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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]

The most currently used ionic liquids (ILs) are protic ionic liquids (PILs), subject to extensive investigation regarding their physical properties. These compounds along with their mixtures with other substances such as salts and solvents, serve as electrolytes in next generation electrochemical smart devices, and emerge as viable candidates to replace conventional Heat Transfer Fluids (HTFs) in various energy applications. Despite the extensive number of studies, important information about this kind of compounds is still unknown, such as the effect of alkyl chain length on thermal and thermophysical properties, as well as toxicity. This work, extending previous studies of our group, summarizes the liquid range, heat capacity and acute toxicity level of six ammonium ILs: specifically, n-alkyl-ammonium nitrate ILs with increasing alkyl chain length (n = 2, 3, 4, 5, 6, 8). For this study, the synthesis of the three ILs with the longest alkyl chain was performed, along with DSC, TGA and toxicity measurements. It was observed that an increase in alkyl chain length resulted in a decrease in short-term thermal stability and an increase in melting temperature, indicating a reduction in the liquid range. A compensation effect between enthalpy and entropy of melting was observed for the studied chain lengths. The isobaric specific and molar heat capacities increase with temperature for all the compounds studied here, and good correlations were obtained between molar heat capacity and the number of carbon atoms in the alkyl chain for every temperature. Finally, most of the ILs are non-toxic, although toxicity increases with alkyl chain length. [ABSTRACT FROM AUTHOR]

The seeds of berry fruits which are considered as a by-product may be valorized by recovering the oil they content. Nevertheless, the conventional extraction methods are time, energy and organic solvents consuming. In order to make extraction more environmental-friendly, alternative methods, like ultrasound-assisted and pulsed electric field-assisted processes, are being developed. The procedure of extraction may however influence the quality of obtained oil. The following study aims to define the effects of ultrasound and pulsed electric field application in the extraction process on the thermal properties, i.e., oxidative stability, melting and cyclic heating/cooling profiles, thermal decomposition characteristics. Additionally, fatty acid profile assessment was included in the study. Seeds of blackberries, blackcurrants, chokeberries, raspberries and redcurrants were used to extract oil. Based on the results, it can be summarized that extraction method influenced the resistance of oils to oxidation. Ultrasound-assisted process resulted in oils with the highest oxidation induction times. Melting profile was slightly influenced by extraction method, with peak temperatures indicating the presence of low-melting and middle-melting triacylglycerol fractions. Differential scanning calorimetry with heat/cool/heat procedure let determine crystallization peak temperatures around − 60 °C, which could be associated with the specific triacylglycerol profile of berry seed oils. The courses of thermogravimetric analysis curves were comparable for all the tested samples. The fatty acid profile study revealed that all the studied thermal properties were affected by the unique fatty acid percentage share, with a great predominance of polyunsaturated fatty acids. Obtained results allowed to conclude that extraction method influenced oxidative stability, thermal properties and fatty acid profile only to some extent. The most promising extraction method among analyzed seems to be ultrasound-assisted extraction as it provided oil with high oxidative stability, typical thermal properties and unchanged fatty acid profile, without being harmful to natural environment due to possible reduction in solvent and time consumption. [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]

Natural fibre-based polymer composites have better improvements owing to their thermal and mechanical properties besides environmentally friendly quality. In the present work, biocomposite fabricated at kenaf fibres (KF) loading (30, 40, 50, and 60 mass%) with bio epoxy matrix by the hot compression moulding method, and their thermal and dynamic mechanical characterisation were investigated and examined. This study was conducted to investigate the thermal behaviour through thermogravimetric analysis (TGA) and the derivative of thermogravimetric analysis (DTG: the maximum thermal decomposition; Tmax), dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). The presented findings from TGA and DTG curves showed that the thermal stability improved with increasing the KF loadings, as evidenced by the higher residual mass % and the lower mass loss %. On the other hand, it was found that the biocomposite sample (50 mass% KF) exhibited higher thermal stability up to 558.82 °C. Furthermore, the DMA findings obtained exhibited the greatest value of the storage modulus (E') with the following order of KF bio composite (KF-50 > KF-60 > KF-40 > KF-30). On the other hand, the values of loss modulus (E'') were increased as follows KF-30 > KF-40 > KF-50 > KF-60. However, the results showed that 50 mass% of KF into epoxy biocomposites recorded higher loss modulus value (323.56 MPa) among all other bio composite samples, while the values of tan δ were increased as follows: KF-30 > KF-40 > KF-50 > KF-60. The results obtained for the TMA revealed a better coefficient of thermal expansion (CTE) for the sample (KF-50) compared to other samples. [ABSTRACT FROM AUTHOR]

Influence of titanium dioxide concentration on thermal properties of germanate-based glasses has been studied. Germanate glasses varying with TiO2 content were examined using DSC methods. The DSC curves exhibit two exothermic peaks, when GeO2 is substituted by TiO2. Based on DSC measurements, characteristic temperatures were determined. The studies demonstrate that glass transition temperature increases, whereas thermal stability parameters are reduced with increasing TiO2 concentration. The DSC curves were also acquired with different heating rates, and the Kissinger method was used to calculate the activation energy. X-ray diffraction analysis for germanate-based glass with TiO2 indicates that crystallization processes are more complex and several phases are formed during annealing. The absorption and emission spectra of glass samples doped with Er3+ ions were also examined before and after annealing process. [ABSTRACT FROM AUTHOR]