Materials Literature
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Based on ab initio calculation, we propose a new structure for the fundamental excitation of the reconstructed 30$^\circ$ partial dislocation in silicon. This soliton has a rare structure involving a five-fold coordinated atom near the dislocation core. The unique electronic structure of this defect is consistent with…
We present momentum-dependent measurements of the density response function of bulk samples of purified single-wall nanotubes probed by electron energy loss spectroscopy. Carbon nanotubes support excitations between both delocalized and localized electronic states. The $\ensuremath{\pi}$ plasmon exhibits a q dependenc…
We introduce an approach to exploit the existence of multiple levels of description of a physical system to radically accelerate the determination of thermodynamic quantities. We first give a proof of principle of the method using two empirical interatomic potential functions. We then apply the technique to feed infor…
The thermal degradation of graphite and glass-reinforced phenolic insulators have been studied at high temperature by using thermogravimetric (TGA) and differential scanning calorimetric analyses. TGA analysis was carried out in a stream of pure nitrogen over temperature range ambient to 900°C and DSC analysis to 500°…
Polydiphenylsiloxane (PDPhS) has been prepared by solution ring opening polymerization of hexaphenylcyclotrisiloxane and characterized by 29 Si solid-state NMR spectroscopy. The thermal characteristics of the polymer have been examined by DSC, dynamic mechanical thermal analysis, linear expansion and X-ray diffraction…
The EPR spectra of [Ru(NH 3 ) 5 (H 2 O)](TFMS) 3 and [Os(NH 3 ) 5 (H 2 O)](TFMS) 3 (TFMS = trifluoromethanesulfonate) have been measured for a range of temperatures for the solid powders and frozen solutions. The g ∥ axis for the “axial” spectrum observed is shown to be perpendicular to the M−O bond axis, as it is per…
Effect of fillers like carbon black, silica, and china clay on the cure characteristics and physicomechanical properties of natural rubber (NR) modified with phosphorylated cashew nut shell liquid (PCNSL) in various proportions has been studied. Prominent cure retardation has been observed with progressive increase in…
The effect of the compatibilizer on the crystallization, rheological, and tensile properties of low-density polyethylene (LDPE)/ethylene vinyl alcohol (EVOH) (70/30) blends was investigated. Maleic anhydride-grafted linear low-density polyethylene (LLD-g-MAH) was used as the compatibilizer in various concentrations (f…
A water-swellable rubber was prepared by blending polychloroprene (CR) with crosslinked sodium polyacrylate (CSP), precipitated silica, poly(ethylene oxide) (PEO), and vulcanizing agents. The preparation process was described and the effect of composition of the water-swellable rubber on its water-absorbent properties…
Profile development and dimensional change in the melt-spinning process of hollow fibers were studied using a finite element method, and a numerical simulation was compared with experimental results. The numerical simulation of a hollow-fiber spinning process was carried out by considering the changes in inner and out…
Polycondensation of squaric acid with a water-soluble pyrrole derivative containing an N -propanesulfonate pendant group gave a water-soluble A−B type oligomer. Similarly, several water-soluble random oligomers were prepared by the polycondensation of pyrrole, sodium 3-(pyrrol-1-yl)propanesulfonate, and squaric acid.…
Soluble conductive polypyrrole (PPy) with room temperature conductivity (2–18 S/cm) has been synthesized by doping polypyrrole with mixed acid containing camphor sulfonic acid (CSA) and dodecyl benzene sulfonic acid (DBSA). The solubility and the room temperature conductivity of PPy doped with mixed acid were measured…
Trisdipicolinate coordination complexes of europium(III), Eu(dpa) 3 3-, have chiral, three-bladed propeller-like structures with either left-handed or right-handed structural helicity about a 3-fold symmetry axis. The left- and right-handed forms of these structures, labeled here as Λ and Δ, respectively, are structur…
As a first step toward the computer simulation of polydisperse polymeric melts, a lattice model containing two types of chains with lengths N 1 = 20 − x and N 2 = 20 + 4 x (0 ≤ x ≤ 10 ) is studied. This variation of x, together with the fixed composition of 80% of short and 20% of long chains, leads to a polydispersit…
Some technical properties (static mechanical properties, dynamic mechanical properties, creep-recovery behavior, thermal expansion, and thermal conductivity) of low-density foams (50 kg/m3) made of blends of low-density polyethylene (LDPE) and the ethylene vinyl acetate copolymer (EVA) were studied as a function of th…
We have investigated the morphology developed in the ordering process for a nearly symmetric polystyrene- block -polyisoprene diblock copolymer when the copolymer is rapidly brought from a disordered state to an ordered state. The ordering process was explored as a function of time and temperature primarily by transmi…
The structure and morphology of nylon 9,2 has been investigated using transmission electron microscopy, selected area electron diffraction, and X-ray diffraction. A unit cell with parameters a = 5.45 Å, b = 8.7 Å, c (chain axis) = 31.8 Å, and β = 47.9° was determined and a C 12 /c 1 space group is postulated. Chain co…
The kinetics of the enzymatic degradation of bacterial poly(3-hydroxybutyrate) (PHB) is studied using PHB-depolymerase A from Pseudomonas lemoignei (Tris−HCl buffer, pH = 8, T = 37 °C). Biodegradation experiments are performed on PHB in the form of both compression-molded films and powder suspension. From WAXS and DSC…
We compute phase diagrams for A n B m starblock copolymers in the strong-segregation regime as a function of volume fraction φ, including bicontinuous phases related to minimal surfaces (G, D, and P surfaces) as candidate structures. We present the details of a general method to compute free energies in the strong seg…
We consider surfaces protected by polymer chains of N monomers grafted at a density σ, that are immersed in a melt of chemically similar chains of polymerization index P . We have used the self-consistent field approximation to analyze the practically useful (but analytically untractable) case of moderately long melt…