Materials Literature
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Using 2 H NMR and high-precision dielectric spectroscopy, we identified in polybutadiene (PB) at low temperatures (20−100 K) a third relaxation process (γ-process) in addition to the α- and β-processes. PB samples with different molecular weights ( M w ) exhibit a strongly varying relaxation strength (Δε γ ) though no…
In this work, we use AFM measurements in conjunction with dialysis experiments to study the synthesis mechanism and physical state of dendrimer-stabilized platinum nanoparticles. For characterizing particle size distributions by high resolution transmission electron microscopy and AFM, sample preparation by drop evapo…
New military requirements have reinvigorated the need for transparent magnesium aluminate (MgAl<sub>2</sub>O<sub>4</sub>) spinel. Surmet has developed a process that yields high quality transparent spinel at production scale. Several issues related to the extreme requirements of processing ultrafine spinel powders are…
Colloidal chemistry routes are exploited to assemble low-dimensional structures. The creation of hybrid assemblies of aligned carbon nanotubes (CNTs) on silica microparticle assemblies (see images) opens up possibilities for controlling CNT growth using colloidal chemistry, and sheds light on factors that may hinder a…
We employ self-consistent field theory to calculate binodals and spinodals of an asymmetric binary polymer blend in a thin film. The film surface and substrate of the film attract both the same component via short-range interactions. The ratios of chain lengths, segment lengths, and segment volumes are chosen to match…
A recently developed constitutive model and a finite element formulation for predicting the thermomechanical response of shape memory alloy hybrid composite (SMAHC) structures are briefly described. Attention is focused on constrained recovery behavior in this study, but the constitutive formulation is also applicable…
The U.S. Naval Research Laboratory (NRL) has developed two unique materials with excellent properties for various military and commercial applications in the UV-Vis-IR wavelength range. These materials are: an amorphous Barium Gallo-Germanate (BGG) glass and a polycrystalline Magnesium Aluminate Spinel. The BGG glass…
Structural behavior and phase transitions in the A-cation deficient perovskite-like solid solutions (1 − x )LaMg 0.5 Ti 0.5 O 3 - x La 2/3 TiO 3 (0 ≤ x ≤ 0.5) were studied to reveal crystal-chemical factors associated with the marked variation of dielectric properties with x -value. Structures and phase transisitons w…
Different non-ionic cellulose ethers like methyl cellulose (MC), hydroxypropyl cellulose (HPC) and hydroxypropylmethyl cellulose (HPMC) were investigated. The characterization of the cellulose ethers was carried out by thermogravimetry and sorption/desorption isotherms. Differences in the properties of the cellulose e…
Both Ni- and Co-MCM-41 may be used for the synthesis of single-wall carbon nanotubes (SWNT). We present a comparative investigation that demonstrates that smaller diameter SWNT with a narrower distribution of diameters are produced using Co-MCM-41. Temperature-programmed reduction and x-ray absorption spectroscopy wer…
ADVERTISEMENT RETURN TO ISSUECommunication to the...Communication to the EditorNEXTDirect Synthesis of Poly(lithium organoborate)s and Their Ion Conductive PropertiesNoriyoshi Matsumi, Kazunori Sugai, Kenji Sakamoto, Tomonobu Mizumo, and Hiroyuki OhnoView Author Information Department of Biotechnology, Tokyo Universit…
Abstract Summary: We used a custom designed dilatometer to measure quantitatively the time evolution of the specific volume of (semi‐crystalline) polymers for an unusual combined wide range of cooling rates and elevated pressures, covering processing conditions. For an isotactic poly(propylene), applying the Schneider…
Basic considerations for implementing combinatorial approach to molecular beam epitaxy (MBE) are discussed, focusing on the key issues relevant to conventional MBE synthesis using solid sources and characterization. The primary objective for implementing combinatorial approach is to make MBE do more, more able to carr…
Dialkyltin dichloride grafted to a cross-linked polystyrene, with the formula [P-H]((1-t))[P-(CH2)nSnBuCl2]t (P=[CH2CH(pC6H4)], t=the degree of functionalization, and n=6 or 11), is investigated as a recyclable catalyst in the ring-opening polymerization (ROP) of epsilon-caprolactone (CL). It is demonstrated that high…
The redox properties of monolayer-protected gold nanoclusters (MPCs) are considered from both the theoretical and experimental viewpoints. The "absolute standard redox potential" ([E0((z/z)-1))]abs) of MPCs is first derived from electrostatic considerations. A linear dependence of the absolute standard redox potential…
Transparent magnesium aluminate spinel is an attractive material for use in a wide range of optical applications including windows, domes, armor, and lenses, which require excellent transmission from the visible through to the mid IR. Theoretical transmission is very uniform and approaches 87% between 0.3 to 5 microns…
An electrochemical method for self-assembling melanin films on the Au(111) surface from melanin aggregates in alkaline media is reported. Electrochemical data combined with scanning tunneling microscopy (STM), atomic force microscopy, and Auger electron spectoscopy show that the amount and structure of the deposited m…
We performed molecular dynamics simulations of the electrostatic assembly of multilayers of flexible polyelectrolytes at a charged surface. The multilayer build-up was achieved through sequential adsorption of oppositely charged polymers in a layer-by-layer fashion from dilute polyelectrolyte solutions. The steady-sta…
This paper presents a robust nonlinear control that uses a state variable estimator for control of a single degree of freedom rotary manipulator actuated by shape memory alloy (SMA) wire. A model for SMA actuated manipulator is presented. The model includes nonlinear dynamics of the manipulator, a constitutive model o…
Structural changes during constrained melting of blown polyethylene (PE) films were followed by in-situ synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques. Results indicated that thermally stable flow-induced crystallization precursor structures (i.e., shish-kebabs) can…