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Abstract MgO containing vanadate glasses of composition V 2- x Mg x O 5-δ (x = 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) have been prepared successfully by melt-quench technique. The structural properties of the as-quenched samples are explored with the help of X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Thermal properties and conductivity of the samples are investigated using differential thermal analysis (DTA) and impedance spectroscopy, respectively. Density, inter-ionic distance, and fragility index are found to decrease with the addition of MgO content. Higher content of MgO improves the glass formation tendency and reduces the thermal stability of the samples. The conductivity of the V 2- x Mg x O 5-δ samples decreases as the MgO concentration increases due to hindrance in the polaronic conduction of vanadium ions. The conductivity of the samples decreases to ̴ 10−4 S m−1 for x = 0.30 at 300 °C, while activation energy increases to 0.38 eV. These samples may find application in solid state batteries and fuel cells due to their higher conductivity. [ABSTRACT FROM AUTHOR]

(a) The figure shows the Ba 3 MgTa 2 O 9 : x Sm3+ (0.01 ≤ x ≤ 0.15) CIE chromaticity coordinates, and the inset on the upper right corner shows the pictures of the Ba 3 MgTa 2 O 9 :0.05Sm3+phosphor samples under daylight and 265 nm lamp irradiation, respectively. (b) The graph shows the color purity of the Ba 3 MgTa 2 O 9 : x Sm3+ (0.01 ≤ x ≤ 0.15) phosphor sample. [Display omitted] • Ba 3 MgTa 2 O 9 :Sm3+ phosphors were firstly synthesized via a high-temperature solid-state reaction. • The phosphor emits bright orange-red light excited by 407 nm. • The phosphor exhibits good color stability and high color purity (98.51 %). • Ba 3 MgTa 2 O 9 :Sm3+ has good thermal stability and suitable color temperature, and is expected to be used in near-UV excited WLEDs. In this study, a Ba 3 MgTa 2 O 9 : x Sm3+ orange-red phosphor was synthesized by a high-temperature solid-phase reaction method, and its fluorescence properties were analyzed. The Ba 3 MgTa 2 O 9 : x Sm3+ phosphor exhibited three emission peaks at 561 nm (4G 5/2 → 6H 5/2), 595 nm (4G 5/2 → 6H 7/2), and 642 nm (4G 5/2 → 6H 9/2) under the excitation of 407 nm. The Ba 3 MgTa 2 O 9 :0.05Sm3+ phosphor had good thermal stability and excellent color stability at different temperatures. Ba 3 MgTa 2 O 9 :0.05Sm3+ phosphor is the best doping concentration phosphor, with a high color purity of 98.52 %. The XRD of the Sm3+ ion-doped phosphor showed that its crystal structure and morphology were stable, and the doping of Sm3+ ions did not affect its crystal structure significantly. Therefore, the Sm3+ ion-doped phosphors in this study have potential applications and are expected to be used in the field of WLED. [ABSTRACT FROM AUTHOR]

A kind of silicon-and-boron-modified phenolic–formaldehyde resin (SBPF) with excellent thermal stability was fabricated via a simple two-step method and used for the matrix of ablation materials. The structure and thermal stability of the modified phenolic–formaldehyde resins (PFs) were characterised. The results showed that boron and silicon elements have been incorporated into SBPF in the form of a chemical bond. Meanwhile, the cured products showed an increase in graphite structure and a decrease in disordered structure due to the incorporation of boron and silicon. Compared with the ordinary phenolic resin, the initial thermal degradation temperature and charring yield at 800°C of SBPF increased by 73°C and 15 wt%, respectively. Further, the modified PFs, nano-Al(2)O(3) powders, glass powders and vitreous silica fibres were used to obtain a novel ceramizable phenolic moulding composite. The morphology, chemical composition and ablative characteristics of the composites were explored. The results showed that a compact and homogeneous SiO(2)–Al(2)O(3) layer formed on the ablated surface and protected the carbonised matrix and fibres from further oxidation. Compared with the ordinary PF composites, the SBPF composites showed a highly decreased linear/mass ablation rates, indicating the synergistic effect of boron and silicon modification on the enhanced ablation property.

Quaternary Co 2 FeAl 0.5 Si 0.5 Heusler alloy thin films have attracted special attention for the application in magnetoelectronic devices. Co 2 FeAl 0.5 Si 0.5 alloy thin films are fabricated by magnetron sputtering at room temperature. The temperature effects on the magnetic, electrical and optical properties in sputtered Co 2 FeAl 0.5 Si 0.5 alloy films are investigated. Thermomagnetic measurements reveal increased magnetization arising from enhanced crystalline ferromagnetic ordering. Anomalous increase in electrical resistivity with temperature is probed in the alloy film, accompanied with significant change in optical reflectance. The large variations in electrical and optical signals in the alloy film can be attributed to the transition of atomic orderings, confirmed by X-ray diffraction measurements. The activation barrier for the transformation of atomic orderings is determined to be 1.22 eV, showing good thermal stability of the Heusler alloy thin film. [ABSTRACT FROM AUTHOR]

(Ba 1− x Bi 0.5 x Sr 0.5 x )(Ti 1− x Bi 0.5 x Sn 0.5 x )O 3 (BBSTBS, 0.02 ≤  x  ≤ 0.1) samples were prepared by a solid state reaction (SSR) method. The phase structure and dielectric properties of BBSTBS ceramics were investigated. X-ray diffraction results illustrated that BBSTBS could form a homogenous solid solution. Optimum properties with a stable ε r (∼13,643–19,000), small Δε/ε 25 °C values (±15%) over a broad temperature range from −61 °C to 210 °C and low tanδ (≤0.025) from −67 °C to 220 °C were obtained at x  = 0.06. [ABSTRACT FROM AUTHOR]

In this present work, material has been developed to have thermal stability over microwave range. The SrBi4Ti4O15 ceramics are perovskite material from Aurivillius family and were produced by solid state reaction method with temperatures lower than other recent works reported. X-ray diffraction patterns have confirmed single phase and afterward the sample data were refined by using Rietveld method. V2O5 was added to the pure specimen with different amounts (5, 10 and 15 wt.%) to possibly enhance electrical and dielectric properties of SrBi4Ti4O15. An impedance analyzer and a network analyzer were used to obtain electrical measurements in the range of microwave. Thermal stability measures over a microwave range were used as well as numerical simulations of dielectric resonator antenna (DRA) using the HFSS software. The obtained results have shown an efficient synthesis, and the dielectric constants indicate a real possibility of miniaturization. It was also found that the specimen for 6 wt.% of V2O5 presented temperature coefficient (τ f ) near zero at microwave region. The bandwidths measured from the specimens were classified as S-type with wide bandwidth and it can be applied for meteorological radars and satellite communications. [ABSTRACT FROM AUTHOR]

Tungsten tetraboride alloys with Y, Sc, Gd, Tb, Dy, Ho, and Er were prepared by arc-melting and investigated for their thermal stability and mechanical properties. The phase composition and purity were confirmed by powder X-ray diffraction (PXRD) and energy dispersive X-ray spectroscopy (EDS). In all cases, except for Sc, a change to a "dendritic" morphology was observed. For alloys with Sc, the metal boride and boron grains became smaller; however, no patterning was observed. This shows that tuning the composition of the alloys of WB4 with transition metals and lanthanides results in a modification of the morphology leading to patterning and smaller grains that enhance mechanical and thermal properties. For alloys of WB4 with Y, Sc, Gd, Dy, Tb, Ho, and Er, an increase in hardness to 50.2 ± 2.4, 48.9 ± 2.5, 48.0 ± 2.1, 46.3 ± 2.6, 48.5 ± 2.3, 46.4 ± 3.4, and 47.2 ± 2.9 GPa at low load, respectively, compared to 41.2 ± 1.4 GPa for WB4 is observed. Moreover, the alloys of WB4 with Y, Sc, and Gd showed an increase in oxidation resistance from ~450 °C for WB4 to ~470, ~525, and 465 °C, respectively. [ABSTRACT FROM AUTHOR]

Conventional polyimide nanocomposites reinforced with graphene-based nanofillers usually possess excellent properties, such as high thermal decomposition temperature, enhanced tensile strength, tensile modulus, etc. However, the elongation at break of the nanocomposites is reduced. Here, we prepared N-doped graphene quantum dots/colorless polyimide nanocomposite (N-GQDs/CPI) films for the first time by in-situ polymerization, whose elongation at break is about 2 times that of the pure film. Meanwhile, the thermal properties and other mechanical properties of the films are improved. Through analyzing FT-IR, XPS, XRD, TAG SEM, etc. of N-GQDs and the films, we consider that the strengthening mechanism of matrix performance is attributed to N-GQDs' well dispersion, its small size effects and strong interface interaction with the matrix. Furthermore, at the indicative wavelength of 550 nm, the optical transmittance of the film with 1 wt% N-GQDs still maintains 79%, indicating the resulting films have excellent optical transmittance. The hydrophilic properties of the prepared films' surface is reduced, their water surface contact angle are increased from 63 ± 2.7° to 92 ± 1.7° with the content of N-GQDs increasing. This research shows that N-GQDs can enhance the various properties of polyimide and provides a high performance nanocomposite films for potential flexible substrates. [ABSTRACT FROM AUTHOR]

In this study, thermosensitive luminous fibers (TLFs) were prepared by wet spinning, using polyacrylonitrile as the filament material and rare-earth long-afterglow luminescent materials as the optical source. Reversible thermochromic cresol red-boric acid (CB) pigment in the TFLs served as the luminescence conversion agent. The reflectivity curves and fluorescence spectra were recorded at 25 and 65 °C to investigate the thermosensitive characteristics of the TLFs. The results demonstrated that CB pigment functioned as a luminescent conversion agent that could convert the luminescence of rare-earth luminescent materials depending on the temperature. The luminescence of the TLFs can be converted from blue to fuchsia upon changing their temperature due to the structural transformation of the CB dye. The thermosensitivity can also be verified by observing the TLFs in water at 65 °C with the naked eye. [ABSTRACT FROM AUTHOR]

DC reactive magnetron sputtered Nb z Al y N x coatings with various Al contents ( y /( y + z )) ranging from 0 to 0.75 were deposited using different ratios of the currents applied to the Al and Nb targets in order to systematically control their chemical composition and crystalline structure, and to enhance their mechanical, tribological and thermal stability performance. The film microstructure and properties were assessed by various complementary techniques such as electron probe microanalysis, X-ray diffraction, nanoindentation, ball-on-disc test, and scanning electron microscopy. It was found that the solubility limit of Al in the NbN lattice is in the range 0.44 < y /( y + z ) < 0.60. The Nb z Al y N x coatings present low compressive residual stress (≤ 3 GPa), and their hardness increases up to 31 GPa with increasing y /( y + z ) up to 0.40. The observed hardening is attributed to the solid solution mechanism. For y /( y + z ) > 0.44, the hardness of the Nb z Al y N x coatings is reduced due to the formation of the soft hexagonal AlN phase. In addition, the coatings exhibit interesting tribological properties: the coefficient of friction is in the range of 0.74 to 0.85, and wear rate is in the range of 4.8–9.1 × 10 − 6 mm 3 /Nm. Thermal stability shows a dependence on the Al content; specifically, the Nb 0.33 Al 0.17 N 0.50 coating was found to be thermally stable up to 700 °C. [ABSTRACT FROM AUTHOR]

The effects of carboxymethylation (CM), hydroxypropylation (HP), and cross-linking (CL) on the physicochemical, thermal, and microstructural properties of oat dietary fiber (ODF) were investigated. ODF extracted from defatted oat flour had 66.14% total dietary fiber, 3.42% protein, 5.15% ash, and 1.86% starch. Chemical modifications (CM, HP, CL) significantly improved the SDF but decreased the IDF content of ODF. Results displayed that all the chemical treatments significantly (p < 0.05) improved the swelling capacity, oil absorption capacity, and water absorption capacity of ODF with carboxymethylation being the highly influential. The CM significantly increased the solubility (7.15%), while CL (4.78%) and HP (4.17%) significantly (p < 0.05) decreased the solubility of ODF. The color evaluation showed a decrease in the L* value of ODF after all three modifications, resulting in an increase in the brown color of ODF. XRD results demonstrated an increase in the crystallinity value of ODF after these modifications (19.23–28.94%). DSC results reflected an increase in decomposition/peak temperature of cross-linked ODF showing enhanced thermal stability of such type of modified DF. The changes in physicochemical, microstructural, and thermal properties of ODF after chemical modifications could be attributed to the variations in chemical composition and structure as demonstrated by XRD, FTIR, and SEM analysis. [Display omitted] • Carboxymethylation greatly affected the physicochemical properties of oat fiber. • Cross-linked oat dietary fiber showed improved thermal stability. • Crystallinity of modified oat dietary fiber increased significantly. • Highest SDF content was found in carboxymethylated dietary fiber. [ABSTRACT FROM AUTHOR]

A new nitrogen-rich energetic salt, 2,4-diamino-6-methyl-1,3,5-triazine dinitramide, was synthesized by combining silver dinitramide and 2,4-diamino-6-methyl-1,3,5-triazine perchlorate. The structure of this new energetic salt was confirmed using single-crystal X-ray diffraction, elemental analysis, Fourier transform infrared spectrometry, ultraviolet–visible spectrophotometry, and nuclear magnetic resonance spectroscopy. The thermal stability was determined using differential scanning calorimetry, differential thermal analysis, and thermogravimetric tandem infrared spectrometry. Results showed that the target compound exhibits good thermal decomposition resistance of up to 470 K and has 59.1% mass loss with E a = 118.2 kJ mol −1 . Additionally, the detonation pressure and velocity obtained using Kamlet-Jacobs equations are 23 GPa and 8.2 km s −1 , respectively. Sensitivity test was also attempted. The impact sensitivity of this new energetic salt is 11.5 J, which is superior to that of RDX (7.4 J). [ABSTRACT FROM AUTHOR]

Three new complexes of 1,3-diethyl-thiobarbituric acid (HDetba), barbiturate-bridged 2D Mn(II) polymer [Mn(H 2 O) 2 (Detba) 2 ] ( 1 ), trinuclear [Mn 3 (H 2 O) 10 (Detba) 6 ] ( 2 ) and discrete molecular [Mn(H 2 O) 4 (Detba) 2 ]·H 2 O ( 3 ) are synthesized and structurally characterized by the X-ray single crystal technique. In 1 – 3 , the Detba − ions are coordinated to Mn(II) only through O atoms with manganese ions in the octahedral environment. In 1 , the Mn(II) ion is coordinated by four μ 2 bridge Detba − ions and two terminal H 2 O molecules. In 2 , the Mn1 ion is coordinated by three terminal H 2 O molecules, two terminal and one μ 2 bridge Detba − ion, and Mn2 is connected with two μ 2 -Detba − ions and four H 2 O molecules. In 3 , the Mn(II) ion is coordinated by two terminal Detba − ions and four terminal H 2 O molecules. There are intermolecular hydrogen bonds O–H⋯O, O–H⋯S in the structures of 1 – 3 which form the 3D networks. Structure 2 is stabilized by the π–π interaction. The compounds thermal decomposition comprises dehydration steps and the organic ligand oxidation. [ABSTRACT FROM AUTHOR]

Copper thin films with thickness of about 500 nm doped with different aluminum concentrations have been prepared by magnetron sputtering on Si substrate and their crystal structure, microstructure, and electrical resistivity after annealing at various temperatures (200°C to 600°C) for 1 h or at 400°C for different durations (1 h to 11 h) investigated by grazing-incidence x-ray diffraction (GIXRD) analysis, scanning electron microscopy (SEM), and four-point probe (FPP) measurements. Cu-1.8Al alloy thin film exhibited good thermal stability and low electrical resistivity (∼5.0 μΩ cm) after annealing at 500°C for 1 h or 400°C for 7 h. No copper silicide was observed at the Cu-Al/Si interface by GIXRD analysis or SEM for this sample. This result indicates that doping Cu thin film with small amounts of Al can achieve high thermal stability and low electrical resistivity, suggesting that Cu-1.8Al alloy thin film could be used for barrierless Cu metallization on Si substrate. [ABSTRACT FROM AUTHOR]

Amorphous TbFeCo material with perpendicular magnetic anisotropy is currently attracting more attention for potential applications in spintronic devices and logic memories. We systematically investigate magnetic, structural, thermal, optical and electrical properties of TbFeCo alloy films. It shows out-of-plane easy axis of the films turns into in-plane orientation after annealing. Significant increase in saturation magnetization in the temperature range between 400 and 450 °C is revealed by thermomagnetic measurements. The occurrence of crystallization and oxidation at high temperatures is confirmed by X-ray diffraction measurements. Pronounced changes in optical reflectance and sheet resistance are observed with temperature, in line with structural relaxation and change. The activation barriers for crystallization and oxidation are determined to be 1.01 eV and 0.83 eV, respectively, for FeCo-rich and Tb-rich samples. Better thermal stability against crystallization and oxidation is demonstrated in the FeCo-rich sample than the Tb-rich type. Our results provide some useful information for the alloy used in device fabrication. [ABSTRACT FROM AUTHOR]

In this study, modified wollastonite nanorods (MWNRs) as core and polystyrene (PS) as a shell [Core-shell nanorods (CSNRs)] was synthesized using atomized microemulsion technique. CSNRs were compounded with styrene butadiene rubber (SBR) on a two-roll mill and compressed into sheet form using compression moulding machine. The encapsulation of MWNRs into PS was confirmed by field emission scanning electron microscope (FE-SEM), transmission electron microscope, X-ray diffraction spectrophotometer (XRD) and Fourier transform infrared spectroscopy. CSNRs/SBR nanocomposites were also characterized by XRD, FE-SEM, differential scanning calorimetry, thermogravimetric analysis, universal testing machine and Mooney viscometer. Incorporation of CSNRs resulted in improvement in rheological, thermal and mechanical properties of the nanocomposites. FE-SEM images showed a perfect dispersion of the CSNRs in SBR matrix at <1 wt% loading. Thermal stability of CSNRs/SBR nanocomposites was also increased significantly by the addition of CSNRs. Graphical abstract: [ABSTRACT FROM AUTHOR]

ABSTRACT The aim of this study was to develop poly(3-hydroxybutyrate- co-3-hydroxyvalerate) (PHBV) bionanocomposites with natural vermiculite (VMT) and modified vermiculite (VMTO), by the melt intercalation technique and to evaluate the thermal behavior, biodegradation, and food-packaging interactions through X-ray diffraction (XRD). Through XRD, we observed the structure of a microcomposite for the systems with natural clay and possibly an exfoliated structure for the systems with VMTO. We observed from the thermogravimetry and differential scanning calorimetry results that the natural systems showed a small increase in the thermal stability, whereas the organoclay systems had a lower thermal stability. A high biodegradability in the pure polymer and the natural bionanocomposites was evidenced by the Sturm test through the carbon dioxide production and high weight loss of the material. We observed that there was no significant migration of PHBV from the bionanocomposites to the simulants. Under these circumstances, the bionanocomposites with VMT presented better thermal stability and a high biodegradability and were possibly inert when in contact with food. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44700. [ABSTRACT FROM AUTHOR]

We present a detailed study of post-deposition annealing effects on contact resistance of Au, Ti, Hf and Ni electrodes on Mg 2 Si thin films. Thin-film Mg 2 Si and metal contacts were deposited using magnetron sputtering. Various post-annealing temperatures were studied to determine the thermal stability of each contact metal. The specific contact resistivity (SCR) was determined using the Cross Bridge Kelvin Resistor (CBKR) method. Ni contacts exhibit the best thermal stability, maintaining stability up to 400 °C, with a SCR of approximately 10 −2 Ω-cm 2 after annealing. The increased SCR after high temperature annealing is correlated with the formation of a Mg-Si-Ni mixture identified by cross-sectional scanning transmission electron microscopy (STEM) characterization, X-ray diffraction characterization (XRD) and other elemental analyses. The formation of this Mg-Si-Ni mixture is attributed to Ni diffusion and its reaction with the Mg 2 Si film. [ABSTRACT FROM AUTHOR]

The effects of hydrogen absorption on the structure, mechanical and thermal properties of Zr 57 Al 10 Cu 15.4 Ni 12.6 Nb 5 amorphous metal were investigated. Structural analysis, using X-ray diffraction, showed that prominent peak shift towards lower angles (from 37.55° to 37.47°) after 1 h of hydrogen charging in 0.1 M NaOH solution which indicates a volume expansion of the amorphous structure. By means of nanoindentation tests, we found that hydrogen-induced glass plasticity could occur in Zr-based metallic glass even for high Zr content (> 50 at.%). The thermal stability against crystallization, evaluated by differential scanning calorimetry (DSC), has been improved by hydrogen absorption. The onset crystallization temperature was increased by 6 °C to 10 °C due to slight hydrogen addition. The resistance to hydrogen embrittlement combined with high thermal stability gives rise to the possibility of the practical use of Zr 57 Al 10 Cu 15.4 Ni 12.6 Nb 5 amorphous alloy as a good metal membrane operating at temperatures below 400 °C. [ABSTRACT FROM AUTHOR]

The strategy for the conversion of an N atom to a C–NO 2 group leading to a "NH 2 –NO 2 –NH 2 " block was described to improve the detonation properties and the thermal stability of an energetic compound simultaneously. [Display omitted] • A strategy of molecular design was proposed to enhance the thermal stabilities. • The "NH 2 –NO 2 –NH 2 "-substituted 3 shows excellent detonation performances. • The relationship between structure and properties was comprehensively studied. Developing energetic compounds with high performances and good molecular stabilities is considered difficult due to its inherent contradiction. In this work, the strategy for the conversion of an N atom to a C–NO 2 group leading to a "NH 2 –NO 2 –NH 2 " block was described to improve the detonation properties and the thermal stability of an energetic compound simultaneously. Based on this strategy, the amino-nitro-amino-substituted nitramine 3 with a high density of 1.96 g cm−3 at room temperature was synthesized. In addition, another amino-nitro-substituted nitramine 9 was also prepared. The structures of 3 and 9 were confirmed by single-crystal X-ray diffraction. Compound 3 exhibits high detonation performances (V D : 8953 m s−1, P : 35.3 GPa) and a good thermal stability (T d : 223 °C), which are superior to RDX, suggesting its great application potentials. [ABSTRACT FROM AUTHOR]

A promising bio-based and biodegradable polybutyrolactam (PBY) fiber with health care function was prepared for the first time by dry-jet-wet spinning. As-prepared PBY fibers possesses the degree of crystallization upto 45.61%, appreciable thermal stability, excellent strength upto 2.1 cN•dtex−1, as well as good resistance to alkalis based on the results of X-ray diffraction, thermal and physical properties. The bio-degradability of PBY fibers were evaluated by the degraded behavior in soil, UV aging irradiation and seawater, showing commendable bio-degradation within 100 days. The analysis of the degradation based on TGA demonstrates that the removal of oligomers preferentially occurs, and then PBY macromolecules are broken. More interestingly, pharmaceutical γ -aminobutyric acid (GABA) is released during the degradation process, and it is beneficial to health care. As a biomass-derived and bio-degradable fiber, the sustainable PBY fiber exhibits an impressively competitive tensile strength among the existing degradable man-made fibers, showing great potential in bio-based fiber materials and health care textiles. [Display omitted] • Polybutyrolactam fiber was prepared for the first time by dry-jet-wet spinning. • The tensile strength of fiber reaches to 2.1 cN.•dtex−1. • Showing a commend bio-degradation performance within 100 days. • Pharmaceutical GABA is released during the degradation process. [ABSTRACT FROM AUTHOR]

In the present study ZnSe quantum dots (QDs) were synthesized by chemical co-precipitation method using mercaptoethanol as the capping agent. These nanostructures were characterized for structure and surface morphology by using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectrometry respectively. The average size of ZnSe quantum dots from XRD and HRTEM is found to be 4-5 nm having cubic crystalline phase. Effect of annealing temperature, which were determined as phase transformation temperatures (299 and 426 °C) using differential scanning calorimetry has been investigated for structural and thermal stability of QDs. The XRD of annealed samples at temperatures 325 and 442 °C (slightly higher than the temperatures corresponding to two crystallization peaks in the DSC scan) have been carried out to find structural changes corresponding to these annealing temperatures. Sample annealed at 325 °C showed no change in the phase except improvement in intensity of peaks (crystallinity) whereas sample annealed at 442 °C showed transitions from cubic phase of ZnSe to ZnO and orthorhombic phases of ZnSeO, ZnSeO. Emergence of ZnO peaks in the XRD pattern of annealed samples have been further verified by Raman spectroscopy of the annealed samples. Besides this crystallization kinetics of ZnSe quantum dots has been employed to determine activation energies of these transitions due to oxidation by employing Kissinger, Augis Bennett and Ozawa's models. Higher activation energy of crystallization corresponding to first crystallization peak shows that the cubic phase is more thermally stable. [ABSTRACT FROM AUTHOR]

In this study, polyaniline-graphene composites with different nano-structures are synthesized and the behaviour of the obtained composites serving as electrode materials in electrochemical capacitors is studied. The morphology, crystal structure, and thermal stability of the composites are examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Thermal gravimetric analysis (TGA). Electrochemical properties are characterized by cyclic voltammetry (CV). According to the results, the obtained composites show different crystal structures and different thermal stabilities, and consequently different electrochemical capacities, when used as electrodes in electrochemical capacitors. A nano-fibre composite is shown to have a good degree of crystallization, 5.17% water content, 637°C degradation onset temperature, and 379 Fg-1 electrochemical capacity. [ABSTRACT FROM AUTHOR]

From 1-D to 3-D zinc coordination polymers based on multifunctional flexible 4-(1,2,4-triazole-methylene)-benzonitrile (tzbt), {[Zn(tzbt)2(bdc)]·2H2O}n(1), [Zn(tzbc)2]n(2), and [Zn(bpdc)(H2O)]n(3) (bdc = 1,4-benzenedicarboxylic acid, tzbc = 4-(1,2,4-triazole-methylene)-benzoic acid, bpdc = 4,4′-biphenyldicarboxylic acid), were synthesized under hydrothermal conditions. The tzbt was synthesized byN-alkylation and hydrolyzedin situto produce tzbc (in2). Single-crystal X-ray diffraction analysis reveals that1displays 1-D wave-like chains based on [Zn(bdc)]n.2is a chiral twofold interpenetrating 2-D architecture constructed with “V”-shaped tzbc.3is a 3-D chiral compound constructed from achiral H2bpdc with right-handed helical chains.1–3display stable blue-emitting luminescence with emission maxima ranging from 383 to 410 nm, depending on ligand-centeredπ*→πtransitions. The effects of different polarity solvents and temperature on luminescence are discussed. TGA and VT-XPRD reveal that2has thermal stability to 360 °C. [ABSTRACT FROM PUBLISHER]

In this work, in order to investigate the reinforcement effects of organic montmorillonite (OMMT) modified epoxy mortar binders (EMBs), a series of OMMT/EMB composites with different OMMT loadings were prepared. The structure and thermal stability of OMMT were studied by X-ray diffraction (XRD), Fourier transform infrared spectrum, and thermogravimetric analysis (TGA). The effects of OMMT on the structure, glass transition, damping properties, thermal stability, mechanical properties and morphology of EMB were characterized by XRD, dynamic mechanical analysis, TGA, tensile test, and scanning electron microscopy. XRD results indicated that epoxy chains intercalated into the OMMT layers and led to the expansion of OMMT layer spacing. The presence of OMMT increased the glass transformation temperature, crosslink density of the neat EMB. Furthermore, the incorporation of OMMT improved the thermal stability of the EMB. The OMMT/EMB composites showed higher tensile strength and Young’s modulus than the neat EMB. Homogenous dispersion of OMMT in EMB matrix was observed. [ABSTRACT FROM AUTHOR]

Stearic acid/diatomite composite form-stable phase change materials (PCMs) have been prepared by using a direct impregnation method without vacuum treatment. The surface morphology, chemical compatibility, thermal properties and thermal stability were characterized by scanning electron microscopy, Fourier transform infrared spectrometer and X-ray diffraction (XRD), differential scanning calorimeter and thermogravimetric analysis (TG), respectively. The results show that there are only physical interactions between stearic acid and diatomite in composite PCM. XRD analysis reveals that crystal type is not affected by composite technology of SA/diatomite composite form-stable PCM with decrease in crystal size due to the limited pores in diatomite. The melting and freezing temperatures of stearic acid/diatomite composite, respectively, are 52.3 and 48.4 °C. The latent heat of SA/diatomite composite reaches 57.1 J g, potential to be used in a practical application. TG result indicates that the decomposition of SA/diatomite composite starts at 192 °C, implying that the SA/diatomite has a good thermal stability. [ABSTRACT FROM AUTHOR]

ABSTRACT A sodium montmorillonite, Dellite HPS, was modified with ionic liquids based on phosphonium salts, such as octadecyltriphenylphosphonium tetrafluoroborate and octadecyltriphenylphosphonium bromide. Thanks to their high thermal stability, these salts can be used during in situ polymerization, a method that favors the achievement of a good dispersion of the clay. Poly(1,4-dimethylcyclohexane adipate) (PCHA), was chosen as an example of aliphatic polyester which can be a suitable matrix for new biocomposites with organo-clays. The organo modified clays prepared were characterized by X-ray diffraction (XRD), ATR-FTIR spectroscopy, and thermal gravimetric analysis (TGA) while biocomposites were analyzed in terms of molecular structure, thermal and thermomechanical properties. The degree of dispersion of the clays in the polymer matrix was studied by XRD. The results show that the clays are well dispersed in the biocomposites, despite an intercalated structure highlighted by XRD analysis. Moreover, the clays confer a certain improvement in mechanical properties to the final materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42467. [ABSTRACT FROM AUTHOR]

The thermal stability of FePdB thin films was studied using nonisothermal and isothermal analyses. X-ray diffraction (XRD) patterns indicated that Fe 40 Pd 40 B 20 and Fe 60 Pd 20 B 20 films with thicknesses in the range 25–75 Å were amorphous, whereas Fe 40 Pd 40 B 20 and Fe 60 Pd 20 B 20 films with thicknesses in the range 100–200 Å exhibited a nanocrystalline FePd (111) structure. The crucial glass forming ability index ( γ and γ m ) was determined using the differential scanning calorimetry (DSC) results of amorphous FePdB films. The Kissinger formula was applied to calculate the activation energy ( Q ) of crystallization for determining the resistance of the films to crystallization. Thermal analysis showed that the thermal stability and incubation time of Fe 40 Pd 40 B 20 are more favorable than those of Fe 60 Pd 20 B 20 . [ABSTRACT FROM AUTHOR]

Thermal stability is one of the critical requirements for commercial operation of high energy lithium-ion batteries. In this study, we use in situ X-ray diffraction technique to elucidate the thermal degradation mechanism of 0.5Li 2 MnO 3 -0.5LiNi 0.33 Co 0.33 Mn 0.33 O 2 lithium rich cathode material in the absence and presence of electrolyte to simulate the real life battery conditions and compare its thermal behavior with the commercial LiNi 0.33 Co 0.33 Mn 0.33 O 2 cathode material. We show that the thermal induced phase transformations in delithiated lithium rich cathode material are much more intense compared to similar single phase layered cathode material in the presence of electrolyte. The structural changes in both cathode materials with the temperature rise follow different trends in the absence and presence of electrolyte between 25 and 600 °C. Phase transitions are comparatively simple in the absence of electrolyte, the fully charged lithium rich cathode material demonstrates better thermal stability by maintaining its phase till 379 °C, and afterwards spinel structure is formed. In the presence of electrolyte, however, the spinel structure appears at 207 °C, subsequently it transforms to rock salt type cubic phase at 425 °C with additional metallic, metal fluoride, and metal carbonate phases. [ABSTRACT FROM AUTHOR]

ZnSbIn/ x wt.% ZnO ( x = 0, 0.5, 1, 2) composite thermoelectric (TE) materials were prepared with ZnO as additive. The materials were characterized by x-ray diffraction analysis, electron probe microanalysis, and use of TE transport measurements. The ZnO additive, distributed throughout the interior of intact part of the bulk material, interacts with diffusing elemental Zn at elevated temperatures, which is beneficial to the thermal stability of the composite TE materials. The electrical conductivity is increased by addition of the ZnO, because of increased carrier mobility, even though the carrier concentration decreases slightly. The Seebeck coefficients are nearly the same for all the composite TE materials below 560 K, and the presence of the decomposition product ZnSb increases the Seebeck coefficient at high temperatures. All the composite TE materials have lower thermal conductivity than pure ZnSbIn, as a result of the lower lattice thermal conductivity, because of the enhanced phonon scattering induced by the ZnO additive. The maximum ZT is 1.16 at 700 K for the sample with x = 1, an increase of 86% compared with that of pure ZnSbIn. Therefore, addition of ZnO can increase the thermal stability and TE performance of ZnSb-based composite TE materials. [ABSTRACT FROM AUTHOR]

ABSTRACT This work focuses on the effect of nanoclay mass fraction on the properties of polyamide 12 matrix. Relationships between mechanical, thermal, and structural properties of polyamide 12/Cloisite® 30B nanocomposites were studied. The material structure, previously described from XRD and TEM experiments, was more thoroughly characterized in the present work using SEM and FTIR techniques. The FTIR results clearly showed that clay galleries are intercalated by PA chains, which leads to a partially exfoliated nanostructure, confirming the TEM observations and the XRD analysis. However, a few micrometric aggregates are evidenced by SEM analysis, particularly at high clay fractions. TGA and DTA measurements showed that the thermal stability of PA12 matrix is slightly modified by the Cloisite® 30B content. Viscoelastic properties of the nanocomposites in solid-state were analyzed as functions of strain, frequency, and temperature. The extent of the linear response regime of the material is shown to be sensitive to the amount of clay: nonlinearities appear at lower strain values as the clay mass fraction increases. Both relative dynamical moduli also increase with increasing clay mass fraction, with frequency dependence for the viscous modulus and without frequency dependence for the elastic modulus. Finally, similarities have been pointed out between viscoelastic properties of the nanocomposites in solid and melt states. For example, the percolation threshold is highlighted at the same clay mass fraction, ∼2%, in both states. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41938. [ABSTRACT FROM AUTHOR]

The calcium iron phosphate glasses were prepared and measured by X-ray diffraction, Fourier transform infrared spectra, Raman spectra, and differential scanning calorimetry. X-ray diffraction analysis has confirmed that all compositions are amorphous. Infrared and Raman spectra indicated that the glass formed the P‒O‒Fe and P‒O‒Ca bonds in Q1units and (P‒O−Ca2+−O‒P) ionic cross-links in Q2units. Increasing calcium oxide content in glass compositions was brought about by the Q1to Q2conversion, which resulted in the more formation of the non-bridging oxygen (P‒O−Ca2+−O‒P) ionic cross-links. The change of glass transition temperature and thermal stability is consistent with structural modification of the glasses. The analyses of the spectra revealed that calcium oxide played the dual role as a network former and modifier. Oxygen to phosphorus molar ratio about 3.0 would contain the relatively higher concentration of Q1and Q2units. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, zinc maleate (ZnMA) and zinc oxide (ZnO) complex (ZnMA/ZnO) was prepared by two methods, namely, by the reaction of maleic acid (MAH) with excess ZnO in aqueous solution and by direct mixing of ZnMA and ZnO at 180°C. The chemical structure of the complex was analyzed by X-ray diffraction, thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. The thermal stabilizing effect of the complex on poly(vinyl chloride) (PVC) was evaluated through static and dynamic stability methods. Compared to calcium and zinc soaps and ZnMA alone, the complex exhibited better thermal stabilizing effect on PVC. The stabilization mechanism was also investigated by ultraviolet-visible spectrometer, FTIR, TGA, and gel content analysis. The results indicated that the complex which involved the replacement of labile chlorine atoms hindered the formation of conjugated double bonds in PVC chains via Diels-Alder reaction, and ZnMA/ZnO complex also exhibited the ability to absorb hydrogen chloride. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41464. [ABSTRACT FROM AUTHOR]

Two 3,6-diiodocarbazole derivatives were prepared from the iodination of the corresponding phenylcarbazole. 3,6-Diiodo-9-phenylcarbazole crystallises in the chiral space group P21 and shows good second-harmonic generation effects. Thermogravimetric analysis of the two compounds shows high thermal stabilities, in which the decomposition temperature for 1 and 2 are 273 and 308 °C, respectively. [ABSTRACT FROM AUTHOR]

The thermal properties and phase compositions of zeolite from the Vanginskoe and Kulikovskoe deposits in Amur Oblast were studied by means of x-ray diffraction. The temperature interval for the existence of the zeolite structure in these deposits was determined. A scheme for obtaining zeolite concentrated was tested. [ABSTRACT FROM AUTHOR]