Search results for "Note"
showing 10 items of 10709 documents
Charge transfer interactions in self-assembled single walled carbon nanotubes/Dawson–Wells polyoxometalate hybrids
2014
We demonstrate the success in self-assembling pyrene-modified Dawson–Wells-type polyoxometalates (POMs) with single walled carbon nanotubes (SWCNTs) by means of π–π interactions. In this context, the immobilization of POMs onto SWCNTs is corroborated by aberration-corrected high-resolution electron microscopy, thermogravimetric analysis, and Raman spectroscopy. From steady-state and time-resolved photophysical techniques we derived evidence for mutual interactions between SWCNTs and POMs in the excited states. The latter are the inception to a charge transfer from the SWCNTs to the POMs. Our results corroborate the suitability of POM–SWCNTs assemblies for photoactive molecular devices.
Lifetime predictions of non-ionic and ionic biopolymers: kinetic studies by non-isothermal thermogravimetric analysis
2021
AbstractIn this paper, films based on sustainable polymers with variable charge have been investigated by non-isothermal thermogravimetry in order to predict their lifetime, which is a key parameter for their potential use in numerous technological and biomedical applications. Specifically, chitosan has been selected as positively charged biopolymer, while alginate has been chosen as negatively charged biopolymer. Among non-ionic polymers, methylcellulose has been investigated. Thermogravimetric measurements at variable heating rates (5, 10, 15 and 20 °C min−1) have been performed for all the polymers to study their degradation kinetics by using isoconversional procedures combined with ‘Mas…
Alkoxide-intercalated NiFe-layered double hydroxides magnetic nanosheets as efficient water oxidation electrocatalysts
2016
Alkoxide-intercalated NiFe-layered double hydroxides were synthesized via the nonaqueous methanolic route. These nanoplatelets exhibit high crystalline quality as demonstrated by atomic resolution scanning transmission electron microscopy combined with electron energy-loss spectroscopy. Moreover, the presence of the alkoxide moieties has been unambiguously demonstrated by means of thermogravimetric analysis coupled to a mass spectrometer. These NiFe-LDHs can be exfoliated in water or organic solvents and processed into homogeneous ultra-thin films (< 3nm thick) with the assistance of O2-plasma. The study of their behaviour as water oxidation electrocatalysts has shown an outstanding perf…
Proton Conducting Electrospun Sulfonated Polyether Ether Ketone-Graphene Oxide Composite Membranes
2017
[EN] A series of novel composite membranes, based on sulfonated poly(ether ketone) (SPEEK) with a graphene oxide (GO) layer, were prepared. One contained a GO layer sandwiched between the SPEEK-polyvinyl alcohol (PVA) matrix (SPEEK/PVA@GO), and another deposited thin layers of GO on the nanofibers of SPEEK-polyvinyl butyral (PVB), with both sandwiched in the phase matrix of SPEEK-PVA (SPEEK/PVA@GO-NF). Various nanofiber thicknesses were studied by varying the electrospinning time. The prepared composite membranes with different nanofiber thicknesses were characterized by scanning electron microscopy, water uptake, ionic exchange capacity, thermogravimetric analysis, mechanical properties an…
Ionic Liquids-Cobalt (II) Thermochromic Complexes: How the Structure Tunability Affects "Self-contained" Systems
2021
With the aim of obtaining thermochromic systems with potential applications in solar energy storage, we evaluated the behavior of some sugar-based ionic liquids (ILs)–Co(NTf₂)₂ complexes, in IL solution, as a function of temperature. Different structural changes on the cation, the nature of the anion, and the nature of the IL used as the solvent were considered. The analysis of the above factors was carried out through a combined approach of different techniques, that is, variable temperature UV–vis and NMR spectroscopies, conductivity, and thermal gravimetric analysis. The thermochromic systems were analyzed both as solutions and as thin films, and the data collected highlight the defining…
Benzyl Alcohol Assisted Synthesis and Characterization of Highly Reduced Graphene Oxide (HRG)@ZrO2 Nanocomposites
2017
We demonstrate a one-step solvothermal synthesis of HRG@ZrO2 nanocomposites using benzyl alcohol as solvent and stabilizing ligand. The as-synthesized HRG@ZrO2 hybrid nanocomposites showed a homogeneous distribution of the ZrO2 NPs (≈ 5 nm) onto HRG nanosheets. High resolution (HR)TEM, X-ray diffraction (XRD), and Raman spectroscopy confirmed the presence of cubic ZrO2. The presence of benzyl alcohol as stabilizing ligand was demonstrated by ultraviolet-visible (UV-vis), Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The reduction of graphene oxide to HRG was also realized by X-ray photoelectron spectroscopy (XPS). A study of the HRG@ZrO2 formation mec…
Improving the high temperature oxidation resistance of pure titanium by shot-peening treatments
2017
International audience; Shot-peening (SP) treatments have shown their capacity to improve the oxidation resistance of titanium and zirconium thanks to the large compressive stresses and the surface hardening induced by this mechanical process. However, shot-peening treatments can produce a surface chemical deposit, which can modify the high temperature oxidation resistance. Here, we study pure titanium samples shot-peened with different type of balls: tungsten carbide, alumina or glass. The oxidation behavior was studied at 700 °C in dry air by thermo gravimetric analysis for short isotherm oxidation periods up to 100 h. Also, long oxidation tests (3000 h) at 700 °C were performed with an i…
Effect of Plasma Treatment on Mechanical and Thermal Properties of Marble Powder/Epoxy Composites
2016
The aim of this work was to study the effect of the plasma treatment on the behavior of composite structures reinforced with marble powder, obtained as processing waste in the “Custonaci” basin. Moreover, different filler amounts (i.e. 10%wt, 20%, 30% in weight) were investigated. For the mechanical characterization, tensile and flexural quasi-static tests, Charpy impact test, and dynamic mechanical thermal analysis (DMTA) were performed. For the thermal stability, thermogravimetric analysis was carried out. Finally, real density and fraction of voids were measured. It was observed that untreated marble powder, on one hand, increases tensile and flexural stiffness and improves thermal stabi…
Nanocomposites based on esterified colophony and halloysite clay nanotubes as consolidants for waterlogged archaeological woods
2017
We have designed an innovative protocol for the consolidation of waterlogged archaeological woods by using acetone mixtures of halloysite clay nanotubes and a chemically modified colophony (Rosin). Firstly, we have investigated the thermal properties of HNTs/Rosin nanocomposites, which have been prepared by means of the casting method from acetone. The HNTs content have been systematically changed in order to study the influence of the inorganic filler on the thermal stability and glass transition process of Rosin. We have observed that the thermal properties of the hybrids are affected by the specific HNTs/Rosin interactions. Then, acetone dispersions of HNTs/Rosin composites at variable f…
Thermal Stability and Flame Retardancy of Polypropylene Composites Containing Siloxane-Silsesquioxane Resins
2018
A novel group of silsesquioxane derivatives, which are siloxane-silsesquioxane resins (S4SQ), was for the first time examined as possible flame retardants in polypropylene (PP) materials. Thermal stability of the PP/S4SQ composites compared to the S4SQ resins and neat PP was estimated using thermogravimetric (TG) analysis under nitrogen and in air atmosphere. The effects of the non-functionalized and n-alkyl-functionalized siloxane-silsesquioxane resins on thermostability and flame retardancy of PP materials were also evaluated by thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR) and by cone calorimeter tests. The results revealed that the functionalized S4SQ resins may for…