Materials Literature
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Polypyrrole (PPy) is one of the most studied conducting polymers. It is well known that the mechanical, physical, and chemical properties of PPy strongly depend on the nature of the dopant anion. In this context, on overwiev of the influence of small anions and metallomacrocycles, for example, metallophthalocy anines…
A series of silicon‐aluminum oxynitride‐glass compositions containing selected rare‐earth (RE) additions were prepared to examine the effects of specific RE, as well as Si:Al:RE and N:O ratio, on properties. The properties that were characterized included density, thermal expansion coefficient (α), glass‐transition te…
The ultrasoft pseudopotential calculations are performed for the ${\mathrm{CaF}}_{2}$-type dihydrides ${\mathrm{TiH}}_{2},$ ${\mathrm{VH}}_{2},$ and ${\mathrm{CrH}}_{2}.$ The calculated lattice constants agree well with the experimental data except for ${\mathrm{CrH}}_{2}.$ We also perform calculations for a solution…
The real and imaginary parts of third-order nonlinear susceptibility χ(3) have been measured for silicon nanocrystals embedded in SiO2 matrix, formed by high temperature annealing of SiOx films prepared by plasma-enhanced chemical vapor deposition. Measurements have been performed using a femtosecond Ti–sapphire laser…
Abstract This article concerns the effectiveness of various types and degrees of surface modification of sisal fibers involving dewaxing, alkali treatment, bleaching cyanoethylation and viny1 grafting in enhancing the mechanical properties, such as tensile, flexural and impact strength, of sisal‐polyester biocomposite…
A new metal-free synthetic approach to the controlled ring-opening polymerization (ROP) of lactide with nucleophilic phosphines as transesterification catalysts is described. P(Bu)3, PhPMe2, Ph2PMe, PPh3, and related phosphines are commercially available, inexpensive catalysts that generate narrowly dispersed polylact…
RATIONALE AND OBJECTIVES: Preclinical in-vivo characterization of a newly developed MR contrast medium consisting of very small superparamagnetic iron oxide particles (VSOP) coated with citrate (VSOP-C184). METHODS: VSOP-C184 (core diameter: 4 nm; total diameter: 8.6 nm; relaxivities in water at 0.94 T (T1) 20.1 and (…
BACKGROUND AND PURPOSE: Ultrasmall superparamagnetic iron oxide particles result in shortening of T1 and T2 relaxation time constants and can be used as MR contrast agents. We tested four hypotheses by evaluating MR images of intracranial tumors after infusion of two iron oxide agents in comparison with a gadolinium c…
Abstract Microfibrillar reinforced composites (MFC) comprising an isotropic matrix from a lower melting polymer reinforced by microfibrils of a higher melting polymer were manufactured under industrially relevant conditions and processed via injection molding. Low density polyethylene (LDPE) (matrix) and recycled poly…
Under healthy conditions, the blood-brain barrier (BBB) limits the passage of solutes and cells from the blood to the CNS. During neurological diseases, BBB permeability increases dramatically and it has been hypothesized that drug carrier systems such as polymeric nanoparticles could cross the BBB and penetrate into…
We present the synthesis of hyperbranched polymer−silica hybrid nanoparticles by self-condensing vinyl polymerization (SCVP) via atom transfer radical polymerization (ATRP) from silica surfaces. ATRP initiators were covalently linked to the surface of silica particles, followed by SCVP of an initiator−monomer (“inimer…
The temperature dependent flow properties of highly filled polymer compounds intended for production of hard-metal parts by powder injection moulding (PIM) technology were studied. The pure binder based on polyethylene, ethylene and butyl acrylate block copolymer and paraffin, and its compounds with hard-metal carbide…
The objective of this study is mainly to review recent work concerning the numerical modeling of the stick-slip and gross melt fracture polymer extrusion instabilities. Three different mechanisms of instability are discussed: (a) combination of nonlinear slip with compressibility; (b) combination of nonlinear slip wit…
Article Improved Mechanical Properties of SiC Fibers Pyrolyzed from Polycarbosilane under Tension was published on April 1, 2002 in the journal Science and Engineering of Composite Materials (volume 10, issue 2).