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In this paper, ultrasonic dispersion and surface chemical modification were used to prepare the modified multi-walled carbon nanotubes (MWNTs)/paraffin composite phase-change materials (PCMs). The surface modification of MWNTs was developed via coating MWNTs with silica dioxide. The modified MWNTs were marked as SiO2@MWNTs. The phase-change properties, thermal stability and chemical functional groups of the MWNTs/paraffin composite PCMs were measured by differential scanning calorimetry, thermogravimetric analysis (TG) and Fourier transform infrared spectroscopy, respectively. The results indicated that paraffin and MWNTs were compound physically. The diameter and content of MWNTs had influence on the phase-change temperature and the latent heat of the MWNTs/paraffin composite PCMs. The smaller the diameter or larger content of the SiO2@MWNTs, the greater the influence was. The reduction degree of PCM1(the diameter of the SiO2@MWNTs is 20–30 nm) in latent heat is about 4.5 times of that of PCM3(the diameter of the SiO2@MWNTs is larger than 50 nm). The thermal stability and the thermal conductivity of the composite PCMs were improved with the addition of the SiO2@MWNTs. When the content of SiO2@MWNTs is 5 mass%, the thermal conductivity of the paraffin PCMs is 0.383 W m−1 K−1). [ABSTRACT FROM AUTHOR]

Lignin-based polycaprolactone (PCL) graft copolymers with various graft ratios were prepared by ring-opening reaction in order to design new lignin derivatives. Molecular length of PCL side chain was varied in a wide range, i.e. caprolactone/hydroxyl group (CL/OH) ratio was varied from 3 to 100 mol mol−1. The effect of lignin on thermal properties of PCL was examined by differential scanning calorimetry (DSC) and thermogravimetry. In DSC heating curves of lignin-based PCL, glass transition, pre-melt crystallization and melting were observed. From DSC results, the phase diagram of lignin-based PCL was established. It was found that glass transition temperature (Tg) decreased until CL/OH ratio reached 20, and then, Tg was maintained at around 200 K. Tg slightly increased when CL/OH ratio became higher than 20. The above facts suggest that the random structure of lignin affects the molecular motion of copolymers in a limited length of PCL chains, and that with increasing PCL chain length, free molecular motion is restricted by crystallization. The amorphous region of lignin–PCL was reorganized at pre-melt crystallization, and crystallinity increased. When CL/OH ratio increased more than 20, two melting peaks were observed; the low-temperature side is PCL crystallite affected by lignin and the high-temperature side melting peak is attributed to melting PCL crystal. The effect of lignin on thermal decomposition is apparently observed for lignin-based PCL when CL/OH ratio is smaller than 20. The above results suggest that lignin-based PCL graft copolymers have the potential of an applicant of novel nature-friendly polymers. [ABSTRACT FROM AUTHOR]

Most of the synthetic polymers that are used for packaging industry come from fossil fuel; thus, when their life cycle is complete, they normally accumulate in the environment. The poly(3-hydroxybutyrate) is a biopolymer produced from bacteria; due to its microbial degradation, great attention has been paid to its research; nevertheless, it has been found to be necessary to improve its mechanical, thermal and barrier properties. One of the approaches to do so is the incorporation of inorganic compounds. Zirconium oxide (ZrO2) and zirconium hydroxide (Zr(OH)4) have outstanding thermal stability and are potential compounds for the improvement in PHB features. Along this study, hybrid films made of PHB with 0.01, 0.05 and 0.1 mass% of ZrO2 and Zr(OH)4 were produced; their properties were evaluated by TG and DSC, which permitted to observe that all the composites have improved thermal resistance; furthermore, 0.01 and 0.05% Zr(OH)4 showed lower Wc. These results suggest that zirconium-based PHB composites can increase the process temperature range, which opens the new door to future applications on food packaging. [ABSTRACT FROM AUTHOR]

The polymerization industry has existed for many years. The advancement of industrial technology is contributed to the related synthesis and application of enduring polymer operation. Organic peroxide (OP) initiators have been used and applied to practical industrial processes which may cause a runaway reaction due to their self-reactive property. OPs have been used for a long time and studied in the related literature. However, there are still emerging OPs that have recently been applied to these processes, and there are few related studies. To ensure the thermal safety of OPs in the process of production, transportation, and storage, the common OP initiator such as dicumyl peroxide (DCPO) was selected to be investigated. First, thermal decomposition characteristics under non-isothermal and adiabatic conditions of DCPO were acquired by differential scanning calorimetry. Second, combined calorimetry with pseudo-adiabatic and isothermal conditions can determine the process of thermal hazards and basic reaction patterns. The gleaned data can input into a mathematical model to evaluate the basic thermal hazards for DCPO, respectively. In addition, based on simulated thermal explosion models and kinetic parameters, hazardous properties of storage and transport can also be acquired. The results show that the DCPO has prominent hazard properties on thermal and explosive hazards in process conditions which should pay much attention to temperature during storage and transportation. [ABSTRACT FROM AUTHOR]

The present research studied a set of phyllite clays from several deposits in southeast Spain. These phyllite clays have traditionally been used as sealing material to impermeabilize roofs, embankments, ponds, construction and waste landfill, with recent applications in the preparation of new mortars. However, studies on thermal behaviour and ceramic properties of phyllite clays have been scarce. The present research showed a summary of previous characterization studies on representative phyllite clays from these deposits with additional results. Mineralogical, by X-ray diffraction, and chemical, by X-ray fluorescence characterization of these samples were summarized. Thermal analysis methods (DTA–TG and thermal diffractometry) were applied to achieve a more complete mineralogical characterization. Several phyllite clay samples were selected for a ceramic study by firing pressed powdered samples up to 1300 °C. Sintered or vitrified materials, with porosities almost zero, were obtained from these phyllite clays after firing at 1100–1200 °C, with apparent densities between 2.1 and 2.4 g cm−3. Higher firing temperatures (> 1250 °C) produced deformation and expansion of the ceramic bodies. These results allowed obtain the vitrification temperature (Tv) and the temperature of the maximum bulk density (Td). According to the previous mineralogical and chemical characterization and the values of these parameters, the phyllite clay samples were classified in three varieties, as follows: (1) Micaceous, characterized by predominant layer silicates, mainly muscovite or illite, alkaline elements (mainly K2O higher than 3.5 mass%) and lower values of both Tv and Td, (2) Quartzitic, with predominant quartz and SiO2 and intermediate values of Tv and Td, and (3) Carbonaceous, characterized by predominant dolomite, medium contents of CaO and MgO and higher values of both Tv and Td. These results are interesting for the application of these phyllite clays as ceramic raw materials. [ABSTRACT FROM AUTHOR]

The reduction of radiation heat transfer in VIPs is an important issue. In VIPs, the radiation heat transfer is reduced by the use of opacifier. However, the amount of opacifier also significantly affects the cost of VIP. In this study, the effect of different types and sizes of opacifiers on VIP thermal conductivity was investigated. For this purpose, 6 VIP samples containing different opacifiers (SiC, graphite and calcium aluminate in 3 different grain sizes) were produced. Fumed silica, glass fiber and opacifier were used as fillers in VIP cores at 65%, 20% and 15% (by mass), respectively. VIP samples were vacuumed up to 0.1 Pa, and their thermal conductivity coefficients were measured according to TS EN 12667 standard. In addition, transmittance ratios (%T) of fumed silica, glass fiber, opacifiers and core samples were measured by FTIR spectrophotometer and the mass extinction coefficients of each sample were calculated. The silicon carbide (F1000) as the opacifier (e: 399 m2 kg−1) and the graphite-containing core among the VIP core samples (e: 149 m2 kg−1) exhibited the highest mass absorption coefficient. In addition, the thermal conductivity of the core samples without barrier was measured under 1 Pa vacuum and then the radiation conductivities were calculated from the obtained data. F800 type SiC significantly reduced radiation heat transfer, while the solid conduction of the core was increased due to its relatively coarse grain size. VIP sample with SiC (F1200) provided the lowest thermal conductivity at 0.1 Pa (3.94 mW mK−1). As a result, F1200 type SiC was found to be the most efficient type of opacifier among the investigated opacifiers. [ABSTRACT FROM AUTHOR]

Bioplastics reinforced by agricultural waste fibres show promise to provide degradation back into the environment when they are no longer needed. These biocomposites have the potential to replace synthetic polymers from non-renewable resources in some applications and may turn out to be one of the material revolutions of this century. Unlike synthetic composites, biocomposites are renewable, carbon neutral, biodegradable and non-petroleum based and have low environmental, human health and safety risks. In this paper, poly(lactic acid) (PLA)-based biocomposites filled with technical cellulose fibres (CeF) and rice husks (RHs) at 10–30 mass% loading were prepared by twin-screw extrusion and injection moulding to enhance stiffness of resulting biocomposites. Particular attention was given to the enhancement of adhesion between the polymer matrix and natural filler through the physical modification by ozone (O3) and dielectric barrier discharge (DBD) plasma (p) surface treatments. Further than, compatibilizing agent based on PLA-g-MAH was produced and introduced into the PLA systems. The non-isothermal crystallization behaviour and thermal properties were investigated through differential scanning calorimetry (DSC) under various cooling rates (5, 10, 20 and 40 °C min−1). The addition of both fillers increased overall crystallization kinetics of resulted biocomposites, especially at high cooling rates. An increase in crystallinity degree from 2.4 (neat PLA) up to 51% has been observed for PLA/30CeFO3 samples at 40 °C min−1 cooling rate. An increase in crystallinity degree based on mass percentage of filler was noticed especially for PLA/RH. Mass percentage increase in CeF did not notice significant increase in PLA crystallinity. The influence of RH and CeF on transformation behaviours of PLA αʹ-/α-polymorphs was observed. The elimination of imperfect αʹ-crystals was observed with increasing amount of RH and CeF. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the thermal and viscoelastic properties of polylactic acid (PLA) blends with the aim of optimizing properties for fused filament fabrication. Additive manufacturing opens many possible applications for materials in processing and application. Determining the most effective thermal and viscoelastic properties is required for printing. PLA blends can be tailored to suit design specification, printers and printing parameters. Quantified analysis of differential scanning calorimetry and rheology is applied to the qualitative property of "printability", with preferences of thermal stability, melt temperature, shear thinning effects and zero shear viscosities. This paper intends to further bridge this gap between physical properties and material printability. [ABSTRACT FROM AUTHOR]

The polymorphism of tolbutamide and chlorpropamide under melting/crystallization was investigated with using DSC and in situ X-ray powder diffraction. The asymmetry in thermal transformations was revealed for both substances. Under heating, all tolbutamide/chlorpropamide polymorphs transform into high-temperature IH/ε polymorph, which melts at 128 °C. The crystal structures of the high-temperature polymorphs, IH and ε, are very similar to each other in the unit cell parameters and in the arrangement of z-shaped infinite hydrogen-bonded ribbons. Under cooling, other polymorph crystallizes from the melt, V for tolbutamide and β for chlorpropamide, thus making easy the obtaining of these metastable polymorphs. The polymorphs of tolbutamide and chlorpropamide crystallized from their melts turned out to be also very similar to each other in their structures (space group, unit cell parameters, arrangement of π-shaped infinite hydrogen-bonded ribbons). Solid–solid transformation V ⇒ II in tolbutamide was detected both in samples stored under room conditions and those melted in capillaries, thus providing new easy way for II tolbutamide crystallization. In generalizing our results, one can expect that if evident similarity is found among the polymorphs of similar molecules in their crystal structure, the similarity in their thermal properties can be also found, and vice versa. [ABSTRACT FROM AUTHOR]

Purple taro tubers (Colocasia esculenta B. Tini) were used in extraction of starch by aqueous methodology. After isolation, the starch was characterised and subjected to physical modification by ultrasound technique, using different amplitudes (40, 50 and 60%). Starch characterisation was performed by thermal analysis, pasting properties, X-ray powder diffractometry and high-resolution scanning electron microscopy. The root presented high carbohydrate content and low protein and lipid content. The apparent amylose content obtained from native starch was 26.45%. From thermal analysis, three major mass loss events were observed for all samples, and due the modification, an increase in thermal stability was achieved. There was a decrease in transition temperatures during the gelatinisation process after sonicated samples. The degree of relative crystallinity was lower for modified starches. An increase in peak and final viscosities was observed for physically modified samples, accompanied by a decrease in pasting temperature. The size of the granules showed a slight decrease, and agglomerations were not observed in this studied amplitude range. [ABSTRACT FROM AUTHOR]

Silver, silver alloys, and composites with silver matrix are used mainly as electric contacts, circuit-breakers, and slide bearings. Contacts working conditions require as high as possible thermal and electrical conductivity, wear resistance during electric arc work, low susceptibility to tacking, and chemical stability. Unreinforced silver alloys do not meet those expectations, hence increasing interest in metal matrix composites. Reinforcing with ceramic particles improves tribological wear resistance and minimizes formability of silver alloys. At the same time, introduction of ceramic particles decreases thermal and electrical conductivity. In this paper, manufacturing method of silver-based composites reinforced with particles Al2O3, SiC, and glassy carbon was described. Composites were subjected to differential thermal analysis. Furthermore, thermal diffusivity measurements using laser flash method, as well as measurements of linear thermal expansion coefficient using dilatometric method were performed in order to determine heat conductivity of the prepared composites. [ABSTRACT FROM AUTHOR]

The purpose of the calorimetric sensor developed is to measure the heat flux transmitted by conduction between the human body surface and a thermostat located inside the sensor. The measurement surface has an area of 2 × 2 cm2. We have verified that the measured heat flux decreases linearly with the increase in the thermostat temperature. This allows us to define an equivalent thermal resistance between the internal temperature of the human body and the temperature of the thermostat. This equivalent thermal resistance can be determined by measuring the heat flux for different constant temperatures of the thermostat. An alternative is to perform a single measurement with linear programming of the thermostat temperature. With this type of measurement and from the calorimetric signal, it is also possible to determine an equivalent heat capacity of the skin in the measurement zone. In this article, we present the modelling and simulation of the sensor operation when the thermostat temperature varies linearly. We also present experimental measurements performed on the human body and with reference Joule dissipations. [ABSTRACT FROM AUTHOR]

The present work investigates the hydration heat of different cement composites by means of conduction calorimetry to optimize the composition of binder in the design of heavyweight concrete as biological shielding. For this purpose, Portland cement CEM I 42.5 R was replaced by a different portion of supplementary cementitious materials (blast furnace slag, metakaolin, silica fume/limestone) at 75%, 65%, 60%, 55%, and 50% levels to obtain low hydration heat lower than 250 j g−1. All ingredients were analyzed by energy dispersive X-ray fluorescence (EDXRF) and nuclear activation analysis (NAA) to assess the content of major elements and isotopes. A mixture of two high-density aggregates (barite and magnetite) was used to prepare three heavyweights concretes with compressive strength exceeding 45 MPa and bulk density ranging between 3400 and 3500 kg m−3. After a short period of volume expansion (up to 4 h), a slight shrinkage (max. 0.3°/°°) has been observed. Also, thermophysical properties (thermal conductivity, volumetric specific heat, thermal diffusivity) and other properties were determined. The results showed that aggregate content and not binder is the main factor influencing the engineering properties of heavyweight concretes. [ABSTRACT FROM AUTHOR]

Iron phosphate glasses are materials that can have many applications like durable matrixes in waste immobilization techniques, biomaterials, optoelectronic devices, etc. Their possible usage is related to their glass network and thermal properties. The influence of Na2O content on thermal properties and crystallization ability of iron phosphate glass of base composition 30 Fe2O3–70 P2O5 mol% were studied. Increasing the content of Na2O causes a decrease in transformation temperature and increase in ΔCp. Characteristic temperatures, thermal stability and crystallizing phases were determined. Increasing content of sodium causes depolarization of iron phosphate glass network which causes a continuous change in ΔCp and glass transformation temperature. Discontinuous change in some glass properties suggests structure rebuilding about 30 mol% of Na2O. [ABSTRACT FROM AUTHOR]

Four new coordination compounds of Cu(II) were synthesized with ethyl-5-amino-1-methyl-1H-pyrazole-4-carboxylate (L) and different co-ligands. In the reaction of warm methanolic solutions of CuX2·nH2O (X = Cl, n = 2; X = Br, n = 0; X = NO3, n = 3) and the ligand in mole ratio 1:2, bis(ligand) complexes Cu(L)2Cl2 (1), Cu(L)2Br2 (2) and Cu(L)2(NO3)2 (3) were obtained. Unlike this, reaction of CuCl2 with the ligand in the presence of LiOAc yielded to the formation of dimeric complex of the formula [Cu(L)(OAc)2]2 (4), with four acetate ions as bridging ligands. In all these complexes, ligand L is coordinated in a monodentate manner through N2 nitrogen atom. The coordination environment in the dimeric complex is octahedral, while in the monomeric complexes the central atom is tetra-coordinated. The molar conductivity data in DMF show that the acetate ions in the dimeric complex are coordinated even in solution. In the monomeric compounds, the molar conductivity data increase in the order 1 < 2 < 3. Since the applicability of the coordination compounds depends on their thermal properties, the thermal decomposition of the complexes was followed by simultaneous TG–DSC measurements. The thermal stability of the monomeric compounds in flowing argon increases in the reverse order as the molar conductivity data. The course of the decomposition is different in the case of the nitrato-compound (3). The decomposition of 3 is followed by a strong exothermic heat effect due to the presence of nitrate ion which is a strong oxidation agent. The decomposition of the other complexes is endothermic, taking place in more or less overlapped reactions. The decomposition of the compounds is completed to 600 °C. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate effects of morphology and precipitation on thermal properties of Al-9.8%Si-0.4%Mg-0.7%Cu (in mass%) alloys using a laser flash apparatus, differential scanning calorimetry, and a thermomechanical analyser. Results revealed that mean particle size and shape of Si depended on mould temperature. Specimens with higher mould temperature had long and needle-like eutectic Si. As-cast specimens were solid solution treated at 535 °C for 6 h and then quenched in warm water of 80 °C. As-solution specimens were then aged at 180 or 190 °C for 1, 5, and 10 h. After artificial ageing treatment, the long needle-like eutectic silicon phase was split into smaller particles. It then gradually became spherical. When the shape of Si phase became similar after artificial ageing treatment, thermal diffusivity and thermal conductivity had similar values. It was found that shape change of Si particles greatly influenced thermal diffusivity and thermal conductivity. [ABSTRACT FROM AUTHOR]

Layered yttrium hydroxides (LYH)- and graphene oxide (GO)-supported layered yttrium hydroxides (GO–LYH) were synthesized by a co-precipitation route. The additives were characterized by X-ray diffraction and Fourier transform infrared spectra. The LYH were homogeneously dispersed on the GO sheets, demonstrated by the transmission electron microscope analysis. Composites of TPU/LYH and TPU/GO–LYH were prepared by a melt-blending method. The morphologies and structures of the composites, revealed by scanning electron microscope, ascertained that the dispersion of the GO–LYH in the TPU was better because of the strong interaction of the hydrogen bonds between oxygen-containing groups and hydroxyl groups. The fire retardancy of the TPU composites was evaluated using limiting oxygen index (LOI), cone calorimetry and thermogravimetric analysis. The TPU/LYH and TPU/GO–LYH composites, filled with 10 mass% LYH, 9 mass% GO, achieved LOI values of 24.4% and 25.3%, while there was a 67.42% and 70.88% decline of PHRR compared with pure TPU. The improved flame retardancy and smoke suppression were attributed to the physical barrier of GO and the catalytic carbonization of LYH indicated by char analysis. [ABSTRACT FROM AUTHOR]

Solar PV panel cooling is essential to achieve maximum efficiency of PV modules. Phase-change material (PCM) is one of the prominent options to cool the panel and reduce the temperature, since PCMs have low thermal conductivity. Expanded graphite particles are used to enrich the structure and stability as well as to increase the thermal properties. In the present research work, polyethylene glycol (PEG) 1000 is used as a base material and expanded graphite for inclusive particle. A novel form-stable PEG1000/EG composite PCM mixture is prepared, using impregnation and dispersion method. Expanded graphite and PEG1000/EG sample phase compositions are investigated, using X-ray diffraction technique. No new peak is identified in the composite PCM sample. The surface morphology and structure of EG and PEG1000/EG are investigated, using scanning electron microscopy (SEM). Chemical stability analysis is done by Fourier-transform infrared spectroscopy. Thermal properties of the prepared composite PCMs are analysed by differential scanning calorimetry, thermogravimetric analysis (TGA) and KD2 pro analyser. Results show that addition of EG in various propositions (5%, 10% and 15%) enhances the thermal conductivity of PCM samples from 0.3654 to 1.7866 W mK−1, while melting point and latent heat of fusion of PCM samples are getting reduced. TGA thermographs are used to investigate the thermal stability of the composite PCM samples. TGA curves show that loss of mass happens above the operating temperature, and it is varied with different mass ratios of EG. Characterization of the prepared composite PCM samples is compared and found that PEG1000-85%/EG-15% is the best form-stable PCM, suitable for cooling the solar PV panel as well as to improve the electrical efficiency coupled with a decrease of temperature in the range of 35 °C to 40 °C. [ABSTRACT FROM AUTHOR]

Poly(ether ether ketone) (PEEK) is a high-performance thermoplastics with outstanding mechanical properties and thermal resistance (serving temperature up to 250 °C). Although many studies have been performed on the stress–strain behavior and related modeling, less attention has been paid on the structural and orientational evolution of PEEK during tensile deformation. In this work, the orientational and structural evolution during tensile deformation at a wide range of temperatures from 30 to 170 °C was probed ex situ by wide-angle X-ray diffraction and differential scanning calorimetry. The enthalpy of cold crystallization of PEEK as a function of strain, which reflects the content of amorphous fraction and the disorder degree of crystals, presents an interesting dependence on tensile temperature. The evolution of orientation with strain is strongly dependent on the tensile temperature. Oriented PEEK presents much improved modulus and tensile strength compared to that of undrawn PEEK. This finding demonstrated that pre-stretching especially at temperatures above Tg is an effective way to improve the mechanical property of PEEK. [ABSTRACT FROM AUTHOR]

Thermal energy storage is one of the most important strategies for sustainable development. Phase change materials (PCMs) can store thermal energy through an economically feasible and eco-friendly way. Herein, we develop a novel solid–solid phase change materials (SSPCMs) based on solvent-free radical polymerization of methyl methacrylate with methacrylate-functionalized polyethylene glycol (PEG). PEG featuring as phase change ingredient is tightly bonded with reliable crosslinking network, which offers the prepared solid–solid phase change materials (SSPCMs) with robust physical properties and good shape-stable properties. The chemical structures, microstructures, crystalline properties and thermal properties of the synthesized SSPCMs are, respectively, characterized by Fourier transform infrared spectroscopy, scanning electron microscope (SEM), X-ray diffraction, polarizing optical microscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). Accelerated thermal cycling test and leakage test are also conducted to illustrate the thermal reliabilities and shape-stable properties. Microphase separation is observed and discussed in SEM analysis. DSC results show that SSPCMs have reversible thermal storage capacities and their phase change enthalpies are related to the concentration of PEG content. TG and accelerated thermal cycling test explain the excellent thermal stability and reliability of SSPCMs. Therefore, the prepared SSPCMs with satisfied properties have potential in room-temperature-use thermal energy storage applications such as buildings, textile industry and so on. [ABSTRACT FROM AUTHOR]

2,2′-Azobis (2-methylpropionate) (AIBME) is a new type of environmental-friendly oil-soluble azo initiator, extensively applied in the radical polymerization industry relying on its extraordinary thermal and physicochemical properties. Nevertheless, the special structure makes AIBME decompose easily under low ambient temperature with a tremendous amount of heat release. To qualify its thermal hazard and obtain the specific safety parameters such as time to maximum rate under adiabatic condition (TMRad) and self-accelerating decomposition temperature (SADT), differential scanning calorimeter (DSC), simultaneous thermogravimetric analyzer (STA), and accelerating rate calorimeter (ARC) were applied to analyze the thermal behaviors of AIBME while conducting the thermokinetic analysis and numerical curve fitting. The results indicate that AIBME decomposes at low temperature, and the SADT of AIBME in 25 kg UN package is 35.2 °C. Moreover, the temperature at TMRad = 8 h is determined at 51.6 °C using Townsend method. Compared with commercially used azo compounds, such as 2,2′-azobisisobutyronitrile (AIBN) and 2,2-azobis(2-methylbutyronitrile) (AMBN)), the predominant heat of decomposition, more gaseous degradation products, quicker heat release rate, and lower decomposition temperature make AIBME more hazardous during production, storage, and transportation. The results of this study can provide the references for the process safety assessment and the design of appropriate safety system in scale-up applications with the wish to avoid the occurrence of AIBME involved accidents. [ABSTRACT FROM AUTHOR]

Intelligent food packaging systems register and monitor food quality through data carriers, sensors or indicators. Food spoilage often leads to pH variations which can be easily evidenced through a colorimetric pH indicator. The objective of this study was to obtain and characterize intelligent pH indicator films based on biopolymers, namely chitosan and polyvinyl alcohol, doped with a new bio-inspired synthetic dye. UV–Vis, FTIR and 1D and 2D NMR techniques were used to characterize the xanthylium dye. The pH-dependent photochromic properties of the synthesized compound were confirmed through a UV–Vis spectroscopy study. The indicator films were obtained by using the solvent casting technique, and their optical and thermal properties were evaluated. When subjected to pH variations in aqueous solutions and in milk stored at improper temperatures, the films showed color changes. The thermal properties of the dye-containing films were evaluated through TG/DTG analysis. It was found that the inclusion of the dye does not change the thermal behavior of the films compared with that of the dye-free chitosan, PVA and chitosan/PVA blended films. [ABSTRACT FROM AUTHOR]

In this experimental study, biomedical composites of different formulations of basalt, Cissus quadrangularis fibers are melt-mixed with polylactic acid in a twin screw extruder. The standard specimens are prepared from extruded pellets using injection molding technique. Controlled crystallization temperatures are maintained throughout the compounding process to reduce degradation of the matrix and fibers. The thermal characterizations of the composites are examined by differential scanning calorimetry and thermogravimetric analysis. The thermal test results clearly indicate that the incorporation of basalt and C. quadrangularis fibers in polylactic acid results in improved thermal properties. The degree of crystallinity percentage is comparatively more for high fiber content composites. The inclusion of basalt fibers increases the polymer degradation temperature and helps to slow down the degradation of polylactic acid. Significant enhancement in the thermal stability of the biomedical composites is specimen having 12 mass percentage of basalt fiber and 0.5 mass percentages of C. quadrangularis fibers in 87.5 mass percentage of polylactic acid. A further increase in the mass percentage of C. quadrangularis affects the thermal property of the composites. The addition of Cissus is to improve estrogenic effect in implants and it is observed that the optimum mass percentage of Cissus is about 1–0.5%. The morphological structure of the composites is studied using scanning electron microscope to understand the structural interlocking characteristics of the fibers in the matrix. [ABSTRACT FROM AUTHOR]

Copper compounds can be used as additives to elaborate polymer materials, which after laser-induced ablation can be directly metallized on the irradiated surface area. In this work, three [Cu(l-tyr)2]n (l-tyr = l-tyrosine) (A), [Cu(bpy)3][CrO4]·7.5H2O (bpy = 2,2′-bipyridine) (B) and [Cu(bpy)2(O2SO2)]·CH3OH (C) copper(II) complexes were evaluated. The complexes were mixed at 20 mass% with polyurethane resin to form the coatings. The coatings were irradiated with ArF excimer laser and electroless metallized. It was found that only complex A was effective metallization precursors. Thermal properties of the copper(II) complexes were considered as crucial for defining effective precursors. TG-FTIR coupled analysis was applied to predetermine thermal properties of the compounds, which can be responsible for effective metallization. It was found that the main reason for unsuccessful metallization of the coatings containing complexes B or C was release of lattice H2O or CH3OH molecules in crystal structures, respectively, which affected ablation of the coatings. Appropriate model of laser ablation was also proposed. [ABSTRACT FROM AUTHOR]

Using palmitic acid (PA), expanded graphite (EG), and carbon fiber (CF) as raw materials, PA/EG/CF composite phase change materials (CPCMs) with diverse CF contents were invented by melt blending approach. The effects of different ratios on thermal properties were studied by experimental characterization and testing. Scanning electron microscopy images displayed that PA was adsorbed in the pores of the EG surface, while CF was disorderly but uniformly embedded in the interior and surface of pores. The chemical stability and thermal decomposition stability of CPCM at low temperature were proved by Fourier transform infrared spectrometer and thermogravimetric analyzer results, respectively. According to the law of heat storage/release time and latent heat variation, the optimal ratio scheme was determined, and its heat storage/release time was 65% and 59% lower than pure PA, respectively. The form-stable materials were prepared by compression forming method, and thermal cycling experiment results demonstrated that the higher the content of CF, the stronger the inhibition of mass loss. Based on the experimental results, the PA/EG/CF CPCM has the advantages of stable phase transition, strong stability, and fast heat storage and release rate, so it has a marvelous application prospect in the field of low-temperature heat storage engineering. [ABSTRACT FROM AUTHOR]

The thermal properties of CL-20 explosive in the bulk and confined in controlled pore glass matrices to nanoscale dimensions were studied using dynamic differential scanning calorimetry. The decomposition reaction of the CL-20 was found to be accelerated in 12-nm-diameter pores compared to the bulk CL-20 with the onset of the decomposition occurring 16–24 °C lower and a fourfold to sevenfold larger reaction rate constant. The total heat of decomposition was found to be independent of pore size and heating rate, and the average activation energy for all samples was found to be 160 ± 7 kJ mol−1. [ABSTRACT FROM AUTHOR]

Two new interesting compounds, ethanedial-1,2-bis-(2-(1-amino-2,2-dinitroethenyl))hydrazone (EDNH) and 3-dinitromethyl-1,2,4-triazine (DNTA), were synthesized by the reaction of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and glyoxal under different acid–base conditions, and reaction processes were discussed. Thermal decomposition behaviors of the two compounds were studied with DSC and TG/DTG methods, and the kinetic equations of decomposition process were obtained. Self-accelerating decomposition temperature and critical temperature of thermal explosion are 193.92 and 209.75 °C for EDNH, and 242.46 and 259.94 °C for DNTA, respectively. Specific heat capacities of the two compounds all present a square relationship with temperature in determined temperature range, and molar heat capacities at 298.15 K are 331.30 and 213.13 J mol−1 K−1, respectively. DNTA and EDNH are relatively insensitive (> 35 and > 25 J), which are much lower than that of AHDNE. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid composites have received much attention of scientists in the recent years due to the notable improvement of thermal properties without using of organic or inorganic nanoparticles. Hence, we have developed a facile strategy to prepare a 3D hybrid network based on silane materials and novolac resin via sol–gel process. At first step, novolac resin was prepared by general procedure with appropriate thermal properties and then modified with (3-chloropropyl)triethoxysilane (CPTES) to form MNR. In second step, to cure MNR and prepare hybrid composite structures, general amine-cured system and sol–gel process were applied to prepare MNH and MNSG samples, respectively. XRD analysis was used to support the formation of silane networks in hybrid samples. Investigation of thermal properties by DSC and TGA showed that cured samples had much higher thermal stability and char yield with respect to novolac and modified resin (MNR) originated from formation of 3D Si–O–Si network. Presented method limited some disadvantages of using nanoparticles such as aggregation and poor distribution. Such hybrid composites with high thermal stability have potential applications in advanced fields such industrial molds, coatings, adhesives and composites. [ABSTRACT FROM AUTHOR]

A novel composite of SrCO3-microencapsulated palmitic acid (PA) (PA@SrCO3 microcapsules) was prepared an evaluated as a phase-change material through a self-assembly approach. Samples of the material were studied by Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometery (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to determine the composition, crystalloid phase, microstructure, and morphology of the product. Also differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to monitor the thermal behavior of the PA@SrCO3 microcapsules. The data obtained through XRD and FTIR indicated the presence of characteristic peaks of PA and SrCO3, which is only possible when the species do not chemically react with each other. SEM images indicated the PA@SrCO3 microcapsules to be spheres with rough surfaces and average diameters of 1.5–2 µm. TEM images proved the samples as being composed of PA cores encapsulated in a SrCO3 coating. The DSC results showed that the samples had phase-change behaviors, similar to those of pristine PA (melting point = 66.9 °C, latent melting heat = 48.8 J g−1, freezing point = 55.7 °C, latent freezing heat = 43.2 J g−1, at a microencapsulation ratio of 43.92%), and TGA results showed improvements in the thermal stability of PA@SrCO3 microcapsules as opposed to PA, due to the presence of the SrCO3 shell. [ABSTRACT FROM AUTHOR]

Thermal energy storage (TES) has been identified as a breakthrough concept in development of renewable technologies. However, the main challenges are related to the development of competitive heat storage materials. Despite the number of studies on heat storage materials, the determination of new alternatives for next generation technologies is still open. In this regard, this paper presents the results of an experimental study of the physical, thermal and mechanical properties of SiC-doped ceramics as potential materials for TES applications. Two kinds of SiC additives (high and low densities) were incorporated with different percentages into the clay matrix in order to produce ceramics via the extrusion process. The addition of low-density SiC (true density 3.16 g cm−3) led to the increasing of porosity with large pore sizes and the decreasing of bulk density. Therefore, the thermal and mechanical properties are decreased up to − 50% for flexural strength and − 15% for thermal conductivity when 20 mass% of low-density SiC was used. On the other hand, when high-density SiC (true density 3.42 g cm−3) was used, properties of the clay ceramic were strongly improved: i.e., increase in the bulk density, decrease in the porosity, increase in the thermal conductivity and increase in the flexural strength. The best material was found with the addition of 20 mass% of high-density SiC which had a thermal conductivity of 1 W m−1 K−1, a specific heat capacity of 0.62 kJ kg−1 K−1 and a mechanical strength of 19.6 MPa. It also showed a high thermal stability after 20 successive heating/cooling cycles. Hence, this study provided a useful insight into how the SiC modified the microstructure and properties of fired clay ceramics. Thus, the current results suggest that clay ceramics with high-density SiC addition are promising materials for thermal energy storage applications. [ABSTRACT FROM AUTHOR]

Rigid polyurethane foam/aluminum diethylphosphinate (RUPF/ADP) composites were prepared by one-step water-blown method. Furthermore, scanning electron microscope (SEM), thermal conductivity meter, thermogravimetric analysis (TGA), limiting oxygen index, Underwriters Laboratories vertical burning test (UL-94) and microsacle combustion calorimetry were applied to investigate thermal conductivity, thermal stability, flame retardancy and combustion behavior of RPUF/ADP composites. Thermogravimetric analysis–Fourier transform infrared spectroscopy (TG–FTIR) was introduced to investigate gaseous products in degradation process of RPUF/ADP composites, while SEM and X-ray photoelectron spectroscopy were used to research char residue of the composites. It was confirmed that RPUF/ADP composites presented well cell structure with density of 53.1–59.0 kg m−3 and thermal conductivity of 0.0425–0.0468 W m−1 K−1, indicating excellent insulation performance of the composites. Flame retardant test showed that ADP significantly enhanced flame retardancy of RPUF/ADP composites, RPUF/ADP30 passed UL-94 V-1 rating with LOI of 23.0 vol%. MCC test showed that ADP could significantly decrease peak of heat release rate (PHPR) of RPUF/ADP composites. PHPR value of RPUF/ADP20 was decreased to 158 W g−1, which was 21.8% reduced compared with that of pure RPUF. TG–FTIR test revealed that the addition of ADP promoted the release of CO2, hydrocarbons and isocyanate compound in first-step degradation of RPUF matrix while inhibited the release of CO in second step degradation. Char residue analysis showed that the addition of ADP promoted polyurethane molecular chain to form aromatic and aromatic heterocyclic structure, enhancing strength and compactness of the char. This work associated a gas–solid flame retardancy mechanism with the incorporation of ADP, which presented an effective strategy for preparation of flame retardant RPUF composites. [ABSTRACT FROM AUTHOR]

In present article, influence of magnetic forces on migration of nanomaterial through a permeable zone via an innovative method is investigated. The porous cavity packed with CuO-water nanofluid, a magneto-hydrodynamic effect is imposed, and the numerical simulation method is CVFEM. The investigations include various radiation terms, Hartmann and Rayleigh numbers and the nanomaterial shape factor and their corresponding effects on thermal properties of nanomaterial. The results reveal that Nusselt number is in direct relation with radiation term, convective mechanism becomes stronger with improve of shape effect, and temperature gradient goes up as the Hartmann number drops or Rayleigh number augments. Finally, established on derived outputs, a precise formula for Nuave as a function of the aforementioned parameters is developed. [ABSTRACT FROM AUTHOR]

In order to improve the flame retardancy of knitted cotton fabrics and investigate the flame-retardant mechanism of the system formed by ammonium polyphosphate (APP) and chitosan (CS), flame-retardant knitted cotton fabrics coated with APP and CS were successfully prepared by layer by layer assembly. APP and CS formed the intumescent flame-retardant system, in which CS acted as the carbon source agent and APP acted as both the acid source and foaming agent. The surface micromorphologies before and after flaming of coated knitted cotton fabrics were exploited by scanning electron microscopy. The flammability, combustion behaviors, thermal degradation properties and flame-retardant mechanism of this system were investigated by vertical burning test, cone calorimetry test and thermogravimetric analysis coupled with Fourier transform infrared analysis in N2 atmosphere, respectively. Compared with the control sample, the deposition of APP and CS endowed the knitted cotton fabrics with improved flame retardancy, higher residual chars, lower heat release rate and total heat release, while increased the smoke production. Improved flame-retardant behaviors are attributed to the thermally stable residual chars, more release of inflammable gases and potential free radical scavengers (PO·) in the gaseous products, named the combination of the condensed-phase and gaseous-phase flame-retardant mechanism. [ABSTRACT FROM AUTHOR]

The thermal properties together with the identification of the emitted volatiles during heating of the starch-graft-poly(geranyl methacrylate) copolymers with the use of a TG/FTIR-coupled method and some of the physicochemical properties of the copolymers were determined. It was found that the use of the geranyl methacrylate monomer to the graft copolymerization with potato starch allowed to replace ca. 1.46 hydroxyl groups per glycosidic units of starch macromolecule by the poly(geranyl methacrylate) chains under the optimal reaction conditions. Generally, all tested starch graft copolymers exhibited a significant increase in polar solvent resistance, moisture resistance and chemical stability as compared to potato starch. However, the thermal stability of the obtained materials was substantially lower as compared to the thermal stability of potato starch. The beginning of the decomposition of the copolymers was observed below 150 °C. It was due to low thermal stability of the poly(geranyl methacrylate) chains. The decomposition of the prepared materials runs at least four, unseparated stages. The first stage was visible up to 220–240 °C. It was connected with the emission of some aldehyde, acid, alcohol, alkene, ester fragments, H2O and CO2 as a result of the depolymerization, destruction and partial decarboxylation of the poly(geranyl methacrylate) chains. The second stage was spread between ca. 220–240 and 358–375 °C. The emission of organic, saturated, unsaturated, aromatic, oxygen-rich fragments, CO, CO2 and H2O as a result of the decomposition and dehydration of starch was confirmed. Heating of the studied materials between 358–375 and 455–477 °C resulted in subsequent decomposition processes of the residues and the creation of some oxygen-rich saturated and unsaturated fragments, CO, CO2, H2O and CH4. Finally, above 455–477 °C, a minor mass loss as a result of the decomposition processes of the residues formed before was observed. The emission of CO, CO2, H2O, CH4 and some oxygen-rich saturated and unsaturated fragments was confirmed. [ABSTRACT FROM AUTHOR]

The influence of composition and neodymium doping on the crystallization kinetic of calcium aluminosilicate glasses, melted under vacuum atmosphere, was investigated. Glass stability was evaluated by means of thermal events. Non-isothermal methods of Kissinger and Ozawa were used to obtain the apparent activation energy and to predict the crystallization mechanism. The isothermal method of Ray and Day was applied in order to obtain the nucleation rate type curve and the maximum nucleation temperature. In the studied glass system, surface crystallization was more favorable than bulk. By confocal Raman microscopy, it was estimated that the crystallized region was 20–30 μ m from surface to center of sample. This observation was further validated by structural investigation with X-ray diffraction, which showed the formation of Ca 9 Al 6 O 18 and Ca 3 Al 2 O 6 phase as a surface layer in the samples. [ABSTRACT FROM AUTHOR]

The results obtained from thermogravimetric (TG) analysis, X-ray diffraction analysis, optical characterization and dielectric measurements of the samples were investigated. In X-ray diffraction patterns, the presence of both BaCO3 and ZnO peaks showed that ZnO and BaCO3 nanocrystals were independently grown. Changes in the band peak position in the FTIR spectra showed that the chemical structure of Ba:Zn nanocomposites changed with the doping of graphene oxide. The optical band gap (Eg) of the samples was calculated as 3.18, 3.19, 3.2, 3.21 and 3.23 eV for BaZn, BaZn25, BaZn50, BaZn75 and BaZn100, respectively. It was determined that the dielectric constants and dielectric losses of the nanocomposites exhibited normal dielectric behavior, decreased with the frequency described in light of Maxwell–Wagner model and increased with increasing graphene oxide concentration. TG measurement showed that the mass loss in the sample decreased with increasing graphene oxide. [ABSTRACT FROM AUTHOR]

In this study, manganese sillenite nano-powders were produced by hydrothermal method by adding graphene oxide in different mass amounts. Structural, morphological, thermal, optical and electrical properties of the obtained undoped and graphene-oxide-doped samples were investigated. XRD results showed that the produced samples had nano-sizes and the crystal sizes changed with the addition of graphene oxide. SEM and TEM images showed that the microstructures of the samples were nano-sized and composed of randomly oriented particles without orientation relationship between them. From FT-IR spectra of the samples, chemical properties and bond structures were determined. With the help of thermal analysis measurements, reactions in the sample structures at increasing temperatures, reaction temperatures, reaction energies and total mass losses were determined. The forbidden energy ranges of the samples decreased at significant rates with the addition of graphene oxide. By checking the P–E hysteresis cycles, the samples are understood to show ferroelectric properties. Dielectric measurements and temperature-dependent electrical conductivity measurements of the produced nano-powders confirmed that the samples exhibited semiconductor behaviour. The obtained results showed that manganese sillenites can be synthesised by low-temperature hydrothermal method and physical, chemical and thermal properties can be controlled by adding different amounts of graphene oxide for use in electronic and energy applications. [ABSTRACT FROM AUTHOR]

The composites were prepared with PVC modified with 3-(dimethylamino)-1-propylamine (aminated PVC) and MWCNT containing 2.5% carboxyl group (oxidized MWCNT) and doped with nanographite in different percentages (1, 5, 8 and 12% by mass). Thermal investigation was performed from DSC and TGA curves. From the DSC curves, it was observed that Tg temperature of aminated PVC increased with the increase in oxidized MWCNT content. At the composite containing 5% MWCNT, Tg temperature of aminated PVC decreased slightly with increasing nanographite, at the composite containing 11% MWCNT increased slightly and at the composite containing 8% MWCNT nearly fixed. While according to initial decomposition temperature doping with nanographite did not affect significantly the thermal stability of composites, the amount of residue at 500 °C increased some with doping. Conductivity was only investigated for aminated PVC/8% oxidized MWCNT/8% nanographite composite. Doping with nanographite significantly increased the conductivity of the composite. (Conductivity increased values from 10−8–10−9 S cm−1 to 10−4 S cm−1). The conductivity increased with increasing temperature at all frequencies. Conductivity-related activation energies were calculated at different frequencies, and while the frequency increased from 630 to 29,500 Hz, the activation energy decreased from 0.0228 to 0.0193 eV. [ABSTRACT FROM AUTHOR]

In the process of multi-seam mining, the measure of water exploration is usually employed for the upper coal seam to prevent and control water accumulation. The residual coal immersed in water for a long time in the upper layer is dried under the action of air leakage, leading to the enhancement of the risk of coal spontaneous combustion. Therefore, it is necessary to study the water soaking–drying process (WSD) on the spontaneous ignition characteristics of coal. In this study, a laser thermal conductivity analyzer was used to investigate the changes in thermal properties of bituminous coal collected from mines in western China after WSD. The results show that compared with the raw (unsoaked) coal samples, the thermal diffusivity, specific heat capacity, and thermal conductivity of the bituminous coal are considerably reduced after WSD; the maximum reductions in the three parameters are 11.11%, 6.64%, and 12.39%, respectively. These reduced thermal parameters indicate that after WSD, bituminous coal is more prone to self-heating, resulting in an increase in the rate of coal–oxygen compound reactions and a significantly increased risk of spontaneous combustion. [ABSTRACT FROM AUTHOR]

The building sector has been showing great interest in incorporating technologically advanced materials with lightweight, ecofriendly, high strength, and stiffness properties in flooring, roofing, and partition walls, etc. In addition to the mechanical properties, these materials should have good thermal properties as well. In response to these requirements, an attempt has been made to study the thermal behavior of green composite sandwich made of flax and agglomerated cork. Composite sandwiches were fabricated by using flax as skin reinforcement and agglomerated cork as core with different densities as 240, 280, and 340 kg m−3 using vacuum bagging method. Glass was also used as skin reinforcement for manufacturing composite sandwiches for comparison purpose. Experiments were conducted to predict thermal properties, viz. thermal conductivity, thermal expansion, flammability, and thermal stability. The experimental results show that the lowest thermal conductivity of 0.03 W m−1 K−1 was observed in flax-based composite sandwich having core density of 240 kg m−3; the lowest thermal expansion of 29.2 × 10−5 °C−1 was observed in glass-based composite sandwich having core density of 340 kg m−3; the highest value of time to ignition was 12 s, and minimum propagation rate was 0.25 mm s−1 in flax-based composite sandwich having core density of 340 kg m−3; The highest initial degradation temperature was 362 °C for glass-based skin and 263 °C for cork having density of 240 kg m−3. [ABSTRACT FROM AUTHOR]

In this study, new thermoplastic sulfur-containing poly(carbonate-urethane)s (PCURs) were synthesized via a one-step melt polyaddition from diphenylethane-derivative diols with two or ten methylene groups in the aliphatic chain, i.e., 4,4′-(ethane-1,2-diyl)bis(benzenethioethanol) (diol E) and 4,4′-(ethane-1,2-diyl)bis(benzenethiodecanol) (diol D) as nonconventional chain extenders, 1,1′-methanediylbis(4-isocyanatobenzene) and 20–60 mol% poly(hexane-1,6-diyl carbonate) diol of M ¯ n = 860 g mol−1 as a soft segment. The PCURs were studied mainly to describe their thermal and mechanical behaviors by means of DSC, TG and TG coupled with FTIR, and Shore hardness and tensile tests. Moreover, their structure and physicochemical and adhesive properties were determined. The results of the study showed that the kind of the chain extender as well as soft-segment content had an impact on the properties of the polymers obtained. They were amorphous or semicrystalline high molar mass materials. The PCURs based on diol D exhibited lower glass transition temperatures in comparison with those based on diol E with shorter aliphatic chain (− 1–24 °C vs. 13–55 °C). Unfortunately, the former polymers revealed somewhat poorer tensile strengths (up to 45.0 MPa vs. 51.8 MPa). Nevertheless, these values were similar to or higher than those obtained for their commercial analogs. The PCURs being diol D derivatives also showed, in general, lower hardness and the modulus of elasticity but higher elongation at break. All the PCURs exhibited a relatively good thermal stability. However, the polymers derived from diol D revealed higher temperatures of 1, 10 and 50% mass losses compared with diol E-based ones (290–298 °C vs. 285–287 °C, 325–336 °C vs. 314–323 °C, 360–381 °C vs. 348–356 °C, respectively). The newly synthesized sulfur-containing PCURs showed better adhesive properties to copper than the analogous polymer based on butane-1,4-diol as a chain extender. [ABSTRACT FROM AUTHOR]

The effects of three different surfactants were analyzed on the stability and thermal conductivity of GO/de-ionized water nanofluids. One surfactant was cationic, cetyltrimethyl ammonium bromide (CTAB), one was anionic, sodium dodecyl sulfate (SDS), and one was nonionic, TritonX-100 (TX-100). These were added to synthesized graphene oxide (GO) prepared in de-ionized water at different concentrations (0.01, 0.05, 0.1, 0.15, 0.2, and 0.25 mass%). The transient hot-wire technique was employed to measure the thermal conductivity of all nanofluids at 20–40 °C. The stability of the GO/de-ionized water nanofluids without a surfactant was better than that of nanofluids with a surfactant. The stability and dispersion of the nanofluid with SDS were considerably better than nanofluids with the other two surfactants. All nanofluids without a surfactant had higher thermal conductivity than de-ionized water at all temperatures. An increase in the GO concentration from 0.01 to 0.2 mass% improved thermal conductivity by 3.05 and 22.03% at 20 °C, respectively. A further increase to 0.25 mass% caused a 23.73% increase in thermal conductivity. [ABSTRACT FROM AUTHOR]

To improve the thermal decomposition property of cyclotrimethylenetrinitramine (RDX), a new nano-energetic combustion catalyst nitrated graphene oxide (NGO), which was synthesized by nitrifying graphene oxide with nitro-sulfuric acid, is introduced to RDX via a solvent–antisolvent method. A scanning electron microscope was used to investigate the morphology of RDX, NGO and the 2% NGO/RDX nano-energetic composite. The properties and the mechanisms of thermal decomposition of the NGO/RDX nano-energetic composites in different blend ratios were analyzed through thermogravimetry–differential scanning calorimetry and thermogravimetry–mass spectra, respectively. In comparison with RDX, the thermal decomposition temperature of 2%NGO/RDX decreased from 246 to 224 °C, and the apparent decomposition heat enhanced from 761 to 1651 J g−1. The tests of impact sensitivity and friction sensitivity were carried out by a standard method. The value of h50 of 2%NGO/RDX increased from 24 to 40 cm and the friction sensitivity of 2%NGO/RDX reduced from 86 to 12% compared with RDX. These results indicated that NGO had an excellent catalytic property upon the thermal decomposition of RDX and it can also improve its impact sensitivity and friction sensitivity. [ABSTRACT FROM AUTHOR]

Nanofluid flow boiling and critical heat flux (CHF) are interesting topics for many researchers and have industrial application for preventing potential damages. On this basis, numerous experimental studies have been performed on the determination of CHF; however, due to the weakness of the existing correlations for this purpose, an accurate numerical study on CHF is yet needed to be reported. In the present study, the subcooled flow boiling of nanofluid has been simulated to predict CHF. For estimating the nucleation site density (NSD), a correlation is used, into which the liquid properties, flow characteristics and surface properties contribute. The studies were performed at different concentrations of alumina nanoparticles. The simulation results indicated error percentages below 10% in CHF estimation, confirming the reliability of the results. No significant difference was observed between the CHF values calculated in the simulation studies considering constant thermal properties for the nanoparticles, as compared to those obtained with variable thermal properties for the nanoparticles. Taking the tube in a horizontal position, rather than the vertical position, increased the CHF value. However, the increase in CHF was negligible. [ABSTRACT FROM AUTHOR]

This work aims to determine the nickel selenate hexahydrate thermal behavior by simultaneous thermogravimetry–differential thermal analysis and differential scanning calorimetry and characterize its thermal intermediates decomposition. Moreover, at 25 °C, this material is a green-colored compound; however, with the temperature increase (until 420 °C), a color change from yellowish green to yellowish orange and finally to yellow was observed. This characteristic is due to the water molecules release, changing the ultraviolet–visible/near-infrared spectroscopy analysis absorption spectra and consequently modifying the crystal structure, as confirmed by X-ray powder diffraction, and resulting in visual changes in photo-DSC. The new data are essential to determine the better conditions to use this material as a precursor in synthesis and also to use it in future applications. [ABSTRACT FROM AUTHOR]

Phosphate glasses are important materials in many fields. However, their usage can be limited due to water corrosion. Addition of Al2O3 significantly improves the water resistance, and as such, the glass of superior water durability can be obtained. Thus, it may be considered as a matrix for waste immobilization. In the paper, thermal properties of 60P2O5–(40−x)Al2O3–xNa2O glasses are presented. The materials were investigated with the application of DSC/TG method and observations of shape change during heating in a heating microscope. Water durability studies are also presented. It was evidenced that glass of low Na2O content crystallizes during heating, which limits their application in waste vitrification. Nevertheless, the obtained glass–ceramic material is characterized by a superior water resistance. The water durability decreases with sodium content. The obtained results are discussed from a waste immobilization point of view, and the optimal glass composition containing 15 mol% of Na2O is indicated due to it low viscosity, melting temperature and very good water resistance. [ABSTRACT FROM AUTHOR]

This work aims to study the influence of torrefaction on the energetic properties and thermal decomposition kinetics of energy cane Saccharum spontaneum. An experimental planning (473–533 K, 15–45 min) was realized, and the best conditions were 503 K and 45 min with mass yield above 70%, which led to the decrease in volatile matter and oxygen contents (15%) and the increase of 14.5% in the heating value. The thermogravimetric analysis (heating rates of 5, 10 and 15 K min−1) under inert atmosphere was used for the application of the independent parallel reactions scheme in the multistep model. The activation energies found were 111, 119, 197 and 51 kJ mol−1 for both raw and torrefied biomasses related to extractive, hemicellulose, cellulose, and lignin, respectively. Then, this approach provided reliable kinetic models capable of describing the thermal decomposition for both raw and torrefied samples (deviation < 3%). [ABSTRACT FROM AUTHOR]

This work examines the effect of heat treatment parameters such as the cooling velocity and the quenching fluid nature on the structural, Rockwell hardness and thermal properties of XC48 steel. The studied specimen is a cylinder of 3 cm diameter and 10 cm length, and the used quenching fluids are oil, water and air. The investigation shows that the XC48 hardness varies from 18 to 58 HRC through the used quenching fluid and decreases along the length of the specimen contrary to the thermal conductivity and thermal diffusivity, which are primarily in the order of 36 W m−1 K−1 and 0.125 cm2 s−1 respectively, and which increase with the quenching velocity. A correlation between these thermo-mechanical properties such as the hardness and the thermal conductivity is realized to obtain a new nondestructive technique permitting to determine the mechanical hardness without measuring it. This technique is of an overwhelming importance and can be used in the industrial and research fields. [ABSTRACT FROM AUTHOR]

In this study, the effects of heating and cooling rate on the thermal properties of high nickel-rich Ni55Ti45 shape memory alloy were investigated. Transformation temperatures and enthalpies were determined by differential scanning calorimetry. R-phase was observed with two-stage phase transformation during cooling. Transformation finish temperatures were affected, while the transformation start temperatures were not changed by heating–cooling rate. Kissinger, Takhor, and Ozawa methods were applied to find activation energy that is needed for phase transformation. The average activation energy value of 200.5 kJ mol−1 was calculated for Ni55Ti45 alloy. The calculated activation energy was found lower than the ones reported in the literature. [ABSTRACT FROM AUTHOR]

The influence of cerium oxide on the thermal properties and the glass structure has been studied for the Li2O–(Na2O–K2O)–B2O3–SiO2 system. It has been established that cerium is completely soluble in the quenched glass during the synthesis if addition of CeO2 is 0–10 mol%. The cubic ceria phase is formed in glass either during the synthesis if addition of CeO2 is 20 mol% or after thermal treatment (annealing) if the glass contains 10–20 mol% of CeO2. The studied lithium borosilicate glasses have low thermal stability and demonstrate significant difference in the crystal phase formation for Ce-free and Ce-containing glasses after annealing. The lithium–sodium and lithium–potassium glasses have much higher thermal stability toward crystallization regardless of Ce content. The obtained results are relevant for improving the properties of matrix materials of similar borosilicate systems used for immobilization of radioactive waste. [ABSTRACT FROM AUTHOR]