Materials Literature
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We interpret some recent calculations of Eisenriegler, Kremer, and Binder [1], and related multi-critical results of Diehl and Dietrich [2]. They show that the monomer concentration profile Φ(x) for isolated polymer chains in a good solvent and in close proximity to an adsorbing wall exhibits a singular behaviour ; i.…
Abstract A new high‐performance amorphous thermoplastic, named polyetherimide, has been developed by the General Electric Company. This resin is characterized by high deflection temperature (200°C at 264 psi), high tensile strength and flexural modulus (480,000 psi), and very good retention of mechanical properties at…
Barium titanate is an important material for both scientific and industrial applications. Much of the interest centres around its ferroelectric properties, since it is structurally the most simple in this class. In addition rare-earth doped ceramics are found to exhibit a very steep positive temperature coefficient of…
Samples of a TiB 2 ceramic containing 0 to 10 wt% Ni were fabricated by hot‐pressing. Several properties, including fracture strength, indentation fracture toughness, and thermal expansion (between 25° and 1000°C) were measured. Resulting data were correlated with sample microstructure and composition.
The effects of structural properties and their changes during cellulose hydrolysis on the enzymatic hydrolysis rate have been studied from the reaction mechanism point of view. Important findings are the following: (1) The crystallinity index (CrI) of partially crystalline cellulose increases as the hydrolysis reactio…
Abstract Differential scanning calorimetry is employed to study the crystallization kinetics of two commercial injection‐molding high‐density polyethylene resins. Also, polarized light microscopy has been used to elucidate the morphological structures formed at various crystallization conditions. Corrections and opera…
Photoconductivity measurements have been carried out for a series of powder Pt/TiO2 catalysts containing from 0.05 to 10 wt% Pt as well homodispersed particles (mean diameter ca. 2 nm). The presence of platinum, at least for contents ca. 1 wt%, caused a decrease in the anatase photoconductance σeq at equilibrium under…
Abstract Research in the past eight years has established the ability of polymer composites made with sufficient electrical conductivity to be suitable as shields against electromagnetic interference (EMI). A number of conductive fillers have been used to produce such composites. These include carbon black, carbon fib…
The reaction of dichlorosilane, H 2 SiCl 2 , with gaseous NH 3 in dichloromethane or diethyl ether solution results in the formation of a silazane oil containing silicon, hydrogen, and nitrogen in good yield. This ammonolysis product can be pyrolyzed in an N 2 atmosphere (temperature to 1150°C) to give α‐Si 3 N 4 in ∼…
Ever since Mauguin described the fabrication of liquid crystal cells by rubbing glass plates with paper to obtain uniform homogeneous alignment, scientists have been attempting to study and understand the mechanism of anchoring and the subsequent alignment of these materials on various substrates. More than 35 differe…
Abstract The degradability of three high molecular weight polycaprolactones (M̄ w = 35,000, 18,600, and 7,130) and one low molecular weight polycaprolactone diol(M̄ w = 2060) by mixed and pure cultures of microorganisms was assayed. A yeast, Cryptococcus laurentii , a gram‐negative rod, Acinetobacter calcoaceticus var…
Abstract The microstructure of melt‐grown dendritic aggregates of the monoclinic α phase of isotactic polypropylene has been examined by optical microscopy, electron microscopy, and electron diffraction. Whereas the tightly crosshatched structure of such dendrites grown in the usual manner from the melt had not hereto…
We argue that the basic mechanism stabilizing the blue phases is the appearance of double cholesteric twist. The free-energy cost of the disclination lattice that inevitably accompanies double twist becomes small near the clearing point. We use the director picture and the Oseen-Frank equations in a computer calculati…
We discuss the director deformation inside a hybrid aligned nematic (HAN) cell, assuming that the surface interaction is of the (w/2) sin2 (φ - Φ) kind, and we suppose that the anchoring energy for homeotropic alignment is greater than the planar one. In the absence of an external electric field, we show that a critic…
Mesure des spectres d'absorption des metaux de transition 3d et des elements de terre rare dans des verres de fluorure de zirconium et evaluation de leur coefficient d'absorption dans l'infrarouge proche a moyen. Afin d'obtenir une fibre de verre de fluorure ayant une perte par transmission inferieure a 0,1 dB/km a 2,…
This paper presents torsional test results for six ductile metals subjected to large shear strains and high strain rates. Included are OFHC copper, Cartridge brass, Nickel 200, Armco IF iron, Carpenter electrical iron, and 1006 steel. Torsional shear strains as high as 700 percent are achieved and strain rates vary fr…
Abstract Three high molecular weight polycaprolactones (M̄ w = 35,000, 18,600, and 7,130) were utilized as the sole carbon source by five of six fungi tested by the American Standards for Testing and Materials (ASTM) agar plate method. The fungi were Aspergillus flavus, A. niger, A. fumigatus, Chaetomium globosum, Pen…
A very large amount of information is available in the open literature on the diffusion, or transport, of small molecules in polymers. A comprehensive discussion of this field would require an amount of space exceeding by far the confines of the present monograph. It is to be hoped that this herculean but extremely us…
The large meso-substituted porphine, meso-tetra(4-N-methylpyridyl)porphine has been identified as a DNA-interactive ligand with a capacity for intercalation (1,2). Subsequently, the 2-N-methyl, 3-N-methyl and N-trimethylanilinium analogues of this porphyrin intercalator have been obtained for physico-chemical analyses…
Les mésophases de molécules discoïdes forment deux classes :