Search results for "Solid"
showing 10 items of 3575 documents
X-ray topographic study of solid-state polymerized poly-[1,2-bis-(p tolylsulphonyloxymethylene)-1-butene-3-inylene]
1976
Local extinction contrast effects have been observed in macroscopic polymer crystals, using Berg-Barrett X-ray topography. Results from as-polymerized crystals indicate that the crystals are perfect enough for defect regions to be imaged. As-polymerized crystals exhibited apparent defects lying along [021]. [010] slip traces in the (100) surface of a crystal were imaged; the slip system here appears to be consistent with (h01) [¯10h], forh, l ≠ 0 and [010] the chain direction.
Different kinds of solid solutions in the V2O5-ZrSiO4-NaF system by sol-gel processes and their characterization
1993
Abstract In the V2O5-ZrSiO4-NaF system, three kinds of substances have been identified by sol-gel methods depending on the V2O5 amounts in the composition. Their characterization by X-ray diffraction, measurements of unit cell parameters, UV-visible (UV-V) spectroscopy, differential thermal analysis and lab colour parameter determination allow the consideration of three kinds of solid solution in the zircon lattice: (a) V+5,V+4-ZrSiO4, thermally stable and with a deep green colour; (b) V+4-ZrSiO4, thermally stable and blue coloured, made by the sol-gel method and with V2O5 amounts lower than 0·03 mol per formula weight; and (c) Na+,F−,V+4-ZrSiO4, a solid solution with a deep blue-turquoise …
Activity of Antimicrobial Silver Polystyrene Nanocomposites.
2012
A simple technique based on doping polymers within situgenerated silver nanoparticles (Ag/PS films) has been developed. In particular, an antiseptic material has been prepared by dissolving silver 1,5-cyclooctadiene-hexafluoroacetylacetonate in amorphous polystyrene, and the obtained solid solution has been heated for ca. 10 s at a convenient temperature (180°C). Under such conditions the metal precursor decomposes producing silver atoms that diffuse into the polymer and clusterize. The antimicrobial characteristics of the resulting polystyrene-based material have been accurately evaluated towardEscherichia coli (E. coli)comparing the cytotoxicity effect of 10 wt.% and 30 wt.% (drastic and …
Nanoclays for Conservation
2019
Within the conservation of artworks materials, this chapter describes innovative strategies based on clay nanoparticles that are promising for protective coating, surface cleaning, and consolidation. We present the preparation of polymer/montmorillonite nanocomposites, which are revealed as efficient protective coatings for highly porous stones, marbles, and bread-made artifacts. Anticorrosive films for metal substrates have been obtained by polymer filling with laponite and halloysite nanotubes (HNTs) containing corrosion inhibitors into their lumen. The dispersion of hydrophobically modified HNTs into chitosan matrix drives to fabricate biofilms with surface cleaning capacity. Rust stains…
Recent Applications of Carbonaceous Nanosorbents in Solid Phase Extraction for the Determination of Pesticides in Food Samples
2018
This article covers recent trends of carbonaceous nanomaterial supported solid phase extraction for the liquid and gas chromatography analysis of pesticides in food samples. Several advanced carbonaceous nanosorbents have been reported over the previous decade for pesticide extraction, such as graphene derivatives modified by combination with silica, amines, polymers, and/or magnetic nanoparticles. The advances in this field have opened possibilities for using neat or modified carbon nanotubes or graphene-type sorbents for the pre-concentration of polar or nonpolar pesticides by solid phase extraction (SPE) or micro-SPE methods or to apply such nanomaterials for the removal of matrix compon…
Dielectric study of orientational disorder in (CO2)1−x(N2O)xmixed crystals
1990
The dipolar relaxation dynamics of solid solutions of carbon dioxide and nitrous oxide has been investigated using dielectric spectroscopy. The temperature dependence of the relaxation rate reveals an ideal Arrhenius behavior for all concentrations, with energy barriers which scale linearly between the two pure compounds. The attempt frequencies are anomalously high. The distribution of relaxation times due to the static random fields as introduced by the substitutional impurity molecules is almost negligible. The melting temperature is determined by a critical relaxation rate of 40 kHz.
Multicomponent solid dispersion a new generation of solid dispersion produced by spray-drying
2020
Abstract The term “multicomponent solid dispersion” is widely used in recent literature to describe solid formulations consisting of a special excipient's mixture and active molecules finely dispersed. However, this term has not yet been defined. In this review, we aimed to improve the definition of multicomponent solid dispersions as a new generation of solid dispersions capable to improve both formulation issues and the therapeutic effect of the final dosage form. As it is well-known the use of solid dispersions to improve drug dissolution rate and solubility, this review describes the field of solid dispersions as well as the formulation strategies available for their production. In part…
Stable Light-Emitting Electrochemical Cells Using Hyperbranched Polymer Electrolyte
2021
The choice of an adequate electrolyte is a fundamental aspect in polymer light-emitting electrochemical cells (PLECs) as it provides the in situ electrochemical doping and influences the performance of these devices. In this study, a hyperbranched polymer (Hybrane DEO750 8500) blended with a Li salt is used as a novel electrolyte in state-of-the-art Super Yellow (a polyphenylenevinylene) based LECs. Due to the desirable properties of the hyperbranched polymer and the homogeneous and smooth films that it forms with the emitting polymer, PLEC with excellent electroluminescent properties are obtained using a pulsed current bias scheme. The devices are very stable, with lifetimes in excess of 2…
Photon correlation spectroscopy to study the dynamics of α- and β-relaxation in amorphous poly(Alkylmethacrylates) above Tg
2008
A short survey of the underlying principles of isotropic light scattering from amorphous bulk polymers is given. The interrelation between the time dependent longitudinal compliance and the autocorrelation function of density fluctuations is briefly reviewed and a comparison with poly(vinylacetate) PVAc is presented. For four poly-(alkylmethacrylates) - poly(methylmethacrylate) PMMA, poly(ethylmethacrylate) PEMA, poly(n-butylmethacrylate) PBMA and poly(n-hexylmethacrylate) PHMA - the results of photon spectroscopic studies are given and discussed in terms of the occurrence of primary and secondary relaxation processes within the accessible time range of the experiment.
Blends from redox active liquid crystal ionomers and amorphous ionomers
1994
Abstract Biphasic blends (mixtures) of liquid crystal ionomers (prepared from ferrocene containing liquid crystal polymers by a redox reaction) and partially sulfonated polystyrene combine the constituent properties in a way, which is dependent on the measuring method. Polarizing microscopy shows homogenous textures similar to the pure liquid crystal polymer. Mechanical measurements show however the elastomeric behaviour of sulfonated polystyrene. The phase separated structure of these blends is proved by differential scanning calorimetry measurements.