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Abstract  

The surface of natural talc was modified with organosilanes (H3 CO)3 SiR, for R = -(CH2 )3 NH2 , -(CH2 )3 NH(CH2 )2 NH2 and -(CH2 )3 NH(CH2 )2 NH(CH2 )2 NH2 , resulting in the inorganic-organic hybrids TC1, TC2 and TC3 . These aminated talcs contain 4.38, 2.56 and 2.03 mmol g-1 of immobilized organic chains for TCx (x =1 to 3), respectively. The chemisorption isotherm data obtained by a batch wise process were adjusted to a modified Langmuir equation, to give the maximum adsorption capacity TC1 >TC2 >TC3 . The chelate effect was illustrated through calorimetric titration, giving the highest enthalpic values for TC2 and TC3 hybrids and favoured for sulfate counter anion. The enthalpic and entropic values indicated favourable reaction between copper-basic nitrogen center atoms on pendant chain covalently bonded to the inorganic backbone.

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Abstract  

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.

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Abstract  

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.

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Journal of Thermal Analysis and Calorimetry
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.

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Abstract  

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 properties.

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Abstract  

A hybrid stable iodine/radioiodine (131I) atmospheric photochemistry box model, including 27 reactions, has been developed and solved using algorithmic programme with the application of the Runge-Kutta method of the order 4(5). This modelling offers a clearer view of relationship among aerosol-associated (inorganic iodine compounds, mostly I2O2), gaseous inorganic (mostly IONO2, HOI) and organic (CH3I) iodine compounds in ambient atmosphere. Summing up the data of the Chernobyl accident, the problem of the standardised method for atmospheric aerosol-associated and gaseous (inorganic and organic) radioiodine activity measurements in the case of the nuclear power plant accident is discussed.

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Abstract  

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.

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Journal of Thermal Analysis and Calorimetry
Authors: G. Bannach, R. Arcaro, D. Ferroni, A. Siqueira, O. Treu-Filho, M. Ionashiro, and E. Schnitzler

Abstract  

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.

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Abstract  

Adaptive or smart hybrid composites consisting of a polymer matrix reinforced by aramid fibres and incorporating pre-strained Shape Memory Alloy (SMA) wires are able to tune some of their properties, such as their shape, the natural vibration frequency or the damping coefficient, in response to an external stimulus. The functional properties of these systems are directly related to the reversible martensitic transformation in the SMA elements. In this work the transformational behaviour of both free SMA wires and SMA wires embedded in polymer matrix is investigated by means of DSC. The martensitic transformation of the constrained wires is impeded by the polymer matrix, while the interface integrity plays a crucial role.

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Abstract  

Thermal properties, ageing resistance and flammability of peroxide vulcanizates of butadiene-acrylonitrile rubber Perbunan NT 1845 (NBR) of Bayer, modified in bulk and on a surface with synthesized hybrid functional poly(methylsiloxanes) were investigated. The derivatographic, DSC, oxygen index and FTIR methods were applied. It was stated that addition of poly(methylsiloxanes) caused distinct increase of ageing resistance and of NBR vulcanizates and decrease of their thermal decomposition rate and flammability, providing self-extinguishing samples. The mechanism of addition reactions of Si–H bond to multiple bonds of NBR has been proposed.

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