Search results for "Thermal analysis"
showing 10 items of 208 documents
Thermal studies of sulphonamide derivative complexes
1991
Abstract A thermal study of a new series of acetazolamidate complexes of Co(II), Ni(II) and Cu(II) using the TG, DTG and DTA techniques in flowing air, static air and N 2 atmospheres is described. From the TG-DTG and DTA curves, different thermal behaviours can be observed. Although in all the complexes the processes of dehydration, deammination and pyrolysis can be clearly observed, in some cases they appear as several well-separated steps and, in others, as continuous stages which take place simultaneously. The differences observed between the pyrolytic decomposition in flowing air and in nitrogen are described. In flowing air, metal sulphate is formed from the thiadiazole ring, except fo…
Development of a new peat-based oil sorbent using peat pyrolysis
2013
The growing use and transport of crude oil and oil products has led to increasing numbers of oil spillages of various scales. Oil sorbents have been extensively used for remediation of the consequences of such accidents. The aim of this study is to investigate the possible use of peat and its thermal treatment products for oil sorption. Peat as an oil sorbent has poor buoyancy characteristics, relatively low oil sorption capacity and low hydrophobicity. However, thermal treatment (low-temperature pyrolysis and synthesis of peat-based activated coal) helps to significantly improve its sorptive characteristics. Peat is a potential material for oil sorption because it has such advantages as lo…
Powder X-Ray Diffraction Investigation of Xylazine Hydrochloride Solid Phase Transformation Kinetics
2013
The kinetics of the solid-state phase transformation of xylazine hydrochloride form X to A has been investigated using powder X-ray diffraction and differential thermal analysis. Three different kinetic models have been used to describe transition kinetics: the Avrami–Erofeev equation, the Cardew equation, and the methodology for simulation of solid-state phase transition kinetics by the combination of nucleation and nuclei growth processes. The latter has been recently developed and has been tested in this paper for the case of a real solid-state transition. The relative humidity, mechanical pressure, temperature, and sample-preparation effect on phase-transition kinetics have been investi…
Heterobimetallic single-source precursors for MOCVD. Synthesis and characterization of volatile mixed ligand complexes of lanthanides, barium and mag…
1999
Several heterobimetallic complexes of general formula [(M 1 Q) m M 2 (dik) n ], where (M 1 Q) is Cu(salen) or Ni(salen) and M 2 (dik) n is a lanthanide tris(β-diketonate) or an alkali-earth element bis(β-diketonate) with more or less fluorinated diketonato(-) ligands, have been prepared and structurally characterized. Some of them were submitted to thermal and mass spectrometry analyses, and to isothermal vacuum sublimation tests, in view of their potential use as MOCVD single-source precursors for the deposition of heterobimetallic materials. The study stresses upon the influence of the nature of the diketone. of the M 2 cation, and of chemical modification of the salen ligand on the therm…
A novel approach to prevent graphene oxide re-aggregation during the melt compounding with polymers
2015
Abstract The technology for the preparation of polymer-GO nanocomposites was investigated by studying the structure-properties relationships of two different systems, based on PA6 and EVA, fabricated by using different preparation methods, i.e. melt mixing, wet phase inversion, and the combination of the two. The morphology of nanocomposites resulted dramatically influenced by the technique adopted and showed to be the critical variable affecting the physical properties of the materials. Finally, the mechanical and dynamic-mechanical of the nanocomposites were improved by using the hybrid technique combining the two procedures.
Suitability of blends from virgin and reprocessed polylactide: performance and energy valorization kinetics
2018
[EN] A blending strategy of virgin and reprocessed polylactide may be postulated as an alternative to reduce the material cost at industrial level, and as a valorisation route to plastic waste management of production scraps. The performance of blends prepared from virgin polylactide and polylactide mechanically reprocessed up to two cycles (PLA-V/R) was assessed in terms of thermo-oxidative stability, morphology, viscoelasticity and thermal kinetics for energetic valorisation. PLA-V/R blends showed appropriate thermo-oxidative stability. The amorphous nature of polylactide was preserved after blending. The viscoelastic properties showed an increment of the mechanical blend effectiveness, w…
A DC behavioral electrical model for quasi-linear spin-valve devices including thermal effects for circuit simulation
2011
An advanced model for quasi-linear spin-valve (SV) structures is presented for circuit simulation purposes. The model takes into account electrical and thermal effects in a coupled way in order to allow a coherent representation of the sensor physics for design purposes of electronics applications based on these sensor devices. The model was implemented in Verilog-A and used in a commercial circuit simulator. For testing the model, different SV structures have been specifically fabricated and measured. The characterization included DC measurements as well as steady-state and transient thermal analysis. From the experimental data, the parameters of the model have been extracted. The model re…
Novel Resistance Measurement Method: Analysis of Accuracy and Thermal Dependence with Applications in Fiber Materials
2016
Material resistance is important since different physicochemical properties can be extracted from it. This work describes a novel resistance measurement method valid for a wide range of resistance values up to 100 GΩ at a low powered, small sized, digitally controlled and wireless communicated device. The analog and digital circuits of the design are described, analysing the main error sources affecting the accuracy. Accuracy and extended uncertainty are obtained for a pattern decade box, showing a maximum of 1 % accuracy for temperatures below 30 ∘ C in the range from 1 MΩ to 100 GΩ. Thermal analysis showed stability up to 50 ∘ C for values below 10 GΩ and systematic deviations for higher …
Evaluation of entropies of fusion of polychlorinated naphthalenes by model congeners: A DSC study
2006
Abstract Thirteen congeners of polychlorinated naphthalenes (PCN) were synthesized and studied by differential scanning calorimetry (DSC). Melting points (Tm) were obtained for all thirteen, and enthalpies of fusion (ΔHf) were obtained for nine congeners. Melting points of other PCNs, except for five, were found in literature. In addition, experimental ΔHf values determined by DSC were found only for 1- and 2-mono-chloronaphthalenes in the literature. The missing or uncertain values of the eight melting points and 64 enthalpies of fusion were estimated by multiple linear regressions using a set of thirteen molecular descriptors as candidates for independent variables. The stepwise model of …
Properties and Structural Studies of Multi-Wall Carbon Nanotubes-Phosphate Ester Hybrids
2013
Long chain phosphate esters bearing at least one or two aryl groups have been synthesized and used for the preparation of stable multi-walled carbon nanotube (MWCNT) hybrids. The non-covalent interaction ester/MWCNT has been investigated by several techniques (SEM, UV-vis, 31P-NMR, RAMAN). The used phosphate ester derivatives demonstrated the ability to produce an excellent dispersion of MWCNT in CHCl3. The obtained dispersions showed a great stability from one to at least three weeks in the range of concentration considered. Thermal analysis showed an increase in the decomposition temperature for the hybrids with respect to pristine MWCNT.