Authors:R. Kotsilkova, V. Petkova, and Y. Pelovski
The thermal behavior of epoxy-smectite nanocomposites (hybrids) is examined by non-isothermal thermogravimetry (TG, DTG and
DTA) in air atmosphere. It has been shown that the thermal stability of hybrids is much greater than that of epoxy resin and
strongly depends on both the smectite loading and the type of the gallery cations of organically modified smectites. The kinetics
of degradation of nanocomposites is significantly influenced by the presence of smectites and proceeds in three stages. Stage
I is attributed to the effect of quaternized ammonium ion exchanged smectite, as stages II and III are associated with the
decomposition of the bulk epoxy resin. Because of the interfacial interactions and thesilicate-polymer multilayered nanoscale
organization, the nanocomposites act as excellent heat insulator and mass transport barrier, which shift the thermal decomposition
peaks towards much higher temperatures.
Authors:C. Ramírez, M. Rico, J. M. L. Vilariño, L. Barral, M. Ladra, and B. Montero
Summary Cubic silsesquioxanes offer access to organic/inorganic hybrids. A system formed by a polyhedral oligomeric silsesquioxane (POSS) with eight epoxy reactive groups per molecule, octaepoxycyclohexyldimethylsilyl-POSS, cured with an aliphatic diamine (bisaniline) was studied in different ratios. The characterization of the POSS was carried out by differential scanning calorimetry (DSC) and thermogravimetry (TG). The distribution of species in the reaction of the mixtures POSS/diamine was followed by gel permeation chromatography (GPC). The degradation was studied by thermogravimetric analysis.
Excitation function measurements are reported for reactions induced in natural nickel with 9–86 Mev -particles. Cumulative cross sections were obtained for the production of60(m+g)Co,58(m+g)Co,57Co and56Co. The stacked-foil method was used to measure product yields by gamma-spectrometry with a Ge intrinsic detector. The experimental data (supplemented with previously reported cross sections by other authors were compared with the calculated values obtained by means of the hybrid model.
Analytical equations related
adiabatic runaway reactions to programmed scanning thermal curves from differential
scanning calorimetry (DSC) were proposed. Thermal or pressure hazards can
be assessed from the adiabatic trajectories expressed in the analytical equations.
These industrially energetic materials include polymerizable monomers, unstable
organic peroxides and nitro-compounds. Various emergency relief behaviors,
such as tempered vapor, gassy, and hybrid were re-evaluated for calculating
vent sizing or mass flow rates from DSC thermal curves and the related physical
Authors:G. Bannach, R. Arcaro, D. Ferroni, A. Siqueira, O. Treu-Filho, M. Ionashiro, and E. Schnitzler
Thermogravimetry (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC) as well as X-ray diffraction
powder (DRX) patterns and Fourier transformed infrared spectroscopy (FTIR) were used to study ketoprofen, ibuprofen, and naproxen.
The chemical or physical properties of the studied compounds were established and when possible by X-ray powder diffractometry
and/or infrared spectroscopy were used. In this investigation, quantum chemical approach was used to determine the molecular
structures using Becke three-parameter hybrid method and the Lee–Yang–Par (LYP) correlation functional. The performed molecular
calculations in this work were done using the Gaussian 03 routine. Theoretical calculations help in interpretations of FTIR
spectra supplying structural and physicochemical parameters.
Authors:N. van der Meulen, G. Steyn, T. van der Walt, F. Szelecsényi, Z. Kovács, and H. Raubenheimer
The production of 133Ba via the nuclear reaction 133Cs(p,n)133Ba on targets of CsF and CsCl has been investigated. Two methods to quantitatively separate 133Ba from the Cs target material, using AG 50W-X4 and AG MP-50 cation exchange resins, respectively, have been developed. Measured
thick-target yield values are presented and some characteristics of the underlying excitation function have been inferred.
For this purpose, calculations using the Geometry Dependent Hybrid model, as implemented in the code ALICE-IPPE, have been
performed. Aspects of the production targetry developed as part of this study are also discussed.
Excitation functions for the production of198mAu,198Au,198(m+g)Au, by (, 2pn) reactions on gold and isomeric ratios for198Au were determined experimentally. The method of activation of metallic foils was employed. The irradiations were performed in the isochronous cyclotron at Karlsruhe (Germany) with -particles at 90 MeV. Gamma-spectrometry by means of an intrinsic Ge detector was used to determine the nuclides produced. In addition, a comparison between the cross sections obtained and a calculation using the hybrid model of pre-equilibrium reactions, in combination with the statistical model development by ERNST is presented.
Excitation functions for the production of194Au,195(m+g)Au,196(m+g)Au,198mAu,195gAu and199Au were determined experimentally. In addition, the yields of thick targets of these products were calculated and a comparison between the cross sections obtained using the hybrid model of pre-equilibrium reactions in combination with the statistical model of compound nucleus is presented. The method of activation of metallic foils was employed. The irradiations were performed in the internal beam of the isochronous cyclotron at Karlsruhe (FRG) with -particles at 90 MeV. Gamma-spectrometry by means of an intrinsic Ge detector was used to determine the nuclides produced.
Mn-nodule is one of the most important deep sea mineral resources to be explored and exploited in the next century. Analytical quality control based on this kind of Certified Reference Materials (CRMs) is therefore necessay. In the present work, nearly 30 elements in two Chinese Mn nodule Reference Materials (RMs), GSPN-2 and GSPN-3, were determined using extendedK0-relative comparison NAA technique, developed in our laboratory. The unique features of this work include; (1) high accuracy obtained by the interal validation function of our technique; (2) extensive determinable elements obtained by the hybrid nature of our software and (3) neutron flux self-shielding corrections.