Search results for "Gravimetry"
showing 10 items of 178 documents
Reactive blending of a functionalized polyethylene with a semiflexible liquid crystalline copolyester
1996
Reactive blends (50/50 w/w) of a low molar mass polyethylene containing free carboxylic groups (PEox) and a semiflexible liquid crystalline polyester (SBH 1 : 1 : 2, by Eniricerche) have been prepared at 240 degrees C in a Brabender mixer, in the presence of Ti(OBu)(4) catalyst, for different mixing times (15, 60, and 120 min). In order to prove the formation of a PE-g-SBH copolymer, the blends have been fractionated by successive extractions with boiling toluene and xylene. The soluble fractions and the residues have been analyzed by Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG and DTG), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM)…
Contribution to the study of framework modification of SAPO-34 and SAPO-37 upon water adsorption by thermogravimetry
1999
Abstract The adsorption–desorption of water vapor in SAPO-34 and SAPO-37 is followed in isobar conditions ( P H 2 O =17.6 mbar ) by thermogravimetry at temperatures from 20°C to 400°C. The phenomenon is reversible in SAPO-34 but not in SAPO-37. The rise in water uptake is the highest at around 60–70°C, i.e. in range where an attack of the frameworks was previously reported. The reversibility (or not) of water adsorption–desorption uptake is linked to this reversible (or not) framework modification. The kinetics of desorption in SAPO-34 is strongly slowed down between 40°C and 60°C. This suggests that the full restructuration of the framework requires some time (700 min in the experimental c…
Selective functionalization of halloysite cavity by click reaction: structured filler for enhancing mechanical properties of bionanocomposite films
2014
Selective modification of the inner surface of halloysite nanotubes (HNTs) by the cycloaddition of azides and alkynes (click reaction) was successfully achieved. Fourier transform infrared spectroscopy and thermogravimetry confirmed that the modification involved only the HNT cavity. Morphological investigations evidenced that the functionalized nanotubes formed microfibers and clusters in the micrometer range. By means of the casting method, these nanomaterials were dispersed into biopolymeric matrixes (chitosan and hydroxypropyl cellulose) with the aim of obtaining nanocomposite films with tunable properties from the physicochemical viewpoint. For comparison purposes, we also characterize…
EVA-montmorillonite nanocomposites: effect of processing condition
2004
The aim of this study is to examine the effect of the compounding apparatus and of processing conditions on the properties of an organoclay-poly[ethylene-co-(vinyl acetate)] (EVA) nanocomposite. The filled materials were prepared using either a discontinuous batch mixer, a single screw extruder, a counter rotating intermeshing twin-screw compounder or a corotating intermeshing twin-screw extruder. The characterization of the obtained nanocomposites was performed by XRD, thermogravimetry, mechanical and rheological measurements. The study has shown the possibility of producing nanocomposites based on EVA and a commercial organoclay (Cloisite 15A) by several mixing equipments. In fact all the…
Injection molding of syndiotactic polystyrene/clay nanocomposites
2006
This study aims at exploring the effect of a commercial organoclay montmorillonite (MMT) on the final properties of syndiotactic polystyrene (sPS) injection-molded samples. To this goal, injection-molded specimens made from neat sPS and commercial MMT modified with various organic compounds were prepared in different molding conditions. Dispersion of clay was attained via melt blending, directly in the injection chamber of the injection-molding machine. The obtained specimens were analyzed by IR spectroscopy, X-ray diffraction, thermogravimetry, and differential thermal analysis, with the aim of elucidating the effect of clay on the microstructures of the samples. Results clearly show that,…
Drug delivery devices based on mesoporous silicate.
2004
A mesoporous material based on aluminosilicate mixture was studied to investigate its ability to include drugs and then release them. Nonsteroidal anti-inflammatory agents such as diflunisal, naproxen, ibuprofen and its sodium salt have been used in this study. The preparation of the mesoporous material and its characterization by X-ray, N2 absorption-desorption isotherm, and thermogravimetry analysis have been described. Drug loading was performed by a soaking procedure. Drug-loaded matrices were characterized for entrapped drug amount, water absorption ability, and thermogravimetric behavior. Drug release studies also were performed at pH 1.1 and 6.8 mimicking gastrointestinal fluids. Exp…
Behaviour of neutron irradiated beryllium during temperature excursions up to and beyond its melting temperature
2015
Abstract Beryllium pebble behaviour has been studied regarding the accidental operation conditions of tritium breeding blanket of fusion reactors. Structure evolution, oxidation and thermal properties have been compared for nonirradiated and neutron irradiated beryllium pebbles during thermal treatment in a temperature range from ambient temperature to 1600 K. For neutron irradiated pebbles tritium release process was studied. Methods of temperature programmed tritium desorption (TPD) in combination with thermogravimetry (TG) and temperature differential analysis (TDA), scanning electron microscopy (SEM) in combination with Energy Dispersive X-ray analysis (EDX) have been used. It was found…
Halloysite nanotubes with fluorinated cavity: an innovative consolidant for paper treatment
2016
AbstractHybrid material based on halloysite nanotubes (HNTs) and sodium perfluorooctanoate (NaPF8) was used as a consolidant for paper treatment. The consolidation efficiency was determined by thermogravimetry as well as by paper grammage determination. Morphological analysis of the treated paper was performed by means of scanning electron microscopy while the effect of modified HNTs on the thermal behaviour of the cellulose fibres was investigated by differential scanning calorimetry which determined the combustion enthalpy of the paper.Water contact angle measurements were performed to study the paper wettability. The physico-chemical properties investigated (mesoscopic structure, thermal…
Bioactive Co(II), Ni(II), and Cu(II) Complexes Containing a Tridentate Sulfathiazole-Based (ONN) Schiff Base
2021
New Co(II), Ni(II), and Cu(II) complexes were synthesized with the Schiff base ligand obtained by the condensation of sulfathiazole with salicylaldehyde. Their characterization was performed by elemental analysis, molar conductance, spectroscopic techniques (IR, diffuse reflectance and UV–Vis–NIR), magnetic moments, thermal analysis, and calorimetry (thermogravimetry/derivative thermogravimetry/differential scanning calorimetry), while their morphological and crystal systems were explained on the basis of powder X-ray diffraction results. The IR data indicated that the Schiff base ligand is tridentate coordinated to the metallic ion with two N atoms from azomethine group and thiazole ring a…
Comparison of Different Classical and Instrumental Analysis Methods for Precise Quantification of Calcium and Phosphorous Ratio in Hydroxyapatite
2019
The largest comparison of analytical techniques, useful for calcium phosphates, has been conducted, presenting recommendations for quality control and research of calcium phosphates. Results from three classical quantification methods (gravimetry, titramety, photometry) and three instrumental measurement methods (XRF, FAAS ICP-OES) are reported to determine the most accurate, fastest and cheapest analysis method. Remarks are given for increasing the accuracy for each method and corrections made for adsorbed water. For routine analysis, a recommendation is given to ICP-OES for a fast analysis, together with a less frequent use of gravimetry to validate the results and provide a periodic cros…