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The stem bark of Acacia caesia, or Senegalia caesia, richly available in the Western Ghats of Tamilnadu and Kerala, India, does potentially offer a ligno-cellulosic fiber, which was characterized in this work, studying its chemical composition, morphology, and thermal degradation. The as-received fibers, which were extracted as technical fibers with diameters ranging between 100 and 150 µm, had a density of 1200 kg/m3. Their composition included 37% cellulose, 20% hemicellulose and 18% lignin, not very dissimilar, among other fibers, from alfa esparto and particularly coir. Their thermal degradation onset was at 308°C, which suggested a potential in composite application with traditional oil-based matrices and possibly also in the long run on bio-based ones. However, their high roughness and easy splitting of the fibers suggested that possible use as the filler for composites would require fiber treatment, namely, to remove undesired loose parts, hence regularizing their geometry. This would also serve to reduce the likeliness of longitudinal splitting, which is a widely recognized occurrence during stripping of bark fibers. [ABSTRACT FROM AUTHOR]

A new method for estimating the thermal properties of composite materials is proposed. It uses a previously developed thermal characterization method that is based on Karhunen–Loève decomposition (KLD) techniques in association with infrared thermography experiments or any other kind of experimental device providing dense data in spatial coordinates. The novelty of this work lies in the introduction of two techniques based on two phase-wise defined test functions that extend the previously developed method to cases where the morphology of the composite material is not straightforward. Thanks to the orthogonal properties of KLD, only a few eigenelements are needed for an accurate estimation, which allows for a significant amplification of the signal/noise ratios. Furthermore, the proposed methods represent an attractive combination of parsimony and robustness to noise thanks to spatially uncorrelated noise being entirely reported on states. The effectiveness and accuracy of both techniques are proven with numerical tests. [ABSTRACT FROM AUTHOR]

New poly(urethane-sulfone)s networks were prepared by the [3 + 2] dipolar cycloaddition of azidomethyl polyethersulfone to urethane-bismaleimides based on various polyols different by their structure and molecular weight. The chemical structure of these polymers was confirmed by the Fourier transform infrared and nuclear magnetic resonance spectroscopy. The new polymers were characterized using thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, as well as by stress-strain and water contact angle measurements. [ABSTRACT FROM AUTHOR]

The technology to produce compatibilized blends of liquid crystalline polymer and highly amorphous cyclic olefin copolymers through two novel approaches were studied. The first approach was to use silane-functionalized halloysite nanotube as nonspecific compatibilizer and the second method was reactive compatibilization. The study of blends and their resulting microstructure; their thermal, mechanical, and viscoelastic properties were investigated. The kinetic study of blends compatibilized through both routes was performed. [ABSTRACT FROM PUBLISHER]

This paper presents a thermal characterization of salt mixtures applying the T-History method (THM) and the differential scanning calorimetry (DSC) techniques. By using water as a standard substance, the original THM was developed to analyze materials with melting points under 100°C. This is the first research that proposes to replace water by glycerin to characterize medium-melting-temperature phase-change materials (PCMs) (140–220°C). Moreover, the DSC technique was used to validate and compare the results obtained with the THM for each mixture. For instance, the system compound of 40% KNO3–60% NaNO3 was studied, and the enthalpy of fusion determined by THM and DSC differs by 2.1% between each method. The results given by the two methods for all mixtures showed that both techniques are complementary and present satisfactory agreement with the specialized literature. [ABSTRACT FROM AUTHOR]

Advances in nano-electronics, nano-optics, energy harvesting materials, and nanoparticle-based photothermal therapies are motivating studies of the thermal properties of micro/nanostructures. Thus, the demands for highly sensitive and accurate thermal measurement techniques are encouraged for both fundamental studies and industrial applications. The time-domain thermoreflectance (TDTR) method, based on an ultrafast pump-probe technique, enables high-fidelity thermal measurements at the micro/nanoscale and the observation of dynamic processes with sub-picosecond time resolution. TDTR is an optical technique, capable of measuring the thermal properties of micro/nanostructures, including thermal conductivity and interfacial thermal conductance of bulk substrates, thin films, and nanoparticles, among others. Here we review some recent developments in the state-of-the-art ultrafast pump-probe method applied to study the thermal and magnetic properties of materials at the micro- and nanometer scales. We also discuss in detail improvements to this technique by presenting several example extensions to its capabilities. [ABSTRACT FROM AUTHOR]

Spent coffee grounds (SCG) and coffee husks (CH) were evaluated as biofuels, after densification, for energy production. CH represent a specific problem for the coffee industry due to a low calorific value, high ash content, and a very low bulk density. Hence, the energetic potential of SCG (95 wt%)/CH (5 wt%) blend and pure SCG (100%) were examined. The blend of SCG and CH was limited to 5 wt% of CH because of the low bulk density of CH. Therefore, physicochemical and energetic characterizations of the produced pellets were performed. Thermogravimetric analyses were performed under nitrogen and air atmospheres to evaluate the CH behavior in the blend. Characterization study shows that both produced pellets could reach the French Agropellets standard (AQI). Thermal degradation showed that the mean reactivity of the SCG/HC pellets was higher than pure SCG. Then, combustion experiments were performed in a domestic combustor, after modification of the boiler power in order to improve its energetic performances. The presence of CH led to a rise of CO, NOx, VOC’s, and particle emissions. Nevertheless, the performances of the biofuels are almost in agreement the NF EN 12809 standard. [ABSTRACT FROM AUTHOR]

Microalgae are viewed as one of the potential feedstock for biomass production. In the present investigation, the technology of thermo gravimetric analysis, carbon, hydrogen, nitrogen elemental analysis combined with Fourier transform infrared spectroscopy was applied to study the characteristics of algal biomass (Scenedesmussp.). The algal biomass samples were analyzed to identify the surface functionality and thermal stability of the biomass and release characteristics of the gas products. Fourier infrared spectroscopy examination of algal biomass revealed the presence of –OH, –COOH, NH2, and C=O organic compound groups. The results suggest that the biomass ofScenedesmussp. is a sustainable green energy source. [ABSTRACT FROM AUTHOR]

There has been much debate in the literature over the past 60 years regarding an appropriate oven-drying temperature for water content determinations in peat and other organic soils. For inorganic soils, the water content is usually based on the equilibrium dry mass corresponding to drying temperatures in the range 100–110°C. However, for peat and other organic soils, several researchers have recommended lower drying temperatures in the range 60–90°C in an attempt to prevent possible charring, oxidation, and/or vaporization of substances other than pore water. However, all of the relevant water is not fully evaporated at too low a temperature, and because specimen dry mass is a function of drying temperature, the resulting water content values are lower than those determined for the temperature range 100–110°C. Experimental data reported in this article show that oven drying of peat and other organic soils at 100–110°C using either gravity–convection or forced-draft ovens is acceptable for routine water content determinations. Because a standardized oven temperature is desirable when correlating water content with other material properties, it is recommended that oven drying of peat and other organic soils be performed over temperature ranges of either 105–110°C or 105 ± 5°C, in line with standardized ranges for inorganic soils. [ABSTRACT FROM AUTHOR]

A new method for thermal characterization of heterogeneous materials has been proposed. As for homogeneous materials in the first part of the paper, the method is based on the use of Karhunen–Loève decomposition (KLD) techniques in association with infrared thermography experiments or any other experimental device providing dense data in the spatial coordinate. Orthogonal properties of KLD eigenfunctions and states are used for achieving simple estimates of thermal diffusivities. It has been proven that diffusivities can be estimated without explicit knowledge of variables and parameters related to heat exchanges at the interfaces (i.e. thermal conductivities, thermal contact resistances). Indeed, the diffusivities estimates only depend on some few KLD eigenelements. As a result, a significant amplification of the signal/noise ratios is reached. Moreover, it is shown that spatially uncorrelated noise has no effect on KLD eigenfunctions, the noise being entirely reported on states (time-dependent projection coefficients). This is particularly interesting because thermal diffusivities estimates involve spatial derivatives of the eigenfunctions. Consequently, the proposed method results in an attractive combination of parsimony and robustness to noise. The effectiveness of the method is illustrated through some simulated experimental applications. [ABSTRACT FROM PUBLISHER]

A new method for reliable thermal characterization of orthotropic, homogeneous materials is proposed. It is based on the use of Karhunen–Loève Decomposition (KLD) techniques in association with infrared thermography experiments or any other kind of experimental device providing dense data in the spatial coordinate. Main problem addressed in this paper is how to deal efficiently with large amount of rather noised experimental data. It is proven that orthogonal properties of KLD eigenfunctions and states allow achieving simple estimates of thermal diffusivities which depend only on the first and the second KLD eigenelements. This means that the 2D KLD approximation of the temperature field provides information enough for estimation purposes. As a result, a significant amplification of the signal/noise ratios is reached. Moreover, we prove that spatially uncorrelated noise has no effect on KLD eigenfunctions, the noise being entirely reported on states (time-dependent projection coefficients). This is particularly interesting because thermal diffusivities estimation involves spatial derivatives of the eigenfunctions calculation. Consequently, the proposed method results in an attractive combination of parsimony and robustness to noise. Indeed, because it does not require analytical solutions of the associated heat conduction problem, the method could be extended to application involving heterogeneous materials. The second part of the paper deals with this extension. [ABSTRACT FROM PUBLISHER]

A series of aromatic polysulfonamides with various monomer ratios of 4,4′-diaminodiphenylsulfone (p-DDS) and 3,3′-diaminodiphenylsulfone (m-DDS) were synthesized to investigate the relationship between copolymer composition and their properties. The copolymer composition was determined from nuclear magnetic resonance (NMR). It was found that the copolymer composition of the polysulfonamides varied little from the monomer ratio; thus, similar reactivity of the two diaminodiphenylsulfones was shown by the results. From the analysis of the thermal properties of the polysulfonamides, high thermal stability of the copolymers was shown both in N2 and air and the decomposition temperature exhibited little dependence on the copolymer composition. However, the glass transition temperatures (Tg ) decreased obviously with increasing m-DDS segments, which is helpful to improve the solubility and spinnability of these polysulfonamides. [ABSTRACT FROM PUBLISHER]

This study aimed at utilizing nutraceutical industrial waste and reducing carbon footprints of plastics. Vinyl ester green composites (VEGCs) have been prepared with turmeric spent A (TS) and organically modified layered silicates (o-montmorilonite, MMT) (organoclays). Tensile behavior and impact strength of vinyl ester matrix thermoset composites were characterized. Thermal characteristics of the vinyl ester/MMT/TS green composites were evaluated by using differential scanning calorimetric (DSC), thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMA). Morphological behavior of nanocomposites has been studied by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). [ABSTRACT FROM AUTHOR]

Novel triphenylamine-based linear, hyperbranched and branched conjugated polyazomethines have been synthesized by free-catalyst solution polycondensation of 1,4-diaminobenzene with 4,4′-diformyl triphenylamine, 4,4′,4′′-triformyl triphenylamine and their mixture in different molar ratios. Linear polyazomethine has a good solubility in organic solvents while branched and hyperbranched polymers are partially soluble. A wholly soluble hyperbranched polyazomethine was obtained by end-capping of polymer at gelation point using a monofunctional aromatic amine, p-anisidine. Characterization of all polymers was made by 1H-NMR, FT-IR and UV-Vis and photoluminescence spectroscopy and thermal methods. Electrochemical behavior of polymers was studied by cyclic voltammetry using thin films cast from THF solution on a platinum disc working electrode in acetonitrile solvent and tetrabutylammonium tetrafluoroborate as electrolyte. [ABSTRACT FROM AUTHOR]

Thermal and dynamic mechanical properties of kenaf natural fiber reinforced polypropylene (PP) biocomposites were examined to compare the effects of natural fiber treatment by electron beam irradiation (EBI) and alkalization. The alpha cellulose contents, the functional groups on the surfaces and the thermal stability of the untreated and treated kenaf fibers were studied. Kenaf fiber/polypropylene(PP) biocomposites were fabricated by means of a compression molding technique using chopped kenaf fibers treated with electron beam (EB) dosages of 100, 200, 500 kGy or with NaOH concentrations of 2, 5, 10 wt%, respectively. The thermal stability, the dynamic mechanical and the interfacial properties of untreated and treated kenaf/PP biocomposites were also investigated through a thermogravimetric analysis, a dynamic mechanical analysis and a fractographic observation, respectively. The results show that the characteristics of kenaf fibers and biocomposites depended on the different treatment level with the EB dosages or on the NaOH concentrations used. In this study, the modification of kenaf fiber surfaces at 200 kGy EBI and treatment with 5 wt% NaOH was most effective for improving the performance of kenaf/PP biocomposites. This study suggests that EBI can be used for modification of natural fiber as an environmentally friendly process and contribute to an improvement in the performances of kenaf/PP biocomposites. [ABSTRACT FROM AUTHOR]

This article reports a detailed finite element analysis for thermal characterization of switched reluctance motors (SRM). Prediction of steady-state and transient thermal characteristics of SRM is presented. The convection coefficient at different heat dissipating walls inside SRM, which is not a material property, but a quantity that solely depends on the air velocity at the respective walls, is the major parameter to be evaluated carefully for an accurate simulation of heat distribution. A computational fluid dynamics (CFD) procedure is implemented for the first time on SRM for this purpose. The basic equations, various steps to be followed during three dimensional finite element thermal analysis, and the results of simulations are presented. [ABSTRACT FROM AUTHOR]

Poly (vinyl alcohol) / Poly (4 vinyl pyridine) copolymer hydrogel was prepared using gamma irradiation as initiator. The effect of PVA/4-VP composition and irradiation dose on the gel content in the prepared hydrogel was determined. It was found that as the content of 4-VP increased the gel percent increased. The increase in irradiation dose resulted in increasing the crosslinked network structure and consequently the gel percent increased. Swelling properties of the prepared hydrogel were also investigated as a function of immersion time, hydrogel composition and gel content. Thermal characterization was determined using TGA and DSC techniques to find that such hydrogel is thermally stable for heating up to 300°C. Thermal parameters are dependent on the hydrogel composition in which the glass transition temperature increased with 4-VP content. The possibility of practical use of the prepared hydrogel in the treatment of water from industrial waste dyes was studied. The effect of treatment time, temperature, pH of feed solution, type of dye and hydrogel composition on the dye uptake was also determined. The prepared hydrogel possessed good hydrophilic and thermal properties, high affinity towards acidic dyes, and good durability, which may make it promising for practical use in the separation processes. [ABSTRACT FROM AUTHOR]