Authors:D. Chinn, Sang -Beom Shim, and J. C. Seferis
Five epoxy resins of different chemistry and functionality were cured with DDS (4,4′-diaminodiphenyl sulfone) using 2, 8 and 14 h curecycles. Both Differential Scanning Calorimetry (DSC) and Thermomechanical Analysis (TMA) were used to characterize reaction behavior and cured properties of the resin systems. In addition, static mechanical tests and density measurements were integrated with the thermal characterization methods to correlate resin properties with process time. Flexural three-point bending experiments showed that the resins tended to have higher yield stress and toughness values at extended cure times. The improved mechanical properties could be attributed to the full development of the epoxy molecular structure, in the form of cross-linked networks and molecular rearrangement. These results suggest that extended cure times or high temperature post-curing may be required to obtain the resin's ultimate mechanical properties for high performance composites.
Authors:Dragana Živković, A. Milosavljević, A. Mitovski, and B. Marjanović
The results of thermodynamics and characterization of alloys in ternary Ag-In-Sn system is presented in this paper. Thermodynamic
properties, in three investigated sections with molar ratio In:Sn=1:1, 1:2 and 1:4, have been calculated at the temperature
of 1423 K using different predicting methods (general solution model, Toop, Hillert, Muggianu, Kohler, Redlich-Kister), compared
mutually and with literature experimental data. The alloys in investigated sections have been characterized using DTA, XRD,
SEM and optic microscopy.
The synthesis and characterization of lanthanide(III) citrates with stoichiometries 1:1 and 2:3; [LnL·xH2O] and [Ln2(LH)3·2H2O], Ln=La, Ce, Pr, Nd, Sm and Eu are reported. L stands for (C6O7H5)3− and LH for (C6O7H6)2−. Infrared absorption spectra of both series evidence coordination of carboxylate groups through symmetric bridges or chelation.
X-ray powder patterns show the amorphous character of [LnL·xH2O]. The compounds [Ln2LH3·2H2O] are crystalline and isomorphous. Emission spectra of Eu compounds suggest C2v symmetry for the coordination polyhedron of [LnL·xH2O] and C4v for [Ln2(LH)3·2H2O]. Thermal analyses (TG-DTG-DTA) were carried out for both series. The thermal analysis patterns of the two series are quite
different and both fit in a 4-step model of thermal decomposition, with lanthanide oxides as final products.
Authors:G. Madhurambal, P. Ramasamy, P. AnbuSrinivasan, M. Suganthi, G. Vasudevan, and S. Mojumdar
Good quality benzophenone (BP) crystals were grown by solution technique using CHCl3 as solvent by adopting slow evaporation method at room temperature. The grown crystals were subjected to various characterization
studies to analyze its purity and applications. The condensation product 2,4-dinitro phenyl hydrazone of benzophenone (DNPBP)
was prepared by adopting standard procedure. Then mixed crystal of BP and DNPBP was also grown by solution growth. Both the
condensation product and mixed crystals were characterized by UV, FTIR, 1H NMR spectra. Thermal (TG and DTA) studies have proved to be very useful techniques not only to study the thermal properties
of BP, DNPBP and mixed crystal but also to study their purity. Second harmonic generation (SHG) efficiency of the grown crystals
Authors:U. Rakibe, R. Tiwari, V. Rane, and P. Wakte
chromatography–tandem mass spectrometry (LC–MS/MS) in human plasma [ 3 – 6 ]. Moreover, there are reports available on synthesis and characterization of process-related impurities of olmesartan medoxomil [ 7 , 8 ]. AT is also reported for the determination of
Authors:S.V. Mulgund, S. Anbazhegan, and S.Y. Gabhe
In the present study, the degradation behavior of Fenofibrate under different International Conference on Harmonization (ICH) suggested conditions was studied. Characterization of degradation products by liquid chromatography–tandem mass spectrometry (LC–MS/MS) studies in solution form was done, and the possible mechanism for the formation of degradants is discussed. Fenofibrate was subjected to different hydrolytic stress conditions and thermal stress condition (in solid form). Successful separation of drug from degradants was achieved on a C18 column using water–acetonitrile (25:75 v/v) as the mobile phase. Other high-performance liquid chromatography (HPLC) parameters were: flow rate, 1 mL min−1; detection wavelength, 286 nm; column temperature, 25 °C; and injection volume, 20 μL. The method was validated for linearity, precision, accuracy, robustness, and specificity and was stability-indicating one, based on the specificity studies. The drug degraded under acidic, basic, and oxidative hydrolytic stress while it was relatively stable towards neutral hydrolysis and thermal stress. The stressed samples were subjected to LC–MS/MS analysis. On the basis of spectral data, the structures of four degradation products and one interaction product were suggested. Degradation products were characterized to be isopropyl acetate, 2-[4-(4-chlorobenzoyl)phenoxy]-2-methyl propanoic acid, 4-hydroxy benzoic acid, and benzoic acid. The structure of one interaction product was proposed as methyl 2-[4-(4-chlorobenzoyl)phenoxy]-2-methylpropanoate.
There is a thin layer of organic lubricant on commercial silver (Ag) flakes that are widely used as the fillers in electrically
conductive adhesives (ECAs). This lubricant layer highly affects the properties such as conductivity of the ECAs. Therefore,
understanding the behavior of Ag flake lubricant layer is essential for developing high performance ECAs. This work is aimed
at studying the chemical nature of the lubricant layer, interaction between the lubricant layer and Ag flakes, and thermal
behavior of the lubricants during heating. A blank Ag powder is ball-milled into Ag flakes with five fatty acids that have
different carbon–hydrogen chain length as lubricants. After lubrication, the Ag flakes are studied using scanning electron
microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetry (TG), and diffuse reflectance infrared Fourier
transform spectroscopy (DRIFTS). It is found that (i) Ag flakes lubricated with fatty acids of different chain lengths have
exothermic DSC peaks and mass losses at different temperatures, (ii) the lubricant layer on the lubricated Ag flake surfaces
is a salt formed between the acid and Ag, and (iii) exothermic DSC peaks (in air) of a lubricated Ag flake is probably due
to the oxidation of lubricant layer on the Ag flake surface.
Authors:A. Siqueira, C. Carvalho, E. Ionashiro, G. Bannach, E. Rodrigues, and M. Ionashiro
Solid-state Ln(L)3 compounds, where Ln stands for trivalent Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y and L is 2-methoxybenzoate have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential
scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy and complexometry were used to characterize
and to study the thermal behaviour of these compounds. The results provided information on the composition, dehydration, coordination
mode, structure, thermal behaviour and thermal decomposition.
Authors:G. Zhong, S. Luan, P. Wang, Y. Guo, Y. Chen, and Y. Jia
thiourea complexes of antimony and bismuth triiodide were synthesized by a
direct reaction of antimony and bismuth triiodide with thiourea powder at
room temperature. The formula of the complex is MI3[SC(NH2)2]3(M=Sb, Bi). The crystal structure of the
complexes belongs to monoclinic system and the lattice parameters are a=1.4772 nm, b=1.6582
nm, c=2.0674 nm and β=90.81 for
and a=1.4009 nm, b=2.0170
nm, c=2.0397 nm and β=90.84 for
The infrared spectra reveal that the trivalent antimony or bismuth ion is
coordinated by the nitrogen atom, not the sulfur atom of the thiourea. Thermal
analysis shows that there are two times structure rearrangements or phase
transformation in the complexes from 100 to 170C.
Authors:Joyce Chau, Iwona Garlicka, Catherine Wolf, and J. Teh
The Modulated Differential Scanning Calorimeter (MDSC) technique, using TA Q1000 instrument, has been applied as a tool to
study the reversible and non-reversible heat flow characteristics of a wide range of polyethylenes. It was found that the
heat flow characteristic is dependent upon the heating rates and modulation period used in the test. By using a set of standard
test conditions, MDSC was found to be useful in studying the effect of previous thermal processing conditions, additive effects,
and also the density, MI, type of comonomer, and molecular architecture.