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

The present work reports role of Bi2O3 and Sm2O3 on the thermal properties of phospho-zinc tellurite glasses with composition 47.5 P2O5‒ 45ZnO‒ (5-x) Bi2O3 ‒ 2.5TeO2‒x Sm2O3 (where x = 0, 0.3, 0.5 and 1 mol%) coded as PZBTS glass series system. Thermodynamic parameters such as Gibb's free energy (GFE) ∆G, entropy ∆S, etc., have been reported. This paper presents a comprehensive analysis of glass-forming tendency (GFT) and thermodynamic properties within the PZBTS glass system, elucidating key factors that influence glass stability and formation. The glass-forming tendency (KT) is a pivotal parameter, showing that higher KT values are associated with enhanced glass stability, while lower values indicate a propensity for devitrification, particularly accentuated with the addition of Bi2O3. Significantly, the mol% of Sm2O3 exerts a diminishing effect on KT, emphasizing the interplay between rare earth elements and glass formation. Specific heat capacity (∆Cp) is identified as an essential indicator, as its superiority to crystalline materials underscores favorable glass formation. Bond enthalpy (∆H) emerges as an effective gauge for estimating chemical bond strength in the glass network, reliant on the composition of Bi2O3 and Sm2O3. Meanwhile, the entropy of heat (ΔS) offers insight into disorder variation, a critical facet for successful glass formation. The ratio ΔG/ΔH becomes a crucial metric for assessing glass-forming ability, with values close to 0.2 signifying favorable characteristics. Moreover, molar density and volume exhibit an upward trajectory with increasing Sm2O3 mol%, leading to higher density and reduced molar volume due to the influx of rare earth ions. The density of rare earth ions (N) is calculated based on molar density and Avogadro's number, shedding light on ion distribution within the glass structure. Polaron radius (rp) provides valuable insights into structural features, while oxygen packing density (OPD) elucidates the intricate nature of the glass network. These findings collectively contribute to a deeper understanding of the thermodynamic and physical properties of the studied glasses, elucidating their glass-forming abilities and showcasing their potential applications in the realm of opto-electronic devices. [ABSTRACT FROM AUTHOR]

In this paper, the research findings about the impact of polydopamine and tannic acid coatings on specific thermal properties of polylactide are discussed. The influence of deposited coatings on the resistance to oxidation, heat resistance, and the temperatures of phase transitions was determined. Therefore, the oxidation induction temperature, thermogravimetry, and differential scanning calorimetry studies were carried out. To gain a deeper understanding of the findings, mass measurements for the samples before and after the deposition process were conducted, as well as scanning electron microscopy studies. Studies have shown that the application of coatings can improve the resistance of polylactide against oxidative and thermal degradation. However, these coatings have minimal impact on the intensity and temperature of phase transformations. The polylactide showed increased thermal resistance when coated with polydopamine, whereas tannic acid coating was found to be more effective in increasing oxidation resistance. The differences observed were likely caused by variations in the structure of the coatings applied, impacting the level of oxygen diffusion and heat transfer within the material. [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]

Polymers are widely employed in many areas, e.g. transport, packaging, electronic devices, etcetera. Among them, acrylonitrile–butadiene–styrene (ABS) is one of the most employed polymers due to its mechanical properties, its ease to mechanize and recyclability. Nevertheless, according to the fire properties, ABS behaviour is usually worse than other polymers, therefore, they have to be upgraded with flame retardant additives. To characterize the fire behaviour of a certain material is necessary to address several typology of tests, providing relevant properties such as thermal conductivity, flammability and heat released. However, researchers may not always be able to run all tests due to the lack of apparatus or samples. Therefore, it is necessary to seek bibliographic sources. As one might expect, for a given material, the property values should be similar, regardless of who performs the test. However, sometimes slightly different results are obtained, which may be due to different causes, such as differences in test set-up and in material composition/manufacture. These differences in properties may lead researcher to doubt which data to use. This paper presents the results of different types of tests using neat ABS polymer. Additionally, these results are compared with the data from literature, discussing the similarities/differences and offering a more comprehensive characterization of ABS. The laboratory techniques included in this work are: thermogravimetric analysis, differential scanning calorimetry, laser flash analysis, smoke density, cone calorimeter, fire propagation and flammability. [ABSTRACT FROM AUTHOR]

The manufacture of flexible devices is of immense interest due to their eco-friendliness, economic prospects and wide range of applications in biocompatible devices. Therefore, this paper reports the characterization and properties of chlorinated natural rubber (Cl-NR)/polyindole (PIN) blend with different contents of nickel oxide (NiO) nanoparticles. The formation of blend nanocomposites was analysed by FT-IR, UV spectroscopy, XRD, FE-SEM, DSC and TGA. The FT-IR and UV spectra proved the effective interfacial interaction between nanoparticles and the blend matrix, with a shift in UV peak intensity with the attachment of NiO at 433 cm−1. The XRD pattern revealed the regular arrangement of the blend matrix due to the presence of nanofiller, resulting in the semicrystalline structure of the composite system. The SEM micrographs revealed a homogeneous distribution of NiO in the blend matrix. The increased degradation temperature in the TGA demonstrated the enhanced thermal stability of the NiO-filled Cl-NR/PIN blend. DSC results showed that the glass transition temperature of the composite increased with NiO content in the blend matrix. The dielectric properties and AC electrical conductivity increased significantly with increasing temperatures, as well as with the addition of nanoparticles up to 5 mass % loading. The inclusion of NiO improved the tensile strength and hardness while reducing the elongation-at-break of nanocomposites. The blend nanocomposite with enhanced thermal stability, glass transition temperature, tensile strength, AC conductivity and dielectric properties enables them to be used in highly flexible electronic applications where traditional elastomeric materials fall short. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyse the thermal properties of glazes from the SiO2-Al2O3-CaO-MgO-Na2O system during the addition of zirconium oxide. The paper describes the effect of the addition of zirconium oxide on characteristic temperatures obtained with a high-temperature microscope and a mechanical dilatometer. Based on these data, the course of the logarithm curves of the viscosity of the glazes was determined on the basis of the Vogel–Tamman–Fulcher model. The analysis of thermal effects during the heating and cooling of glazes was also carried out on the basis of measurements made by means of differential scanning calorimetry and analysis of the phase composition at selected temperatures. The obtained results constitute a comprehensive characteristic of the thermal properties of glazes, in which the amount of zirconium oxide increases—from 0 to 24 mass%. [ABSTRACT FROM AUTHOR]

This paper describes the composites of silane cross-linked polyethylene (PEXb) mixed with four different fillers dedicated to improving thermal conductivity, such as multi-walled carbon nanotubes, graphite, boron nitride, and mineral filler. Using the mathematical modeling, the concentration of each filler was estimated to reach the value of 0.675 W m−1 K−1 suitable for the usage PEXb in the production of geothermal pipes. From tested fillers, all improve the thermal conductivity of pure PEXb; however, above the required value, only 28 mass% of boron nitride (0.937 W m−1 K−1). It was associated with its perfect dispersion and the highest gel content achieved, also resulting in the highest flexural modulus. Graphite at 5 mass% and mineral filler at 35 mass% allowed the thermal conductivity to equal 0.622 W m−1 K−1 and 0.624 W m−1 K−1, respectively, with a simultaneous medium effect on the mechanical properties. Carbon nanotubes increased PEX's conductivity to a small extent, due to their occurrence as agglomerates. [ABSTRACT FROM AUTHOR]

The increased interest in the use of polymer composites with natural, biodegradable and renewable fillers is the result of increased awareness of the environment. Therefore, the search for new materials that meet the above expectations is becoming a current issue. The article presents the results of research on composites containing pistachio shells (Pistacia vera L.), which are common agricultural waste, with unsaturated polyester resin based on post-consumer recycled poly(ethylene terephthalate) and vinyl ester resin based on bisphenol-A. The environmentally friendly polymeric cobalt solution was used as the accelerator. In order to study the degradation of the composites, accelerated ageing, immersion in various solvents, and high temperature were used. From the obtained results, it can be observed that accelerated aging resulted in the additional cross-linking of the resin, while the filler absorbed the UV light. During immersion, the polymer matrix was degraded in acetone, whereas the incorporation of pistachio increases its water sorption and the plasticisation effect was also observed. The alkali environment initiated the hydrolysis of ester linkages. The vinyl ester resin-based materials were more chemically and thermally resistant than those from the unsaturated polyester. [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]

Graphite films are frequently used in the thermal interface materials (TIM) of thermal dissipation due to its high thermal conductivity. However, accurately measuring the thermal diffusivity of graphite films requires careful consideration of key parameters. In this study, four typical graphite films were analyzed to identify these parameters. The results revealed that pulse width was the most important parameter in accurately measuring thermal diffusivity. Specifically, when the pulse width was less than 1.8% of the half-heating time, thermal diffusivity measurements were more accurate. Conversely, when the pulse width exceeded 1.8% of the half-heating time, heating curves were affected, resulting in a gradual decrease in thermal diffusivity. Additionally, pulse voltage had little effect on thermal diffusivity measurements. These findings provide important guidance for accurately characterizing the thermal properties of graphite films and can inform the accurate measurement and development of efficient thermal interface materials. [ABSTRACT FROM AUTHOR]

Thermal properties and the decomposition path of more environmentally friendly polymers in both atmospheres: inert and oxidizing have been studied with a use of simultaneous TG/FTIR/QMS and DSC methods. The polymeric materials in the UV-polymerization process of cyclohexyl methacrylate and methacrylate monomer obtained from natural terpene alcohol: citronellol, using different compositions of monomers were prepared. The glass transition temperature (Tg) and thermal stability of these high solvent and chemical resistant materials were dependent on the composition and increased with increasing cyclic monomer content in the compositions. The Tg changed from 9.8˚C to 47.5˚C and a thermal stability from 195˚C to 222˚C (inert atmosphere) and from 160˚C to 217˚C (oxidizing atmosphere). The TG/FTIR/QMS analysis proved the emission of cyclohexyl methacrylate, citronellyl methacrylate and their lower molecular mass decomposition fragments, e.g., propene, cyclohexane, citronellol, citronellal, formic acid, methacrylic acid and CO, CO2 during heating of these materials in helium and air atmospheres. It indicated the same radical mechanism of their decomposition in both atmospheres which meant that the presence of oxygen did not affect the course of decomposition but reduced the initial decomposition temperature of the copolymers. [ABSTRACT FROM AUTHOR]

This study explores the impact of different levels of halloysite nanotubes (HNT) and d-isomer on the non-isothermal crystallization behavior of the polylactic acid (PLA). The processing conditions, thermal flow, molecular orientation and the presence of nanofillers can affect the crystallinity and properties of PLA. In this work, PLA-based nanocomposite filaments were produced and their crystallization kinetics was studied. The data obtained through experiments, using differential scanning calorimetry at various cooling rates, were analyzed employing the Jeziorny and Mo models. And the activation energy of crystallization was determined by the Friedman method. The results showed that the growth of PLA crystals is three-dimensional, the HNT can accelerate the crystallization process, and crystallization occurs at higher temperatures in the presence of flow. The activation energy increased with addiction of more HNT in the nanocomposite. The study also found that the d-isomer has a more significant influence on the crystallization of PLA than HNT, which can inhibit crystal formation in some cases. These findings provide insights into the factors that can influence the properties of PLA nanocomposites and how they can be optimized. [ABSTRACT FROM AUTHOR]

Paraffin- and titania (TiO2)-based nano-encapsulated phase change materials (NePCMs) were synthesized by the sol–gel process to improve thermal as well as phase change performance. Nine different samples of NePCMs were prepared by varying core/shell mass ratios, and their effect was investigated on thermal performance. The paraffin/TiO2 nanocapsules were characterized by Fourier transform infrared spectrophotometer (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and dynamic light scattering (DLS). The characterization techniques confirmed that the paraffin was successfully contained in the TiO2 shell. The maximum effective melting (73.47 Jg−1) and solidification (71.87 Jg−1) latent heat for the NePCMs were found to be at a 52.33% encapsulation ratio. The mean size of the NePCMs was approximately 238 nm measured from DLS. The thermal properties of the same sample stayed almost the same even after 100 thermal cycles validated by the differential scanning calorimetry (DSC) curves, and thermal stability was evaluated by a thermogravimetric analyzer (TGA). [ABSTRACT FROM AUTHOR]

Polysilsesquioxanes are extensively studied as durable and anti-adherent coatings for medical devices due to their superhydrophobic properties. However, their particular influence on the thermo-mechanical properties and biocompatibility of poly(lactic acid) (PLA)-based materials obtained by melt compounding is scarce. Herein, a facile and promising method to improve the performances of PLA for biomedical applications via the incorporation of different mass proportions of POSS nanoparticles with allyl-heptaisobutyl (AH-POSS) substituent through a melt-blending technique is proposed. The thermal, morpho-structural, mechanical properties at room (RT) and body temperatures (BT), and in vitro biocompatibility of the developed PLA/AH-POSS nanohybrids were investigated. AH-POSS nanoparticles were found to have simultaneous nucleation and plasticizing effects on the PLA nanohybrids, inducing enhanced thermal resistance and easy control of crystallinity while preserving PLA's biocompatibility. An interesting effect of AH-POSS on the mechanical properties of PLA at body temperature was observed. These results indicate the considerable potential of the PLA/AH-POSS nanohybrids obtained by melt compounding in the fabrication of biomedical devices. [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]

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

Aliphatic polycarbonates (APCs) have become an essential packaging material because of their renewability, biodegradability, and biocompatibility. In this study, a series of high molecular weights APCs have been successfully synthesized using dimethyl carbonate (DMC) and different lengths of aliphatic diols with even carbon (n-CH2 = 4–12) via melt polymerization. Thermal properties, isothermal crystallization behavior, crystal structure, and scale of microstructure of APCs indicated that the flexibility and crystallization of molecular chains gradually increased with the increasing number of methylene groups of repeating units. However, due to the rigidity of ester group was higher than methylene group, and crystallization could increase the rigidity of chain segments, yielding strength and Young's modulus of APCs decreased first and then gradually increased with the increasing number of methylene groups in the repeating units. Furthermore, the scale of microstructure indicated that Brill transition increased the distance between intermolecular chains. Therefore, although the trans-gauche coexistence chain conformation simultaneously decreased the rigidity and crystallization of chain segments, barrier property of poly(octamethylene carbonate) with Brill transition was similar to long-chain APCs because of the lengthened diffusion path. The analytical mechanism of structure-performance relationship from the viewpoint of molecular interactions and chain structure will provide an entirely new thought for developing new barrier materials. [ABSTRACT FROM AUTHOR]

Nickel-based superalloys are an important group of advanced engineering materials used for high-temperature and/or corrosive environments. Lately, in order to improve their mechanical properties, carbide reinforcement is added to a metal matrix, creating composites of improved hardness, shear resistance, or tensile resistance. In order to preserve the wide applicability of those materials, thermal properties, and corrosion resistance must also be evaluated. Presented research evaluated the thermal properties of Inconel 625—(Ti,Zr)C0.85 composites obtained at 1000 °C by spark plasma sintering process. Sinters containing 5–20 mass% of carbide phases were initially characterized in terms of their density, phase composition, and microstructure. A thorough examination of their thermal properties included: dilatometry, laser flash analysis, and differential scanning calorimetry. Conducted experiments revealed that a growing amount of carbide reinforcement decreased the thermal diffusivity and conductivity of samples. Other materials had a nonlinear correlation with that parameter. Performed analysis allowed to make an initial evaluation of oxidation resistance at 800 °C. It was shown that above 5 mass% addition of (Ti,Zr)C0.85 there is a considerable mass gain change shown by samples during the first hour of oxidation before passive layers were created. Suitable chemical reactions were predicted in order to describe the oxidation process of obtained composites. [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]

Structural, thermal and energetic properties of quinoa, kiwicha and kañiwa native Andean-pseudocereal flours have been studied. Moisture, protein and fat contents and also metallic and semi-metallic levels were, in general, within of the range values reported in the literature. Empirical formulas of quinoa, kiwicha and kañiwa flours have been determined as CH1.87O0.81N0.06S0.0015, CH1.90O0.82N0.05S0.0019 and CH1.76O0.73N0.06S0.0017, respectively. The elemental carbon concentration (Cflour) in organic matter follows the trend, Ckañiwa (45.6%) > Ckiwicha (43.2%) ≈ Cquinoa (43.3%), which reflects the greater structural similarity between the quinoa and kiwicha flours, with respect to kañiwa flour. Regarding thermal and energetic properties: (i) in the temperature range of 261.15–343.15 K, we found no significant differences among the specific heat capacities of the three flours, which are ranged between 1.3 and 1.9 J g−1 K−1; (ii) the organic matter decomposition temperature (Tdec) followed the trend, Tdec,kañiwa (489.8 ± 1.6 K) > Tdec,kiwicha (479.1 ± 1.5 K) ≥ Tdec,quinoa (477.1 ± 1.5 K) indicating a greater thermal stability range of kañiwa flour; (iii) the gelatinization temperatures and also the gelatinization enthalpy of kañiwa flour (4.3 ± 1.6 J g−1) were lower than corresponding thermal gelatinization parameters of quinoa and kiwicha flours; and (iv) the standard massic energy of combustion (− Δcu°) or its associated net calorific value (qNCV) of kañiwa flour (18.77 ± 0.15 kJ g−1 or 4487 ± 36 kcal kg−1) was slightly greater than for kiwicha (18.47 ± 0.11 kJ g−1 or 4415 ± 26 kcal kg−1) and quinoa (18.60 ± 0.16 kJ g−1 or 4445 ± 39 kcal kg−1) flours. Taking into account the associated uncertainties, qNCV trend is similar to the Cflour and Tdec trends. Accordingly, our results indicate a greater range thermal stability and greater net calorific value for kañiwa flour than for kiwicha and quinoa flours. [ABSTRACT FROM AUTHOR]

In this work, the effect of uniaxial stretching on the crystallization and melting behaviors, miscibility, crystal structure, and mechanical properties of neat poly(L-lactide) (PLLA) and miscible PLLA/poly(vinyl acetate) (PVAc) blends was investigated. Stretching process could generate remarkable influence on thermal properties of neat PLLA and PLLA/PVAc blend. With stretching ratio increasing, macromolecular chains orientation and crystallization were promoted, resulting in a decrease in cold crystallization temperature and an increase in glass transition temperature, and a significant increase in crystallinity. In addition, after stretching process PVAc still inhibited the crystallization of PLLA. PLLA/PVAc blends were completely miscible blend system which had only one glass transition temperature before and after stretching process, and phase separation did not occur after stretching process. When stretch ratio increased, amorphous PVAc had greater influence on the tanδ transition peak and storage modulus increased markedly, which was benefit to the improvement of heat resistance. The α′ crystal form was produced in blends after stretching process. Stretching process with moderate stretch ratio can be utilized to improve the mechanical properties of PLLA with simultaneous enhancement of tensile strength, fracture strain and stiffness. The findings in this work provide an insightful understanding of the effect of stretching process on miscible PLLA blend and the improvement of toughness, which will facilitate the large-scale practical application of PLLA. [ABSTRACT FROM AUTHOR]

The nanohybrid consists of polyvinyl chloride (PVC) and polyvinylidene fluoride (PVDF) nanostructure network with BaZrO3 and BaTiO3 nanoparticles separately. The mass ratios of PVC-PVDF-BaZrO3/BaTiO3 were chosen to be 60:36:04. The structural morphology of nanohybrid was examined by using Raman spectroscopy and scanning electron microscopy (SEM). The Raman spectroscopy is enabled to explain strong interaction between the nanoparticles and polymer matrix. The PVC-PVDF- 4 mass% BaTiO3 nanohybrid shows high dielectric permittivity, breakdown strength and the energy density as compare to pure polymer matrix. DSC analysis of nanohybrid is attributed the good thermal stability due to crystallization effect in presence of nanoparticles. The findings of present work enable to design the energy storage devices. [ABSTRACT FROM AUTHOR]

With the continuous development of battery technology, there are new research investments in materials of various parts. In the field of electrolytes, ionic liquids (IL) are considered to be excellent electrolytes and have been widely studied in distinct energy fields. However, it is necessary to pay attention to the safety characteristics of ionic liquids at high temperature due to the application of energy. Still, there is little research on the reaction and kinetics of ionic liquids. To ensure the safety of ionic liquids, such as high temperature, the common ionic liquid 1-hexyl-3-methylimidazolium nitrate ([Hmim] NO3) was selected for analysis. The exothermic mode is obtained from the data of differential scanning calorimetry. The basic reaction parameters of [Hmim] NO3 were determined with thermodynamic equation simulation. For ionic liquids in the actual situation, consider adding a heat balance model to estimate its temperature change pattern and determine the hazard temperature and related safety parameters. Temperature changes were assessed by constructing 25.0 g and 50.0 g packages to simulate material reactions and heat transfer in the external environment. The results showed that [Hmim] NO3 had shorter TMRad and TCL (< 1 day) when the temperature was above 200 °C. [ABSTRACT FROM AUTHOR]

Present embodiment is an account of work done on impregnation of thermoplastic polyether imide (PEI) [ULTEM 1000] into high-temperature biphenyl-based phthalonitrile (PN) thermosetting resin to form a semi-interpenetrating network (s-IPN) in order to find an optimum composition with little compromise on glass transition temperature (Tg) and thermal stability of base resin system. The PEI has been cured with PN resin in varied ratios of 5–30 mass% in arithmetic progression to study its effect on thermal and physical properties. Fourier transform infrared spectroscopy, differential scanning calorimetry and thermos-gravimetric (TG) measurements of the s-IPN compositions were carried out to assess the extent of curing, curing enthalpy, glass transition (Tg), thermal stability and char yield, respectively. The dynamic mechanical analysis (DMA), measurements were done to ascertain the effect of PEI component in PN system on its storage modulus, Tg under dynamic load with respect to temperature. PN95 composition having PN/PEI ratio in 95:05 stoichiometry has demonstrated the best desirable properties with respect to PEI content with least compromise in Tg temperature. More than 5 mass% PEI has resulted in drastic change in Tg of s-IPN from > 673 K to 525 K in case of 10 mass% PEI as evaluated by DMA. The morphological analysis of 30% PEI-containing s-IPN showed interesting cross-linked patterns probably formed by the fibrillar orientation of the thermoplastic resin in the PN matrix. [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]

In the present study, various properties, viz. physiochemical, rheological, tribological and thermal properties of polyolester (POE) lubricant, a widely used lubricant in household refrigerator compressor, is evaluated by loading it with alumina nanoparticles and also blending it with sesame oil (SESO)—an environment-friendly lubricant and the results are compared in order to visualize the effects. The mass fraction of alumina nanoparticles used is from 0.05 to 0.15% and the blend ratio of sesame oil is from 12.5 to 87.5%. The rheological properties were evaluated for the temperature ranges from 25 to 100 °C. High-frequency reciprocating rig is used to perform tribological studies. The results show that the values of viscosity, viscosity index, flash and fire point enhanced for all the synthesized lubricants with an increase in alumina nanoparticles proportion and the sesame oil ratio in the base POE oil and all of the synthesized lubricants showed Newtonian behaviour as well. The thermal stability (TGA results) of the POE + SESO blend and POE + Al2O3 nanolubricant was found increasing with the increase in the proportion of sesame oil and the alumina nanoparticles in the base POE oil. The contact angle and surface tension of the synthesized lubricants were initially found decreasing with the addition of sesame oil and alumina nanoparticles to the base POE oil and then increased, as the sesame oil and alumina nanoparticles proportion in the base oil approached the maximum limit. Among the POE + Al2O3 nanolubricants, the POE + 0.125%Al2O3 and among the POE + SESO blend 15POE + 25SESO exhibited much better results in tribological studies. The sesame oil-blended POE oil was found less toxic and more biodegradable when compared to the POE + Al2O3 nanolubricant. [ABSTRACT FROM AUTHOR]

Natural brightness of epoxy adhesives can be reduced by adding cork. Besides, when cork was magnetized, it was possible to move them depending on the properties required in each section of the adhesive bond (PAT354/2019). The main objective of this work was to study possible changes in the thermal properties of the adhesive due to the addition of magnetic cork particles. If changes were significant, the use of magnetic cork particles would be compromised. To this end, natural cork particles and magnetic cork particles, with two different particle size (53–38 and 250–125 μm) and percentage (1 and 5 v/v%), were compared as reinforcement material. Magnetic cork was obtained by co-precipitated coating, according to patent number WO2019025651. The thermal properties studied by Differential Scanning Calorimetry were activation energy of curing reaction, glass transition temperature (Tg) and thermal conductivity. Two different hardeners were studied and a factorial design (2k with k = 4) was carried out. It allowed to determine which variable or combination of variables had most impact on thermal properties. Results showed that the main parameter affecting thermal properties was the hardener, regardless of the kind of particle used. However, the presence of magnetic cork highlights further the differences found between hardeners. The conclusion of this study was that magnetic cork particles can be used as fillers in epoxy resin to make graded joints, since they do not affect the thermal properties of the resin. [ABSTRACT FROM AUTHOR]

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

The main objective of this work is to investigate how the addition of the magnesium hydroxide particles affects thermal properties and consequently the mechanism of thermal degradation of polyethylene oxide. With this aim, polyethylene oxide composites, with different composition of magnesium hydroxide particles derived from the sea bittern residual, were prepared via hot melt extrusion. Non-isothermal thermogravimetry in nitrogen atmosphere was utilized, and on gained data, the kinetic analysis was performed. Activation energy, pre-exponential factor and kinetic model were calculated and compared. TG analysis revealed that thermal degradation of composites starts at lower temperatures, which could be an indication of magnesium hydroxide destabilizing effect on polyethylene oxide. Kinetic analysis showed that all composites degrade through three degradation stages. In the first stage, the sample with max load of inorganic particles resulted in the diffusion as the rate-controlling process, while in the second, denoted as the main stage, thermal degradation of all samples proceeded via the same accelerating reaction type. However, at higher mass fraction of inorganic particles, the addition of the magnesium hydroxide particles altered the mechanism of thermal degradation of polyethylene oxide. [ABSTRACT FROM AUTHOR]

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

Bi doped 2CaO-Al2O3-SiO2 (gehlenite) glasses were prepared by conventional melting. The concentration of Bi3+ was 0, 0.25, 0.50 and 1.50 mol. %. The prepared samples were X-ray amorphous except of the undoped sample and the sample with the highest content of Bi3+, for which XRD records revealed traces of crystalline gehlenite. Differential thermal analysis (DTA) was used to study the thermal properties of prepared glasses, performed in the atmosphere of nitrogen at 5 different heating rates. The DTA records of all studied samples contained only one exothermic effect. Based on the results of XRD analysis, the exothermic effect was attributed to the crystallization of gehlenite. The XRD patterns of all samples measured after DTA analysis contained gehlenite as the main crystalline phase (01–074-164 COD). The DTA records measured at a heating rate of 10 °C.min−1 revealed a significant decrease in the temperatures of maxima of the exothermic peaks (from 982 °C to 943 °C) with the increasing Bi doping. The model approach using the Johnson–Mehl–Avrami-Kolgomorov (JMAK) equations with six different values (1.5, 2, 2.5, 3, 3.5 and 4) of Avrami parameters (m) was used to study crystallization kinetics of gehlenite glasses. The model that best describes the experimental data was found, using the AIC (Akaike criterium) and wAIC (Akaike weight) criteria: A (frequency factor) and Eapp (apparent activation energy) were determined. Based on kinetic parameters values, it is concluded that the nucleation rate is constant. Irrespective of the Bi content, the movement of the growth zone is controlled by diffusion and 3D growth is characteristic for the gehlenite crystals growth. [ABSTRACT FROM AUTHOR]

The structural and thermal properties of sodium niobium phosphate glass are studied to analyse its suitability for immobilizing long-lived radioactive waste from nuclear reprocessing plants. Two series of sodium niobium phosphate glasses such as (A) xNb2O5–(50−x)Na2O–50P2O5 and (B) xNb2O5–(50−x/2)Na2O–(50−x/2) P2O5 (x = 0, 10, 20, 30, 40 mol.%) are prepared by the conventional melt–quenching technique. The influence of the incremental addition of Nb2O5 on the structural and thermal properties of the above two series is investigated. The FTIR and Raman spectra of these glasses revealed that the number of [NbO6] octahedral chain increases with Nb content and dominates as the major structural unit over the number of PO4 tetrahedra unit. The glass transition temperature (Tg), crystallization temperature (Tc) and melting temperature (Tm) are measured by using a differential scanning calorimeter (DSC). Other thermal stability parameters such as Hruby (KH), Angell (KA), Saad–Poulain (KSP) and Weinberg (KW), the total relaxation time of transformation and fragility are evaluated and compared between different composition of glasses. For both series A and B, the glass transition temperature increases with Nb content, suggesting the formation of a larger number of P–O–Nb or Nb–O–Nb linkages compared to the PO4 tetrahedra, resulting in a more rigid network. This is confirmed by Raman spectra which show an increase in the number of Nb–O–Nb bonds with Nb content. The major crystalline phases formed by devitrifying these glasses are identified by XRD and are found to be mainly NaPO3, NbOPO4, Na2Nb6P4O26 and Na4Nb8P4O32. [ABSTRACT FROM AUTHOR]

Thermal resistance is a very important parameter when assessing the therapeutic usefulness of potential pharmaceutics. Therefore, the thermal behaviour and the decomposition mechanism in the atmosphere of helium and synthetic air of disubstituted fused 1,2,4-triazoles—which may be potential anticancer and antibacterial agents—were studied with a use of simultaneous thermal analysis: thermogravimetry/differential scanning calorimetry (TG/DTG/DSC) coupled online with Fourier transform infrared spectroscopy. It was confirmed that the thermal stability of the tested compounds is directly depended on their structure and thus on the number of chlorine atoms as substituents. The pyrolysis process of disubstituted fused 1,2,4-triazoles in inert conditions runs in two main, non-well-separated stages connected with the emission of NH3, HCN, acetonitrile, aromatics with an OH group, aromatics with a NH2 groups, H2O, CO2 and alkene fragments. However, the thermal stability of those compounds in synthetic air atmosphere is comparable or lower than their thermal stability in helium atmosphere. The decomposition of the tested compounds runs through at least three main stages, resulting in the emission of the same type of volatiles as in inert conditions plus the additional emission of CO and some carbonyl fragments for compounds with no or one chlorine atom as a substituent. The results indicate a simultaneous cleavage of C–N, N–N and C–O bonds during heating of the tested disubstituted fused 1,2,4-triazoles in inert conditions and additional combustion process of pre-formed residues in oxidative conditions. [ABSTRACT FROM AUTHOR]

Ionanofluids (INF) are combinations of ionic liquid (IL) and nanoparticles (NP) with superior thermophysical properties. In the present study, measurement of thermophysical profile of IL, 1-ethyl-3-methylimidazolium chloride ([EMiM]Cl) in which Al2O3 NPs are dispersed were undertaken in the temperature range of 303.15–333.15 K. INFs were prepared by dispersing Al2O3 NPs in different mass concentrations of 0.5, 1.0, 2.5, 5.0, and 10%. The results showed that specific heat and thermal conductivity increase with both concentration and temperature. In contrast, the viscosity and density increase with concentration and decrease with temperature rise. The maximum INF thermal conductivity and viscosity enhancements were 21.9% and 77.6% for a mass concentration of 10% compared to IL at 333.15 K and 303.15 K. Electrical conductivity decreases with NP addition and increases linearly with an increment in temperature. Based on the measured results, a correlation for the specific heat, thermal conductivity, and viscosity of INF was proposed. Further, the heat transfer performance of studied INF is theoretically estimated based on the experimental thermophysical properties. Finally, for high-temperature applications methylimidazolium chloride-based INFs can be used as an efficient candidate as primary heat transfer fluid. [ABSTRACT FROM AUTHOR]

Melamine–formaldehyde resin-coated bamboo fiber (MFBF) and ammonium polyphosphate (MFAPP) were prepared, and then flame-retardant polypropylene (PP)/bamboo fiber composites based on MFBF/MFAPP were obtained by melt blending. The water resistance, flame retardant, and thermal properties of the composites were studied. The results show that MFBF and MFAPP have excellent water resistance with the water contact angles 130.85° and 119.78°, respectively. Compared with pure PP, the limit oxygen index (LOI) of the prepared composite increased from 18.5 to 25.5% with the UL-94V-0 rating. The peak heat release rate of the composite decreased from 1011.8 to 344.3 kW·m−2 and the total heat release decreased from 100.6 to 58.8 MJ·m−2. Meanwhile, the total smoke release decreased from 1453.3 to 922.0 m2·m−2. After soaking in 70 °C water for 36 h, the composite still reached the V-0 rating in UL-94 test, demonstrating a good water resistance. This work provides an effective method to improve the water resistance and flame retardancy of PP/bamboo fiber composites. Melamine–formaldehyde resin-coated bamboo fibers (MFBF) and ammonium polyphosphate (MFAPP) were prepared, then flame-retardant PP/BF composites were obtained based on MFBF/MFAPP. The results show that prepared composite exhibited excellent water resistance and flame-retardant properties. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries should continuously be operated at the optimum temperature range 15 ∼ 40 ∘ C for the best performance. Surface temperature monitoring is critical for the safe and efficient operation of the battery. In this study, initially, the electrical parameters of the battery are determined by applying a second-order equivalent circuit model. This model then is integrated with a thermal model based on the temperature dependent behavior of the electrical parameters and the heat generated. The input parameters to the electro-thermal model include the current, the ambient fluid temperature and the output parameters include the terminal voltage, state of charge, cell core temperature and cell surface temperature. In this research, the entropic coefficient and battery thermal parameters have been taken into consideration concurrently, which will lead to both saving plenty of time and cost compared to other methods. The accuracy of the suggested analytical approach for estimating the surface temperature and the amount of heat generation is validated with the pulse-rest tests of an 18,650 cylindrical lithium-ion battery with a nominal capacity of 2600 mAh at three different ambient temperatures and three charge/discharge current rates. The comparison of results indicate that the maximum error of the proposed algorithm is about 0.6 K under a wide range of test conditions. [ABSTRACT FROM AUTHOR]

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

In recent years, with the adaptation of nanotechnological engineering applications to complex systems, the use of nanofluids with better thermo-physical properties compared to conventional fluids has become widespread. In addition, studies on the preparation techniques of nanofluids, improving their thermal properties and evaluating their thermal performance are increasing. This study presents a review about preparation, evaluating and enhancement of the stability and thermal properties of nanofluids. Furthermore, the recent advances about the thermo-hydraulic, thermodynamic and thermo-economic performances of nanofluids in different types of thermal systems are summarized as well. The stability of nanofluid is a significant factor affecting its applicability. Various techniques have been used in the literature to enhance the stability of nanofluids such as surfactant addition, ultrasonic mixing and pH control. By using nanofluids, the desired thermo-physical properties can be obtained in order to improve the heat transfer property in the system. Some researchers recommend to hybrid nanofluids because of the hybrid effect of two or more particle types they contain. The reviewed literature also indicates that the use of nanofluids instead of conventional working fluids is an effective way to increase the thermo-hydraulic performance of thermal systems. In addition, according to the literature review, minimum entropy generation is an effective way to increase the energy efficiency and improve thermodynamic performance of the thermal system and the use of nanofluids provide a significant reduction in entropy production. [ABSTRACT FROM AUTHOR]

In this study, a series of phase change nanocomposites using microencapsulated phase change material and graphene nanoplatelet (as an additive material) is synthesized to enhance PCM thermal properties. Paraffin as a PCM is encapsulated by melamine–formaldehyde as a shell material via in situ polymerization method. Graphene nanoplatelet as a heat transfer promoter is added among the microencapsulated phase change materials (MPCMs) in different mass fractions to form phase change nanocomposites. By the applied technique, the defect of leakage and the low thermal conductivity of the phase change material can be overcome simultaneously. The experimental measurements show that the thermal conductivity of the PCNs effectively enhances without a significant influence on their phase change enthalpy. The results indicate that when the amount of the graphene nanoplatelets increases, the thermal diffusivity and thermal conductivity enhance. By using 10 mass % graphene nanoplatelets in the PCN, the PCN's thermal diffusivity and thermal conductivity are raised by 93% and 48%, respectively. The DSC results show that the maximum latent heat of the PCNs is 95.97 J g−1 (PCN with 1 mass % of graphene). However, the maximum difference in the latent heat of PCNs with different graphene percentages is less than 4%. Thermal stability experiments show that the PCNs have a stable structure up to 165 °C without damaging the microcapsule shell. The fabricated PCNs, compared to many previous works, have good thermal properties and low cost which can properly be considered in thermal energy storage and thermal management applications. [ABSTRACT FROM AUTHOR]

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

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

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

The thermal properties and evolution of mineralogy and colour of kaolinitic clay from the Terra Alta region were studied. The mineralogy of these materials consists mainly of kaolinite (13–27 mass%) and quartz (48–86 mass%). Minor illite, hematite, K-feldspar and calcite also occur. The linear expansion and absorption curves were used to predict the optimal firing temperature of the raw clays. During firing, from 1100 °C the water absorption decreases steeply, due to an increase in liquid phase, which penetrates into the pores and close the porosity. At this temperature, the firing shrinkage increases progressively. The fired clays are mainly composed of quartz, cristobalite and mullite, with minor hematite and rutile. Mullite starts to appear at 1050–1100 °C. SEM observations show that porosity decreases with the firing temperature. The colour properties were measured in the raw clays and in the fired bricks at different temperatures. The lightness, L*, is lower in the fired test pieces respect to the natural clays. This colour varies according to the hematite content, being from white to reddish in the fired samples. [ABSTRACT FROM AUTHOR]

In order to adjust buildings temperature, a dodecanol (DD)-palmitic acid (PA)/hydroxylpropyl methyl cellulose (HPMC) composite phase change material was prepared by vacuum impregnation. DD-PA was absorbed into the HPMC, which was verified by specific surface area, pore size (BET) and scanning electron microscopy (SEM) analysis. The results of Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD) indicated that the HPMC and DD-PA were only physical combination. The differential scanning calorimetry (DSC) analysis revealed that the phase change temperature and latent heat were 19.34 ºC and 113.12 J g−1, which means good energy storage capacity. The 5% mass loss temperatures (T-5%) of thermo-gravimetric analysis (TG) was higher than 50 ºC, showing the good thermal stability of composite phase change materials. About 60% DD-PA was absorbed in HPMC, which detected by DSC and TG. After 100 thermal cycling, the latent heat, onset temperature (T0), peak temperature (Tpeak) and end temperature (Tend) had changed −1.02%, −8.20%, −4.29% and −5.60%. The result showed that the composite phase change materials own good thermal reliability. In addition, the 2% multi-walled carbon nanotubes (MW CNTs) were added to improve the thermal conductivity. And the thermal conductivity was increased from 0.130 to 0.172 W (mK)−1, the total thermal storage-release time was decreased from 3740 to 2310 s. [ABSTRACT FROM AUTHOR]

The different MSEP/SA composite phase change materials were prepared by direct impregnation method with SEP-v, SEP-p, SEP-f as supporting material. The thermal stability of the composite phase change materials was analyzed and the differences in the thermal properties and thermal reliability were compared, and provided reference for the study of different SEP to adsorb stearic acid (SA). The results indicated that there is no chemical reaction during the preparation of the composite PCMs. SEP-f has great advantages as a supporting material and its composite (65SEP-f/SA) has a good leak-proof performance with remaining mass ratio is above 99% for leakage test of 50 h. Besides, melting and freezing latent heat of three composite PCMs are similar, For 65SEP-f/SA, the melting latent heat is 76.10 J g−1 corresponds to the phase change temperature of 344.15 K and the freezing latent heat is 75.59 J g−1 corresponds to the phase change temperature of 336.85 K. The 65SEP-f/SA has the highest thermal conductivity of 0.9460 W m−1 K−1. It can be conducted that 65SEP-f/SA have great application potential in the field for low temperature phase change energy storage. [ABSTRACT FROM AUTHOR]

Microstructure, phase transitions and thermal properties including thermal diffusivity and thermal conductivity of four Ag–Ge alloys with 20, 40, 60 and 80 at % of Ge were experimentally investigated in this study. Observation and analysis of the alloy microstructures and morphologies of (Ge) phase in the hypereutectic alloys were carried out using optical microscopy and scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM–EDS). Phase transitions of the alloys were studied using differential scanning calorimetry (DSC). Experimentally determined temperature of the eutectic reaction was 650.9 °C. The xenon flash method was used for thermal diffusivity measurements in the temperature range from 25 to 400 °C. Based on the measured values of thermal diffusivity, thermal conductivity of the solid Ag–Ge alloys was determined. It was found that both thermal diffusivity and thermal conductivity show a minimum at 20 at % Ge which is close to the eutectic composition. The obtained results were compared with the results of thermodynamic calculation and literature data, and a close agreement was observed. [ABSTRACT FROM AUTHOR]

Epoxy asphalt bond coat (EABC) is one of the thermosetting polymer-modified asphalts, which has been widely employed as a strong waterproof bonding layer between the asphalt concrete and the orthotropic steel bridge deck. In the present work, the influences of asphalt content on the phase separation, viscosity, thermal stability, viscoelastic behavior, mechanical performance, pull-off strength, and adhesive performance of EABCs were characterized by various instruments. Laser scanning confocal microscopy observations showed that phase separation occurring in EABCs depended on the curing time. The asphalt merged to form large spherical particles in the continuous epoxy phase during the cure reaction. The size of asphalt particles increased in the asphalt content. Viscosities of EABCs were higher than that of the pure epoxy and increased with the asphalt content in the initial curing stage. However, the opposite trend was observed in the latter curing stage. The presence of asphalt slightly improved the glass transition temperature and the damping properties of the pristine epoxy. For EABCs, the damping behaviors slightly increased with the asphalt content. The thermal stability of the pristine epoxy was enhanced by the incorporation of asphalt. The addition of asphalt decreased the mechanical, adhesive properties, and pull-off strength of the pristine epoxy. What's more, these properties of EABCs decreased in the asphalt content. [ABSTRACT FROM AUTHOR]

Microstructure, melting behavior and thermal conductivities of three Bi–Ag alloys with 5, 20 and 45 mass% of Ag were experimentally studied in the present work. Phase morphology of the alloys was analyzed by the light microscopy and scanning electron microscopy with energy-dispersive X-ray spectrometry. Phase transition temperatures and their heat effects were measured using differential scanning calorimetry (DSC). The calculation of phase diagrams method was used for the computation of thermodynamic functions such as enthalpy and specific heat capacity of the investigated alloys. Experimentally obtained DSC heating scans were compared with the simulated DSC scans derived from thermodynamic data, and good mutual agreement was noticed. The flash method was used for determination of thermal diffusivity and thermal conductivity of the investigated alloys. It was found that increase in silver content to 45 mass% resulted in modest increase in thermal conductivity of the investigated alloys. Thermal conductivities for all three investigated eutectic alloys slightly decrease with increasing temperature. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents may develop a pivotal role in future technologies considering sustainability and safety as pivotal aspects for chemistry developments. The possible application of these fluids for heat transfer operations is of great relevance for which the knowledge of thermal properties such as thermal conductivity is required as well as inferring structure–property relationships which allow reverse design of the fluids according to the technological requirements. Considering the technological relevance of this property, the available literature on the thermal conductivity for deep eutectic solvents is critically discussed showing strengths and weaknesses. The analysis of the state-of-the-art shows the future needs in this research field considering the application of these solvents for thermal-related technologies. The review indicates the scarcity of reliable experimental data and the need of predictive methods, which could be used for process design and solvent screening purposes. Likewise, considering the relevance of developing predictive methods for in silico design of these fluids according to industrial needs, the available predictive theoretical approaches are analysed showing their reliability as well as future needs. Finally, considering the need of developing suitable and reliable structure–property relationship, the molecular level basis of thermal conductivity in deep eutectic solvents is discussed, showing the role of hydrogen bonding and the effects rising from the involved hydrogen bond donors and acceptors as well as the eutectic compositions. This work reports the first literature review and analysis on thermal conductivity for deep eutectic solvents considering an experimental and theoretical approach as well as providing support for the molecular basis of this technologically relevant property, thus contributing to the development of environmentally friendly materials for thermal-related technologies. [ABSTRACT FROM AUTHOR]