Materials Literature
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Abstract The optical properties of thermally crystallized polyethylene terephthalate (PET) were investigated using the methods of small‐angle light scattering, density, and haze measurements. The results indicate that the haze in crystallized PET results from scattering due to crystalline aggregates called spherulites…
Measurements have been made of the velocity of sound and the velocity of free retraction for stretched strips of vulcanized natural rubber. Both of these velocities are found to increase markedly with increasing strain, in agreement with earlier work. The velocity of sound is shown to be related to the appropriate mod…
Abstract The probable number of hydrogen bonds has been calculated as a function of the imino acid content for water‐bridged collagen structures. With increasing imino acid content in collagen, the number of hydrogen bonds stabilizing triple‐helical structures become saturation. This might explain the asymptotic chara…
Abstract A model of the manufacture of rigid polyurethane foams by free rising is presented. The extent of cream and rise periods as well as the amount of blowing agent necessary to give the desired foam density are theoretically predicted. The rate of blowing agent evaporation is calculated from an experimental boili…
Fused silica and flowing hydrogen gas react in the experimental temperature range of 1200° to 1400°C to form SiO and H 2 O vapors. Above a critical flow rate of hydrogen gas, the reaction rate is independent of gas flow rate and is not transport‐controlled. The apparent activation energy for the overall process was 34…
The high‐temperature structure of a–Al 2 O 3 was studied by powder neutron diffraction up to 2000° C. The changes in the structural parameters (unit cell and positional parameters and thermal B factors) with temperature give evidence of low aluminum and oxygen mobilities; Al ions are, however, always more mobile than…
Abstract X‐ray diffraction (XRD), differential thermal analysis (DTA), and transmission electron microscopy (TEM) were used to characterize the phyllosilicates in a catena of soils derived from serpentinite in southwestern Oregon. Serpentine (variety chrysotile) and chlorite were the phyllosilicates in the bedrock and…
Electron diffraction patterns have been obtained from regions of a thin crystal of partially ordered copper-gold alloy, Cu3Au, which have a diameter of about 15 Å and contain an antiphase domain boundary. The superlattice diffraction spots show a characteristic splitting similar to the splitting which appears in all s…
A brief review is first given of the important considerations involved in numerical simulation of solidification. This is followed by presentation of an explicit finite-difference treatment for directional freezing of alloys, in which emphasis is laid on modelling the detailed internal response of the metal. Particula…
The morphology and fine structure of six species of the monoraphid diatom genus Cocconeis Ehr. have been investigated. The raphid valve is concave and thinner than the convex araphid valve. The vela are located near the internal openings of the areolae in the raphid valve but near the outer surface in the araphid valv…
Abstract Oxygen consumption and yield of oxidation products during γ‐irradiation were studied on five types of polyethylene (PE), ethylene–butene copolymer (EB), and ethylene–propylene copolymer (EPR) using gas chromatography, mass spectrography, and high‐resolution NMR. Samples were irradiated in oxygen under pressur…
Abstract A new kinetic model for cure reactios has been developed from the concept of nonequilibrium thermodynamic fluctuation theory in which a distribution function relaxation spectrum is used for explaining cure kinetics of polymer–filler systems. It is found that an increase in filler loading reduces the relaxatio…
Results of X-ray diffraction experiments on lithium nitride (Li3N) in the temperature range between 294 and 888 K show strong anharmonic effects. The deviations from harmonicity cannot be interpreted by interstitial sites or split positions. The application of an anharmonic temperature factor which is based on the Gra…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew trinuclear, oxo-centered, basic carboxylate compounds of transition metals. 3. Syntheses and x-ray studies of the trivanadium(III,III,III) and trivanadium(II,III,III) compounds [V3(.mu.3-O)(CH3CO2)6(CH3COOH)2(THF)]+[VCl4(CH3COOH)2]- and V3(.mu.3-O)(CF3CO2)6(THF)3 with "c…
The authors present the results of high resolution measurements of bremsstrahlung excited Auger electron spectra in the 5d series. The spectra provide an experimental test of atomic models. The measured effective Coulomb interaction between the final state holes displays a jump in value between Pt and Au, analogous to…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTVariable-temperature Raman and infrared spectra of the copper acetate dimer Cu2(O2CCH3)4(H2O)2 and its derivativesY. Mathey, D. R. Greig, and D. F. ShriverCite this: Inorg. Chem. 1982, 21, 9, 3409–3413Publication Date (Print):September 1, 1982Publication History Published on…
Abstract During weathering of forsterite and tephroite under the humid, tropical conditions of the Ivory Coast, intermediate Mg,Fe 3+ − or Mn 2+ -smectites appear prior to widespread development of iron or manganese oxyhydroxides. In forsterite, the smectite varies from an Mg-trioctahedral variety near the centres of…
This paper describes an algorithm for representing the transformer hysteresis. This algorithm is useful under transient conditions and has the capability of representing minor loops. It allows the multi-valued hysteresis behavior to be represented as a linear element at each instant of time. This algorithm has been im…
David W L Hukins 1981 Oxford: Pergamon ix + 164 pp price £11.95 Most books on x-ray diffraction relate to crystalline materials (where the solving of structures has become a rather mechanical process) and, because of the breadth of the subject, are either very superficial or indulge in considerable mathematical detail…
Abstract The preparation of a series of macrocycles, formed by reaction of HO‐(‐CH 2 ‐CH 2 ‐O‐) n H with 1,10‐phenanthroline‐2,9‐dicarbonyl chloride (n = 2,3,4) and 1,8‐naphthyridine‐2,7‐dicarbonyl chloride (n = 3,4), is described. An improved synthetic route to 2,7‐dimethyl‐1,8‐naphthyridine 9 is also reported.