Search results for "25"
showing 10 items of 3263 documents
High-performance thermoplastic elastomers/carbon nanotubes nanocomposites: Mechanical behavior, rheology, and durability
2015
Advanced polystyrene-b-polybutadiene-b-polystyrene (SBS) based nanocomposites containing bare carbon nanotubes (CNTs) and CNTs bearing hydroxyl functional groups (CNTs-OH) have been formulated and fully characterized. In particular, the reinforcement effect of CNTs and CNTs-OH on SBS was deeply investigated through mechanical and dynamical thermo-mechanical analysis and the rheological response of SBS-based nanocomposites was investigated and discussed. The mechanical properties of SBS/CNTs and even more of SBS/CNTs-OH nanocomposites are substantially superior to those of neat SBS, due to the uniformly dispersed nanofillers throughout the polymeric matrix. The presence of -OH groups onto CN…
Effect of nano zinc oxide as UV stabilizer on the weathering performance of wood-polyethylene composite
2016
Abstract In this study, the effect of using nano-sized zinc oxide (ZnO) particles on the enhancement if the degradation resistance of wood-high density polyethylene (HDPE) composite was investigated through artificial weathering. Samples with different amounts of ZnO mixing ratio (0, 1, 2, and 4 wt%) were manufactured using an internal mixer followed by compression molding. The prepared samples were then exposed to the artificial weathering process in a QUV weatherometer. The weathering behavior of samples was characterized using tensile strength, contact angle analysis, colorimetry, ATR-FTIR spectroscopy and FE-SEM. The results indicated that the amount of surfaces crack, tensile strength …
Concentration-dependent anti-/pro-oxidant activity of natural phenolic compounds in bio-polyesters
2017
Abstract In this work, the potential of several naturally occurring phenolic compounds, such as Ferulic Acid (FA), Vanillic Acid (VA), Vitamin E (VE) and Quercetin (Q), as stabilizers against the photo-oxidative degradation of Polylactic acid (PLA) has been assessed. Specifically, PLA-based films containing different amounts of considered stabilizers have been formulated and their photo-stability under UVB exposure has been evaluated. The preliminary characterization of the formulated films shows that all used stabilizers exert plasticizing action, as probed by rheological analysis, due to their low molecular weight. Moreover, no significant modification of the PLA crystallinity has been no…
Investigation of Annealing Conditions on Electrochemically Deposited CZTS Film on Flexible Molybdenum Foil
2016
In thiswork, the electrodeposition of Cu2ZnSnS4 thin films on molybdenum thin foilwas reported. In order to guarantee co-deposition of elements with different standard electrochemical potential, an aqueous electrolyte added with ligand agents was used. I addition, deposition parameters were carefully chosen, in order to ensure good quality and suitable composition of the films. The deposited films were sulfurized in controlled atmosphere at 580?C, scrutinizing the influence of the annealing conditions on the features of the films. Structure, morphology and composition were investigated by XRD SEM, EDS and Raman spectroscopy. Results reveal the growth of good quality films, with a uniform mo…
Physico-Chemical Characterization of Anodic Oxides on Hf as a Function of the Anodizing Conditions
2016
Anodic films were grown to 5 V (Ag/AgCl) on mechanically polished Hf in 0.1 M ammonium biborate and 0.1 M NaOH. Independent of the anodizing conditions, the photoelectrochemical characterization allowed the observation of optical transitions at 3.25 eV, i.e. at photon energy lower than the bandgap of HfO2. They are attributed to localized states inside the gap of the oxide induced by the presence of oxygen vacancies. From the cathodic photocurrent spectra, it was possible to estimate an energy threshold of ∼2.15 eV for internal electron photoemission phenomena. The impedance measurements proved the formation of insulating oxides with ϵ =19. The anodizing occurs under a high field regime wit…
Effect of High Temperature Oxidation Process on Corrosion Resistance of Bright Annealed Ferritic Stainless Steel
2017
The corrosion resistance of stainless steels is determined by the thickness, structure, composition and electronic properties of the oxide layers grown on their surface and isolating the metallic substrate from the environment. In the present work, ex situ XPS (X-Ray Photoelectron Spectroscopy) and ToF-SIMS (Time of Flight Secondary Ions Mass Spectrometry) have been combined to in situ PCS (PhotoCurrent Spectroscopy) in order to perform an integrated physicochemical characterization of surface oxide films grown on bright annealed ferritic stainless steel (AISI 434) as-received and after thermal post-treatment in air. The surface oxide film on as-received samples has a bilayer structure with…
Effects of Pulse Current Mode on Plasma Electrolytic Oxidation of 7075 Al in KMnO4Containing Solution
2017
Plasma electrolytic oxidation of 7075 Al alloy was performed in alkaline silicate electrolyte containing KMnO4as an additive using unipolar (U) and bipolar pulsed current modes (B1 and B2). The coating grown using the bipolar current with longer cathodic pulse time (B2) revealed a more dense foam-like surface morphology with fewer volcano areas providing higher thickness, which is mainly raised by reduction in discharge intensity. Also, a lower concentration of electrolyte elements (Si and Mn) was incorporated into the coating providing a brighter appearance. EIS results showed very high inner layer resistances for the coatings indicating this layer controls the overall corrosion performanc…
Metallic interconnects for SOFC : characterization of their corrosion resistance in hydrogen/water atmosphere and at the operating temperatures of di…
2006
International audience; Chromia forming alloys are one of the best candidates for the interconnecting materials in solid oxide fuels cells (SOFC). Recent research has enabled to decrease the operating temperature of the SOFC from 1000 °C to 800 °C. However, low electronic conductivity and high volatility of the chromia scale need to be solved to improve performance of interconnects. In the field of high temperature oxidation of metals, it is well known that the addition of reactive elements into alloys or in thin film coatings, improve the oxidation resistance of alloys at high temperature. The elements of the beginning of the lanthanide group and yttrium are the most efficient. The goal of…
Static strength and fatigue life of optimized hybrid single lap aluminum–CFRP structural joints
2017
Hybrid bolted/bonded joints are used to assemble structural components, commonly made by carbon fiber reinforced plastics (CFRP), with aluminum frames. Hence, they have become common solutions in a number of modern structural applications in the industrial fields, as well as civil constructions. Unfortunately, due to the lack of understanding of the relationships between the multiple parameters of influence that characterize their mechanical performance, only limited improvement have been achieved so far over classical bonding approaches, in terms of static and fatigue strength. As a result, further studies are needed in order to better exploit the potential of hybrid bolted/bonded joints a…
1,2,4-Triazolium ions as flexible scaffolds for the construction of polyphilic ionic liquid crystals
2018
A novel scaffold for the construction of self-organised ionic liquids and ionic liquid crystals bearing both perfluorocarbon and hydrocarbon moieties has been developed. The phase behaviour and physical properties of these materials can be tuned as a function of chain length and fluorine content and significant structural elaboration is possible, giving a highly flexible system.