Search Results
Abstract
DTA was used to study thermal properties and thermal stability of (50-x)Li2O-xTiO2-50P2O5 (x=0–10 mol%) and 45Li2Ot-yTiO2-(55-y)P2O5 (y=5–20 mol%) glasses. The addition of TiO2 to lithium phosphate glasses results in a non-linear increase of glass transition temperature. All prepared glasses crystallize under heating within the temperature range of 400–540°C. The lowest tendency towards crystallization have the glasses with x=7.5 and y=10 mol% TiO2. X-ray diffraction analysis showed that major compounds formed by annealing of the glasses were LiPO3, Li4 P2O7, TiP2O7 and NASICON-type LiTi2(PO4)3. DTA results also indicated that the maximum of nucleation rate for 45Li2O-5TiO2-50P2O5 glass is close to the glass transition temperature.
Abstract
Lignin-and molasses-based polyurethane (PU) foams with various lignin/molasses mixing ratios were prepared. The hydroxyl group in molasses and lignin is used as the reaction site and PU foams with various isocyanate (NCO)/the hydroxyl group (OH) ratios were obtained. Thermal properties of PU foams were investigated by differential scanning calorimetry (DSC), thermogravimetry (TG) and thermal conductivity measurement. Glass transition temperature (T g) was observed depending on NCO/OH ratio in a temperature range from ca. 80 to 120°C and thermal decomposition temperature (T d) from ca. 280 to 295°C. Mixing ratio of molasses and lignin polyol scarcely affected the T g and T d. Thermal conductivity of PU foams was in a range from 0.030 to 0.040 Wm−1 K−1 depending on mixing ratio of lignin and molasses.
Abstract
Since some combustible, oxidative and reductive chemicals are used in the extracting process in the nuclear reprocessing plant the process has potential hazards of a fire and explosion due to the undesired reaction. In this study to obtain a better understanding of the thermal properties of hydrazine in nitric acid solution which is used for preventing the oxidation of extracted plutonium, thermal analysis was carried out for the mixtures in various conditions. From the results of DSC it was revealed that the vessel material has an influence on the thermal decomposition of hydrazine. It was also found that hydrazine reacted with nitric acid in an autocatalytic manner, and concentration of nitric acid has a strong influence on the thermal hazard of hydrazine and nitric acid mixtures.
Center 2012 [5] Dynamic thermal properties calculator , Published by MPA, The Concrete Centre, Meadows Business Park, Station Approach, Blackwater, Camberley
Thermal properties of globulin from buckwheat ( Fagopyrum esculentum Moench)
Effects of salts and protein perturbants
Abstract
The thermal properties of buckwheat (Fagopyrum esculentum Moench) proteins with different lipid contents (2.5, 6.5 and 17.8%) were studied by differential scanning calorimetry (DSC) under various medium conditions. From DSC curves, many DSC characteristics including denaturation temperature (T d), enthalpy change (ΔH) and the width at half peak height (ΔT 1/2) of endothermic peaks were obtained and evaluated. The DSC curves of various buckwheat proteins (BWPs) in the 0.05 M phosphate buffer (pH 7.0) showed a major endotherm at about 102°C and a minor endotherm at about 80°C, attributed to thermal transitions of 13S and 8S globulins, respectively. T d and ΔH of the globulins of BWPs were independent of their lipid contents, while the presence of high lipid content (17.8%) to some extent increased the ΔT 1/2. The progressive increase in T d of 13S globulins with increase in NaCl concentration, suggests a more compact conformation with higher thermal stability. The influence of chaotropic salts on the DSC characteristics of 13S globulins was also independent of their lipid contents. Thermal analysis of the 13S globulins in the presence of protein perturbants (including urea, sodium dodecyl sulfate, ethylene glycol, dithiothreitol and N-ethylmaleimide) indicated that hydrophobic and hydrogen bondings are the major interactions for stabilizing protein conformation of buckwheat 13S globulins and the SS-SH interchange also attributes to the stabilization of the protein conformation.
Abstract
In this article, synthesis, characterization, and thermal properties of diacrylic/divinylbenzene copolymers based on the new aromatic tetrafunctional acrylate monomers are presented. The new monomers were generated by treatment of epoxides derived from various aromatic diols: naphthalene-2,3-diol (NAF), biphenyl-4,4′-diol (BIF), bis(4-hydroxyphenyl)methanone (BEP) or 4,4′-thiodiphenol (BES), and epichlorohydrin with acrylic acid. The addition reaction was carried out by a ratio of 0.5 mol of suitable epoxy derivative and 1 mol of acrylic acid in the presence of 0.7 wt% of triethylbenzylammonia chloride (TEBAC) as a catalyst and 0.045 wt% of hydroquinone as a polymerization inhibitor. The chemical structure of the prepared acrylate monomers was confirmed by 13C NMR and GC MS spectra. The emulsion–suspension polymerization of acrylate monomers with divinylbenzene (DVB) in the presence of pore-forming diluents (toluene + decan-1-ol) allowed obtaining microspheres containing pendant functional groups (hydroxyl groups). This process was carried out at constant mol ratio of acrylate monomers: DVB (1:1), and constant volume ratio of pore-forming diluents to monomers (1:1). The different concentrations of toluene in the mixture with decan-1-ol were used for qualifying the effect of the diluents on the microsphere characteristics. The influence of synthesis’s parameters on the properties of copolymer beads, e.g., pore size and surface area by BET method, the surface texture by AFM, swelling behavior in polar and non-polar solvents as well as thermal stability by differential scanning calorimetry (DSC), and thermogravimetric analysis (TG) was studied and discussed.
The thermal properties of chitin ammonosphosphate complexes with methanol are discussed. The endothermic effect of chitin ammonophosphate decomposition is dependent on the substitution degree. The chitin ammonophosphates have a lower ability to form complexes with methanol than chitin itself. The bonding energy of methanol with chitin ammonophosphates is dependent on the substitution degree of the ammonophosphate group. As the substitution degree increases, the quantity of methanol bonded to the chitin ammonophosphate decreases, as does the bonding energy of the methanol; this is manifested in a lower endothermic effect and a lower temperature of the maximum of this effect.
The temperature dependence of the thermal properties (specific heat,C p, thermal diffusivity,a, and thermal conductivity,K) of endellite clay has been investigated over the temperature rangeR·T⩽T≲/280 °C using the plane temperature wave technique. The experimental results showed that in the initial stage of temperature rise botha andK diminish exponentially with increasing temperature up to ∼100 °C. Above 100 °C, the thermal parameters are found to reach stable values, namely,C p=0.22±0.008 cal g−1 deg−1,a=(5.0±0.18)−10−4 cm2 sec− 1 andK=(2.2±0.16) · 10−4 cal cm−1 sec−1 deg−1. The explanation of the results was supported by using DTA and TG analysis.
Characterization of sugar palm (Arenga pinnata) fibres
Tensile and thermal properties
thermal properties give significant contribution in understanding the behaviour of their fibres and composites [ 28 – 36 ]. This paper studies the tensile and thermal properties of sugar palm fibres obtained from different heights (1, 3, 5, 7, 9
preparation of AC is the determination of their thermal properties. Thermal properties of CTPes and pitch-polymer compositions are evaluated mainly on the basis of the measurement of softening point. In this study, DSC method was proposed for this evaluation
