Authors:J. Mano, S. Lanceros-Méndez, A. Nunes and M. Dionísio
Dielectric experiments are often performed in non-isothermal conditions. Thus, there is a difference between the temperature of the sample and the sensor temperature. In this work we propose and compare three temperature calibration methods based on the detection of transitions or relaxations: i) the melting of high-purity metallic standards (indium and tin), ii) the 2nd order phase transition of a ferroelectric crystal (TGS); iii) the -relaxation of an amorphous polymer (poly(carbonate)). The results obtained from the three different methods were used to construct a calibration curve for a given heating rate.
Authors:A. Hensel, J. Dobbertin, J. E. K. Schawe, A. Boller and C. Schick
The results from temperature modulated DSC in the glass transition region of amorphous and semicrystalline polymers are described with the linear response approach. The real and the imaginary part of the complex heat capacity are discussed. The findings are compared with those of dielectric spectroscopy. The frequency dependent glass transition temperature can be fitted with a VFT-equation. The transition frequencies are decreased by 0.5 to 1 orders of magnitude compared to dielectric measurements. Cooling rates from standard DSC are transformed into frequencies. The glass transition temperatures are also approximated by the VFT-fit from the temperature modulated measurements. The differences in the shape of the curves from amorphous and semicrystalline samples are discussed.
The Unified Grain Moisture Algorithm is
capable of improved accuracy and allows the combination of many grain types
into a single “unified calibration”. The purposes of this research were to
establish processes for determining unifying parameters from the chemical and
physical properties of grains. The data used in this research were obtained as
part of the United States Department of Agriculture-Grain Inspection, Packers
and Stockyards Administration's Annual Moisture Calibration Study. More than
5,000 grain samples were tested with a Hewlett-Packard 4291A Material/Impedance
Analyzer. Temperature tests were done with a Very High Frequency prototype
system at Corvinus University of Budapest. Typical chemical and physical
parameters for each of the major grain types were obtained from the literature.
Data were analyzed by multivariate chemometric methods. One of the most
important unifying parameters (Slope) and the temperature correction
coefficient were successfully modeled. The Offset and Translation unifying
parameters were not modeled successfully, but these parameters can be estimated
relatively easily through limited grain tests.
Authors:Libby Yoerg, M. Ellen Matthews, Lakshmi Kaza, Naullage Indika Perera, David W. Ball, John Moran and Alan T. Riga
, including melting point (for crystalline materials) and glass transition (for amorphous materials). Dielectric analysis (DEA) reveals increasing amorphicity and molecular rearrangement depicted by the increased organization of the dielectric relaxation
goes beyond that of modifying the filler surface to achieve better dispersion of the dielectric filler particles. The interfacial properties in nanocomposite material could be amplified by the high surface area of nanofillers. This concept was
Authors:Varghese Mathew, Lizymol Xavier, C. K. Mahadevan and K. E. Abraham
simplicity of the process [ 7 ]. In this investigation, manganese malonate dihydrate crystals have been grown in silica gel and characterized by thermal and dielectric studies. Herein the authors report the results obtained.
Nelson, Stuart O. (1992) Correlating dielectric properties of solids and particulate samples through mixture relationships. Trans. ASAE 35(2): 625-629.
Correlating dielectric properties of solids and particulate samples through
By means of thermo-dielectric analysis, some natural and synthetic zeolites were studied (clinoptilolite, mordenite,X, Y andA). The results indicate the existence of two effects, one related to water evolution, reflected in a decrease of dielectric constant; the second peak is related to ionic conduction at high temperature. Both peaks characterize zeolites, in thermo-dielectric analysis.