Areas under the linear tan δ–temperature (tA) and linear loss modulus–temperature (LA) curves of the polyacrylate and polymethacrylate homologous series and their interpenetrating polymer networks (IPNs) were inves...
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Areas under the linear tan δ–temperature (tA) and linear loss modulus–temperature (LA) curves of the polyacrylate and polymethacrylate homologous series and their interpenetrating polymer networks (IPNs) were investigated. For poly(methyl acrylate), LA values are independent of crosslinking level through 25%, but tA decreases. With increasing side group length, on the other hand, tA remains nearly independent of side group length for both homologous series, having values near 50 and 65 (units of K) for the acrylate and methacrylate series, respectively. However, LA decreases steeply with increasing side group length. A phenomenological treatment of areas is presented in order to explain tA and LA behavior semiquantitatively. Both tA and LA exhibit areas characteristic of the structure of the particular polymers. The homopolymer LA areas are additive in determining the area under the corresponding curve for the IPN. This suggested a group contribution analysis for LA, where each moiety contributes specific values to the area.
Black crystals, displaying a micaceous habit, result from heating the 90 K superconducting phase YBa2Cu307_;above 1050 °C. The crystals are tetragonal, PA/mmm, a = 3.863 (2) A, c — 11.830 (4) A, Z= 1, yOcai — 6...
Over the past three years, a superconducting solenoid, cryogenic electron beam ion source has been designed, constructed and tested at Cornell University. The source is designed for atomic physics experiments requirin...
Over the past three years, a superconducting solenoid, cryogenic electron beam ion source has been designed, constructed and tested at Cornell University. The source is designed for atomic physics experiments requiring low energy, very highly charged ion beams. The present status of the source is discussed and its use in some preliminary atomic physics experiments is described.
Sulfide capacities of Na2O-SiO2 melts at 1473 and 1623 K were calculated a priori from a model using free energies of formation of Na2S and Na2O and the activities of Na2O in the binary Na2O-SiO2 melts. Our calculatio...
Sulfide capacities of Na2O-SiO2 melts at 1473 and 1623 K were calculated a priori from a model using free energies of formation of Na2S and Na2O and the activities of Na2O in the binary Na2O-SiO2 melts. Our calculations are in excellent agreement with available experimental data and appear to be more more accurate than currently used empirical predictions of sulfide capacities, based on correlations with optical basicities using Pauling electronegativities.
The submerged arc welding process uses a D.C. arc under a protective slag cover to melt a consumable wire electrode. The purpose of this work is to investigate the relative influence of electrochemical and thermochemi...
The submerged arc welding process uses a D.C. arc under a protective slag cover to melt a consumable wire electrode. The purpose of this work is to investigate the relative influence of electrochemical and thermochemical reactions at the surface of the electrode of the composition on the liquid metal droplet. chemical analyses were carried out on the melted wire electrode tips and on the detached droplets for both reverse polarity (wire is anodic) and straight polarity (wire is cathodic) polarities. The results suggest that both thermochemical and electrochemical reactions are important in altering the composition of the detached droplet.
An extensive literature review indicated that the law of mixture rule can at times account for stress-strain behavior of two-ductile phase alloys in terms of the stress-strain behavior of component phases. In the pres...
An extensive literature review indicated that the law of mixture rule can at times account for stress-strain behavior of two-ductile phase alloys in terms of the stress-strain behavior of component phases. In the present investigation, various factors which can contribute to the stress-strain behavior of two-ductile phase alloys are considered, using Ti-Mn alloys as the model system. Particular attention is focused on the effect of elastic, elasto-plastic, and plastic interactions between the phases on the stress-strain behavior. It is shown that the law of mixture cannot adequately explain the stress-strain behavior. The following equation is proposed to describe the stress-strain behavior of two-ductile phase alloys: Pα-β = fαPα c + fβPβ c + Iα-β p, where Pα-β is a given stress-strain property, fα and f/gb are respective volume fractions of α and β-phases, Pα c and Pβ c are corrected properties of α and β-phases, and Iα-β p is the interaction term. It is found that for α- β Ti-Mn alloys, for 0.2 pct yield strength, Iα-β p is positive, negative, or zero depending on the microstructure; but Iα-β p is always positive for the ultimate tensile strength and strain hardening rates and its magnitude depended on the microstructure. The reasons for the nature or sign of the interaction parameter for a given property are discussed in detail.
The exposure of dielectrics to moisture in the presence of an electrical field can result in the growth of water trees possibly leading to premature failure (1). Although investigated extensively, the mechanisms of in...
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The exposure of dielectrics to moisture in the presence of an electrical field can result in the growth of water trees possibly leading to premature failure (1). Although investigated extensively, the mechanisms of initiation and growth of water trees remain unclear. In relation to this, the mode of water transport through treed polymeric materials is a subject of considerable controversy. It has been suggested that the voids constituting the water trees are interconnected by channels which develop under the influence of electrical stress and collapse due to surface tension once the field is removed (2). If this is the case, one must consider the possibility that the observed stress dependence of the rate of water-tree growth is controlled by the effect of the stress of the rate of water transport through a damaged dielectric. To date, all work dealing with fluid transport studies show no indication of the existence of these channels. However studies were carried out either with undamaged materials (3) or without an applied field (4,5).
AbstractInterpenetrating polymer networks (IPN\'s) can be defined as a combination of two polymers in network form, at least one of which was synthesized and/or crosslinked in the immediate presence of the other. ...
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AbstractInterpenetrating polymer networks (IPN\'s) can be defined as a combination of two polymers in network form, at least one of which was synthesized and/or crosslinked in the immediate presence of the other. Historically, the science of IPN\'s began with the papers of J. R. Millar in 1960 on homo‐IPN\'s made from polystyrene, but the first recorded publication is a patent by J. W. Aylsworth in 1914. This latter system was based on phenol‐formaldehyde for one network, and sulfur cured natural rubber for the other network. Early academic laboratories interested in IPN\'s include the Frisch team at Detroit and SUNY, who soon added their former student, Danny Klempner, and Yuri Lipatov\'s team at the Ukranian SSR Academy of sciences in the USSR, as well as the author\'s laboratory. More recent academic teams interested in IPN\'s include Douglas Hourston at the University of Lancaster, England; Robert Cohen at MIT; S. C. Kim at the Korea Advanced Institute of science and Technology, Seoul, Korea; G. Meyer and J. M. Widmaier in Strasbourg, France; and many others. Numerous industrial laboratories are interested, noting that about 90 U.S. patients have been granted, most of them in the past ten years. Systems of special interest include the new thermoplastic IPN\'s, which are really hybrid materials between polymer blends and IPN\'s, and the IPN‐based RIM (reaction injection molding) materials. Other materials include the sequential IPN\'s and the SIN\'s, which have both polymers simultaneously polymerized, and the latex IPN\'s, which often exhibit core‐shell characte
Advanced ion sources such as the electron beam ion source (EBIS) and electron cyclotron resonance ion source (ECRIS), originally developed for nuclear particle accelerators, are increasingly being used as sources of l...
Advanced ion sources such as the electron beam ion source (EBIS) and electron cyclotron resonance ion source (ECRIS), originally developed for nuclear particle accelerators, are increasingly being used as sources of low energy, highly charged ions in atomic physics experiments. This paper discusses the design of a superconducting solenoid, cryogenic EBIS specifically intended for experiments with low energy, very highly charged ions of medium to high Z elements.
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