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In this study, a series of binary mixtures of N-butyl stearate (nBS) and methyl palmitate (MP) were used to produce a novel composite phase change material (CPCM) for potential application in the eastern China, and their thermal properties were investigated by differential scanning calorimetry (DSC). The results of DSC indicated that the mixture consisting of 10 mass% nBS and 90 mass% MP is optimum as the CPCM in terms of the phase change temperature ranges ( T = 19.74-5.59 °C; T = 18.34-33.80 °C) and latent heats (Δ H = 176.8 J g; Δ H = 189.3 J g). On the other hand, the thermal reliability and chemical stability of the CPCM after 120, 180, 240, 300, 360 and 500 accelerated thermal cycling tests were studied by DSC and fourier transform infrared (FTIR) analysis. The results demonstrated that the CPCM had good thermal reliability and chemical stability. [ABSTRACT FROM AUTHOR]

In this work, the stability of formed CaF and its influence on the thermal behavior of C-S-H in CaO-silica gel waste-HO system were investigated. The hydrothermal synthesis of calcium silicate hydrates was performed at 200 °C, when the duration of synthesis and the molar ratios of the primary CaO/SiO mixtures were 0.55 (16 h), 0.66 (48 h), 0.83 (48 h), and 1.0 (48 h). Later on, synthesized products were calcined in a 600-1000 °C temperature range for 30 min. It was determined that fluoride ions, from silica gel waste, participated not only for the formation of CaF, but also intercalated into the structure of products during hydrothermal synthesis and, also, exchanged the formation sequence of new compounds. It was found that, during calcination, the chemical composition of synthesized C-S-H affects the stability of formed CaF, because it remained stable in the system with C/S molar ratio of 0.55 and 0.66. Meanwhile, in the system with higher C/S molar ratio of 0.83 and 1.0, CaF fully recrystallized into cuspidine. Moreover, it was estimated that the recrystallization processes and the formation of new compounds influenced the morphology of calcined products. In addition, EDX analysis showed that 9.05 mass% of fluorine are present in the crystal structure of calcination products. The obtained results were confirmed by the XRD, STA, FT-IR, and SEM/EDX analysis data. [ABSTRACT FROM AUTHOR]

A series of flame-retarded epoxy resins (EPN) loaded with methyl phenyl silicone resin (Si603) and DOPO (9, 10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) have been prepared. The morphology of these EPN composites were characterized by differential scanning calorimentry (DSC). The mixed epoxy systems all exhibit single glass transition temperature which indicates a homogeneous morphology of these mixed epoxy systems. The thermal stability and flammability of these EPN composites were investigated with limiting oxygen index, UL 94 vertical burning, and themogravimetric analysis tests (TG). The results showed that the DOPO and Si603 system had excellent flame retardancy and antidripping properties for EPN. The TG curves suggested that there was a distinct synergistic effect of DOPO and Si603, and this effect greatly promoted the char formation of the EPN composites and hence improved the flame retardancy. Additionally, the structure and morphology of char residues were studied with Fourier transform infrared and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Thermal properties and structure of bulk glasses of (AsS)(SbS) system ( x varies from 0 to 60 mol%) were studied by differential scanning calorimetry and Raman spectroscopy. It was found that with increasing Sb content the glasses can be sorted out to the three groups. The structure of glasses with x ≤ 10 is build-up mainly from AsS pyramidal units and the well-known crystallization resistance of AsS can explain the reluctance of these undercooled liquids against crystallization. In glasses with a higher content of antimony, i.e., 10 < x ≤ 30 mol%, the vibration characteristics of AsS clusters appear. Undercooled melts of these glasses crystallize forming both β-AsS and high-temperature phases of SbS. Structure of glasses with the highest antimony content ( x > 30 mol%) is based on SbS structural units significantly lowering stability of their undercooled melts from which only SbS crystallizes. [ABSTRACT FROM AUTHOR]

The present paper describes the test results concerning the thermal properties and flammability of the selected sealing plates and rubbers that may become components of plates. The thermal analysis methods (DTA, DSC, TG, and DTG) and flammability methods (OI, rate of burning in air, and ignition temperature) were used in this study. The thermal analysis of plates was also performed under isothermal conditions. It was stated that investigated sealing plates belong to the group of flame-retardant materials and type of rubber included in plate influences its thermal stability and combustibility. [ABSTRACT FROM AUTHOR]

The paper concerns thermal properties of epoxy/nanotubes composites for aircraft application. In this work, influence of carbon nanotubes on thermal stability, thermal conductivity, and crosslinking density of epoxy matrix was determined. Three kinds of nanotubes were used: non-modified with 1- and 1.5-μm length, and 1-μm length modified with amino groups. Scanning electron microscopy observations were done for examining dispersion of nanotubes in the epoxy matrix. Glass transition temperature ( T) was readout from differential scanning calorimetry. From dynamic mechanical analysis, crosslinking density was calculated for epoxy and its composites. Also, thermogravimetric analysis was done to determine influence of nanotubes addition on thermal stability and decomposition process of composites. Activation energy was calculated from TGA curves by Flynn-Wall-Ozawa method. Thermal diffusivity was also measured. SEM images proved the uniform dispersion of carbon nanotubes without any agglomerates. It was found that nanotubes modified with amino groups lead to the increase of epoxy matrix crosslinking density. The significant increase in T was also observed. On the other hand, addition of carbon nanotubes leads to the decrease of thermal stability of polymer due to the increase of thermal diffusivity. [ABSTRACT FROM AUTHOR]

The thermo-physical properties of diglycidyl ether of bisphenol A (DGEBA)/isophoronediamine (IPDA) with iron nanoparticles were investigated using DSC, DMT, and TG analysis. Because of the higher values of the glass transition, it is recognized that the optimum behavior of the three-component system corresponds to the 10% loading level of iron nanoparticles. The addition of iron nanoparticles into the epoxy matrix resulted in a significant increment in the storage modulus and crosslink density. Also, the DGEBA/IPDA/10% iron nanoparticles showed an enhanced thermal stability owing to the introduction of iron nanoparticles as reinforcing filler. Curing reaction of DGEBA/IPDA with 10% iron nanoparticles was investigated by DSC at dynamic mode. Activation energy was calculated based on Kissinger method (66.52 kJ mol). Also, the advanced isoconversional method is utilized to describe the curing reaction process. In the dynamic DSC analyses, the curing kinetics could be successfully described with the two-parameter autocatalytic model (Sěsták-Berggren equation) and the overall reaction order was about 2.78. [ABSTRACT FROM AUTHOR]

New branched polymethylvinylborosiloxanes (PMVBSs) with random structures were prepared, and their chemical structures were studied by spectroscopic methods (FTIR, H-, Si-, and B-NMR) and elemental analysis (% C, % H, % Si, and % B). Average molecular weights M and M were determined by a size exclusion chromatography (SEC), and dynamic viscosities were measured in Brookfield cone-plate reoviscometer HBDV-II+cP. Thermal properties of PMVBSs were studied under air and under nitrogen atmosphere. Thermal curves were interpreted from the point of view of physical and chemical transitions, taking place during the heating process of PMVBSs. Parameters of their thermal stabilities and glass transition temperatures ( T) were determined. The synthesized PMVBSs are characterized by low glass transition temperatures ( T: from −122 to −137 °C) which depend on their chemical structures. It was concluded that gaseous products (such as volatile siloxanes, silanes, CO, HO, CHO, methanol, and formic acid), which could be liberated during the heating process of PMVBSs, promote ceramization processes, leading to the formation of the ceramics of a type SiBCO-a borosilicate glass and silica. [ABSTRACT FROM AUTHOR]

High-density polyethylene-based nanocomposites were prepared through a melt compounding process by using surface functionalized fumed silica nanoparticles in various amounts, in order to investigate their capability to improve both mechanical properties and resistance to thermal degradation. The fine dispersion of silica aggregates led to noticeable improvements of both the elastic modulus and of the stress at yield proportionally to the filler content, while the tensile properties at break were not impaired even at elevated filler content. Thermogravimetric analysis showed that the selected nanoparticles were extremely effective both in increasing the decomposition temperature and in decreasing the mass loss rate, even at relatively low filler loadings. The formation of a char enriched layer, limiting the diffusion of the oxygen through the nanofilled samples, was responsible of noticeable improvements of the limiting oxygen index, especially at elevated silica loadings. In contrast with commonly reported literature results, cone calorimeter tests also revealed the efficacy of functionalized nanoparticles in delaying the time to ignition and in decreasing the heat release rate values. Therefore, the addition of functionalized fumed silica nanoparticles could represent an effective way to enhance the flammability properties of polyolefin matrices even at low filler concentrations. [ABSTRACT FROM AUTHOR]

The aim of this study was to characterize tensile and thermal properties of sugar palm ( Arenga pinnata) fibres obtained from different heights (1, 3, 5, 7, 9, 11, 13, and 15 m) of sugar palm tree. This study has confirmed that in a mature sugar palm tree, degradation was occurred and altered the properties of its fibre. Fibres obtained at the area of live (green) palm frond were found to have a better tensile properties as a result of its optimum chemical composition especially cellulose, hemicelluloses and lignin. For the fibre obtained from the upper part of sugar palm tree, it shows slightly decreasing trend in tensile properties compared to mature fibres. It is due to the fibres are juvenile where their cell walls are progressively built up thus give slightly lower properties than matured fibres. For the fibre obtained from the area of dead palm frond, the fibres are considered to be degraded biologically. It is believed that polymeric chains in microfibrils were broken and their cellulose content was decreased which demonstrated inferior properties (tensile strength, modulus, elongation at break and toughness). The use of such fibre for application as reinforcing fibre in composite is not recommended since the strength of the fibre and composite will be reduced. There were four phases of decomposition of the fibres where the sequence of decomposition started with decomposition of moisture, followed by hemicelluloses, then cellulose and next is lignin while the ash was the last component left. The thermal degradation of these components were found in ranges of 45-123, 210-300, 300-400, 160-900 and 1723 °C, respectively. Thermogravimetric analysis and derivative thermogravimetric analysis curves showed that the fibre of 1 m showed higher thermal stability than the fibres of 3-15 m. The different thermal stability for each fibre was due to different chemical compositions especially when the fibre containing high ash content which result in higher thermal stability. [ABSTRACT FROM AUTHOR]