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The red-emitting material SrBaMoO4:0.16Eu3+ was synthesized by using a high-temperature solid-state method. X-ray diffraction (XRD) and fluorescence spectroscopy were employed to analyze the crystal structure and luminescent properties. The results revealed that the sintering temperature had an influence on the crystal structure of the samples, with an optimal sintering temperature of 800℃. SrBaMoO4:0.16Eu3+ synthesized at 800℃ for 6.5 h exhibited a pure crystalline phase of SrBaMoO4. The luminescent intensity of the SrBaMoO4:0.16Eu3+ sample under excitation at 394 nm was tested at different temperatures. When the temperature reached 100℃, the luminescent intensity was 72.11% of the initial intensity, and the temperature reached 175℃, it dropped to 35.27% of the initial intensity. The sample demonstrated efficient excitation by blue light (464 nm), resulting the emission peak at 615 nm corresponding to the 5D0-7F2 transition of Eu3+. The luminescent intensity of the sample was found to increase with increasing Ba2+ concentration, reaching its maximum intensity when the Ba2+ doping concentration x was 0.27, followed by a gradual decreaseat excessive doping concentration, indicating concentration quenching. The CIE coordinates were calculated for the sample under excitation at 464 nm, revealing exhibited the best red emission at the Ba2+ doping concentration of x = 0.27. Additionally, first-principles calculations were used to determine the band structure and density of states of the sample. [ABSTRACT FROM AUTHOR]

In this paper, a novel composite phase change material (CPCM) is prepared with inorganic PCM through impregnation and dispersion method which can be used for thermal management applications. Inorganic PCMs have high latent heat and good thermal conductivity and are non-flammable, but there exist leakage (shape stability) and corrosion problems. To overcome these issues, a porous structured material is impregnated with the inorganic PCM (disodium hydrogen orthophosphate dodecahydrate). The CPCM is prepared by loading various wt% of expanded graphite and boron nitride nanoparticles with the PCM, and characterization is performed to find the thermal properties and stability. The findings from FTIR and XRD analyses validate both the chemical compatibility and crystalline nature of the samples. DSC thermographs reveal the CPCM5 sample has a latent heat value of 168.05 J/g during the heating process, an encapsulation efficiency of 78.8% and a thermal conductivity of 4.69 W/mK. The thermal stability and resistance to corrosion of the composite samples are also enhanced. The best composite PCM sample is then selected, and subsequently, the thermal performance of the heat sink is experimentally investigated. The thermal performance of rectangular cavity heat sink filled with CPCM5 is the highest for various power sources and temperatures with a maximum enhancement ratio of 6.57. [ABSTRACT FROM AUTHOR]

The traditional high-temperature preparation process of polyimide can cause many problems and limits the wider application in extreme conditions. An important challenge to be solved urgently is the reduction of imidization temperature. In this work, twelve kinds of polyimide films with different chain rigidity were prepared at low temperature of 200 °C, in the absence or presence of imidazole used as the catalyst. The molecular rigidity and free volume were theoretically calculated, and relationship between structure and properties were systematically studied. The results show that imidization reaction under low temperatures is significantly affected by the rigidity of molecular chains. The rigid structure of polyimide is not conducive to the low-temperature imidization, but this adverse effect can be eliminated by adding catalyst, resulting the notably increased imidization degree. The optical and thermal properties can be improved to a certain extent for the chemically catalyzed system, resulting in relatively higher heat resistance and thermal stability. While the mechanical performance could be determined by complicating factors, greatly different from polyimide films prepared by high temperature method. To investigate aggregation structures of films, the effect of chain rigidity and catalyst on the stacking or orientation of molecular chains was further elaborated. This work can contribute to the understanding of chemically catalyzed imidization that is rarely reported in the existing research, and will provide guidance for the low-temperature preparation of high-performance polyimides. [ABSTRACT FROM AUTHOR]

Composites are fabricating by reinforcing waste bambara nut shell powder (BNSP) as a bio-filler into an epoxy resin matrix. The composite is fabricated by varying the mass fractions of filler in the range of 5–35 wt%. The effects of bio-filler content on physical, mechanical, and thermal properties are evaluated. The studies reveal that the tensile strength, tensile modulus, flexural strength, and impact strength increased with increasing bio-filler content. The highest mechanical properties of BNSP-loaded epoxy composites are achieved at bio-filler mass content of 15 wt%, whereas hardness increased for 5–35 wt% with peak value at 35 wt%. The water absorption and thickness swelling of the BNSF/epoxy composites increased with increasing bio-filler contents, while the density decreased with an increase in bio-filler content. The TGA results revealed that an increasing bio-filler content decreased thermal stability, whereas the Tg and Tm of the composites increased with increasing bio-filler content. [ABSTRACT FROM AUTHOR]

Stereolithography (SLA) is a highly versatile additive manufacturing technique that utilizes various ink formulations to fabricate 3D-printed nanocomposite structures with desired properties. Zinc oxide (ZnO) is a promising candidate due to its excellent mechanical and thermal stability, and compatibility with various polymeric matrices. In this work, varying ink formulations containing ZnO nanoparticles, along with employing appropriate post-printing curing parameters to fabricate SLA 3D-printed acrylate-based nanocomposites with improved mechanical and thermal properties, were reported. This study can significantly contribute to expanding its potential use in practical applications such as biomedical and structural applications. [ABSTRACT FROM AUTHOR]

New manganese(II) and nickel(II) 1-D zigzag coordination polymers [M2+(pQ2−)·2(solv)]n (M2+ = Mn2+, solv = N,N'-dimethylacetamide (1) and M = Ni2+, solv = N,N'-dimethylformamide (2); pQ2− - dianionic form of 2,5-di-hydroxy-3,6-di-tert-butyl-para-quinone) have been synthesized and characterized. Both compounds 1 and 2 are isomorphic. Their physicochemical properties such as thermal stability, gas sorption, redox and magnetic properties are described. [ABSTRACT FROM AUTHOR]

Physical parameters are necessary to determine the suitability of the chalcogenide materials for specific applications. The present study reports the physical characteristics of the multicomponent GeTe2-x(SeSb)x (x = 0, 0.2, 0.4, 0.6) chalcogenide glasses synthesised by the melt-quench technique. The differential scanning calorimetric (DSC) technique has been used at separate heating rates β = 5, 10, 15, 20 °C / min. XRD and SEM–EDX studies have been carried out for structural and morphological analyses. The average coordination number and constraints of the compound have been calculated which indicates that the composition forms a glassy system. Lone pair electrons present in the composition have been evaluated. R parameter has a value greater than 1, indicating that the composition has sufficient chalcogen, chalcogen–chalcogen and heteropolar bonds. The overall bond energy of the compound has been calculated using the chemical bonding approach to understand the fine-structure properties of the compound. Cohesive energy has been observed to increase with composition. Thermal stability, glass transition temperature and glass forming ability of the compound have been calculated using different relations like Saad and Poulin relation, Dieztal relation, Hurby parameter (Hr) and reduced glass transition temperature (Trg) and studied theoretically to examine the thermal stability of the composition that shows that the prepared samples are suitable for data storage. [ABSTRACT FROM AUTHOR]

The uncertainty of the structure of melamine-formaldehye polymer is one of the important factors limiting its widespread application. The chemical reactions of melamine are almost always reversible, so controlling the microstructure is difficult. For the synthesis of polymer particles in water, it is unclear how the type of catalyst affects the microstructure of melamine-formaldehye polymers. Therefore, we conducted a detailed study to understand how different catalyst types(including 10% NaOH, trimethylamine, and a Na2CO3-NaHCO3 buffersolution)affect the hydroxymethylation reaction, structure and the thermal properties of the melamine-formaldehye polymer). The results showed that with the same molar ratio and pH conditions, the use of triethylamine as catalyst in the melamine-formaldehye polymer increased the possibility of side reactions in the hydroxymethylation reaction. However, the occurrence of side reactions has a favorable effect on the thermal properties of melamine-formaldehyepolymers. Specifically, melamine formaldehyde polymers synthesized using triethylamine as a catalyst exhibit higher thermal decomposition characteristic temperatures, lower kinetic values, and higher reactivity. These results provide insights into the effect of catalyst type on the reaction mechanism, microstructure and thermal properties of melamine-formaldehye polymers, which may prove useful for their improved and controlled synthesis. [ABSTRACT FROM AUTHOR]

In pursuing enhanced performance for electronic applications, we synthesized ferroelectric materials, specifically Ba(1-x)Nd2x/3TiO3 (BNdTx) nanoceramics, utilizing solid-state reaction techniques coupled with microwave heating treatment. Our investigation involved varying Nd3+-doping levels (x = 0%, 2%, 4%, and 8%) to tailor the material's properties. XRD analysis confirmed the presence of a single-phase tetragonal perovskite structure (space group P4mm). A comprehensive examination of the partial density of states for both undoped and Nd3+-doped BaTiO3 was undertaken to discern the impact of Nd3+-doping on the energy bands. Microscopic analysis revealed the presence of pores in the samples, accompanied by a reduction in grain size with increasing Nd3+ content. The introduction of Nd3+ induced a shift in the Curie temperature (TC) towards room temperature. Simultaneously, the dielectric characteristics exhibited a consistent value above 1900, with a low loss of less than 5% observed across a range of temperatures (30–100 °C). Notably, the sample with x = 4% demonstrated thermally stable dielectric properties, suggesting its potential suitability as a material for Multilayer Ceramic Capacitor (MLCC) applications. Integrating microwave sintering and ball milling techniques is a significant development in advanced materials engineering, specifically in producing Multi-Layer Ceramic Capacitors (MLCC). The practical implementation of these novel methodologies is essential in decreasing particle size, which is a critical determinant in improving thermal stability. Ball milling further refines the particle size distribution, whereas microwave sintering guarantees a more uniform and fine-grained microstructure through its rapid and effective heating capabilities. The capacitors acquire enhanced thermal stability and a more refined material granularity through this synergistic combination. By achieving a more uniform and compact ceramic structure, these processes result in a finer particle size, enhancing the overall performance and dependability of MLCC capacitors. The increasing need for miniaturized and high-performance electronic components has focused on utilizing microwave sintering and ball milling. These processes are at the forefront of technological advancements in the pursuit of improved thermal properties and increased efficiency in manufacturing MLCC capacitors. [ABSTRACT FROM AUTHOR]

The objective of this work was to investigate the influence of selected drying temperatures (50, 60, and 70 °C) and ethanol treatment (ET) on the degradation of carotenoids (storage at 35 °C for 35 days), thermal features (TGA and DSC; thermogravimetric and differential scanning calorimetry analysis), and zeta potential of avocado pulp powder produced by foam-mat drying (FMD). Results showed the goodness-of-fitting between the zero and first-order models (R2 > 0.99) for carotenoids degradation kinetics, and further, the ET combined with increasing drying temperatures improved the stabilization of carotenoids during storage. The GAB model presented the best adjustment to the water adsorption isotherms (R2 > 0.99, P < 5%), being classified as type III. Great thermal stability was highlighted by both TGA and DSC curves, pointing out that the main endothermic events were linked to the carbonization of the organic content and degradation of proteins, lipids, and polysaccharides of the powder. In addition, the synergistic effect between drying temperature and ET enhanced the initial, peak, and conclusion temperature and reduced the enthalpy variation. Zeta potential analysis confirmed the stability of FMD-produced avocado powder due to the negative charges ranging from − 29.756 to − 26.826 mV. Overall, these results bring innovative and creative end-uses for avocado in the food industry, establishing FMD as a simple, efficient, and creative process to convert food matrices such as avocado into stable powders. [ABSTRACT FROM AUTHOR]

The effect of T4 and T6 treatment on the microstructures, precipitates, thermal expansion and thermal conductivity properties of Mg-2Nd-4Zn alloys was systemically investigated. The number of NdZn2 phase increased subjected to T6 treatment. The coherent relationship between the NdZn2 phase and Mg matrix was observed in the Mg-2Nd-4Zn alloys, which plays a great influence on improving the thermal expansion, thermal conductivity and mechanical properties of Mg-2Nd-4Zn alloys. The decrease in the coefficient of thermal expansion (CTE) and the thermal conductivity of Mg alloys were ascribed to the existence of solute atoms in alloys after the T4 treatment. It was also found that the T6-treated alloy has smaller area of the hysteresis loop, which has better thermal stability. Therefore, the high performance was mainly due to T6 treatment, the thermal conductivity of T6-treated Mg-2Nd-4Zn alloy is 124.4 K·m−1·K−1 at room temperature, and TYS of 235.5 MPa, CYS of 393.7 MPa, elongation of tension and compression are 31 and 27%, respectively. [ABSTRACT FROM AUTHOR]

2,6-Di-tert-butyl-4-methylphenol (BHT) is an excellent antioxidant that is easily oxidized to 2,6-di-tert-butyl-4-hydroperoxyl-4-methyl-2,5-cyclohexadienone (BHTOOH). For the safety of BHT production and usage, it is meaningful to study the thermal stability and decomposition properties of BHT and BHTOOH. In this paper, the thermal decomposition properties of BHT and BHTOOH were compared by the mini closed pressure vessel test (MCPVT) and differential scanning calorimetry (DSC). Their kinetics of thermal decomposition were studied using thermogravimetric analysis (TGA). The thermal decomposition products of BHT and BHTOOH were analyzed by gas chromatography-mass spectrometry (GC–MS). The results show that there was no significant change in temperature pressure when BHT was warmed up under a nitrogen atmosphere, indicating that BHT was stable within 400 K. The thermal decomposition reaction of BHTOOH was rapid with an initial reaction temperature of 375.2 K. The initial exothermic temperature (Ti) and heat release (QDSC) of DSC were 384.9 K and 865.0 J g−1, respectively. The apparent activation energies (Ea) for the thermal decomposition reactions of BHT and BHTOOH calculated by the Kissinger method were 151.8 kJ mol−1 and 66.07 kJ mol−1, respectively. The main decomposition products of BHT were isobutene and 2-tert-butyl-4-methylphenol. The thermal decomposition products of BHTOOH included BHT, 2,6-di-tert-butyl-4-ethylphenol, 3,5-di-tert-butyl-4-hydroxybenzaldehyde, 4,4′-(1,2-ethanediyl) bis [2,6-bis (1,1-dimethylethyl) phenol, etc. Based on the thermal decomposition behavior and products, the reaction pathway has been described. These results indicate that BHT is a potential thermal hazard during production, storage and application. For the safety of the chemical industry, the oxidation of BHT should be avoided. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is a bioresorbable and biodegradable polymer extensively used in various biomedical and engineering applications. In this study, we investigated the mass loss and thermal properties of PLA-multi-walled carbon nanotube (MWCNT) composites under simulated physiological conditions. The composites were prepared by melting PLA with 0.1, 0.5, 1.0, and 5.0 wt% MWCNTs using an ultrasonic agitator, and FTIR analysis confirmed composite formation. Subsequently, the composites were subjected to hydrolysis under simulated physiological conditions (pH 7.4 and 37 °C) for up to 60 days. The results revealed that the mass loss of the composites decreased with increasing MWCNT content, suggesting that the presence of MWCNTs decelerated the hydrolysis process. On day 58, the mass loss of pure PLA was 12.5%, decreasing to 8.34% with 0.1% MWCNT, 5.94% with 0.5% MWCNT, 4.59% with 1% MWCNT, and 3.54% with 5.0% MWCNT. This study offers valuable insights into the behavior of PLA-MWCNT composites under physiologically simulated conditions, facilitating the development of new polymer composites with enhanced thermal stability and degradation resistance for biomedical applications. [ABSTRACT FROM AUTHOR]

The potential cooling solutions for the next generation are represented by nanofluids, offering several advantages for various technological applications. The intriguing realm of glycine-based acetone-based Al 2 O 3 nanofluids was explored in the present investigation, with meticulous attention to details given to scrutinizing their stability and thermophysical properties. The stability of the nanofluids was determined through a trifecta of analytical methods, namely visual inspection, UV absorbance measurement, and zeta potential analysis, all applied with caution. The results revealed that stability was observed for a duration of 3 days without glycine, and an impressive 6 week period was achieved when supplemented with the surfactant. The incorporation of glycine enhanced the stability of the colloidal suspension without compromising its thermophysical attributes. Furthermore, the study involved an in-depth examination of the density, viscosity, specific heat, and thermal conductivity of the prepared nanofluids, yielding interesting outcomes. The data showed a marked increase in nanofluid density, viscosity, and thermal conductivity with a corresponding rise in volume concentration, while specific heat exhibited a noticeable reduction. These significant observations were meticulously compared to various existing theoretical models and proposed correlations in the literature. The heat transfer performance of the nanofluid in the context of pulsating heat pipes was evaluated and the results proved riveting. The nanofluid demonstrated superior performance compared to the base fluid, confirming its remarkable efficacy. [ABSTRACT FROM AUTHOR]

The chloride salts have great potential used as high-temperature thermal energy storage (TES) medium for the concentrated solar power system. In this study, LiCl, KCl and CaCl2 were selected as energy storage materials in order to further broaden the working temperature of ternary chloride salt and improve its energy storage density. The new high-temperature energy storage ternary chloride composed of LiCl, KCl, and CaCl2 was developed based on the phase diagram generated by FactSage. Three components of LiCl-KCl-CaCl2 with the mass ratio of 37.85%-53.38%-8.77%, 30.90%-13.82%-55.28% and 1.78%-18.61%-79.61% were developed, of which the corresponding melting temperature (Tm) 340.93, 433.57 and 626.85°C, respectively, was obtained either. Considering that Tm of the third group of salts was too high, only the first two groups of salts were tested. DSC test showed that the actual melting point was only 0.46% and 1.64% different from the melting point predicted by Factsage. The thermal properties of the two ternary chloride salts were also compared. The solid and liquid-specific heat of ternary salts was determined by DSC using sapphire as the standard reference. The vapor pressure and decomposition temperature of ternary chloride salts were investigated. The results showed that the vapor pressure of salt 1 was almost constant below 650°C by FactSage. Meanwhile, the TG results showed that the upper working temperature of salt 1 was 650°C under the air atmosphere. In addition, the ternary chloride salts after short-term cycling still exhibited excellent thermal properties, which revealed that these good thermal properties make them have broad application prospects in high-temperature thermal energy storage systems. [ABSTRACT FROM AUTHOR]

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]

In this study, wet ball milling and hot press methods were used to prepare nanocomposite from ultra-high molecular weight polyethylene (UHMWPE) as a matrix, and modified multi wall carbon nanotubes (MWCNTs) as reinforcement nano-additives. Two batches of MWCNTs were used (Pristine-MWCNTs-B1, and Pristine-MWCNTs-B2). First, the MWCNTs were oxidized (oxide-MWCNTs) by wet chemistry using strong acids, then further functionalized with an amide group (A-MWCNTs). Fourier-transform infrared spectroscopy (FTIR), and Thermal gravimetric analysis (TGA) results confirm the functionalization of the MWCNT with the amide group. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to examine the surface morphology and crystalline behavior of MWCNT after functionalization. Ball milling was used to mix the UHMWPE with pristine MWCNT (1.5% wt), Oxide-MWCNT (1.5% wt), and A-MWCNTs (0.5–2% wt). Then, hot press melting was used to prepare the nanocomposite sheets. Fourier transform infrared spectroscopy (FTIR) confirmed the impact of the balls milling process with time factor on UHMWPE crystallinity and the interaction of the functionalization MWCNT with the UHMWPE matrix. The structure (crystallinity, crystal size) was validated using X-ray diffraction (XRD) patterns. Thermal gravimetric analysis (TGA), differential scanning calorimeter (DSC), and universal testing machine (UTM) were utilized to analyze the structural, thermal, and mechanical properties of the nanocomposites, respectively. The results showed that UHMWPE crystallinity increased after 2 h of ball milling, while crystallinity decreased when pristine-MWCNT, oxide-MWCNTs, and A-MWCNTs (0.5–2 wt%) were added without affecting the crystal structure of UHMWPE. The results showed that adding 1.5 wt% A-MWCNTs-(B1, B2)/UHMWPE increased thermal stability by 16 °C and elongation at the break by up to 74% when used 1.5 wt% A-MWCNT-B1 and 2 wt% A-MWCNT-B2. This shows that the ball milling methods and amide group improved the dispersion and interface interaction between MWCNTs and UHMWPE matrix. [ABSTRACT FROM AUTHOR]

This study focused on an important global issue containing both environmental pollution control and energy storage. Polyaniline has been utilized as a supporting material to load paraffin in order to form highly thermal conducting and shape-stable phase change material (PCM). Three different weight percentages (wt%), i.e., 10, 15, and 20 wt%, of polyaniline have been used to obtain shape-stable composite materials. The paraffin leakage of the prepared samples PPCM1, PPCM2, and PPCM3 has been examined by 500 thermal cycles in a hot air oven at 80 °C. Among three samples, the PPCM3 composite with 20 wt% of polyaniline in paraffin has shown excellent leakage-bearing properties with only ~ 0.06% leakage after 500 thermal cycles. Further, the chemical, structural, and morphological analyses of the PPCM3 composite have been carried out by FTIR, XRD, and FESEM. The thermal performance of the prepared sample has been studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis, which revealed that the impregnation of polyaniline polymer has improved the thermal stability and thermal conductivity of paraffin with a small decrement in latent heat capacity of the PPCM3 composite. The latent heat of the composite decreased by 18.36% and thermal conductivity increased by ~ 65.45% for a 20 wt% concentration of polyaniline in paraffin with the maximum latent heat capacity. To check the thermal reliability of the formulated PPCM3 composite, the composite has been subjected to thermal cycling of 500 thermal cycles. With increased thermal conductivity, high latent heat capacity, good shape stability, excellent leakage-bearing capability, and improved thermal reliability, paraffin/polyaniline composite PCMs look promising for application in thermal energy storage areas. [ABSTRACT FROM AUTHOR]

In this study, new proton conducting membranes were prepared using poly-2,2'-(m-phenylene)-5,5'-bibenzimidazole (PBI) and varying amounts of methylimidazoliumtriflate[MeIm/TfO], a protic ionic liquid, by the solution casting method. The thermal properties and conductivity of these membranes were investigated. The obtained parameters, such as high thermal stability (235–255°C) and the conductivity of 0.7–1.6 mS/cm at 145°C, indicate that PBI membranes doped with either MeIm/TfO or BuIm/TfO, which were previously studied by our group, are quite interesting for further investigation as potential electrolytes for PEMFCs. [ABSTRACT FROM AUTHOR]

Starch is an important part of the human diet; however, this macromolecule has undesired physicochemical properties associated with its limited water solubility, low viscosity, and poor thermal stability, limiting its food applications. Cold plasma (CP) is an emerging and nonthermal technology used in recent years to modify the physicochemical properties of starch powders. This paper comprehensively reviewed the application of CP in starches, including information about reactors and gases used to modify starches with CP, the application in starch granules, and the combination with other treatments such as hydration, dry heat, chemical and enzymatic treatments, extrusion, ultra-high-pressure, and microwave. Modified starch granules by atmospheric CP showed depolymerization of starch molecules, impacting the amylose content, crystalline structure, water solubility, and thermal properties. Certain gases used in CP, such as hexamethyldisiloxane and helium, can induce cross-linking in starch granules, increasing thermal and mechanical properties. CP associated with physicochemical treatments is more efficient in inducing starch depolymerization, improving the modification of the physicochemical properties of this macromolecule. CP is a useful tool for modifying the properties of starch granules; however, further research and development are necessary to elucidate its industrial application. [ABSTRACT FROM AUTHOR]

The laser ablation technique was utilized to fill the carboxy methyl cellulose (CMC) solution with zirconium dioxide (ZrO2) and copper oxide (CuO) nanoparticles with different concentrations. Different techniques have been used to study the physical behavior of fabricated compositions. CuO has shown different peaks at related to the monoclinic phase of the prepared CuO NPs lattice constants (JCPDS No. 02-1225). According FTIR results, ZrO2 has exhibited vibrating bands at 460 cm−1, 477 cm−1, 670 cm−1, and 690 cm−1 which are corresponding to Zr–O vibration. In addition, CuO has shown vibrating bands at 439, 494, and 594 cm−1. The dielectric properties have been investigated. The TGA results showed that the sample CMC-ZrO2-CuO/20 min has excellent thermal stability as the weight loss is 36% of its initial weight at 796 °C. The optical and electrical characterization showed that the addition of ZrO2 and CuO has changed and enhanced the electrical characterization of CMC. The enhancement in electrical conductivity of the system encourages it for electrical applications. [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]

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]

Sealants are easily subjected to microbial attachment, colonization, and deterioration in humid environment. Developing antimicrobial sealants have become an extremely imperative strategy to solve this problem. A kind of antimicrobial sealant was prepared with silane-modified polyether (SMPE) as a matrix and 3-(trimethoxysilyl) propyldimethyloctadecylammoniumchloride (TPOAC) as an antimicrobial agent in a room-temperature curing system. The tack-free time testing indicated that the introduction of TPOAC can significantly accelerate the curing rate of sealants. The effects of TPOAC on the mechanical, bonding, and thermal properties and surface wettability of the antimicrobial SMPE sealants were investigated through mechanical testing, thermogravimetric analysis (TGA), and water contact angle measurement. The mechanical properties of sealants were improved with an appropriate content of TPOAC, and the sealant exhibits optimal mechanical properties with the TPOAC content of 1.5%. Furthermore, TGA results indicated that the thermal behavior of SMPE sealants displayed a one-step weight loss process by heating in a nitrogen atmosphere and the introduction of TPOAC has little effect on the thermal stability of SMPE sealants in a nitrogen atmosphere. Moreover, the sealants exhibit more and more hydrophobic with the amount of TPOAC increased. The findings of this investigation indicated that using TPOAC as an antimicrobial agent is a practical way to obtain antimicrobial SMPE sealants with favorable properties. [ABSTRACT FROM AUTHOR]

The matrix's dielectric constant can be reduced with little quantity of POSS because of its unique cage skeleton structure and remained air in the caves. After epoxied, epoxy polyhedral oligomeric silsesquioxane (EPPOSS) promoted its compatibility with bisphenol A cyanate ester (BADCy) and bisphenol A benzoxazine (BA-a) by a curing processing between BADCy and EPPOSS and further copolymerizing with ring opened BA-a. Consequently, two Tgs were observed in the integrated nanocomposite, attributing to the BADCy homopolymer and the BADCy and BA-a copolymer. The more quantity of EPPOSS, the lower dielectric constants of nanocomposites achieved, as well as the initial storage modulus and Tgs due to the flexible ether bonds generated by EPPOSS. With up to 15 wt.% EPPOSS, the dielectric constant decreased to 2.72 at 1 MHz. The toughness and thermal stability of the nanocomposites also enhanced through increased the crosslinking density and inorganic Si–O–Si framework of EPPOSS. [ABSTRACT FROM AUTHOR]

The Li-Mn-O system is a crucial constituent of cathode materials used in lithium-ion batteries (LIBs). Numerous research teams have focused on enhancing its electrochemical properties and thermal stability at lower temperatures to develop high-performance cathode materials. However, in the recycling of LIBs in pyrometallurgical processing, the high temperature phase behavior of the Li-Mn-O system is important. Today, there is still a lack of systematic understanding regarding the high-temperature phase behavior of the Li-Mn-O system under well-defined atmospheric conditions, which is highly sought after in the pyrometallurgical process route to increase the recycling efficiency of lithium from spent LIBs. In this study, we investigate the high temperature phase behavior of the pseudo binary system Li2O-MnO under inert atmosphere. Thermal and caloric properties are measured as well as the contact angle at high temperatures to identify the solid-liquid transition. Based on the obtained phase behavior, thermodynamic database of Li2O-MnO within the Calphad framework is developed, where the liquid phase is modelled by the Modified Quasichemical Model (MQM). [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]

In this study thermal and structural properties characterization were performed for prepared ultra-high molecular weight polyethylene/carbon nanotube (UHMWPE/CNT) nanocomposite sheets by using a melt compounding method. The sheets were prepared by using six types of CNTs; pristine single walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs), oxidized- SWCNT and MWCNT, and amide- SWCNT and MWCNT. Thermogravimetric analysis results revealed that the addition of CNTs increased the nanocomposites thermal stability (17 °C) being produced by P-MWCNT. Differential scanning calorimetry and x-ray diffraction (XRD) results show no significant crystalline structure changes compared with the pure polymer, and increase in crystallinity (4%) for O-SWCNTs additions (4%). Scanning electron microscope images showed improved bridging in the polymer matrix by using oxidized and functionalized CNTs compared with pristine CNTs. These findings suggest that the durability of UHMWPE is enhanced by this nano-modification method, improving its suitability for many lightweight, high strength material applications. [ABSTRACT FROM AUTHOR]

Developing of high-performance thermosets with outstanding thermal properties has attracted increasing attention. Herein, a combined strategy, acetylene modification and copolymerization with bismaleimide, has been utilized for a novel bio-based tri-functional benzoxazine monomer. The monomer (RES-pa) was successfully synthesized using biomass resources, resveratrol, as raw material. Three systems with different ratios (RES-pa: bismaleimide = 1:0, 1:1, 1:2) were designed. The thermal derived polymerization of three systems was monitored by DSC and in situ FT-IR. Thermal stability of derived thermosets was systemically investigated in detail by dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). Specially, poly(RES-pa-co-DDM-BMI-1/1) is found to show a high Tg value of 374 °C and Td10 of 387 °C. Promisingly, the combined strategy used in the work may grant efficient way for design and preparation of high-performance thermosets. [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]

A method was proposed for the synthesis of Eu(III) compounds with para-methoxycinnamic acid anions and neutral ligands, starting from the sodium salt of para-methoxycinnamic acid. Using the methods of chemical elemental and thermal analyses and IR spectroscopy, the composition of the complexes and the coordination mode of carboxylate anions were determined. It was found that europium(III) methoxycinnamate with hexamethylphosphotriamide has the highest luminescence intensity. Luminescent polymer materials with synthesized europium(III) methoxycinnamates were obtained. [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]

This paper focuses on the use of castor oil plant (Ricinus communis) as filler in rotomolded parts using polyethylene (PE) and polylactic acid (PLA) as polymer matrixes. The vegetable shredded material was used in 5 and 10% weight following a dry blending procedure and then rotomolded to obtain cube test parts. This material was characterized to determine its chemical composition, thermal stability, and structure. The NaOH-treated material shows reduced hemicellulose content and higher thermal stability. Obtained composite materials were characterized in terms of mechanical (tensile, flexural, and impact) and thermal properties, morphology, and bio-disintegration behavior. The use of Ricinus as filler in rotomolded PE composite decreases, in general terms, mechanical properties of neat PE, while no significant changes in thermal or bio-disintegration properties are found. On the contrary, PLA composites show higher tensile strength and similar Young's modulus than the matrix, although with reduced flexural and impact properties. Alkali-treated Ricinus material produces parts with higher porosity and thus, lower mechanical properties than composites with untreated material. Finally, the incorporation of this vegetal material modifies to a great extent the thermal properties of the PLA matrix. The bio-disintegration rate increases due to the use of fibers, probably because of the higher moisture absorption of composites. [ABSTRACT FROM AUTHOR]

This study aimed to production, optimization, and characterization of an exopolysaccharide (EPS) by Bacillus coagulans IBRC-M10807. The maximum EPS production (234.21 ± 4.83 mg/L) was obtained under optimal incubation temperature 54.95 °C, incubation time 31.36 h, initial pH 5.73, casein peptone concentration 3.93%, and lactose concentration 1.33%. The monosaccharide compositions of EPS were mannose, rhamnose, glucose, and galactose, with an average molecular weight of 4.22 × 105 Da. Differential scanning calorimetry and thermogravimetric analysis showed that the EPS had high thermal stability with a melting point of 262.5 °C and degradation temperature of 276.29 °C. DPPH radical scavenging, hydroxyl radical scavenging, and reducing power of EPS were 85.25% ± 0.55%, 80.08% ± 0.31%, and 0.824 ± 0.008 at 2 mg/mL concentration, respectively. These results indicated that the EPS produced by B. coagulans IBRC-M10807 could be a promising candidate for use as a safe and natural antioxidant as well as a functional ingredient in the pharmacy and food industry. [ABSTRACT FROM AUTHOR]

There has been a broad demand for materials with high thermal stability and low dielectric constant in the field of microelectronic devices and communication technology. In this paper, a novel fluorinated poly(aryl ether) (FPAE) was prepared by SN2 nucleophilic polycondensation. FPAE was demonstrated to possess a favorable dielectric constant of 2.68 at 1 MHz and its dielectric relaxation behavior at various temperatures and frequencies was analyzed. The resin performed excellent thermal stability and heat resistance, with a 5% mass loss temperature of 514 °C and a glass transition temperature of 260 °C. FPAE exhibits high solubility in N, N-dimethyl-formamide, acetone, ethyl acetate and other solvents. Excellent solubility gives FPAE good film formation and processability. The tensile strength and tensile modulus of FPAE were 67.0 MPa and 2.1 GPa, displaying decent mechanical properties. Attributed to the characteristics of the fluorine atoms, FPAE demonstrated a certain hydrophobicity with a water contact angle of 97.9°, as well as satisfactory water absorption (0.17%) and a low surface energy of 21.71 J/mm2. These data indicate that FPAE is expected to be used as low-dielectric material in microelectronics and communication technology. [ABSTRACT FROM AUTHOR]

In this work, we studied, the vibrational and the thermal properties of the Tl2O–TeO2, V2O5–TeO2 and Tl2O–V2O5–TeO2 glass-forming systems by means of Fourier Transform Infrared (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC). Thermal properties, such as the glass transition temperature (Tg), thermal stability (S), and thermodynamic fragility (F), were determined and correlated with the structural characteristics of the glasses. The binary glass-forming system Tl2O–TeO2 exhibits the transformation of TeO4 trigonal bipyramids into TeO3 trigonal pyramid units due to the presence of Tl2O. The decreasing trend of Tg with Tl2O content, along with the increase of the thermodynamic fragility, indicates that the structure becomes less interconnected and floppier. Concerning the V2O5–TeO2 glass system, we observed that V2O5 causes structural modifications in the TeO2 sub-network by changing the coordination number of Te atoms. Furthermore, the glass rigidity reduces as indicated by the glass transition temperature variation with composition. We also found that the 0.5V2O5–0.5TeO2 glass exhibits the highest resistance to thermal shocks and possesses the most rigid network. Concerning the structure of the ternary glass-forming Tl2O–TeO2–V2O5 system, the incorporation of Tl2O into the mixed vanadate–tellurite glasses decreases the glass transition temperature implying that Tl2O acts as a network modifier affecting the network's rigidity. The decreasing trend of the thermodynamic fragility indicates that the glass network becomes more rigid. Finally, the significantly high values of thermal stability reveal that the ternary glass-forming system can be considered as a glass with superior resistance against thermal shocks making it an ideal candidate for relevant technological applications. [ABSTRACT FROM AUTHOR]

Enhancing the high temperature mechanical properties and the thermal stability of aluminum alloys are in urgent demand for the lightweight application scenarios (such as pistons, fan blades, crankshafts) working at elevated temperatures. The fabrication of aluminum matrix composites is a promising solution. In this work, TiB2 nanoparticles were in-situ introduced to a typical heat resistant Al–Cu–Mg–Fe–Ni (Al2618) alloy matrix and subjected to hot extrusion. Microscopically, the extruded TiB2/Al composite exhibited refined and bimodal sized grain structure, which was stable after long-time thermal exposure associated with TiB2 particle banding along the extrusion direction. The TiB2/Al composite showed an evident improvement in high temperature strength as well as the strength retention after long-time thermal exposure up to 300 °C, compared to the unreinforced alloy. The strengthening effect was remarkable especially at 200 °C with an increase of ~ 20% (60–70 MPa) in tensile strength and strength retention after thermal exposure but without the trade-off of ductility. The effects of TiB2 particles on the temperature-dependent strengthening mechanisms and microstructure evolutions were investigated. This work inspires the design, processing and evaluation of novel high strength and heat resistant particle-reinforced aluminum matrix composites for the potential applications under elevated temperature service conditions. [ABSTRACT FROM AUTHOR]

The separator is an essential component of lithium-ion batteries (LIBs), and polyimide (PI), a high-performance polymer with outstanding mechanical and thermal properties and a strong electrolyte affinity, has received substantial research as a potential separator material. In this work, we fabricated a PI composite separator (PI/WO3) by combining the components in one step with concurrently electrospinning the precursor solution and electrospraying the WO3 nanoparticles. The one step mixing method made the WO3 uniformly distribute on the PI nanofiber surfaces with a result of porosity decrease. Although the introduction of WO3 nanoparticles did not alter the chemical structure and the excellent thermal stability, the electrolyte wettability, mechanical strength and electrochemical performance of PI separator were all significantly improved by the nanoparticles, endowing the composite separator with superior cycle stability. Therefore, the use of WO3 in a polyimide separator has practical significance for high safety and high performance of LIBs. [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 cellulose (Cel)-polyvinyl alcohol (PVA)-sodium alginate (SA) composite aerogels are prepared by adding PVA and SA to the Cel suspension, followed by freeze-drying. The structure and properties of Cel-PVA-SA composite aerogels are determined by FT-IR, scanning electron microscopy, thermogravimetric analysis, limiting oxygen index method and cone calorimetry. The results reveal that sodium alginate is uniformly distributed within the aerogels. The as-synthesized composite aerogels possess excellent compressive resilience properties. In addition, the addition of sodium alginate significantly reduces the flammability of cellulose. Therefore, this study provides a simple method to prepare green flame-retardant Cel-PVA composite aerogels materials, and the aerogels demonstrate excellent potential for application in construction materials. [ABSTRACT FROM AUTHOR]

Physical cross-linking by hydrogen-bonds (H-bonds), providing a good combination of application properties of thermosets and processability of thermoplastics, is a potential strategy to resolve the recycling problem of traditional chemically cross-linked polyethylene. However, ureidopyrimidone (UPy), the most widely used H-bonding motif, is unfavorable for large-scale industrial application due to its poor thermal stability. In this work, H-bonds cross-linked polyethylene was successfully prepared by reactive melt blending maleic anhydride grafted polyethylene (PE-g-MAH) with 3-amino-1,2,4-triazole (ATA) to form amide triazole ring-carboxylic acid units. Triazole ring can easily generate multiple H-bonds with carboxylic acid and amide. More importantly, these units are more thermal stable than UPy due to the absence of unstable urea group of UPy. The introduction of H-bonds cross-linking leads to an obvious improvement in mechanical properties and creep resistance and a good maintain in thermal properties and recyclability. Furthermore, the reinforcement effect monotonically improves with increasing the density of H-bonds. The obtained good properties are mainly attributed to largely enhanced interchain interactions induced by H-bonds cross-linking and intrinsic reversibility of H-bonds. This work develops a novel way for the simple fabrication of H-bonds cross-linked PE with high performance through reactive melt blending. [ABSTRACT FROM AUTHOR]

The thermal stability and degradation, near-to-surface mechanical properties, and scratch resistance and damage mechanism of poly(etheretherketone) (PEEK)/reduced graphene oxide (RGO) nanocomposite coatings are analyzed and discussed in terms of their nanosheet content and microstructure. Although RGO modified the thermal stability and degradation of the polymeric matrix, for instance, by slightly reducing the onset degradation temperature, its addition was not a limiting factor in the PEEK processing. Respecting the microstructural features induced by the nanosheets, the nanocomposite coatings were found to exhibit (i) a partially exfoliated and large-scale co-continuous morphology related to RGO nanosheets whose basal planes were mainly aligned with the coating surface, (ii) a dendritic morphology of PEEK domains related to transcrystallinity, (iii) and irregular domains associated with the deposition of PEEK particles wrapped by the nanosheets. The changes provoked by RGO in the morphology and PEEK crystalline phase influenced the near-to-surface mechanical properties, scratch resistance, and scratch damage mechanism of the nanocomposite coatings. Within this context, the interlayer strength between the nanosheets in the large-scale co-continuous morphology and PEEK transcrystallinity had an important effect. Furthermore, the random-bumpy surface texture formed by the irregular PEEK domains together with the conformal cracking damage mechanism was decisive in the scratch response of the PEEK/RGO nanocomposite coatings. The comprehensive characterization carried out in this work concludes that PEEK/RGO electrophoretic coatings are suitable for a variety of applications requiring tribo-mechanical resistance. [ABSTRACT FROM AUTHOR]

In this work, 1-aminoethyl-3-methylimidazolium bromide ionic liquid was used to modify the surface of graphene nanosheets (GNs) through "π–π" interaction to achieve good dispersion and conductivity. By introducing ionic liquid-modified graphene nanosheets (IGNs) into the PI matrix, the ultra-lightweight and multifunctional IGNs/PI aerogels were prepared via freeze-drying and thermal imidization. Benefiting from the porous structure and the introduction of conductive IGNs, the IGNs/PI aerogels exhibit excellent electromagnetic wave (EMW) absorption properties, compression properties, thermal insulation properties and thermal stability. Notably, when the volume content of IGNs is 10%, the IGNs/PI-10 aerogels show the best EMW absorption performance with a minimum reflection loss (RLmin) of −24.8 dB at 2.44 mm and an effective absorption bandwidth (EAB) of 3.6 GHz at 3.00 mm. These promising characteristics including excellent EMW absorption, compression properties and thermal insulation endow IGNs/PI aerogels great application prospects as multifunctional EMW absorbers. [ABSTRACT FROM AUTHOR]

Bio-based semi-aromatic poly (decamethylene terephthalamide) acid (PA10T) and a series of poly (decamethylene terephthalamide/hexamethylene terephthalamide) (PA10T/6 T) were synthesized by an efficient one-pot melt polymerization reaction. The chemical structures of the obtained samples were evaluated by fourier infrared spectroscopy (FT-IR). And the influence of addition of 1,6-hexanediamine (HAD) for copolyamides PA10T/6 T on melting points, thermal behaviors, crystallization performances, and mechanical characteristics of PA10T and PA10T/6 T were also analyzed thoroughly. The thermal analysis demonstrates that PA10T/6 T possess excellent thermal stability, and the melting temperatures can be tuned effectively by adding a suitable copolymerization content of the third monomer HAD to improve the processing properties appropriately. POM and XRD were used to research the crystallization behaviors showing that the addition of HAD did not alter the crystalline structure of PA10T essentially. Mechanical properties such as bending modulus and tensile strength of PA10T/6 T remarkably improved with increased HAD content. Moreover, this work provides an approach for preparing plant-derived semi-aromatic copolyamides PA10T/6 T, and these copolyamides exhibit outstanding processing performances, wider processing temperature range, high thermal stability, adjustable mechanical characteristics, and excellent comprehensive properties. [ABSTRACT FROM AUTHOR]

In the present work, coatings of Inconel 718 were deposited on a self-mating substrate by friction surfacing process. The bonding between the coating and the substrate was sound. The microstructure in the coating volume was analysed in detail through electron back-scattered diffraction. The coating microstructure contained fine grains (1–2 μm) and majority (> 74 pct) of boundaries had high angle character. The fine grains were formed by discontinuous dynamic recrystallization process. Local occurrence of continuous dynamic recrystallization was also observed in the microstructure. The microstructure was heterogeneous across the coating width. On the retreating side, the grain size distribution was wide and the grains had higher retained deformation (strain) inside them. There was variation in the fraction of twin boundaries across the coating width. The difference in the microstructural features is attributed to the variation in strain rate and temperature across the coating width during friction surfacing. A temperature variation of 50 °C was recorded across the coating width through infrared camera. The coating hardness was significantly higher than that of the substrate. The coating microstructure was stable against the double ageing treatment, which was carried out to generate the strengthening precipitates, post friction surfacing. The coating hardness further improved on the double ageing treatment. Annealing at 800 °C for 1 hour did not change the grain size in the coating, however, the hardness dropped. This was possibly due to over-ageing/dissolution of the strengthening precipitates. A further decrease in hardness and grain growth was observed in the coating when annealed at 900 °C and 1000 °C for 1 hour. [ABSTRACT FROM AUTHOR]

Rapid progress in modern technologies demands zero thermal expansion (ZTE) materials with multi-property profiles to withstand harsh service conditions. Thus far, the majority of documented ZTE materials have shortcomings in different aspects that limit their practical utilization. Here, we report on a superior isotropic ZTE alloy with collective properties regarding wide operating temperature windows, high strength-stiffness, and cyclic thermal stability. A boron-migration-mediated solid-state reaction (BMSR) constructs a salient "plum pudding" structure in a dual-phase Er-Fe-B alloy, where the precursor ErFe10 phase reacts with the migrated boron and transforms into the target Er2Fe14B (pudding) and α-Fe phases (plum). The formation of such microstructure helps to eliminate apparent crystallographic texture, tailor and form isotropic ZTE, and simultaneously enhance the strength and toughness of the alloy. These findings suggest a promising design paradigm for comprehensive performance ZTE alloys. Zero thermal expansion (ZTE) alloys with multi-properties are important for high-precision applications, but scarce. Here the authors incorporate a boron-migration-mediated solid-state reaction to construct a dual-phase ZTE alloy with enhanced mechanical properties and cyclic thermal stabilities. [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]

Thermal stability of N-alkylpyridinium tetrachloroferrates(III) [C5H5NR]FeCl4 [R = C4H9, (CH2)3CN, CH2C6H5, C8H17, and C10H21] in air in the range of 25–600°C has been studied, as well as the thermal stability of N-alkylpyridinium chlorides. The equivalent electrical conductivity of N-alkylpyridinium tetrachloroferrates(III) in acetonitrile solution at 25°C has been investigated. The ionic association constants Ka, the limiting molar electrical conductivity (λ0), and the standard Gibbs energy of the association (ΔG°) in the acetonitrile solutions have been calculated based on conductometric data via the Lee–Wheaton method. [ABSTRACT FROM AUTHOR]