Search results for " Thermal analysis"

Low-temperature Ti-containing 3:2 and 2:1 mullite nanocrystals from single-phase gels

2007

Abstract TiO 2 -containig single-phase gels with (Al 2 O 3  + TiO 2 )/(SiO 2 ) molar ratios 3/2 and 2/1 were prepared by gelling mixtures of aluminium nitrate, tetraethylorthosilicate and titanium isopropoxide. Gels were fast heated at several temperatures up to 1100 °C. Dried and heated gels were characterized by differential thermal analysis (DTA), magic angle spinning nuclear magnetic resonance (MAS-NMR), X-ray powder diffraction (XRD), and scanning and transmission electron microscopies (SEM and TEM). Coupled DTA and XRD results of gels fast heated at 900 °C showed the crystallisation of two mullites as well as a small amount of alumina-silica spinel. 27 Al NMR spectra showed the format…

Enrichment and activation of smectite-poor clay

2011

A new method of smectite clay enrichment has been developed. The method is based on dispersing clay in a phosphate solution and sequential coagulation. The product of enrichment is characterized with X-ray powder diffraction, wavelength dispersive X-ray fluorescence spectrometry, differential thermal analysis and thermogravimetry. Sorption of methylene blue and hexadecylpyridinium bromide on raw and purified clays was studied.

Dielectric Spectroscopy of Recycled Polylactide

2014

The effects of multiple mechanical recycling on amorphous polylactide (PLA) were simulated by means of five successive injection-grinding cycles. The influence of the induced thermo-mechanical degradation on the dielectric properties of PLA was analysed. The relaxation spectra were studied in terms of the complex dielectric permittivity (ε0 and ε00) and the dielectric loss tangent, tg(d) in the frequency range from 102 to 107 Hz over the temperature interval from 0 C to 140 C. It was possible to distinguish two relaxations zones, one at low temperatures and high frequencies (b relaxation) and another at higher temperatures and lower frequencies (a relaxation). The individual relaxations wer…

Water diffusion and swelling stresses in ionizing radiation cured epoxy matrices

2017

Abstract In this work a DGEBF epoxy monomer was cured by electron beam radiation in the presence of an iodonium salt and the obtained system was hydrothermally aged as such and also after a thermal treatment, in order to obtain two systems having different uniformity in the cross-linking degree. On both systems, the transient stress field arising from swelling was measured and monitored by an optical Photoelastic technique and the results were commented with reference to a thermally cured epoxy system containing the same monomer and already discussed in a previous work. Beam samples with identical dimensions, obtained from the irradiated systems, have been aged at 80 °C in water, and charac…

Effect of some additives on the development of spinel-based glass-ceramic glazes for floor-tiles

2005

Abstract The feasibility of developing spinel-based glass-ceramic glazes from a glass with composition in the system ZnO–MgO–B 2 O 3 –Al 2 O 3 –SiO 2 was examined. To do it additional fluxes and/or nucleants were added to a parent glass before melting. Pressed pellets of powdered glasses were submitted to standard thermal treatments up to 1200 °C. The crystallization path and the microstructural development at several temperatures were followed by several experimental techniques. The results showed that additions of TiO 2 as nucleant or additional B 2 O 3 as flux to the chosen glass favored the crystallization of cordierite or mullite as main crystalline phase. Glasses which also contained …

Modelling phase transition kinetics of chenodeoxycholic acid with the Runge–Kutta method

2009

Abstract The phase transition kinetics of two chenodeoxycholic acid polymorphic modifications— form I (stable at high temperature), form III (stable at low temperature) and the amorphous phase has been examined under various conditions of temperature and relative humidity. Form III conversion to form I was examined at high temperature conditions and was found to be non-spontaneous, requiring seed crystals for initiation. The formation kinetic model of form I was created incorporating the three-dimensional seed crystal growth, the phase transition rate proportion to the surface area of form I crystals, and the influence of the amorphous phase surface area changes with an empirical stage poin…

Structural transformations in amorphous selenium as studied by the differential thermal analysis and exoelectron emission technique

2007

The parameters (temperature, activation energy) of the surface and volume glass transition (retrification process) in amorphous selenium produced by rapid quenching of the liquid phase have been determined using the EEE and DTA techniques. EEE is a surface effect connected with structural transformations in the surface layer whereas the DTA measurements give the information about the transformations occurring in the volume of the sample. It has been found that the surface retrification of selenium occurs with activation energy smaller than the volume retrification, both observed in the first heating run. The value of activation energy for the volume retrification measured in the second DTA …

Paper consolidation with Halloysite nanotubes. TGA, DMA and contact angle investigations

2013

DSC Studies and Stability of Frozen Foods

1991

This paper discusses the role played by the “WLF decrease in viscosity” above the temperature of the glass transition (Tg) in the temperature dependence of the stability of frozen foods. In the first part, the complex features observed before the melting endotherm on DSC/DTA thermograms of sugar-water solutions are examined; they are suggested to be representative of a glass transition associated with enthalpy relaxation. In the second part, the values of Tg for some complex foods are discussed. It is shown that ice melting adds an important contribution to the WLF effect on the decrease of the viscosity of the freeze-concentrated phase. The temperature dependence of the deterioration proce…

Parametric thermal analysis for the optimization of Double Walled Tubes layout in the Water Cooled Lithium Lead inboard blanket of DEMO fusion reactor

2019

Abstract Within the roadmap that will lead to the nuclear fusion exploitation for electric energy generation, the construction of a DEMOnstration (DEMO) reactor is, probably, the most important milestone to be reached since it will demonstrate the technological feasibility and economic competitiveness of an industrial-scale nuclear fusion reactor. In order to reach this goal, several European universities and research centres have joined their efforts in the EUROfusion action, funded by HORIZON 2020 UE programme. Within the framework of EUROfusion research activities, ENEA and University of Palermo are involved in the design of the Water-Cooled Lithium Lead Breeding Blanket (WCLL BB), that …