Materials Literature
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The anisotropy of heat conductivity that develops on uniaxial stretching of amorphous high polymers has been examined theoretically and experimentally. Experimental measurements on oriented polystyrenes and polymethylmethacrylates show a linear increase in conductivity (parallel to stretching) with increasing elongati…
It has been found that anions have a dual role in relation to the stability of the oxide film on mild steel. They contribute both to the destruction of the oxide film and to the passivation process in which the film is stabilised. The dependence of these functions on concentratinn differs, so that the aggressive actio…
Abstract Diffusion coefficients and solubilities of methane in polyisobutylene have been measured at four temperatures between 102 and 188°C. in the pressure range 23–341 atm. Diffusion coefficients extrapolated to atmospheric pressure range from 1.72 × 10 −6 cm. 2 /sec. at 102°C. to 1.5 × 10 −5 cm. 2 /sec. at 188°C.…
A new design of a low pressure sputtering system of magnetron type is described. The optimum sputtering conditions are discussed in relation to the system. It is shown that this system is able to produce uniform thin films with good reproducibility, and especially to produce a metal oxide film by reactive sputtering.…
Abstract Detailed crazing behavior in several plastic/rubber twophase polymer systems was studied by means of direct observation of ultrathin sections under the electron microscope by employing osmium tetroxide staining and hardening procedure. Samples used are ABS polymer, high ‐impact polystyrene and several PVC/rub…
The structure of pollucite from Rumford, Maine has been determined and refined. The space group is Ia 3 d with cell edge a = 13.69 Å. The structure was investigated using 213 independent reflection intensities measured on a single crystal diffractometer. Pollucite has the analcime framework with the cesium atoms occup…
Abstract Fine structures of several plastic/rubber two ‐phase polymer systems were studied by means of direct observations of ultrathin sections under the electron microscope using osmium tetroxide staining and a hardening procedure developed recently by Kato. Samples used are several types of both ABS polymers and hi…
Abstract Synopsis The diffusion of six solvents in three crosslinked, glassy epoxy polymers is studied. Case II swelling and Fickian sorption are observed as two simple limiting cases. The mechanism of diffusion changes from one limit to another as the nature of the solvent or the crosslink density of the polymer is a…
Summary The main advantage of high voltage in electron microscopy is greater penetration. When using an aperture of optimum size the thickness of specimen that can be imaged increases almost linearly with applied voltage in the case of light elements, both when the criterion is image intensity and when it is resolutio…
The dislocation sub-structure and surface markings formed during the early stages of fatigue in copper single crystals at room temperature were studied. For the first few cycles the structure is similar to that associated with stage I of tensile deformation. A three-dimensional network of interconnected veins packed t…
Abstract Weathering products formed on surfaces of both potassium and plagioclase feldspar (An 70 ), which were continuously leached in a Soxhlet extraction apparatus for 140 days with 7·21 of distilled water per day at a temperature of approximately 78°C, are morphologically identical to natural products developed on…
A relatively simple thin-film structure using vanadium dioxide is analyzed in detail to show that high-temperature, low-resistivity filaments can exist in VO2under appropriate electrical bias. These filaments will dominate both the static and dynamic electrical behavior of the structure, giving rise to V-I characteris…
An analysis of electron energy loss spectra of some 12 transition metal dichalcogenides has given useful information towards the understanding of the band structures of these layer-type solids. Using the experience gained from studying graphite in which the valence band consists of two groups, namely π and σ bands, a…
An investigation of the effects of small additions of Fe 2 O 3 to lead zirconate‐lead titanate ceramics with compositions between 45 and 60 mol% lead zirconate has shown that, with 2 moles of PbO to balance each mole of Fe 2 O 3 , the solubility of Fe 2 O 3 was about 0.8 wt% in compositions near the tetragonal‐rhomboh…
Element abundance distribution, systematic compositional variations, environmental and genetic factors, diagenesis (recrystallization to low-Mg calcite)
Abstract Dynamic mechanical properties determined with a torsion pendulum were used to ascertain the glass transition temperature T g of poly‐ε‐caprolactone. By measurements on compatible blends of poly‐ε‐caprolactone and poly(vinyl chloride), the T g of amorphous poly‐ε‐caprolactone was shown to be 202°K at about 1 c…
Abstract Cysteine synthetase in Salmonella typhimurium is a multifunctional protein complex of molecular weight 309,000 which catalyzes the two-step synthesis of l-cysteine from l-serine, acetyl-CoA, and sulfide. Certain enzymic and chemical properties of a purified preparation of cysteine synthetase have been studied…
An experimental study is described of the formation and growth of gas bubbles in crosslinked elastomers. A critical condition for bubble formation is found to hold in most cases: The gas supersaturation pressure must exceed 5G/2, where G is the shear modulus of the elastomer. The kinetics of bubble growth are shown to…
An empirical equation is developed for the prediction of total penetration distance of a projectile in many natural earth targets. Development of this equation was based on approximately 160 full-scale penetration tests into a variety of targets, including rock, gypsite, permafrost, ice, desert alluvium, silt, sand an…
The geometry of the deformation produced by the climb of edge dislocations is defined and the conditions are determined under which dislocation climb, by itself or in conjunction with glide, can produce a general change of shape. The results are important in understanding the high-temperature deformation (T > 0.5Tm) o…