Materials Literature
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Abstract A redox initiator, cerium ammonium nitrate, was used to initiate the graft copolymerization of vinyl acetate (VAc) onto the chitosan chain in a dispersion polymerization at 60°C. With an addition of 0.5–7.5 g of chitosan based on 50 g of VAc, the monomer conversion was found to be between 70 and 80% after 2 h…
In particulate materials, such as emulsions and granular media, a "jammed" system results if particles are packed together so that all particles are touching their neighbours, provided the density is sufficiently high. This paper studies through experiment, theory and simulation, the forces that particles exert upon o…
Three ion-pair complexes, [RbzPy](+)[Ni(mnt)(2)](-) (mnt(2)(-) = maleonitriledithiolate; [RbzPy](+) = 4-R-benzylpyridinium; R = Br (1), Cl (2), and NO(2) (3)), with unusual magnetic properties have been synthesized and characterized. The crystal structures of 1 and 2 have been solved. The two complexes belong to the P…
Significant improvements in both the hydrothermal stability and the acidity of mesostructured aluminosilcates have been reported recently. New assembly pathways, along with post-synthesis treatment methods, have made it possible to form structures with thick and more highly crosslinked framework walls. The resulting s…
The results of a plane-wave pseudopotential study on the mechanical and electronic properties of twelve III–V zinc-blende (ZB) and wurtzite (WZ) semiconductors under pressure are presented. The lattice parameters, bulk moduli B 0 , energy band types, band-gaps E g Γ at the Γ point, and pressure dependences of E g Γ ar…
In this paper we report the existence of a giant magnetocaloric effect (MCE) in a intermetallic compound non-containing rare-earth. This effect is associated with the concomitant occurrence of a structural and a magnetic transition. The result has been compared with that obtained in a parent compound in which magnetic…
We study the dynamics of metallic vertical stripes in cuprates within the three-band Hubbard model based on a recently developed time dependent Gutzwiller approximation. As doping increases the optical conductivity shows transfer of spectral weight from the charge transfer band towards i) an incoherent band centered a…
The coupling of translational modes to the reorientational motion is an essential property of systems with internal orientational degrees of freedom. Due to their high complexity most of those systems (molecular crystals, glasses...) present a major puzzle for scientists. In this paper we analyze the Raman scattering…
High-Tc Cu oxides consist of the alternating stack of the superconductive CuO2 layer and the block layer, such as Bi2Sr2O4 or La2-xSrxO2. By changing the block layer, we can change their physical properties, such as transition temperature Tc. The thermoelectric Co oxides have a similar layered structure composed of th…
Abstract Modified soy‐based vegetable oil polyols were successfully incorporated as a replacement for conventional polyols to produce flexible slabstock polyurethane foams. The oil was characterized for its hydroxyl value and fatty acid composition. The modified oils had higher hydroxyl values and lower unsaturated ac…
A series of novel hybrid poly(acetoxylstyrene- co -isobutylstyryl-POSS)s (PAS−POSS) and poly(vinylpyrrolidone- co -isobutylstyryl-POSS)s (PVP−POSS) are synthesized and characterized. The POSS content in these hybrids can be controlled by varying the monomer feed ratio. The polyhedral oligosilsesquoixane (POSS) moiety…
Two hydrogen-related defects in ZnO are identified by a combination of local vibrational mode spectroscopy and first-principles theory. The H-I center consists of one hydrogen atom at the bond-center site oriented along the c axis of the crystal. The H-II center contains two inequivalent hydrogen atoms primarily bound…
A simple one-step procedure is described for the synthesis of spherical mesoporous silica, in which the size of the particles is controlled over a range of diameters from 65 to 740 nm by varying the initial silicate/surfactant concentration under dilute conditions. The particles were characterized using X-ray diffract…
Abstract Polypropylene (PP), as a commodity recyclable thermoplastic, was studied in this research to evaluate the potential environmental impact resulting from volatile organic compounds (VOCs) emitted during multiple melt reprocessing. Unstabilized PP (U‐PP) and stabilized PP (S‐PP) resins, simulating recycled mater…
Abstract Postconsumer recycled polypropylene, filled with 15% CaCO 3 was restabilized at various degrees utilizing different processing stabilizers, one of which is especially prepared to counter the deactivating effects of fillers and other moieties. The polymer was then subjected to multiple extrusion cycles for the…
Abstract Plastic energy dissipation (PED) of individual polymer pellets as well as of densified polymer particulate assemblies may be the dominant heating/melting mechanisms in intermeshing corotating twin‐screw extruders (Co‐TSEs). In the present paper, the amount of PED is evaluated by conducting the uniaxial unconf…
Thermal oxidation of metallic Ge yields patterned nanowires of α-GeO2. A significant proportion (∼50 %) of the nanowires possess a common wire morphology with a uniform structure, while some of them have distinctive patterned structures consisting of either a regular array of Ge dots or penetrating holes along their a…
Abstract A novel water‐diluted hybrid coating, consisting of fluorinated poly(urethane‐acrylate) (PUA) and colloidal silica, was prepared by introducing a small amount of fluorinated methacrylate units into the PUA chains. The surface composition and surface morphology of the hybrid film were studied extensively. Atte…
Abstract The screw profile of a twin‐screw extruder can be designed to contain kneading and conveying elements inducing different levels of degradation in the polymer melt. In this work, the level of degradation in polypropylene has been measured after multiple extrusions—for various screw profiles—using size exclusio…
Molecular orientation and relaxation of the trans and gauche conformers of poly(ethylene terephthalate), during and after an uniaxial deformation above the glass transition temperature, between 85 and 100 °C, were investigated using polarization modulation infrared linear dichroism. At all temperatures, it was found t…