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

The study of the P3HT synthesis was carried out to investigate the effect of reaction time on thermal, optical, electronic, and morphological properties. It has been demonstrated that the variation in polymerization time over 30 min did not significantly affect the optoelectronic properties of polymers. Regarding the thermal properties, the P3HT synthesized in the shortest time presented a decomposition temperature of 20 K higher than the others. There was no difference in glass transition temperature or melting temperature, while both crystallization temperature and crystallinity content have slightly increased with polymerization time. The regioregularity of all polymers was 98%. The advantage is that a short reaction time is possible to obtain a polymer with suitable properties and, consequently, savings in the process. P3HT-30 was evaluated in a PSC active layer with the configuration of ITO/PEDOT: PSS/rrP3HT:PC71BM/Ca/Al, and PCE was 1.94%. [ABSTRACT FROM AUTHOR]

Hydroxyl-terminated polyether (HTPE) propellant and HTPE/Poly(ε-caprolactone) (PCL) propellant were compared to explore the effects of introducing PCL to HTPE propellant on the mechanical and thermal properties at the wide temperature range of − 50 °C to 70 °C. The energetic properties of HTPE and HTPE/PCL propellants were also evaluated, the ideal specific impulse and density of HTPE/PCL propellant were found to be slightly enhanced comparing with those of HTPE propellant. The tensile mechanical properties results revealed that the introduction of PCL could improve the maximum tensile strength (σm) of HTPE/PCL propellant at the wide temperature range of − 50 °C to 70 °C, its σm increased from 0.38 to 0.75 MPa at 20 °C, 0.25 to 0.48 MPa at 70 °C and 4.01 to 4.77 MPa at − 50 °C separately comparing with those of HTPE propellant. The thermal decomposition behavior at 0.1 MPa showed that the introduction of PCL could promote RDX and AP in HTPE/PCL propellant to decompose. Bu-NENA was hardly to evaporate from HTPE/PCL propellant at higher pressure, which was beneficial to its thermal decomposition. The introduction of PCL could be more effective to inhibit the evaporation of Bu-NENA from HTPE/PCL propellant at 0.1 MPa, the activation energy of evaporation of HTPE and HTPE/PCL propellants was 53.66 kJ mol−1 and 77.90 kJ mol−1, respectively. [ABSTRACT FROM AUTHOR]

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

MnO2 particles were prepared by a hydrothermal method and characterized via the SEM imaging, XRD and FTIR analyses, showing that the individual particles were spherical and less than 1.0 μm in diameter but were clustered in α type crystal. The particles were then added into the n-octadecane to form a new class of phase-change energy storage composites. After that, the composite powder was wrapped into polyethylene by the suspension polymerization, forming microcapsules with an average size 4.9–5.6 μm in diameter. Eventually the morphology and thermal properties of the microcapsules were analyzed. No forming of chemical bond between the core material and the shell material was found during the microcapsule synthesis process. The latent heat and encapsulation efficiency of the microcapsules with addition of 0.5 mass% MnO2 particles in the n-octadecane were measured at 107.5 ± 1.3 J g−1 and 95.3 ± 1.2%, respectively, which are higher than the microcapsules with pure n-octadecane, measured at 84.9 ± 1.2 J g−1 and 75.3 ± 1.4%, respectively. The thermal conductivity of the n-octadecane microcapsules modified with 0.5 mass% MnO2 was enhanced by about 103.3% at 15.0 °C compared with the microcapsules without MnO2. Thermogravimetric and thermal cycling studies showed that the modified new microcapsules had good thermal stability. Such a modification provided an effective way to prepare phase-change energy storage microcapsules with better thermal properties and higher encapsulation efficiency. [ABSTRACT FROM AUTHOR]

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

In this presented study, the convective air drying method at three drying temperatures (50, 60 and 70 °C) was applied to investigate in terms of energy and exergy analysis, drying kinetics, modeling, microstructure and thermal properties of banana slices. Results of data analysis displayed that the energy and the exergy efficiencies were reduced, while the drying temperature surged. The drying process at 70 °C shortened the overall drying period (300 min), which was followed by 60 °C (480 min) and 50 °C (720 min), respectively. Moreover, the process occurred in the decreasing rate with time. At each drying temperature, various models (Midilli et al. for 50 °C, diffusion approach for 60 °C and logarithmic for 70 °C) described the best models for the drying curves. The convective-dried banana samples were imaged by the thermal camera and scanning electron microscopy, and a breakdown of cell walls without any regional burns was determined in dried samples at 50 °C. The result of this study could be used as a convective drying in industrial purposes. [ABSTRACT FROM AUTHOR]

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

This work aims to study the enhanced thermal conductivity of silicone oil on increasing mass % of hard magnetic Sm-Co based nanoparticles (NPs) in the presence of external magnetic fields. Sm-Co NPs were synthesized using the low temperature 'Pechini-type sol–gel' process. The presence of mixed phases is evident through XRD, FESEM, and TEM. The average hydrodynamic size of Sm-Co NPs was measured 51 nm by DLS. The study of magnetization vs. magnetic field reveals the weak ferromagnetic ordering along with the paramagnetic behaviour of the Sm-Co NPs. Thermal conductivity enhancement of Sm-Co nanofluids showed an increasing trend with the rising particle concentration and magnetic flux density. A high thermal conductivity enhancement of ~ 373% is reported at 15 mass % concentration of Sm-Co nanofluids and at a magnetic flux density of 0.5 T. The mechanism behind this thermal conductivity enhancement in the presence of an externally applied magnetic field has been discussed on the basis of near field magneto-static interactions of the magnetic nanoparticles. Microstructural, magnetic, and heat transport studies of Sm-Co based MNFs are very useful for device applications. [ABSTRACT FROM AUTHOR]

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

As an energy-saving equipment, task/ambient air conditioning (TAC) system was widely used in sleeping environment in recent years. The TAC can deliver cooling air directly to the sleeping person, resulting that the micro climate around the human body becomes very critical in the evaluation of human beings' thermal comfort. Different from sitting and standing, sleeping human body is always at lying posture, and thus at a lower metabolic rate than at waking status. To understand the heat balance between a sleeping body and the surrounding environment, investigation on the heat loss of human body becomes necessary. Hence, a numerical study on the body heat loss characteristics of a thermal manikin at sleeping state in a bedroom utilizing a TAC system was carried out. The convective heat transfer, radiative heat transfer, evaporative heat loss from skin and respiratory heat loss and their ratios were quantitatively analyzed. The results indicate that the convective heat transfer took the first place, accounting for about 80% of the total heat loss, and Latent heat loss accounted for 15.9%–21% of the total heat loss. In addition, the heat loss at different supply conditions was numerically studied. Results showed that the supply air temperature, flowrate and humidity play different effects on body heat loss. Contributions of this study are meaningful for the accurate control of micro climate of human activities. [ABSTRACT FROM AUTHOR]

The poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was used to prepare biocompatible composites modified by the hemp fibers. The aim of the study was to assess the structure and selected thermal and mechanical properties of the obtained biocomposites. The morphology of samples was analyzed using a scanning electron microscope and a computed tomography analysis. The phase transitions of composites and polymer matrix were investigated using differential scanning calorimetry. Moreover, the non-equilibrium and equilibrium thermal parameters of composites and the unfilled PHBV were established based on the thermal history. Knowing equilibrium parameters, i.e., the heat of fusion for the fully crystalline materials, ΔHf (100%), and the change of heat capacity at glass transition temperature (Tg) for the fully amorphous, ΔCp (100%), composites, the degree of crystallinity, mobile, and rigid amorphous fractions were estimated. The addition of hemp fibers to the PHBV matrix caused around a two-time increase in the degree of crystallinity in reference to the unfilled PHBV. It was also observed that the addition of hemp fibers caused a decrease in heat capacity for fully amorphous material for all the biocomposites obtained. A similar relationship was observed in case of values of the heat of fusion for fully crystalline material. Simultaneously, the decrease in amorphous phase contents was noted. It was also noted that the rigid amorphous fraction exists only for the unfilled polymer matrix. Some mechanical properties of investigated materials were also measured and presented. [ABSTRACT FROM AUTHOR]

Polyethylene from renewable resources produced using sugarcane as raw material was modified with phosphonium ionic liquids. Tensile properties and thermal behavior of modified biopolyethylene in air and nitrogen atmosphere were studied. The thermal degradation of ionic liquids and their influence on thermal degradation of polyethylene from renewable resources were studied by thermogravimetric analysis (TGA). In general, modification of biopolyethylene with phosphonium ionic liquids resulted in improvement of tensile properties, i.e., tensile strength and Young's modulus. Thermal degradation of biopolyethylene modified with phosphonium ILs proceeds in one step in the range of 400–500 °C in nitrogen atmosphere. Modification of polyethylene with trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate ionic liquid resulted in increase in DTGpeaks and T10% temperatures toward higher temperature for modified polyethylene in comparison with unfilled PE sample both in air and nitrogen atmosphere. [ABSTRACT FROM AUTHOR]

The N,N′-dimethylformamide (DMF) was used in the microwave-assisted (MW) solvothermal method for the preparation of lanthanide(III) complexes with biphenyl-4,4′-dioxydiacetic acid (H2L) of the formula Ln2L3·xDMF⋅yH2O where Ln = lanthanide(III) ions from La(III) to Lu(III) with the Pm(III) exception x = 1.5–3; y = 2 for Yb and Lu or 0 for the remaining complexes and L = C14H12O2(COO)22−. The obtained complexes were characterized by the elemental analysis, infrared spectroscopy (ATR-FTIR), X-ray diffraction patterns and different methods (TG-DSC and TG-FTIR) of thermal analysis. Crystalline complexes contain N,N′-dimethylformamide molecules in their structures. Additionally, water molecules are present in the structures of Yb(III) and Lu(III) complexes. Coordination of lanthanide ions occurs through carboxylate oxygen atoms from the biphenyl-4,4′-dioxydiacetate ligand and most probably carbonyl oxygen atom from N,N′-dimethylformamide. The investigated compounds exhibit different thermal stability, and removal of solvent molecules takes place in a more complex way in the group of heavy lanthanide complexes. Their desolvated forms are an unstable [except Yb(Lu)2L3 compounds], and their further heating leads to the formation of suitable lanthanide oxides (air atmosphere). Thermal stability of the investigated compounds is higher in nitrogen atmosphere. The TG-FTIR methods allowed to propose way of thermal decomposition of investigated compounds through identification of volatile products such as: DMF, H2O, CO2, CO and CH4 evolved during heating of complexes. The luminescent properties of terbium(III) and europium(III) complexes were also investigated. [ABSTRACT FROM AUTHOR]

In this work, polyurethane (PU) insulating panels containing different amounts of a microencapsulated paraffin with a nominal melting temperature of 24 °C, used as phase change material (PCM), were produced. The resulting panels behaved as multifunctional materials able to thermally insulate and simultaneously storing/releasing thermal energy near room temperature. The panels were characterized from a microstructural, thermal and mechanical point of view. Viscosity measurements highlighted an increase in the viscosity values of the PU liquid precursors due to the addition of the capsules, and this could lead to some difficulties during the production stages, especially in the mixing and foaming phases. From optical microscopy micrographs and density measurements, it was observed that the introduction of paraffin tended to destroy the cellular structure of PU foams, and for PCM contents above 30 mass/% the foams were characterized by an open-cell morphology. SEM observations showed that PCM was preferentially distributed in the cell walls intersection, and a rather limited interfacial adhesion between capsules and PU could be detected. Thermogravimetric analysis evidenced that the introduction of the PCM tended to increase the degradation resistance of the foams, while from differential scanning calorimetry tests it was possible to conclude that PCM addition was able to impart good thermal energy storage properties to the foams, with specific melting enthalpy values of 70 J g−1 for a microcapsules concentration of 50 mass/%. As expected, thermal conductivity (λ) of the foams increased with PCM amount, but this enhancement was not directly related to the higher λ of the PCM itself, but rather than to the cell opening effect promoted by the PCM introduction. The microcapsules addition progressively increased the stiffness of the foams, reducing the failure properties both under quasi-static and impact conditions. Moreover, the mechanical properties were strongly affected by the testing temperature (i.e. the physical state of the wax contained in the microcapsules). [ABSTRACT FROM AUTHOR]

Conventional surfactants such as CTAB (cetrimonium bromide), SDS (sodium dodecyl sulphate), SDBS (sodium dodecyl sulphonate) are combined with nanofluids to improve the stability and thermal conductivity of nanofluids. These nanofluids are mainly used for heat transfer applications where heating and cooling are usual courses of action which result in surfactants producing foams and polluting the heat transfer media, affecting the total system performance. Besides, the common surfactant molecules that augment the thermal resistance between the nanoparticles and base fluid also affect the thermophysical properties of the nanofluid. In this paper, [Bmim][Cl] (1-butyl-3-methylimidazolium chloride), a high purity ionic liquid (IL) with higher thermal stability was used to provide a comparative study on the stability and thermal properties with that of the conventional surfactants (CTAB, SDS, SDBS) on multiwalled carbon nanotubes (MWCNT)/propylene glycol (PG) nanofluid. The transient hot-wire based KD2-Pro and zeta potential results demonstrated that the inclusion of ionic liquid improved the thermal conductivity and stability of the formulated nanofluid. However, much like the conventional surfactants, the strong electrostatic repulsive force created by the ionic liquid was found to decrease when the temperature is increased. The outcome demonstrated the most extreme thermal conductivity upgrade of 33.7% at 303 K and maximum dispersion stability of more than one month without any aggregation for the nanofluid containing ionic liquid. [ABSTRACT FROM AUTHOR]

The present work deals with thermal energy storage behavior of the nano-enhanced phase change materials (NEPCMs) for building space cooling application. The NEPCMs have been prepared using Deionized (DI) water as the base phase change material (PCM) and multi-walled carbon nanotubes (MWCNTs) as nanomaterial with mass concentration of 0.25%, 0.5%, and 0.75%. For better stability of additive materials in the base PCM, sodium dodecyl-benzene sulfonate (SDBS) has been chosen as an additive element. The sub-cooling of the DI water has been completely eliminated for a mass concentration of 0.75% of MWCNT. The differential scanning calorimetry(DSC) analysis has been conducted to measure the phase transition properties of NEPCMs. The enhancements of 12.8% and 14.13% in latent heat values for charging and discharging processes, respectively, were observed for maximum mass concentration. It has also been observed that the onset temperature for charging is reduced from − 12.8 to − 9.7 °C for NEPCM with maximum concentration. The maximum thermal conductivity (k) augmentation of 23% (solid phase) and 11.2% (liquid phase) has been achieved by the NEPCM having a mass concentration of 0.75% MWCNT at − 10 °C and 15 °C, respectively. According to the study results the reductions in total charging times are 28% and 19% with the NEPCM holding a mass concentration of 0.75% MWCNT for − 8 °C and − 6 °C heat transfer fluid (HTF) temperatures, respectively. The environmental pollution remediation can be achieved by the reduction in energy input to the chiller by minimizing the total time taken for the charging the PCM. [ABSTRACT FROM AUTHOR]

The effects of the microwave treatment (MWT) and mechanochemical treatment (MChT) on the structure and physicochemical properties of precipitated zirconium oxide were investigated. The obtained materials were characterized using the N2 adsorption/desorption, thermogravimetry (TG, DTG, DTA), XRD and UV–Vis/DRS methods. Photocatalytic properties of the samples were also studied as regards the rhodamine B (RhB) degradation in the aqueous solution. The results show that the microwave and MChT, differing in mill rotation speed, temperature or treatment media, causes significant changes in the porous structure of the obtained samples. In most samples, the specific surface area increase was observed. The DTA and XRD results showed the formation of crystalline structure during MWT. As follows from the investigations, each way of modification results in the shift of the absorption edge toward higher wavelength values and causes photocatalytic degradation of RhB under UV irradiation and makes the obtained materials effective photocatalysts in the visible region. [ABSTRACT FROM AUTHOR]

New coordination compounds have been synthesized by reacting Zn(II) and Co(II) nitrate or acetate in the presence of triethylamine with Schiff-base ligands containing diazine-ring, pyridine-2-carbaldehyde phthalazine-1-hydrazone, HzPYH, and di(2-pyridyl)ketone 3-chloro-pyridazine-6-hydrazone, HpDPKH. Complexes of [Co(HzPY)2]·3.4H2O, [Zn(HzPY)2] and [Co(HpDPK)2]NO3·H2O were obtained. The crystal and the molecular structure of [Co(HzPY)2]·3.4H2O were determined using X-ray diffraction structure analysis. The compounds were characterized by elemental analysis, FT-IR and UV–Vis spectral data, conductivity and magnetic measurements, too. Except for the diamagnetic Co(III) compound with a nitrate counter-ion, [Co(HpDPK)2]NO3·H2O, all the complexes are neutral-type. The magnetic moment of [Co(HzPY)2]·3.4H2O indicated a low-spin octahedral complex which is relatively rear amongst octahedral Co(II) complexes. Hence, its magnetic moment was measured in the temperature range of 3–300 K. To obtain products in the form of single crystals and/or to increase the yield, the reactions were carried out in solutions with different solvents or recrystallized from solvent mixtures. To determine the nature of the solvent (if any) in the crystalline products and to gain better insight into the decomposition mechanism, coupled TG–MS measurements were carried out. The desolvated compounds were stable at relatively high temperatures (> 200 °C). The cytotoxic, antiproliferative and efflux pump inhibitory effects of the compounds were tested in multidrug-resistant mouse T-lymphoma cells to study their effect on the suppression of MDR. The antibacterial activity of the compounds was also tested. The results of the antibacterial tests were analysed to understand better the effect of the central atoms and the structure on a specific activity. [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]

Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) were used to examine the thermal decomposition of benzoyl peroxide (BPO). The interruption rescanning method was adopted to examine the effect of thermal history on the autocatalysis and thermal decomposition of BPO. Autocatalysis of BPO was verified through isothermal experiments. According to the DSC linear temperature rise data of BPO, mathematical methods were used to decouple and divide the peaks. Kinetic analysis using both the Kissinger and Friedman methods was performed. The initial decomposition temperature of the decoupled BPO ranged between 101.4 and 104.6 °C. The peak temperature was 110.9–126.2 °C, and the decomposition enthalpy was 229.7–524.2 J g–1. The apparent activation energy was higher in the coupling state than after decoupling one. The thermal history and isothermal experiments demonstrated that BPO possessed autocatalytic properties. Results revealed that initial decomposition temperature tended to decrease with the increase in interruption temperature. In addition, the apparent activation energy of BPO decreased following the thermal history analysis because of the formation of intermediate products from BPO in the thermal history experiments, which further promoted BPO's thermal decomposition. This effect led to a decrease in BPO's initial decomposition temperature. [ABSTRACT FROM AUTHOR]

One of the dubious aspects of polymer/clay nanocomposites is its thermal stability compared to the pristine matrix since we can find works indicating different directions with relatively similar materials. This work aims to evaluate the influence of the sepiolite content and the PP-g-MA compatibilizer presence in the polypropylene/sepiolite nanocomposites degradation. PP/Sep nanocomposites were prepared in a twin-screw extruder with 0.75–5 mass% of Sep and with or without 2.5 mass% of PP-g-Ma as a compatibilizer. Material characterizations were performed by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis (TGA). Morphology showed that the nanocomposites presented some needles agglomeration inside the polymer matrix, indicating the use of compatibilizer PP-g-MA was not enough for dispersion in the nanocomposites produced in this work. TGA results showed different results according to the nature of the atmosphere. In the oxidative atmosphere, the stability of nanocomposites was not significantly influenced by the sepiolite concentration, for concentrations lower than 1 mass%, and slightly influenced by the presence of PP-g-MA as a compatibilizer, while concentrations as large as 5 mass% of sepiolite showed a strong influence on the clay concentration. In the inert atmosphere, we observed the influence of the sepiolite concentration, decreasing the stability of the nanocomposite in the whole range of studied concentration. Regarding the presence of 2.5 mass% of PP-g-MA, all the formulations exhibit almost the same profile of mass loss, evidencing that the compatibilizer prevented the catalytic effect of the sepiolite in the thermal degradation of the nanocomposite. [ABSTRACT FROM AUTHOR]

As the global temperature increases over time due to different environmental pollutions, apparel clothing with excellent thermo-physiological comfort needs to be developed to improve human health and comfort. Thermo-physiological comfort of apparel clothing must be suitable for the wearer both in winter and summer seasons. Poor thermo-physiological properties can lead to discomfort, fluctuation in body temperature, poor sweat management during wear and can affect human health as well as work efficiency. For this reason, optimum thermo-physiological comfort of clothing is a prerequisite for users at any given weather. The aim of this study was to investigate the effect of cotton yarn parameters on thermo-physiological comfort of woven fabrics. Four types of woven fabrics were developed from cotton yarn with different counts, twist, coefficient of variation of mass (CVm), neps, hairiness, thin places, thick places, strength and elongation. Yarn samples were produced separately by carding and rotor spun before they were woven on an air jet machine with same settings. Finally, the woven fabrics were finished in a combined finishing treatment process. Thermal resistance, thermal conductivity, thermal absorptivity, thermal diffusivity, air permeability and relative water vapor permeability of the woven fabrics were measured and analyzed. Statistically analyzed results showed that thermal resistance, thermal conductivity, thermal absorptivity and air permeability of fabrics had statistically significant change with P-values of.029,.035,.005 and.000, respectively. However, from the results, the yarn parameters did not affect thermal diffusivity and water vapor permeability of fabrics. Model equations were developed based on the results to predict the comfort of the fabric from the yarn parameters. [ABSTRACT FROM AUTHOR]

The effect of ethylene vinyl acetate (EVA) concentration and vinyl acetate (VA) content of EVA on the mechanical, morphological, and rheological properties of bio-based high-density polyethylene (BioPE)/EVA blends was investigated. The blends were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and rheological measurements under oscillatory shear flow. The degree of crystallinity of BioPE decreased with the increase in the EVA concentration and was unaffected with the increase in the VA content. DMTA results showed a decrease in the storage modulus (E′) with the increase in EVA content and that the BioPE/EVA19 blends showed higher E′ values than BioPE/EVA28 blend. The impact strength substantially increased with the addition of EVA concentration above 5 mass% and was higher for the blends containing the highest VA content. The blends containing a higher content of VA exhibited the higher EVA dispersed phase domain size, which increased with the increase in EVA concentration. The complex viscosity increased with the increase in the EVA content, being higher for the BioPE/EVA blends containing higher VA content. The storage modulus increased, at low frequencies, with the increase in the EVA content and can be ascribed to the increase in the EVA dispersed phase domain size. [ABSTRACT FROM AUTHOR]

In this work, tea powder was used as a filler to produce low-formaldehyde-emission tea-based melamine-modified urea–formaldehyde resin (TMUF). The thermal stabilities of TMUF and the resin without tea powder (MUF0) were characterized using thermogravimetry. The optimal amount of tea powder m(tea)/m(tea + urea) was equal to 0.15. The formaldehyde emission of the three-layer plywood produced by TMUF was reduced by 75.43%, and the wet bonding strength of the plate was increased by 26.67% as compared with the plywood prepared by MUF0. Compared with MUF0, the thermal degradation peak temperature of TMUF resin was shifted to higher temperature, while the carbon residue was increased. The thermal degradation activation energies of TMUF and MUF0 were similar, while TMUF had a lower pre-exponential A. The Flynn–Wall–Ozawa model-free method is used to estimate various activation energy values at different conversion rates and to predict possible reaction mechanisms. Judging the reaction mechanism according to the slope of the straight line fitted by different models, the best model was based on random nucleation. [ABSTRACT FROM AUTHOR]

The aim of this study is to achieve a synergy with positive properties of zeolites such as thermal performance and pozzolanic admixture. For this aim, in the study, analcime and clinoptilolite, the two different natural zeolite minerals, were used as pozzolanic replacement material for blended cements. The replacement ratios with Portland cement of zeolites were 0, 10, 30 and 50%. The clinoptilolite which is widely used in the market was used in comparison with zeolite for the determination of similar properties for analcime. Mortars/concretes containing analcime and clinoptilolite blended cements were produced. In the study, (1) physical, chemical, mechanical, mineralogical, petrographic, thermal properties and pozzolanic activities for analcime and clinoptilolite, (2) conformity tests of blended cements, and (3) strength and the thermal performance for mortars/concretes containing blended cements were determined. The test results have been compared among themselves and with each other. According to the test results, without compromising in terms of strengths of mortars/concretes due to pozzolanic activity, it has been determined that thermal performance of the mortars/concretes containing analcime and clinoptilolite blended cements could be improved. Also, it has been concluded that the analcime has showed similar properties to clinoptilolite in terms of its thermal performance and strength. In some cases, due to these similar properties, analcime may be an alternative pozzolanic additive to clinoptilolite which is commonly used. [ABSTRACT FROM AUTHOR]

In this work, thermal and mechanical properties of cationic cassava starch-g-poly(butyl acrylate-co-methyl methacrylate) films with different amounts of cationic cassava starch (CCS) were studied. The objective of this work was to substitute a portion the monomers (BA/MMA) by CCS in the copolymer and to investigate the consequent effects on the properties of the polymer latex films (e.g., graft percentage, surface tension, thermal and mechanical properties). The results show that the grafting percentage decreased as the concentration of CCS increased. Thermal and mechanical properties of polymer films showed a direct relationship with respect to the content of CCS used and the grafting percentage. Higher grafting percentage led to improvement of the thermal degradation, which indicated better thermal stability than neat poly(BA/MMA). DSC analysis showed that the Tg of the graft copolymers was a little lower as compared to Tg values of un-grafted copolymers. The addition of CCS increases the tensile, elastic modulus and hardness properties of the polymer film, but the elongation at break decreased dramatically. The optimal CCS contents that maximized not only thermal properties, but also mechanical properties, were 7 and 10 mass%, which are directly related to the grafting percentage and CCS content in the formulation. In addition, these results create a new approach for the application of CCS graft-polymer as an adhesive for wood, paper and shoes insole applications. [ABSTRACT FROM AUTHOR]

Over many years, great efforts have been made to develop new fluids for heat transfer applications. In this paper, the thermal conductivity (TC) and viscosity of SiO2–P25 TiO2 (SiO2–P25) hybrid nanofluids were investigated for different nanoparticle volume concentrations (0.5, 1.0 and 1.5 vol%) at five various temperatures (20, 30, 40, 50 and 60 °C). The mixture ratio (SiO2:P25) in all prepared hybrid nanofluids was 1:1. Besides, pure SiO2, P25 nanofluids were prepared with the same concentrations for comparison with the hybrid nanofluids. The base fluid used for the preparation of nanofluids was a mixture of deionized water and ethylene glycol at a ratio of 5:1. Before preparing the nanofluids, the nanoparticles were analyzed with energy-dispersive X-ray analysis, scanning electron microscope, X-ray powder diffraction, and Fourier transform infrared spectroscopy. The zeta potentials of the prepared nanofluids except SiO2 nanofluids were above 30 mV. These nanofluids were visually observed for stability in many days. The TC enhancement of the hybrid nanofluid was higher than the pure nanofluid. In particular, with 1.0 vol% concentration, the maximum enhancement of SiO2, P25 and SiO2–P25 nanofluids were 7.5%, 9.9% and 10.5%, respectively. The rheology of the nanofluids was Newtonian. The viscosity increment of SiO2, P25 and hybrid nanofluids were 19%, 32% and 24% with 0.5 vol% concentration. A new correlation was developed for the TC and dynamic viscosity of SiO2–P25 hybrid nanofluid. [ABSTRACT FROM AUTHOR]

Polyaniline nanotubes (PANI NTs) blended in refined, bleached and deodorized palm olein (RBDL) nanolubricants were prepared via a two-step method. Initially, the synthesized PANI NTs were characterized to investigate the morphology and elemental composition of the obtained PANI NTs. The obtained image from transmission electron microscopy clearly showed the presence of flake-like structure of PANI NTs. The presence of these PANI NTs was further affirmed with energy-dispersive X-ray analysis, which shows the presence of high carbon atoms (the main element for PANI NTs). The formulated surfactant-free nanolubricants were stabilized using ultrasonication with volume concentrations of 0.01, 0.03, 0.05, 0.1, 0.3 and 0.5%. The dispersion behavior of nanolubricants was investigated using visual sedimentation capturing, UV–Vis spectrophotometer and dynamic light scattering (DLS) method. The sedimentation observation of the nanolubricants over the duration of almost 1 month showed there was no sedimentation of the nanoparticles. UV–Vis spectra indicated that all the prepared PANI/RBDL nanolubricants followed Beer–Lambert law. The value of absorbance was found to be slightly decreased, with respect to the duration of time after sample preparation. The dispersion stability analysis supported by DLS method revealed that the amount of particles agglomeration increased after 1 month of preparation. The chemico-physical properties of prepared PANI/RBDL nanolubricants were further investigated by analyzing the chemical bonding using Fourier-transform infrared spectroscopy (FTIR). Additionally, this study intends to investigate the influence of PANI NTs toward the life cycle of base oil via thermogravimetric (TG) analysis. FTIR analysis showed that nanolubricants were chemically stable as there were only physical interactions between PANI additives and RBDL base oil, while the degradation behavior in TG curve demonstrated that the nanolubricants could withstand higher temperature as the volume concentration of nano-additives increased. Rheology and thermal conductivity properties of PANI/RBDL nanolubricants were performed by using rheometer and thermal properties analyzer, respectively. Viscosity measurement revealed that PANI/RBDL nanolubricants exhibited Newtonian behavior. Also, viscosity was found to have been increased with a volume concentration of PANI NTs but decreases with the increase in temperature. From the thermal conductivity measurement, it is proven that the PANI NTs dispersed in the RBDL palm base oil support the thermal properties enhancement. The 0.5% PANI/RBDL nanolubricants had achieved the highest thermal conductivity of 0.4301 W m−1 K −1 at 80 °C with enhancement percentage of 25.76% when compared to conventional base oil at a similar temperature. [ABSTRACT FROM AUTHOR]

In this study, different nanofluids synthesized with aluminium oxide (alumina) and titanium dioxide in mass ratios of 1%, 3%, and 5% were tested in an electric oil radiator heater. The base fluid is heat transfer oil, and the nanofluids were synthesized using the two-step method. Simultaneously, optimum ultrasonic mixing times and surfactant amounts were determined to increase the nanofluids' stability values. The stability of the nanofluids produced with alumina and titanium dioxide in mass ratios of 1%, 3%, and 5% was determined by using the sedimentation method. Among the alumina and titanium dioxide nanofluids whose thermal properties were measured, the nanofluids with the highest stability and the best thermal properties were used in heating experiments. The highest thermal improvement rates were 6% for alumina nanofluid and about 9% for titanium dioxide nanofluid, in the 5% mass ratio of nanoparticles. The temperature differences of the alumina and titanium dioxide nanofluids with respect to the base fluid were highest in the first region, at 8% and 10%, respectively, while the highest 11% and 27% temperature differences in the second region were measured, respectively. The stability values of the nanofluids in which significant increases in thermal values were obtained were maintained for long periods. It has been shown that nanofluids can be used in an industrial device. [ABSTRACT FROM AUTHOR]

In this paper, the detailed characterization of mechanical, electrical and thermal properties of Ag nanoparticle-reinforced Al6061 alloy was studied. Four composites with Al6061 alloys and different mass percentages (3%, 6%, 9% and 12%) of Ag nanoparticles were processed by stir casting method. The chemical analysis was used to confirm the elemental composition. The microstructural examination was carried out using optical microscopy. The phase analysis of the samples was studied using X-ray diffraction technique. The density and hardness were measured as per ASTM standards. Four-point probe tester and differential scanning calorimetry were used to measure the electrical conductivity and specific heat. In addition, the thermal conductivity and thermal diffusivity were measured using laser flash method. The results reveal the presence of Ag nanoparticles can significantly enhance the mechanical, electrical and thermal properties. [ABSTRACT FROM AUTHOR]

In this paper, a new designed silicon-containing nitrogen and phosphorus flame-retardant system containing ammonium polyphosphate, modified molecular sieve and methylcellulose was used to prepare the flame-retardant corrugated cardboards (FRCCB). The samples before and after treatment were tested for combustion and thermal stability using vertical burning test (VBT), limiting oxygen index (LOI), cone calorimetric test (CCT) and thermogravimetry (TG). To further analyze the flame-retardant properties of the flame-retardant system, the microstructure, surface elements and functional groups of the materials were characterized by the scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the samples were tested to analyze the effect of flame-retardant treatment on the strength. The VBT and LOI tests showed that the samples after the flame-retardant treatment were able to self-extinguish after ignition, achieving the flame-retardant B-1 grade. The CCT tests showed that the total heat release of treated samples was reduced by 49.90%, and the total smoke production was decreased by 27.64%. TG tests showed that the thermal decomposition temperature of FRCCB decreased but the residual carbon content increased largely. FTIR tests showed that the functional group changed at different temperatures. After flame-retardant treatment, a dense carbon layer was formed on the surface of the treated sample, including N, P, Si and Cu, measured by SEM and EDS. Combining with various characterization methods, the flame-retardant system can retard flame by releasing nonflammable gases, forming covers and catalyzing char formation. [ABSTRACT FROM AUTHOR]

Artificial neural network/kriging interpolation method optimization method which is evaluated concerned the hybrid nanofluid composed of iron oxide (Fe2O3) and aluminum oxide (Al2O3) nano-powders to improve the thermal properties of 10w40 engine oil at different amounts of volume fraction and temperature. An input-target dataset contains 30 input-target pairs. The proposed model is examined at non-trained inputs throughout the investigated intervals beside the first derivatives of the thermal conductivity with respect to temperature and nanoparticle mass fraction. It can be seen that the obtained results have suitable smoothness and continuity. Accordingly, the kriging method shows the acceptable outcomes through the experimental prediction of Al2O3/Fe2O3 nanoparticles dispersed in 10w40 engine oil. [ABSTRACT FROM AUTHOR]

The review presents the results of the investigations of the thermal properties of selected II–VI binary, ternary, and quaternary semiconductors. All tested crystals were grown from the melt using the high-pressure vertical Bridgman–Stockbarger method with different composition The main objective of the work was systematic examination of the thermal properties of the crystals using contact (PPE photopyroelectric) and non-contact (active thermography) measurement techniques. As a result of the studies, the values of the thermal diffusivity and the effusivity of all tested samples were obtained. For the selected series of crystals, their heat capacity was also determined. The thermal conductivity was calculated using simple relationships that combine all the thermal parameters. In this way, a complete thermal characterization of the crystals was carried out. For several ternary mixed crystals diagrams of the thermal conductivity versus composition were analyzed applying model for mixed semiconducting crystals given by Sadao Adachi. Thanks to that a contribution of the thermal resistivity arising from the lattice disorder to the total resistivity of the crystal has been determined. Although the PPE method itself is fairly simple, each material class requires a different approach. For samples with strongly different conductivity or thickness, different frequency ranges and a suitable detector should be used. This is not a simple task for the samples with unknown thermal properties. It is to mention that the PPE technique is a contact method and its main disadvantage in case of solid samples is to provide good thermal contact between the sample and the detector. In practice, it is realized by gluing a sample to the detector with a small amount of different types of liquids. It has been shown that the influence of the coupling layer can be minimized by appropriate modification of the experimental system and proper selection of the coupling fluid. In this way, the photopyroelectric method has been satisfactorily adapted for the thermal characterization of II–VI crystals. [ABSTRACT FROM AUTHOR]

In this study, ethylene glycol (EG)–water (35:65 %v)-based nanofluids have been prepared to study enhancement in thermal conductivity. Nanofluids containing nanoparticles of materials CuO, Al2O3 and TiO2 of different mass concentrations from 0.2 to 2% were prepared using ultrasonication. Thermal conductivity measurement was carried using KD2 Pro thermal properties analyser in the temperature range of 30–60 °C. The study investigated the effect of concentration of nanoparticles, temperature and nanoparticle material on effective thermal conductivity of nanofluids. The results showed a significant improvement in effective thermal conductivity due to the addition of nanoparticles to the base fluid. Correlations were developed for predicting the effective thermal conductivity considering each material separately, and a generalized correlation considering the three materials. Subsequently, ANN modelling was carried out for predicting the effective thermal conductivity of nanofluids and compared with developed correlations. The modelling work carried out in this study is more generalized as literature results were considered in addition to the results from the present study. ANN modelling predicts the effective thermal conductivity better than the proposed correlations. [ABSTRACT FROM AUTHOR]

The present analysis describes the effect of dissipative heat energy transfer in Ethylene–Glycol (EG) based on conducting nanofluid over a heated semi-infinite vertical plate past through a porous medium. Uniform magnetic field, heat source/sink, and the effect of particle concentration also have been discussed by incorporating in the energy and solutal transfer equations, respectively. In addition to that, the thermal properties of the nanofluid are affected by the thermal slip boundary condition since; the temperature slip is favorable for the reduction in the heat transfer. Assuming self-similar transformations, the governing PDEs are transformed into non-linear coupled ODEs. These transformed equations are solved by using semi-analytical techniques such as Adomian Decomposition Method (ADM). The characteristics of different parameters on the flow phenomena are obtained and presented via graphs. The numerical values of the thermophysical properties of both the nanoparticles and the base fluid are shown in the table. Validation of the present work is obtained by comparing our result with the earlier established result and it is found that both the results are coinciding with each other. However, the main quantified results are the following: due to heavy density of the Cu nanoparticles, increasing volume fraction in ethylene–glycol base fluid resists the fluid motion and the inclusion of dissipative heat energy is favorable to enhance the nanofluid temperature. [ABSTRACT FROM AUTHOR]

Given the excellent thermal properties of MXene, MXene nanomaterials-based nanofluids may have the potential of being used as heat transfer fluids. In this work, we have investigated the dynamic viscosity of MXene-palm oil nanofluid. To prepare the nanofluid, MXene ( Ti 3 C 2 ) nanoflakes were first synthesized by the wet chemistry method. Then, nanofluids with 0.01, 0.03, 0.05, 0.08, 0.1, and 0.2 mass% concentrations of MXene nanoflakes were prepared, and their dynamic viscosity values were determined for a wide temperature range of 18–100 ∘ C . The dynamic viscosity of the developed nanofluid, for each concentration, was found to be a strong function of temperature and decreased with increasing temperature. The effect of MXene nanoflakes concentration on the dynamic viscosity was found to be more significant at lower temperatures than at higher temperatures. A multilayer perceptron artificial neural network model was also developed in the study. To develop the model, temperature and nanoflakes concentration were given as inputs to the ANN model, whereas dynamic viscosity was the output of the model. The optimum model was found through the trial and error method. Statistical parameters such as mean square error, mean average percentage error, and correlation coefficient (R) were used to evaluate the performance of the developed model. The values of these parameters, for the optimum ANN model, were found to be 4.733E−05, 0.507%, and 0.99975, respectively. 95.67% of the deviations were also found to be in range of ± 2%. The developed model showed good performance, and its predictions were in excellent agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Nanofluids are considered a promising alternative to the classic fluids used in heat transfer processes. One interesting application of nanofluids is their use as a heat transfer fluid in thermosolar plants, such as those using concentrating solar power (CSP) technology. Therefore, this study presents the preparation of nanofluids based on TiO2 nanoparticles and the most common thermal oil used in CSP plants. The nanofluids were prepared using a one-step method by means of the solvothermal synthesis of TiO2 and also using a two-step method by means of ultrasonic waves and stabilizing the nanoparticles using 1-octadecanethiol as a surfactant. The stability of the nanofluids was analysed using UV–Vis spectroscopy, particle size and ζ potential measurements. The formation of TiO2 nanoparticles in the one-step method was detected using X-ray diffraction, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Thermophysical properties were also measured obtaining an atypical improvement of isobaric specific heat of up to 25.4% for the nanofluids prepared by the two-step method. For the nanofluids prepared by the two-step and one-step methods, thermal conductivity increased by up to 52.7% and 31.4% at higher temperatures, respectively. Finally, enhancements of up to 35.4% of the heat transfer coefficient were estimated, which means these nanofluids are suitable for being used as heat transfer fluids in CSP plants. [ABSTRACT FROM AUTHOR]

Buckwheat starch is an alternative source to supply the high global demand for starch. The properties of starch can be modified through chemical and physical methods; one of them is the milling process, which can be considered as green method according with the green chemistry principles. Thus, this work aims to use the milling process and study its effects on thermal and crystalline properties of starch extracted from common buckwheat (Fagopyrum esculentum). It was observed in differential scanning calorimetry and X-ray powder diffraction that after the milling process, the starch losted its crystallinity and was pre-gelatinized. Nevertheless, the samples showed similar decomposition, dehydration and oxidation profiles, as observed by thermogravimetry and differential thermal analysis curves. The thermal stability did not show considerable difference (less than 5 °C) after the milling process. Moreover, the medium infrared spectroscopy showed that the milling process did not change the functional groups of starch. The morphology of the starch granules, as observed by scanning electron microscope presented surface roughness, and also the decrease of the average diameter of the modified starch was observed. [ABSTRACT FROM AUTHOR]

Porous microspheres obtained from 2,3-epoxypropyl methacrylate (GMA) and 1,4-di(methacryloyloxymethyl) naphthalene (DMN) were modified by the reaction of active oxirane group with 1-(2-hydroxyethyl)-2-pyrrolidone (HP). Spherical shape of the copolymers was confirmed by scanning electron microscopy whereas low-temperature nitrogen adsorption–desorption method was applied to determine their porous structure. It was found that the modification process did not change noticeably the internal structure of the materials. The specific surface area for both types of materials ranged from 41 to 106 m2g−1 depending on the molar ratio of the monomers. Changes, however, were observed in reference to thermal properties. They were studied using differential scanning calorimetry and thermogravimetry coupled with FTIR in inert and oxidative conditions. The reaction with HP reinforced thermal stability of the modified microspheres in helium atmosphere. Their initial decomposition temperatures (IDTs) increased to 273–281 °C. In air atmosphere, the values of IDTs were at the same level (248–269 °C). The modified beads decomposed in three (helium) or two (air) stages. [ABSTRACT FROM AUTHOR]

Phenolic foam (PF) has excellent performance in fire resistance, thermal insulation and other fields. It has the advantages of lightweight, flame retardant, no dropping and low level of toxic gas emission during combustion. In order to learn the relationships between density and properties, PF samples with density of 40, 50 and 60 kg · m−3 were obtained by adjusting the amount of blowing agent. Their micro-characteristics were analyzed with Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) experiments. Mechanical properties were measured with universal extending machine. Thermal properties and stability were tested by laser thermal conductivity analyzer and thermogravimetry analysis (TG), respectively. FT-IR spectra of samples demonstrate that chemical structure will not be affected by the ratio of foaming agent. Higher density comes with better sealing property of the cell holes and leads to better compressive strength. Changing PF density with foaming agent dosage could affect insulation effect, and the sample with density of 60 kg · m−3 showed poor performance compared with the other foams. TG–DTG curves of the PF samples are similar. Evaporation of water, volatilization of phenols and aldehydes, and pyrolysis of surfactant and curing agents are the main reason for the mass loss. Residues of samples increased with the increase in density at 900 °C. Results of this study can clarify that changing the density of PF with amount of foaming agent will not affect its chemical properties, but the ratio has impact on its physical properties. [ABSTRACT FROM AUTHOR]

At present, inhibitors have been widely used in the field of coal fire prevention and control, but there are some defects in the use of them. So it is necessary to find a new practical and economical inhibitor. Dissolvable tiny-foam extinguisher (DTE) is environment-friendly, high in thermal stability, and fast in cooling. In view of the good performance of the product, the thermal behavior effects of DTE on coal spontaneous combustion were investigated through experimental tests. A scanning electron microscopy was used to study changes in the surface microstructure of raw coal after DTE treatment. Laser thermal conductivity analysis and simultaneous thermal analysis were used to test the effects of DTE at mass fraction of 0%, 5%, 10%, and 15% on the thermophysical properties, mass loss, characteristic temperature, and heat release of coal during heating. The surface of the DTE-treated coal sample was covered in a dense film. The treated coal sample had lower thermal diffusivity and thermal conductivity values and a higher specific heat capacity. Moreover, coal treated with DTE showed no obvious oxygen absorption or mass gain during initial heating, and the dry cracking temperature was greatly increased by 37 °C, 53 °C, and 100 °C, respectively. The initial heat release temperature increased by more than 170 °C, and the amount of the initial heat absorption was more than 52.2 times that of untreated samples. Oxidation kinetics were applied to calculate the activation energy of the coal during thermal decomposition and ignition, and the activation energies of the treated samples at the thermal decomposition and combustion stages increased by 161%, 179%, and 173%, respectively. From these results, we concluded that DTE could inhibit heat accumulation by blocking oxygen contact with the coal and greatly reducing heat release during heating. Besides, only a small quantity of DTE was needed to effectively inhibit coal self-ignition. These results provide reference for the field application of DTE in restraining coal spontaneous combustion. [ABSTRACT FROM AUTHOR]

Energy storage plays an important role in improving the applicability of a wide range of energy systems. Buildings could be considered as a desirable place for this purpose. Incorporating phase change materials (PCMs) as form-stable composites into the building materials has been widely taken into consideration in recent years. However, there are still some shortcomings in applying this technique. In this study, we focused on a surface modification method to prevent leakage of PCM from porous aggregates during heating/cooling cycles. Paraffin (PA) as phase change material was impregnated into the expanded perlite (EP) particles by vacuum impregnation method, and prepared EP/PA composite was coated by a layer of polystyrene. Thermal characterization of obtained composite samples was conducted by DSC and TG analysis. Also, a simple apparatus was prepared to evaluate thermal behavior of a concrete block made by these modified form-stable PCMs during the heating process. Oozing circle method and visual observation for leakage were conducted for surface-modified EP/PA particles and final concrete blocks, respectively. Finally, compressive strength test was applied to evaluate the feasibility of using concretes made by EP/PA composites as structural concrete. The results showed that using polystyrene as a coating material for EP/PA particles was a promising method for PCM leakage prevention. Latent heat value decreased about 18% for surface-modified EP/PA but no leakage trace was observed; also in spite of decreasing in compressive strength up to 40%, it is still in acceptable range for structural purposes. [ABSTRACT FROM AUTHOR]

High-pressure crystallization and resulting polymorphic composition of long-chain branched polypropylene (LCB-PP) were studied and compared with common linear isotactic polypropylene (PP). Commercially available LCB-PP and PP with similar melt flow indexes were crystallized under several high pressures (20, 40, 80, 120 and 160 MPa) at constant cooling rate 5 °C min−1. Structure of crystallized samples was evaluated via wide-angle X-ray scattering, differential scanning calorimetry and scanning electron microscopy. It was shown that under low pressure LCB-PP crystallizes at higher crystallization temperature than PP due to its higher nucleating density. The opposite situation is observed at high pressures (120 and 160 MPa): crystallization temperature of PP exceeds that of LCB-PP as a negative effect of branching is pronounced. Polymorphic analysis proved that LCB-PP tends to crystallize into orthorhombic γ-form. This crystalline form becomes to be dominant at 40 MPa, and LCB-PP samples crystallized at 120 and 160 MPa contain solely γ-form. On the other hand, no pure γ-form sample was prepared from PP in this study, although positive effect of pressure on its formation is observed. Thermodynamic stability of LCB-PP crystalline structure is systematically lower compared to PP. With pronounced crystallization pressure, the melting peak broadens and finally splits, indicating the presence of dominant amount of γ-form in LCB-PP. In comparison with PP, crystallites in LCB-PP structure are considerably smaller due to lower crystal growth rate and higher nucleating density. [ABSTRACT FROM AUTHOR]

Marquetry method is important in the culture of the Italian community as can be witnessed from the large quantity of artworks that have been realized in this way. The monitoring of the integrity of such pieces poses a great challenge given the need for a reliable and nondestructive technique able to detect surface and subsurface defects. In this work, two ancient marquetry samples containing natural defects were inspected thanks to active thermography by using time-tested, safe, and resilient advanced signal processing algorithms (i.e., principal component thermography, correlation contrast, pulsed phase Fourier transform amplitude and phase, cold image subtraction contrast, and polynomial fitting). The latter have been applied to provide a 2D map of the defects. Anyway, in the cultural heritage field, one of the main interests of restorers is the volume of the subsurface defects for structural analyses. The emphasis in this study is placed on the use of dynamic thermal tomography (DTT) as an advanced technique of active thermal nondestructive testing. The main concepts of DTT are illustrated in the manuscript, while a special technique for defect thermal characterization has been used during the second analysis to validate tomographic results. Finally, the position of the main defects retrieved by means of the established techniques applied during the first analysis has been confirmed by DTT. [ABSTRACT FROM AUTHOR]

The granules containing nitrogen of various content (12.2–13.3%) and stabilizers (centralite I, centralite II, akardite II, triphenylamine) were obtained in laboratory scale, and the study of their physicochemical and thermal properties was conducted. It has been observed that the helium density of granules depends on the degree of gelling of nitrocellulose by the stabilizer as well as the lack of effect of the stabilizer type on the heat of combustion value. In turn, the heat of combustion depends on the content of nitrogen in nitrocellulose. Granules of 13.3% N nitrocellulose were characterized by a more rapidly developing thermal decomposition than the granules containing 12.2 and 12.9% N nitrocellulose. The maximum temperature of decomposition shifts toward higher temperatures (from 207.6 to 209.8 °C) with decreasing nitrogen content in nitrocellulose for granules containing triphenylamine as a stabilizer. All values of heat generation rate obtained for granules with triphenylamine were lower than the respective rates for granules with centralite I. Thermal properties and chemical stability of granules containing triphenylamine have better properties, when compared to other examined stabilizers. On the basis of differential scanning calorimetry and thermogravimetry, kinetic parameters were calculated by means of Ozawa–Flynn–Wall analysis. The effect of stabilizers and nitrogen content on kinetic parameters was determined. The kinetic model of thermal decomposition of granules was adjusted—the best fit was nth-order reaction with autocatalysis. The activation energy of thermal decomposition process according to the adopted chemical reaction model increases from 190 to 239 kJ mol−1 with increasing nitrogen content in the granulate. [ABSTRACT FROM AUTHOR]

The thermal properties of chitosan and hydroxyapatite (HAp)-crosslinked polyurethanes (PU) prepared in a two-step bulk polymerization were investigated. Synthesis of PU was carried out using 1,6-hexamethylene diisocyanate, poly(ethylene glycol) 2000 and dibutyltin dilaurate as a catalyst. Various molar ratios of chitosan and 1,4-butanediol were applied, and the effects of incorporating different HAp amounts and the chitosan-to-BDO ratio were studied. It was found that the thermal properties of PU materials depend on polysaccharides and bioceramics load, which was confirmed by differential scanning calorimetry and thermogravimetry. The glass transition temperature increases with increasing chitosan fraction. Similarly, the onset temperature of degradation increased with chitosan addition. On the other hand, the presence of ceramics did not show a significant impact on the thermal properties of PU composites. Successful polymerization and chain extension of the isocyanate groups with hydroxyl moieties from chitosan and HAp were confirmed by Fourier transform infrared spectroscopy, and the morphology was examined using scanning electron microscopy. [ABSTRACT FROM AUTHOR]

A thermoplastic elastomeric blend from acrylonitrile butadiene rubber (NBR) and plasticized polyvinyl chloride (PVC) in the ratio (1:1) was prepared. This blend was loaded with different concentrations of mechanically ground fine powder of Moringa oleifera (MO) leaves that have an antibacterial activity, to form polymeric-based composites. The prepared composites were characterized to investigate their surface morphology and swelling behaviors. Besides, their mechanical and thermal properties were investigated. The tensile and hardness properties increased upon loading (MO) up to 20 phr. Thermogravimteric analysis (TGA) and derivative thermogravimetry (DTG) curves did not show complete deterioration upon introducing MO into the polymeric matrix. Differential scanning calorimetry (DSC) showed some shifts in the endo- and exotherms of DSC curves for PVC and NBR/PVC blend in the presence and in the absence of M. oleifera. The samples were tested biologically against Gram-positive and Gram-negative bacteria to show significant antibacterial activities. The antibacterial potency of the NBR/PVC blend increased with elevating the concentration of MO powder from 5 to 25% by mass. [ABSTRACT FROM AUTHOR]

COVID-19 is an epidemic virus arising from a freshly discovered coronavirus. Most people involved with the coronavirus will experience slight to moderate respiratory disease and recover without needing particular therapy. In this work, the atomic stability of the coronavirus at different thermodynamic properties such as temperature and pressure, was studied. For this purpose, the manner of this virus by atomic precession was described with a molecular dynamics approach. For the atomic stability of coronavirus description, physical properties such as temperature, total energy, volume variation, and atomic force of this structure were reported. In molecular dynamics approach, coronavirus is precisely simulated via S, O, N, and C atoms and performed Dreiding force field to describe these atoms interaction in the virus. Simulation results show that coronavirus stability has reciprocal relation with atomic temperature and pressure. Numerically, after 2.5 ns simulation, the potential energy varies from − 31,163 to − 26,041 eV by temperature changes from 300 to 400 K. Furthermore, this physical parameter decreases to − 28,045 eV rate at 300 K and 2 bar pressure. The volume of coronavirus is another crucial parameter to the stability description of this structure. The simulation shows that coronavirus volume 92% and 14% increases by 100 K and 2 bar variation of simulation temperature and pressure, respectively. [ABSTRACT FROM AUTHOR]

This paper experiments the trio influence of nanoparticles size (NS), per cent mass ratio (PWR), and temperature (T) on the thermal properties of MgO–ZnO/deionised water (DIW) nanofluids. MgO nanoparticles (20 nm and 100 nm) were hybridised with ZnO nanoparticles (20 nm) and suspended in DIW to formulate 0.1 vol% hybrid nanofluids at PWRs of 20:80, 40:60, 60:40, and 80:20 (MgO/ZnO). The pH, electrical conductivity (σ), viscosity (μ), and thermal conductivity (κ) of the hybrid nanofluids were experimentally determined at temperatures of 20–50 °C. The stability was monitored, while the morphology was examined using standard instruments. Findings showed that the suspension of the hybrid nanoparticles enhanced the pH and thermal properties of DIW. The hybrid nanofluids with 100 nm-MgO nanoparticles were observed to possess slightly higher values of pH, σ, and μ than those with 20 nm-MgO nanoparticles except for κ. An increase in temperature augmented κ and σ of MgO–ZnO/DIW nanofluids, while it detracted pH and μ. Maximum enhancements of 453.70–550.62% (40:60), 14.95–22.33% (40:60), and 8.29–17.46% (60:40) were evaluated for σ, κ, and μ, respectively. The influence of PWR, NS, and temperature on the σ, κ, μ, and pH of the hybrid nanofluids was in the order of PWR > NS > T, NS > PWR > T, T > NS > PWR, and T > NS > PWR, respectively. Subject to the experimental data obtained, correlations were developed for each hybrid nanofluid and thermal property as a function of temperature. The MgO–ZnO/DIW nanofluids with a 40:60 PWR appeared to be the best in terms of heat transfer capability. [ABSTRACT FROM AUTHOR]