Search

The study primarily focuses on the in situ synthesis of polystyrene (PS) and copper oxide (CuO) nanocomposites. An extensive analysis was conducted on the optical, thermal, mechanical, and electrical properties of PS with different CuO concentrations. The effective inclusion of CuO into PS was characterized by Fourier-transform infrared spectroscopy (FTIR), UV–visible spectroscopy, filed emission scanning electron microscopy (FE-SEM), X-ray diffractometry (XRD), differential scanning calorimetric analysis (DSC) and thermal gravimetric analysis (TGA). The reinforcement of CuO into the PS was established through FTIR. The optical bandgap energy deduced from UV–visible spectra decreases with CuO addition, whereas the refractive index rises significantly with the addition of CuO nanoparticles up to 7 mass%. The XRD analysis revealed the amorphous to crystalline transformation of PS with the homogeneous dispersion of nanoparticles. The SEM–EDX analysis revealed the uniform distribution of CuO nanofillers in the PS matrix. The CuO addition considerably increased the glass transition temperature and thermal stability of PS. The tensile strength, impact resistance and hardness of nanocomposite were significantly increased with the loading of CuO in the polymer matrix. The AC conductivity and dielectric constant of the PS was improved with the addition of CuO nanoparticles. The effect of temperature on conductivity, activation energy, and pre-exponential factor was determined using the universal power law and the Arrhenius equation. The highest electrical and mechanical properties were observed for 7 mass% nanocomposite. The synthesized PS/CuO nanocomposites with excellent optical characteristics, thermal stability, electrical conductivity, dielectric constant and mechanical strength can be used in supercapacitors and flexible nano-electronic devices. [ABSTRACT FROM AUTHOR]

The researchers attract nanofluids due to their improved thermal and physical properties compared to the base fluid. The colloidal mixture of nanometre-sized particles with conventional fluid is known as nanofluids. Compared with single nanofluids, hybrid nanofluids show better enhancement in thermophysical properties. Combining nanoparticles into the host fluid is called a hybrid nanofluid. The preparation of nanofluid needs more importance. However, the physiochemical properties of the nanofluid mainly depend on the stability of the nanofluid. The article aims to provide detailed information about preparing different types of single and hybrid nanofluids dispersed in various base fluids, preparation techniques, stabilization processes, applications and challenges. Different types of surfactants and characterization methods are suggested to improve the stability of the prepared solution. It was observed that all types of nanoparticles and hybrid nanoparticles could be synthesized with different base fluids with the help of the sonication process, particle-to-surfactant ratio, magnetic stirrer and many more. The two-step method is mostly preferred by the researchers compared to the single-step method to prepare the nanofluid. Application of single and hybrid nanofluids has been highlighted in different areas; few challenges have also been identified and must be checked before implementation in the industry. [ABSTRACT FROM AUTHOR]

In this study, Ni20Ti50Sn30 (atomic %) sample was prepared using the arc melting method. Some thermodynamic parameters (phase transformation temperatures, PTT; enthalpy, ΔH; and phase transformation hysteresis, H) obtained from the phase transformations of the alloy were determined using differential scanning calorimetry (DSC). The sample exhibited high-temperature shape memory alloy (HTSMA) properties. X-ray (XRD) analysis was performed to determine the crystal structure properties at the alloy. The presence of B2, B19′, Ti2Ni, β-Ti, Ni3Sn4, TiNiSn and Ti3Sn phases was identified through X-ray analysis of the alloy. Scanning electron microscopy (SEM) was used to examine the pre- and post-corrosion surface morphologies of the sample, with EDX analysis being performed to reveal chemical structure determinations (matrix phases, precipitates and weathering zones). The presence of dendritic arms was observed, while martensite plates were absent in all SEM images. Particularly in the SEM image taken after corrosion, it was noted that the TiO2 layer placed on the surface of the matrix rich in Ti elements altered the surface morphology of the alloy. The presence of Ti and O elements in the post-corrosion EDX analysis confirmed the existence of this layer. Biocompatibility studies of the alloy were conducted using potentiodynamic corrosion tests and electrochemical impedance spectroscopy (EIS) methods. It was determined that the NiTiSn sample was in the excellent stability class according to corrosion standards. [ABSTRACT FROM AUTHOR]

Ashes from various Polish coal-fired power plants were analysed in this investigation as the source material for preparing simulants of lunar regolith. The chemical and phase constituents were the most important parameters used to describe these ashes. The second parameter was particle size and morphology, specifically characterising technological properties such as flowability or density. The final element of the investigation was related to the characterisation of thermal properties. Differential thermal analysis yields information on phase transitions, melting temperatures and other characteristic temperatures of stimulants. Thermogravimetry with Fourier transform infrared analysis provides information on evolved gas species and their evolution temperature profiles. [ABSTRACT FROM AUTHOR]

Increasing the surface quality of porcelain tiles, preferred in public, commercial, and living centers, where human density is high, is one of the crucial goals. Surface applications can be applied on the tiles produced as glazed and unglazed tiles in different versions. In lappato glazed tiles, staining-resistance is of great importance besides glossy-surface and wear-resistance. In this study, technical properties such as staining, chemical agent-resistance, color-parameters, thermal-behavior (heat microscopy), roughness, abrasion resistance, and microstructure of glazes (SEM/EDS) depending on the optimizing grinding time were examined with compared to standard lappato-glaze under the industrial conditions. It was observed that with the increase of the glaze grinding, the whiteness value and the increasing smoothness, and higher staining chemicals resistance and the glaze which has lower characteristic temperatures than the standard. As the surface roughness decreased due to grinding, the number and size of pores in the microstructure decreased. The glassy phase exhibited homogeneous distribution due to the dissolution of anorthite crystals. [ABSTRACT FROM AUTHOR]

We study the thermal properties of a bulk Ni 55 Fe 19 Ga 26 Heusler alloy in a conduction calorimeter. At slow heating and cooling rates ( ∼ 1 K h - 1 ), we compare as-cast and annealed samples. We report a smaller thermal hysteresis after the thermal treatment due to the stabilization of the 14 M modulated structure in the martensite phase. In ultraslow experiments ( 40 mK h - 1 ), we detect and analyze the calorimetric avalanches associated with the direct and reverse martensitic transformation from cubic to 14 M phase. This reveals a distribution of events characterized by a power law with exponential cutoff p (u) ∝ u - ε exp (- u / ξ) where ε ∼ 2 and damping energies ξ = 370 μ J (direct) and ξ = 27 μ J (reverse) that characterize the asymmetry of the transformation. [ABSTRACT FROM AUTHOR]

The growing interest of human skin thermal properties is motivating the development of new instruments, either by contact or by remote sensing. In this work, we show the ability of a skin calorimeter to monitor the temporal evolution of the heat capacity and the equivalent thermal resistance of the skin, in two small skin lesions. The first one consists of a forehead wound of 10 × 2 mm2. The other injury consists of a second degree burn on the volar wrist area, of 10 × 20 mm2. We studied the temporal evolution of the thermal properties of both injuries. The variation of heat capacity was significant. For first injury, heat capacity decreased by 21% and full recovery was achieved after ten days. For the second case, the heat capacity decrease was 55% and recovery was achieved after 3 weeks. These skin recoveries are monitored by the measured heat capacity value. The returning of the heat capacity to its normal value coincides with the recovery from the injury. [ABSTRACT FROM AUTHOR]

Composite materials have garnered considerable interest in the thermal industry on account of their remarkable mechanical properties and thermal resistance. The objective of this research work is to analyse the impacts of integrating porcelain infill particles into basalt fibre-reinforced polymer (BFRP) composites. Particularly, the study aims to evaluate the consequential modifications in critical thermal and mechanical characteristics. The results of mechanical testing indicate that the incorporation of porcelain fillings significantly influences the composite tensile strength, flexural strength, and impact resistance. Additionally, by employing scanning electron microscopy (SEM), significant knowledge is acquired regarding the interfacial bonding mechanisms and microstructural properties of the filler particles, polymer matrix, and basalt fibres. Utilizing dynamic mechanical analysis (DMA), the maximal values of storage modulus (3429 MPa), loss modulus (489 MPa), and damping factor (0.17) are investigated in relation to the dynamic mechanical properties across a range of temperature conditions. The research additionally illustrates enhancements in thermal characteristics, including heat deflection temperature, thermal conductivity, and coefficient of linear thermal expansion, all of which are improved by 37% when porcelain infill is incorporated into the composite. In addition, thermal gravimetric analysis (TGA) examines the degradation and thermal stability properties of the composites over an extensive temperature spectrum, reaching a maximum of 390 °C. The insights derived from this analysis are particularly pertinent to applications involving thermal insulation. [ABSTRACT FROM AUTHOR]

Biodegradable chitosan-based films containing different concentrations of jatobá fruit peel extract (0.0%, 0.04%, 0.07%, 0.1% and 0.3%) were prepared and evaluated for their antioxidant and antimicrobial activities, physicochemical, morphological and thermal properties. The extract from jatoba fruit peel was obtained and incorporated into formulations of chitosan films. The films were characterized for thickness, moisture, solubility, water vapor permeability, optical properties, color and morphology. Also, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, in vitro antioxidant activity and antimicrobial activity were performed. The addition of extract at increasing concentrations increased the in vitro antioxidant activity by about 9–60 times compared with the film without extract. Films with lower extract concentrations were more effective at inhibiting nine bacterial strains, with emphasis on Escherichia coli (95.0% inhibition), Bacillus cereus (92.5% inhibition), Bacillus subtilis (96.5% inhibition), Pseudomonas aeruginosa (94.4% inhibition), Salmonella Typhimurium (90.4% inhibition) and Salmonella Enteritidis (93.9% inhibition). Addition of the extract improved the physical properties of the film, such as moisture, solubility, WVP and luminosity. The thermal stability of the films was slightly reduced with addition of extract at increasing concentrations. Films incorporating jatobá fruit peel extract showed potential utility as 'green' bioactive, biodegradable packaging, an alternative to packaging containing petroleum derivatives. [ABSTRACT FROM AUTHOR]

This contribution presents the results of structural investigations on the cured and high temperatures of three series of geopolymers. The specimens were synthesized at 80 °C from coal fly ash and three activators of variable composition based on sodium hydroxide and sodium silicate solutions. Structural and microstructural analysis was performed, especially using in-situ measurements of XRD patterns and IR spectra as a function of temperature. The cured compounds' phase content and compressive strength changed slightly depending on the starting chemical composition. All analyzed materials experience a mass loss due to water removal at 300 °C, followed by increased porosity from disintegrating compounds above 300 °C. Higher alkali content improves strength (400–600 °C) possibly due to nepheline formation. The amorphous phase gradually softens during heating, influenced by alkali content. Structural analyses were supported by model calculations of a number of aluminosilicate structures. The cluster analysis using the k-means algorithm was used to divide the PCA space into regions that represent structural similarities, and analyzing specific point positions in the space allowed for several conclusions to be drawn about the studied materials, including that changes in chemical composition and thermal treatment can promote the transformation from sodalite to nepheline and that the glass network has elements that are nepheline-like and may promote its crystallization. [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 most important thermal and rheological properties of water-based CaCO3/SiO2 dual hybrid nanofluid (DHNF) at overall volumetric concentrations of the nanoparticles from 0.1 to 0.5 and different volume fractions at temperatures of 15–60 °C have been studied. Prepared DHNFs consisted using SDS and ultrasonic homogenizer. Stability analysis of the DHNFs performed by changing ultrasonication time and power. The optimum consistency conditions and volume fractions of the nanoparticles determined for the prepared DHNFs. Specific heat capacity, thermal conductivity and resistivity, usual viscosity and density of the DHNFs studied, experimentally, compared with preexisting models, and finally, theoretical models with 99% precisions suggested. Maximum augmentation in thermal conductivity attained to 21.8% for 80:20 corresponding volume ratio and 0.5 vol% total concentration. At these conditions, maximum reduction in heat capacity occurred as 1.08%, and the greatest reduction in thermal resistivity got about 22.2% at 60 °C. Usual viscosity and density increased as 36.9 and 1.2%, respectively. [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]

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 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]

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]

Oxy-fuel co-combustion of biomass and coal/semicoke is recognized as a promising technique for negative CO2 and low NOx emissions. Oxy-fuel co-combustion thermal properties and volatile emission characteristics of pine sawdust (PS) and Shenmu semicoke (SC) blends were investigated using thermogravimetric-mass spectrometry (TG-MS) and an innovatively designed two-tube reactor. PS and SC were mixed in a mass ratio (mass%) of 0:100, 10:90, 20:80, 30:70, 40:60 and 100:0. The effects of combustion temperature, blend ratio and atmosphere on NO emissions were also studied. Results showed that the SC combustion characteristics significantly improved when blended with PS. The thermal conversion properties of PS/SC blends in a CO2/O2 atmosphere were divided into four reaction stages, namely drying, pyrolysis, combustion and mineral decomposition at the temperature of < 200, 200–350, 350–700 and > 700 ºC, respectively. The main contribution to the increase in the NO conversion rate was the synergistic effect between char-N and volatile-N from PS. As the reaction temperature increased from 850 to 1000 ºC, the NO release time for the SC and PS sample reduced from 500 to 300 s and 80 to 50 s, respectively. The NO conversion rate increased initially and then decreased, with the highest rate at 900 ºC. In addition, increasing oxygen concentrations may significantly enhance the combustion rate. Based on the experimental results, the synergistic effect of nitrogen migration during the oxy-fuel combustion of biomass and coal char blends was proposed. The research results can provide scientific guidance for the clean and efficient utilization of SC in pulverized coal boilers of a power station. [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]

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]

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]

We have developed an analytical method to quantitatively analyze differential scanning calorimetry (DSC) experimental data. This method provides accurate determination of thermal properties such as equilibrium melting temperature, latent heat, change of heat capacity which can be performed automatically without intervention of a DSC operator. DSC is one of the best techniques to determine the thermal properties of materials. However, the accuracy of the transition temperature and enthalpy change can be affected by artifacts caused by the instrumentation, sampling, and the DSC analysis methods which are based on graphical constructions. In the present study, an analytical function (DSCN(T)) has been developed based on an assumed Arrhenius crystal size distribution together with instrumental and sample-related peak broadening. The DSCN(T) function was successfully applied to fit the experimental data of a substantial number of calibration and new unknown samples, including samples with an obvious asymmetry of the melting peak, yielding the thermal characteristics such as melting and glass transition temperature, and enthalpy and heat capacity change. It also allows very accurate analysis of binary systems with two distinct but severely overlapping peaks and samples that include a cold crystallization before melting. [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]

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]

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]

Ceramic sanitaryware products are produced using inorganic and non-metallic raw materials such as clay, kaolin, quartz and feldspar at certain rates. After mixing and grounding process, the slip is obtained. The products are shaped in gypsum or synthetic resin moulds. Green bodies are fired at 1250 °C for 16–18 h, and their water absorption values are less than 0.5%. Nowadays the most important issues are raw materials and energy costs. In this study, the sintering behaviour of Na-feldspar and K-feldspar, which are widely used in ceramic sanitaryware, is analysed by reducing to different grain sizes. The grain sizes of the samples containing Na-feldspar were reduced under 63 µm. It was found that the decrease in grain size of Na-feldspar contributed to the decrease in sintering temperature. Potassium feldspar was also added instead of Na-feldspar in order to develop deformation behaviour at higher temperature. The increase in the amount of K-feldspar contributed to the decrease in deformation values. However, the flexural strength of the bodies decreased. A decrease in grain size of Na-feldspar resulted in a reduction of 10 °C at the sintering temperature. The decrease in sintering temperature will provide a cost advantage of around 3%. It was also found that technical properties such as firing shrinkage, bulk density, and flexure strength increased as the grain size of Na-feldspar decreased. [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]

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]

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]

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]

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 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]

The degradation of cement products at high temperature with different amounts of zirconium diboride nanoparticles (0, 0.5, 1, 3, and 5 mass%) with the nano-filling effect was investigated in the experimental program. The ZrB2 nanoparticle incorporation in the cement matrix showed a remarkable influence on the thermal protection of the composite at high temperature, whose mass loss was 6 mass% after 30 min at 1000 ℃. ZrB2 is converted to zirconia (ZrO2) and boron trioxide (B2O3) when the temperature rises and oxidative conditions are created in the environment to protect the surface from oxygen by cutting off the penetration of channels. The mechanical test results indicated that cement compressive strengths were improved with the increase of ZrB2 nanoparticle concentrations by as much as 45% for 5 mass% nanoparticles, compared to only a 4% increase with the addition of 0.5 mass% ZrB2 nanoparticles to the cement sample after 28 days. On the other hand, the samples modified with 5 mass% ZrB2 nanoparticles do not show the effect of spalling, as a result of the effect of filling the apparent pores and increasing the particle packing in the nanocomposite. [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]

Thermal properties such as thermal conductivity, heat capacity, and thermal diffusivity and physical properties such as calorific value, density, and kinematic viscosity of liquid fuels play a significant role in the combustion process. These properties vary with the chemical structures and the fatty acid profiles of biodiesels. Making correlations for various properties with respect to fatty acid profile helps to analyze the combustion process. Most of the reported works generated correlations using data taken from the literature, and the correlations based on the fatty acid profile for thermal properties of biodiesel are unavailable. As coconut oil, sunflower oil, and palm oil have entirely different fatty acid profiles, in this study, biodiesels produced from these three waste cooking oils and their three hybrids (each in a 1:1 ratio) were used for biodiesel production, followed by correlation formulation. Higher thermal conductivity (0.2211 W mK−1) and thermal diffusivity (0.2459 mm2 s−1) and lower heat capacity (0.8993 MJ m−3 K−1), density (862.8 kg m−3), kinematic viscosity (2.71 cSt), and calorific value (36.73 cSt) were observed for coconut-based biodiesels compared with other biodiesels. The addition of coconut content to hybrid biodiesel enhanced thermal conductivity and thermal diffusivity and reduced heat capacity, density, and kinematic viscosity. From the experimental data of thermal conductivity, heat capacity, thermal diffusivity, density, kinematic viscosity, and calorific value, empirical correlations were proposed with the fatty acid profile. Good agreement was obtained between experimental and calculated values. [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]

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]

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]

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 present study aims to investigate the physical, chemical, and thermal properties of chia (CM) and okra (OM) mucilages powders. The mucilages were extracted and dehydrated at 70 °C; then they were evaluated for the profile of total phenolic compounds and mineral profile, colorimetric parameters, morphology by scanning electron microscopy (SEM), infrared by fourier transform (FTIR), X-ray diffraction (XRD), and thermal properties by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA/DTG). It was found that OM had higher amounts of total phenolic compounds, mainly flavonols, with a predominance of quercetin 3-glucoside. On the other hand, CM had the highest content of flavonoids, the most significant being catechin. CM had the highest mineral content, being surpassed by okra mucilage in terms of calcium and copper. The OM had the highest luminosity, with values tending toward yellow and green tones, while the CM was darker and presented yellow and red tones. The mucilages presented morphologically irregular particles with different sizes and shapes, with an amorphous structure. The FTIR showed the bands of the main components, indicating that the mucilages are constituted mainly by polysaccharides (OM), pectins, and soluble proteins (CM). The DSC showed sharp endothermic peaks, indicating greater uniformity and purity of the samples. The thermogravimetric curves and their derivatives showed the greatest mass loss in the second evaluation phase for both materials, followed by the carbonization of organic matter and the formation of fixed mineral residue. The study revealed that mucilages have distinct characteristics, but with excellent properties, which offers great potential as a raw material for industry. [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]

In order to improve the mechanical and combustion properties of composite solid propellant, the CuO@AP with core–shell structure was prepared by solvent–nonsolvent recrystallization method, and it was applied to AP/HTPB composite solid propellant. The thermal decomposition properties, sensitivity properties and tensile properties of CuO@AP propellant were studied and compared with ultrafine AP propellant, ultrafine spherical AP propellant and the mixture of CuO and AP (CuO/AP) propellant. The results show that the Ea of ultrafine spherical AP propellant is 8.16% lower than that of ultrafine AP propellant with the same particle size, and the rate constant increases by 13.64%; the Ea of the CuO@AP propellant is 23.63% lower than that of CuO/AP propellant with ultrafine AP of the same particle size, and the rate constant increases by 172.7%. What's more, the catalytic effect of CuO@AP is obviously better than that of CuO/AP. The impact sensitivity of ultrafine spherical AP propellant is 29.61% lower than that of ultrafine AP propellant with the same particle size, and the εb is increased by 51.35%. The impact sensitivity of the CuO@AP propellant is 25.38% lower than that of CuO/AP propellant with ultrafine AP of the same particle size, and the εb is increased by 63.76%. The above shows that the CuO@AP composite particles with core–shell structure have potential application prospects in AP/HTPB propellant. [ABSTRACT FROM AUTHOR]

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

The construction of energy-efficient buildings is very important as it can lower the energy consumed for construction and reduce the energy required for the heating and cooling effects of buildings and reduce the global warming caused by carbon emissions in buildings. It is therefore necessary to check the thermal characteristics of any construction material. Chopped Basalt Fiber (BF) is dispersed to the fine-grained concrete matrix and after determining the optimum percentage of fiber content cement is partially replaced in the matrix with ground granulated blast furnace slag (GGBS) by different percentages. GGBS helps in providing improved structural performance and also reduces the waste material generated by the steel industry. In addition, thermogravimetric analysis (TGA) is done to ascertain the thermal stability of the material when subjected to higher temperatures. The thermal conductivity of fine-grained concrete is determined to check the conductance of heat through the sample for thermal evaluation of the structure. Furthermore, the specific heat capacity, thermal resistance and thermal diffusivity of the material are also studied. The fine-grained concrete with basalt fiber and GGBS shows better thermal properties than controlled fine-grained concrete. [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]

A series of bisphenol A-based polyarylates was synthesized by using 2,2-bis (4-hydroxyphenyl) propane (BPA), terephthaloyl dichloride (TPC), and isophthaloyl dichloride (IPC) as raw materials and p-tert-butylphenol as a capping agent through interfacial polymerization to investigate the effect of end group structure on polymer properties. And the polymer films could be obtained by solvent casting method. The successful introduction of p-tert-butylphenol into the backbone adjusted molecular masses and achieved a regulable improvement of the polymer's thermal properties. The thermal mass loss 5% temperature of the polymers raised above 470 °C, which indicated the thermal properties were broadly in line with that of the commercial product U-100. Besides, the addition of capping agent also improved the light transmission of the polymers and the transmittance reached above 83% at a wavelength of 450 nm. In addition, the thermal degradation mechanism of polyarylate and U-100 was investigated by simultaneous thermal analysis (STA)-IR and Py/GC–MS. It was discovered that PAR decomposed thermally at their end groups and ester groups first, followed by the breakage of their carbon–carbon bonds, which coincided with U-100's thermal degradation mechanism. The thermal degradation mechanism of bisphenol A-based polyarylates was proposed. [ABSTRACT FROM AUTHOR]