Search results for "COMPOSITE"
showing 10 items of 4584 documents
Extruded Expanded Polystyrene Sheets Coated by TiO2 as New Photocatalitic Materials for Foodstuffs Packaging
2012
Nanostructured, photoactive anatase TiO2 sol prepared under very mild conditions using titanium tetraisopropoxide as the precursor is used to functionalise extruded expanded polystyrene (XPS) sheets by spray-coating resulting in stable and active materials functionalised by TiO2 nanoparticles. Photocatalytic tests of these sheets performed in a batch reactor in gas-solid system under UV irradiation show their successful activity in degrading probe molecules (2-propanol, trimethylamine and ethene). Raman spectra ensure the deposition of TiO2 as crystalline anatase phase on the polymer surface. The presence of TiO2 with respect to polymer surface can be observed in SEM images coupled to EDAX …
Study of morphology, mechanical properties, and thermal degradation of polycarbonate-titania nanocomposites as function of titania crystalline phase …
2013
Titania nanoparticles were prepared using a sol–gel method and calcination at 2008C and 6008C to obtain anatase and rutile phases, respectively. The obtained powders were used to prepare polycarbonate (PC)-titania nanocomposites by melt compounding. The effect of different crystalline phases and amounts of titania, in the range 1–5 wt%, on the morphology, mechanical properties, and thermal degradation kinetics of PC was investigated. The results show that the filler modified the plasticity or rigidity of the polymer and influenced the degradation kinetics, in different ways depending on the type and amount of titania. POLYM. COMPOS.,
Enzyme pretreatment and negative pressure cavitation extraction of genistein and apigenin from the roots of pigeon pea [Cajanus cajan (L.) Millsp.] a…
2012
Abstract An enzyme pretreatment and negative-pressure cavitation extraction (E-NPCE) method was investigated for extraction genistein and apigenin from pigeon pea roots. The important parameters involved in E-NPCE process were optimized by single-factor experiments and then critical parameters were investigated by a 2 3 full factorial central composite design (CCD) to optimize extract conditions. Under optimal conditions, the yields of genistein and apigenin were 0.628 mg/g and 0.359 mg/g, which represented an increase of 44.70% and 53.05%, respectively, compared to standard NPCE. Furthermore, from DPPH scavenging activity test the extract of E-NPCE showed better antioxidant activity than t…
Synthesis of gold nanotubes with variable wall thicknesses
2013
We report the synthesis of gold nanotubes with variable wall thicknesses that is accomplished by the deposition of sacrificial hydrophobic polymer cores followed by gold shells within an anodic aluminum oxide template. We demonstrate that by varying polymer core hydrophobicity, the resulting gold shell thickness can be varied. There are two requirements for gold shell formation: (1) the polymer core must be able to be electrodeposited into a tubular (as opposed to wire-like) structure, and (2) the polymer must be hydrophobic, such that it collapses upon exposure to an aqueous solution. An array of gold nanotubes has variable plasmonic properties and can function as a surface enhanced Raman …
Fine tuning of the catalytic effect of a metal-free porphyrin on the homogeneous oxygen reduction.
2011
The catalytic effect of tetraphenylporphyrin on the oxygen reduction with ferrocene in 1,2-dichloroethane can be finely tuned by varying the molar ratio of the acid to the catalyst present in the solution. The mechanism involves binding of molecular oxygen to the protonated free porphyrin base, in competition with ion pairing between the protonated base and the acid anion present.
Considering lithium-ion battery 3D-printing via thermoplastic material extrusion and polymer powder bed fusion
2021
Abstract In this paper, the ability to 3D print lithium-ion batteries through Pmnbspace thermoplastic material extrusion and polymer powder bed fusion is considered. Focused on the formulation of positive electrodes composed of polypropylene, LiFePO4 as active material, and conductive additives, advantages and drawbacks of both additive manufacturing technologies, are thoroughly discussed from the electrochemical, electrical, morphological and mechanical perspectives. Based on these preliminary results, strategies to further optimize the electrochemical performances are proposed. Through a comprehensive modeling study, the enhanced electrochemical suitability at high current densities of va…
Hybrid Molecular Materials Based upon Organic π-Electron Donors and Inorganic Metal Complexes. Conducting Salts of Bis(ethylenediseleno)tetrathiafulv…
2002
Abstract The synthesis, structure and physical characterization of three new radical salts formed by the organic donor bis(ethylenediseleno)tetrathiafulvalene (BEDS-TTF or BEST) and the paramagnetic hexacyanoferrate(III) anion [Fe(CN)6]3− or the photochromic nitroprusside anion [Fe(CN)5NO]2− are reported: (BEST)4[Fe(CN)6] (1), (BEST)3[Fe(CN)6]2·H2O (2) and (BEST)2[Fe(CN)5NO] (3). Salts 1 and 3 show a layered structure with alternating organic (β–type packing) and inorganic slabs. Salt 2 shows an original interpenetrated structure probably due to the unprecedented presence of (BEST)2+ dications. The three salts are semiconductors although salt 1 exhibits a high room temperature conductivity …
Hydrolytic degradation of PLA/Posidonia Oceanica green composites: A simple model based on starting morpho-chemical properties
2021
Abstract In this work, we studied the degradability of PLA-based biocomposites containing Posidonia Oceanica flour at different loading levels and aspect ratios. Hydrolytic tests were carried out in neutral (pH = 7.4) and alkaline (pH = 10) environment. Time-dependent evolution of some key features, including residual mass and solution uptake, was monitored, and correlated with the changes observed in both morphology and chemical structure of the matrix. The results pointed out that biocomposites degraded much faster than neat PLA in both conditions, up to lose 70% of their initial weight after 1000 h immersion. A complex mechanism was unveiled, evidencing the crucial role of the fillers, c…
Novel Polycaprolactone Nanocomposites Containing Thymol of Interest in Antimicrobial Film and Coating Applications
2008
It is well-known that the nanocomposites technology can significantly enhance, among others, the thermal, mechanical, and barrier properties of plastics. It is also known that most bioplastics, including the thermoplastic biopolymers, have lower than desired levels for certain properties which makes their use in certain packaging applications problematic. The combination of active technologies such as antimicrobials and nanotechnologies such as nanocomposites can synergistically lead to bioplastic formulations with balanced properties and functionalities for their implementation in packaging applications. The present work presents the development and characterization of novel nanocomposite…
Electrical treeing in EVA-bohemite and EVA-montmorillonite nanocomposites
2009
The present experimental work focuses on the growth of electrical treeing inside different Ethylene-vinyl acetate (EVA) nanocomposites containing Bohemite (an aluminum oxide hydroxide) and Montmorillonite (a phyllosilicate clay mineral) nanoparticles. Bohemite and Montmorillonite particles have different aspect ratios: the first one has a nanometric cube-like symmetry, while the latter has a typical layered structure. The results evidence that the growth of the electrical treeing inside the original polymer can be altered significantly by the dispersion of inorganic nanoparticles.