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  • Inorganic Chemistry  (788)
  • Chemical Engineering  (386)
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  • 1970-1974  (1.174)
  • 1971  (1.174)
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  • 1970-1974  (1.174)
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  • 1
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A mathematical model has been developed to predict radial temperature gradients in polymers during dielectric heating. The time-temperature model includes parameters for rate of dielectric heating, thermal conductivity, density, heat capacity, surface coefficient of heat transfer, and sample radius. The application of this model was checked experimentally on a 2-in. cylinder of cured polyisoprene.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 129-138 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A crosslinked epoxy resin consisting of a 60/40 weight ratio of Epon 815 and Versamid 140 and composites of this material with glass beads, unidirectional glass fibers and air (foams) were tested in tension, compression and flexure to determine the effect of time and temperature on the elastic properties, yield properties and modes of failure. Unidirectional continuous fiber-filled samples were tested at different fiber orientation angles with respect to the stress axis. Strain rates ranged from 10-4 to 10 in./in.-min and the temperature from -1 to 107°C.Isotherms of tangent modulus versus strain rate were shifted to form master modulus curves. The moduli of the filled composites and the foams were predictable over the entire strain rate range. It was concluded that the time-temperature shift factors for tangent moduli and the time-temperature shift factors for stress relaxation were identical and were independent of the type and concentration of filler as well as the mode of loading.The material was found to change from a brittle-to-ductile-to-rubbery failure mode with the transition temperatures being a function of strain rate, filler content, filler type and fiber orientation angle, indicating that the transition is perhaps dependent on the state of stress.In the ductile region, an approximately linear relationship between yield stress and log strain is evident in all cases. The isotherms of yield stress versus log strain rate were shifted to form a practically linear master plot that can be used to predict the yield stress of the composites at any temperature and strain rate in the ductile region. The time-temperature shift factors for yielding were found to be independent of the type, concentration and orientation of filler and the mode of loading. Thus, the composite shift factors seem to be a property of the matrix and not dependent on the state of stress. The compressive-to-tensile yield stress ratio was practically invariant with strain rate for the unfilled matrix, while fillers and voids raised this ratio and caused it to increase with a decrease in strain rate. The yield strain of the composites is less than the unfilled matrix and is a function of fiber orientation and strain rate.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 247-257 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A theoretical model for melting in plasticating extruders is described. Compared to previous models, this model introduces more accurate and less restrictive assumptions, adds a mass balance on the entire channel, and replaces certain approximate solutions by exact solutions. Flow of the solid bed is represented by a solid bed acceleration parameter, SBAP, which permits solid bed acceleration in a screw compression section. New experimental melting data for a variety of screw designs, polymers, and extruder sizes are presented and compared to the theoretical predictions. With the optimum SBAP, reasonably accurate model prediction of the melting profiles is observed for a wide variety of cases.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 295-304 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A torsional pendulum which operates throughout the temperature range  -  180° ⇄ +650°C, and permits the examination of specimens which conform to ASTM standard D2236 is reported. The same apparatus is used for torsional braid analyses for which a composite specimen is prepared by impregnating a multifilament glass braid with a solution of polymer and thermally removing the solvent. A linear-with-angle no-drag optical transducer which employs the linear transmission region of a pair of polarizers is described. The apparatus has been used for examining thermo-hysteresis effects in polymers. Hysteresis can arise in polymers from physical time-dependent phenomena such as crystallization ⇄ fusion, dry atmosphere ⇄ water vapor, annealing ⇄ cracking, and from chemical reactions. Thermally-induced chemical reactions can be regulated so as to freeze out preferentially longer range relaxations, thereby extending the glassy state behavior to higher temperatures. A comparison of the thermomechanical behavior of a commercially available polyimide film and of a polyimideforming varnish is reported using torsional pendulum and torsional braid analyses.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 211-219 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Glass-reinforced thermoplastics are being considered in many structural applications and fabricators require design information on these materials. Basic creep data are, in many cases, the most useful for design purposes. The work reported here concerns the development of methods of increasing our efficiency in generating creep data. The methods developed are applicable to polypropylene and coupled, glass-reinforced polypropylene. A stress-time superposition procedure has been found valid for extending creep data generated on coupled glass-reinforced polypropylene at several glass levels and at temperatures of 23 and 80°C.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 353-360 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Experimental studies were performed with low density polyethylene, acrylonitrile-butadiene-styrene polymers and on polyvinyl chloride to elucidate the nature of the plasticating process in a reciprocating-screw injection molding machine. Melting data, obtained by use of the “cooling experiment,” and plastic temperature data reveal that the screw recharge process is a transient plasticating extrusion process which gradually approaches the equilibrium extrusion behavior as the screw rotates. If the screw rotation time is a high percentage of the total cycle time, the plasticating behavior is very similar to steady-state extrusion behavior, but if the screw rotation time is a small percentage of the total cycle time, the plasticating behavior is significantly different. Furthermore, better plasticating is obtained by use of a low RPM and high percentage rotation time than by a high RPM and low percentage rotation time.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 381-384 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The peculiar behavior of thermoplastic elastomers in molding suggested that the processing steps (mainly shearing) to which the material had been submitted had a great influence on the morphology. Experiments were carried out on two polysstyrene-polybutadiene-polystyrene elastomers. The effects of melt-shearing and cooling were examined both by mechanical testing and low angle X-ray scattering. Melt-shearing creates a marked morphological anisotropy but a form of annealing can occur at sufficiently high temperatures.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971) 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 361-368 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A theoretical model for the transient melting behavior in a reciprocating-screw injection molding machine is proposed. The model is based on a steady state extrusion model, Neumann's melting problem, and a heuristic postulate for the transient behavior. The model predictions are compared to experimental melting data for low density polyethylene, acrylonitrile-butadiene-styrene polymers and polyvinyl chloride for a variety of operating conditions and two screw designs. A useful degree of correlation is demonstrated for all experimental cases.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 385-394 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An experimental study is carried out to elucidate the melt fracture mechanism. For the study, the electrical outputs of the melt pressure transducers, mounted on the wall of a circular tube, are recorded on a Sanborn recording system. It has been observed from this study that the wall pressures start to fluctuate prior to the inception of visible melt fracture. The frequency and amplitude of the excursion signals are increased as the shear rate is increased up to and beyond the critical value. This behavior has been observed for three polymer samples tested: polystyrene, high density polyethylene, and low density polyethylene. The fluctuations of wall pressures are interpreted as due to an irregular flow of polymer melts at the tube wall. It is further investigated to find the effects of the die entry angle of a capillary, and capillary length-to-diameter ratio on the critical shear rate. A correlation between exit pressure and shear stress has been found for polystyrene and low density polyethylene. It is found that at and above the critical stress, the exist pressure increases abruptly. This is interpreted to be a sudden change in the elastic properties of the materials above melt fracture since Han et al have shown that the exist pressure is a measure of the elastic properties.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
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  • 11
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The current art for image-wise photopolymerization is reviewed and the prospective future developments are briefly assessed. Photomechanics, photoengraving, gravure, lithography, chromophores, dye sensitization, cyanine photopolymerization, bathochromy, and phototanning are covered. Primary photoprocesses, their sensitization by cyanines, Oster photopolymerization, photovinyls, diazo and diazido-sensitized systems, and secondary photoprocesses are discussed. A bibliography is provided.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 93-98 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Various solid conveying, melting, and metering theories developed for plasticating screw extrusions are reviewed. Some recommendations for improving the present melting theories are presented. It is pointed out that the overall performance of a screw extruder can be predicted only by combining the solid-conveying, melting and metering theories into a complete mathematical package because the three functions of a screw extruder depend on each other and cannot be separated. A suggestion is made on how to combine these three theories.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 205-210 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A correlation is developed between the melt elasticity and temperature, the melt elasticity being defined by the normal stress difference. The correlation follows the form of the Arrhenius equation, for the temperature range tested, for high density polyethylene and polypropylene melts. Measurements were taken using the capillary rheometer which is described in detail in the author's earlier publications. The author further presents a correlation between the pressure drop at the entrance of a capillary and the residual pressure at the exit of the capillary (exit pressure). The correlations presented in the paper support the author's earlier contention that the exit pressure is indeed a manifestation of elastic behavior.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 233-239 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Cobalt promoters presently used in the polyester processing industry suffer from many shortcomings ranging from shelf instability to strong discoloration of the resins and relatively poor activity. This paper describes the various performance improvements obtainable with coordination complexes of cobalt which can be used as polymerization accelerators in presence of organic peroxide initiators. These complexes appear to present significant advantages over the conventional cobalt carboxylates. Catalytic activity up to ten times that of cobalt soap was recorded with some complexes in various resin systems, without deleterious effects on physical properties. As gel-cure modifiers, the compounds evaluated seem to increase the long term shelf stability of pre-promoted resins while reducing the discoloration and air inhibition during the curing process of polyester thin films.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 28-34 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The forces required to compress billets of crystalline polymers below their melting points were determined and related to the initial billet dimensions and amount of deformation. The studies involved the use of three high-density polyethylenes and an acetal copolymer. The results were found to obey an equation derived from plasticity theory using, at each temperature and for each material, a single parameter very nearly equal to the yield strength determined in ordinary tensile tests, and having the same temperature dependence. An empirical equation that describes the pressure required to form cups by backward extrusion of metal billets is also successful for the same process with polymers, using the yield parameter from the compression experiments. Cold working causes a high degree of orientation, increased clarity, and greatly increased tensile strength.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 274-283 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effects of polymer molecular weight, molecular weight distribution, and orientation on the rate of relaxation-controlled sorption of n-pentane by glassy polystyrene were studied. The sorption follows Case II kinetics but for films which sorb slowly the sorption rate increases at relatively long times until sorption is sharply terminated. This rate increase may be explained by the development of dispersed microvoids within the unrelaxed film core. Overshoot of the equilibrium n-pentane content occurs in sorption experiments in which accelerated sorption is pronounced.The sorption rate is independent of polymer molecular weight and molecular weight distribution per se over a broad wrange of these parameters. Essentially identical vapor sorption kinetics were observed for well annealed polystyrene films of different molecular weights and distributions. Conversely, for vapor sorption by uniaxially oriented films and for liquid sorption by partially annealed films, high molecular weight film (1,880,000) exhibits greater sorption rates than low molecular weight film (ca. 200,000). These differences in rate are not due to molecular weight differences per se, but are a consequence of the dissimilar response of free volume and strain development for films of different molecular weight prepared with a given time-temperature-strain history.Crazing of carefully annealed polystyrene films occurs during desorption of n-pentane from partially saturated films. The depth of craze penetration reflects the point of advance of the discontinuous Case II sorption boundary.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 320-323 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: It has been well established in the literature that the internal pressure, Pi = (∂E/∂V)T, of a polymer in the glassy state is about half the value expected from the behavior of the polymer just above the glass temperature, Tg. Consideration of this behavior in terms of a recent analysis of factors affecting internal pressures leads to the conclusion that the expression for the total energy of a glass must include a volume-dependent stored energy term, a term not present above Tg. This stored energy could be associated with actual bond and segment deformations in the glassy state. Brittleness and solvent cracking behavior of glasses will be strongly dependent on this stored elastic energy which can be modified by altering the molding conditions under which the glass is formed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 18
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effects of fiber volume content, fiber-matrix bonding, heat treatment, and age hardening on the transverse mechanical properties of undirectional aluminum matrix fibrous composites have been investigated. Test results have indicated that the increase of the matrix strength is directly responsible for the increase of the transverse strength of a composite fabricated under heat-treated conditions, as compared with the corresponding strength for the annealed condition. The composite transverse tensile strength and elastic modulus have been calculated by using the finite-element method and the von Mises-Hencky criterion. Both the square and hexagonal arrays have been considered for the fiber configuration in the matrix. The analytical results are compared with the experimental data obtained at room temperature and low strain rate.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 377-380 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The thermal stability of polyethylene containing conventional antioxidants is adversely affected by contact with copper, by certain pigments, and by the addition of a few percent of polypropylene as a processing aid. Polyethylene inhibited with 0.1% of phenolic antioxidants has approximately the same oxidative stability when in contact with a copper surface as the unprotected polymer. A mechanism is suggested to account for the loss of stability in the presence of copper. Pigments vary in the extent to which they adversely affect the oxidative stability of polyethylene. Since several factors may combine to decrease the stability of protected polyethylene compositions, as determined by accelerated tests, it is essential that their contribution under service conditions be determined. The predicted life at temperatures encountered in service is determined by extrapolating accelerated test data to that constant temperature which is calculated to cause the same degree of degradation as would occur during the daily and seasonal temperature cycles encountered in use.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 401-404 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Heat transfer to polymer solutions or melts flowing in parallel plate systems is an important aspect of polymer processing as for example in extrusion through a wide slit.The present work solves the equation of energy for pseudoplastic non-Newtonian fluids flowing between parallel plates. An exact velocity profile rather than an approximation is used. Equations are derived both for temperature profiles and mean temperatures. The results are shown to correctly represent the physical situation.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 421-425 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polymethylmethacrylate has been sensitized to 4880 A light and used as a holographic recording medium. The polymer is sensitized with a material which may itsel be degraded by exposure to ultraviolet light. The new process is, therefore, both self-developing and fixable without chemical processing. Holographic diffraction gratings written into this material have diffracting efficiencies as high as 70 percent. Various parameters such as angular selectivity, film thickness, variation of diffracting efficiency with writing angle etc., have been studied. The spontaneously produced diffracted intensity is so high that efficient interference between first and zero ordes is observed during the writing process.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 463-473 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effect of hydrostatic pressure, up to 112,000 lb/in.2, on the tensile properties of four polymers is reported. The pressure soaking of polystyrene in castor oil had no significant effect on the material's residual properties when tested under ambient conditions. When tested under pressure polystyrene necked, like a metal, and exhibited a brittle ductile transition at 40,000 lb/in2. Between 40,000 to 112,000 lb/in.2 the tensile strength increased by about 30%. Young's modulus and yield strength were only slightly affected by pressure. Similar results were obtained for specimens sheathed to prevent possible plasticization of the polystyrene. Polymethylmethacrylate tested at 112,000 lb/in.2 failed just short of its instability point and with only a slight increase in Young's modulus. These amorphous polymers thus behaved under pressure in a generally similar manner to metals.Pressure had a marked effect on the stress-strain curves of two crystalline polymers polyethylene and nylon. Young's modulus and tensile strength were considerably increased and elongation decreased. Pressure inhibited ‘drawing’ of the materials. Deformation was restricted to a small necked region.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 265-273 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The kinetics of uncatalyzed autoxidations for polyolefin films, such as atactic and isotactic polypropylene and poly-(butene-1) are reviewed in light of recent work. Reaction temperatures generally varied from 100 to 150°C and oxygen concentrations from 5 to 100% by volume. A general reaction scheme is suggested and kinetic expressions subsequently derived therefrom have been satisfactorily applied to account for experimental results. Linear relationships between a maximum rate and concentration of oxygen for both low and high concentrations were obtained.In the case of the catalyzed autoxidations [Co(III) acetylacetonate] the general reaction scheme was modified to take into account the presence of the catalyst. From this modified scheme, various kinetic expressions relating maximum rate and concentrations of oxygen, polymer and the catalyst were derived. First-order reaction with respect to the concentration of the catalyst was found at low concentrations of the catalyst, and near zero-order at relatively high catalyst concentrations. A correlation between catalytic activities of metal acetylacetonates [Co(III), Mn(III), Cr(III), Fe(III) and Cu(II)] and the oxidation-reduction potentials has been established.Experimental dependencies of maximum carbonyl formation rates as a function of polymer concentration were found to agree well with the theoretical both for catalyzed and uncatalyzed oxidations.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 24
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 305-311 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Melt viscosity and melt elasticity data were obtained over a broad range of temperatures and shear rates on a series of four polypropylenes of different molecular weight but approximately the same molecular weight distribution. The superposition technique was used with both temperature and molecular weight to shift flow curves for all four materials at three temperatures each along the shear rate axis to generate a master flow curve at a given temperature and molecular weight. For polypropylenes of this type, and molecular weight distribution shift, factors which can be used to extend the useful range of experimentally obtained flow data were determined. The dependency of apparent viscosity on weight average molecular weight at shear stresses as high as 106 dynes/cm2 is shown. The dependency of melt elasticity on molecular weight and temperature is discussed.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 433-445 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Extensional flows have been the object of study in several laboratories in recent years. Polymeric systems have been studied in most cases because of their interesting behaviour and also because of the importance of their rheological properties to the plastics engineer. Controlled, steady elongation is more difficult to achieve in the laboratory than the more traditional viscometric flows. Moreover, it is not in general possible to predict the response of a viscoelastic material to steady extension based on knowledge of its viscometric functions.This review begins by presenting some useful expressions describing the kinematics of extensional flows. Then some results of interest from rational mechanics are presented and the behaviour predicted by a number of constitutive equations for viscoelastic fluids are discussed. After presenting the pertinent relations of linear viscoelasticity for extensional flows, experimental methods and results for steady simple extension are reviewed and some possible implications for the processing of molten polymers are discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 26
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 452-462 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Controlled changes in crystallization conditions and shear history prior to and following both extrusion and compression molding were shown to drastically alter the mechanical properties of the polymer studied. This material, Poly[3,3-(bischloromethyl) oxacyclobutane], is an essentially linear polymer with a number average molecular weight of 300,000. The effect of heat transfer, as limited by experimental conditions, had a primary influence upon the crystallization phenomenon and therefore also upon the morphology and the resultant mechanical properties.By proper selection of processing conditions it was possible to alter the mechanical properties of this polymer from brittle behavior to the ability to form a neck and draw to high degrees of elongation. Using conditions that imparted the ability to neck and draw, it was shown that this process is sensitive to both strain rate during testing and extrusion rate during processing. The underlying cause of the effects upon mechanical properties appear to be the dramatic changes occurring in morphology as a result of the selected processing conditions.A chemical etching agent was used on these samples prior to replication, and observation in the electron microscope. Using this technique the internal morphology was studied and compared to the surface morphology. There was not a gradient of morphology in these samples. Furthermore, the use of this etching agent that attacked non-crystalline regions preferentially, suggested that the lamellar fine structure of spherulites is composed of smaller units.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971) 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 28
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 57-63 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A new analytical technique, differential thermal analysis using high frequency dielectric heating (DTA/HF), has been developed which senses the rate and extent of the enthalpy change accompanying curing. These two parameters relate simply and quantitatively to curing reaction kinetics.In DTA/HF cylindrical samples of uncured elastomers, 2-in. in diam and about 1-in. high, enclosed in glass rings and covered, are heated in a high frequency (86 mc) electrical field simultaneously with an identically-shaped precured reference disc of the same elastomer. Both sample and reference are clamped securely between 3 × 5-in. rectangular output electrodes. The sample is cured isometrically under pressure generated by thermal expansion. Temperatures at the core of the sample and reference are monitored continuously using ungrounded junction thermocouples with stainless steel probes; both sample temperature and temperature differences between sample and reference are recorded.To test the validity of DTA/HF it was first applied to the dicumyl peroxide (DCP) curing of several cis-1,4-polyisoprene calcium carbonate mixtures for which reaction mechanisms and reaction kinetic data are available.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 73-82 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The stress-cracking of polycarbonate by a gaseous or liquid agent results from the diffusion of this agent into the polymer. The low molecular weight polymer fractions and the chain ends within the bulk of the polymer become more ordered during the diffusion and swelling process by their partial solubility in the crazing agent, causing crystallization. The creation of interfaces at areas of order-disorder causes high shearing forces at this boundary and voids within the bulk of the polymer. These voids are then propagated as crazes or cracks at stresses much lower than the tensile strength of the polymer. Therefore, a stress-cracking agent need not diffuse rapidly, but must be an effective environment for swelling and/or crystallization. Data from diffusion, density, thermal and molecular analyses are presented to support this mechanism.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 30
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 109-123 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The problems encountered with cold formed thermoplastic material, namely, low heat distortion temperature and stress and solvent crazing, can be overcome by using a laminate consisting of a reinforced thermosetting core sandwiched between two drawable face sheets. This process imposes a restriction on the material by the need for a curing cycle to transform the core into a hard, three dimensional network. To take full advantage of the very fast metal forming technique, the curing should be accomplished outside of the forming apparatus and without external restraint. In order to impart a practical shelf life to the laminate at room temperature, the chemical requirements of the core can only be met with an elevated temperature cure. This in turn places an additional restriction on the face sheets, as they will have to withstand the curing conditions without external constraint and without dimensional changes of the formed part. Finally, the face sheets then have to become an integral part of the formed laminate upon curing of the latter, involving a high adhesive strength between the cured core and the face sheets. The criteria for the selection of the materials for various layers are presented as well as the limitations on the construction of the entire laminate.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
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  • 31
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 152-159 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The universal calibration and universal correction curves for the correction of resolution dispersion and skewing are established for polyvinylchloride (PVC). The effect of solution concentration on skewing is also demonstrated. The application of these curves to the determination of number and weight average molecular weights of PVC samples is illustrated. The results obtained are consistent with those determined by membrane osmometry and light scattering.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 32
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 165-173 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Strips of ductile, amorphous thermoplastic polymers such as polycarbonates, acrylonitrile-butadiene-styrenes, polysulfones and polyphenylene oxides have been reduced in thickness by passing them through a metalworking rolling mill at room temperature. Properties of the rolled strips were studied as a function of the thickness reduction. In addition to rolling unidirectionally, cross rolling (biaxial rolling) was also studied using equal thickness reductions in each direction. The maximum thickness reduction (to  -  tf)100/to which could be achieved was approximately 60 per cent regardless of the polymer studied here. Stress-strain curves, density changes, thermal stability, hardness and Izod impact strengths have been determined as a function of thickness reduction and sheet direction.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 187-193 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A new gel permeation chromatography (GPC) method is proposed for determining the unperturbed end-to-end distance, \documentclass{article}\pagestyle{empty}\begin{document}$ \left({\frac{{r_0 ^2 }}{M}} \right)^{0.5} $\end{document}, of polymers of known molecular weights, Mn and Mw. This method requires the value of \documentclass{article}\pagestyle{empty}\begin{document}$ \left({\frac{{r_0 ^2 }}{M}} \right)^{0.5} _{{\rm ps}} $\end{document} of polystyrene which was determined through viscometry to be 0.735 \documentclass{article}\pagestyle{empty}\begin{document}$ \left({\frac{{{\rm {\AA}}^2-{\rm mole}}}{{gm}}} \right)^{0.5} $\end{document} Polyvinyl chloride (PVC) was chosen to illustrate the method and \documentclass{article}\pagestyle{empty}\begin{document}$ \left({\frac{{r_0 ^2}}{M}} \right)^{0.5} _{pvc} $\end{document} was found to be 0.99 from GPC data which is in agreement with the result obtained from viscometry, \documentclass{article}\pagestyle{empty}\begin{document}$ \left({\frac{{r_0 ^2}}{M}} \right)^{0.5} _{pvc} $\end{document} = 1.01. All \documentclass{article}\pagestyle{empty}\begin{document}$ \left({\frac{{r_0 ^2 }}{M}} \right)^{0.5} $\end{document} values were determined at 30°C. The advantage to this method lies in its speed and economy of materials.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 34
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 220-225 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A large number of composite materials are polyphase systems in which one phase exhibits time-dependent properties. This paper presents an analysis of the stress redistribution in such a viscoelastic material system under the influence of applied external loads. In order to perform this study an appropriate idealized model, a series of which would tend to approximate the composition of a polyphase material, is formulated. The solution of the time-dependent stress field is obtained by applying the “correspondence principle” to the elastic stress field solution which, for the selected model, has previously been obtained in numerical form.Application of the solution to a model of an actual polyphase composite material system yields results which clearly indicate that, under certain normally encountered conditions of external loading, the principal stresses in certain areas of such a system will increase significantly with time.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 35
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971) 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 174-176 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An experimental study of the inflation of a thin polymer sheet has been conducted to determine whether this technique can be used to measure the biaxial extensional viscosity of bulk polymers. Viscosities were determined at various extensional strain rates using two undiluted polyisobutylene samples having different molecular weights. Advantages, limitations, and errors associated with the method are discussed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 37
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 194-199 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effects of temperature, strain rate and filler content on tensile properties of SAN/glass bead composites are studied. A point of discontinuity on the stress-strain curves for unannealed composites is investigated, annealing results in smooth curves with no discontinuities. A simple model for the filler effect on yield stress is suggested and shown to be in a good agreement with experimental data. A double shifting procedure to account for the temperature and filler effects on yield stress as a function of strain rate is proposed. A single master curve that can be represented by the equation: \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{\sigma yc}}{{{\rm 1 - 1}{\rm .21}\phi ^{{\rm 2/3}} }} = A + B\,{\rm ln (}\dot \epsilon a_T) $$\end{document} relates composite yield stress to strain rate, temperature and filler volume fraction.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 335-343 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polymethyl methacrylate, polyacetal and polypropylene samples were subjected to constant-load uniaxial creep in tension and compression up to 3% strain in times up to 105 sec. A higher creep resistance was obtained in compression compared with tension due to the influence of free volume on mobility. Square wave cyclic creep tests alternately in tension and equal compression for dwell times of 10, 100, 1000 sec were also conducted on each material up to a total time of 105 sec. Under low cyclic creep stresses tension creep cancelled out compression creep in each successive half cycle so that there was no overall increase in creep strain as cycling proceeded. The unidirectional creep data was used successfully to predict this behavior. At higher cyclic stress levels creep strain range increased steadily throughout the test indicating a softening process. A few tests were conducted in unidirectional and cyclic stress relaxation on polymethyl methacrylate.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 39
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 426-430 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A new photoresist stable to 500°C has been developed. The addition of potassium dichromate to a polyamic acid, believed to be the condensation product of pyromellitic dianhydride and 4,4′-diaminodiphenylether, results in a photosensitive polymer which can be cast or spun. The resultant film after exposure, development and post-bake is a crosslinked aromatic polyimide. An efficient developing solution consisting of a 5:1 mixture of hexamethylphosphoramide and dimethylsulfoxide has been discovered. The system has been fully characterized in terms of composition, film formation, exposure, development, hardening and removal. This material has already proven useful as an area-controlled, thermally stable dielectric and as a sputter-etch resist. It has been demonstrated that under the conditions of sputter-etching (bombardment of substrate with Ar, Ar+ species with energies from 1-300 eV) commercial photoresists, of the polyisoprene variety, char to the extent of being ineffective as a masking material. Under these same conditions, the thermally stable resist retains its film integrity and uniform sputter-etch rate. An exemplary processing sequence is included as an appendix.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 40
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 474-483 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: This paper examines two aspects in the design of large extruders. An analysis of the thermal problems in the flowing melt is given in terms of dimensionless groups and the results are applied to the scale-up problem in extruder design. An analysis of the mechanical stability of extruder screws is also given including the effect of axial buckling and whirling. The results are examined as a possible limitation on extruder dimensions.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 502-506 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Determination of the change in electrical dissipation factor and capacitance of epoxy/graphite and polyimide/graphite composites during compression molding provides a reproducible means of obtaining low void content composites by permitting accurate application of low pressure at the resin gel point. Of the two parameters, change in dissipation factor was found to be the more sensitive to molecular changes in the resin matrix as well as to variations in solvent content, particularly with the polyimide systems. The simple laboratory equipment required to carry out these electrical measurements is described.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 42
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 492-501 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A new method of etching is described, the principle of which is the vibration of the sample being etched within the etchant. Because only small samples can be used this method is not suitable for commercial etching. As a test procedure however it has several advantages: a small volume of etchant (about 100 cc) is sufficient, the pressure of etchant attack can be varied and measured continuously, and the temperature can easily be controlled. Examples are given to demonstrate that vibration etching can be applied for characterization as well as for control of photoresist giving data of etch resistance, etch factor, adhesion, flexibility. Also the characteristics of different etchants and the etch behavior of different metal substrates can easily be compared.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 43
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 19-27 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An apparatus was designed and built which allowed an investigation concerning the morphology and kinetics of crystallization of a deformed polybutene-1 melt. The polymer was quenched from a temperature above its melting point to one of two crystallization temperatures. The supercooled melt was then sheared and allowed to crystallize isothermally while the internal stress in the melt was continuously recorded. A polarizing microscope was employed for the simultaneous study of the resulting morphological changes. By properly accounting for thermal contractions within the apparatus caused by the quenching operation, as well as the imposed shear strain, a strain history of the polymer during crystallization was developed. From this strain history and the assumption that the volume contraction resulting from crystallization was isotropic, approximate kinetics of crystallization in a deformed polymer melt were determined.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 44
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 46-50 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Holographic reflective interference patterns arising from a small displacement of the surface of polymer solids provide a very sensitive means for detecting the internal stress related to molecular orientation, as well as measuring very small time dependent deformations not accessible by conventional means. Applicability of this technique using 6328Å laser light on various mechanical studies in polymeric solids is discussed.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 45
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971) 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 46
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 83-92 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A temperature probe system to measure radial temperature profile of polymer flowing in a rod die and a method to systematically correct the conduction and the frictional shear effects were developed. Experimental data obtained on a 1-1/2-inch extruder using a blow molding compound show that both conduction and frictional shear heating effects are significant in melt temperature measurement and that the radial temperature profiles of the melt in the rod die are influenced by the RPM of the screw and the die-wall temperature.The reliability of the temperature data obtained was compared with the solution obtained from the equations of motion and energy. A good agreement between the predicted versus experimental temperature profile exists. For this polymer system, the relationship between local Nusselt number and the velocity parameter could be adequately described with the theory of Van LeeuWen.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
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  • 47
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 124-128 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: In order to predict the processing behavior of a high density polyethylene resin one must know the resin flow behavior over a wide range of shear rates. Low shear properties are important in applications where melt strength, sagging, etc. are critical. On the other hand, high shear flow properties are a determining factor in applications where melt instability, melt fracture and heat generation are important. The flow behavior of a resin can be established by measuring the zero shear viscosity, η0, the maximum relaxation time, τ0, and the shape of the flow curve. We have measured these basic rheological parameters on a large number of high density polyethylene resins. A shear sensitivity parameter which is independent of molecular weight was derived from a correlation between η0 and τ0. This parameter, together with η0, provide the vital information needed in order to predict the processing behavior of the resin. This method is applicable to other polymer systems provided that the rheological parameters η0 and τ0 can be experimentally obtained.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 48
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 160-164 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A mathematical solution for the Arrhenius temperature dependency for the first-order decomposition of organic peroxide catalysts has been used to prepare computer-generated data for concentration vs time when a linearly rising temperature program is used. The resulting plots, of a double exponential nature, are used to show the effects of heating rates and type of organic peroxide on peroxide concentration and polymerization reactions.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 49
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 177-181 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The free volume, vf, of liquids is defined in many ways. Comparison of solid and liquid behavior indicates that the definition for free volume in terms of the internal pressure of the liquid (∂E/∂V)T, is physically reasonable. Application of the definition of free volume, vf = RT/(∂E/∂V)T, to polymethylenes, coupled with surface energy values, leads to an evaluation of both polymer segmental volume, Ṽs, and free volume per segment, (vf)s, as a function of temperature. These equilibrium thermodynamic measurements of Ṽs and (vf)s lead to an energy of activation for viscous flow in good agreement with viscosity studies. Information of this type could be of great use in considering many current problems in polymer flow such as the effect of pressure on viscosity.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 50
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 200-204 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: This article uses Graessley's theory of viscosity to predict the flow curve for several high-density and low-density polyethylene melts using the molecular weight distribution data obtained from the gel permeation chromatograph. The agreement with the experimental flow curve obtained from the Weissenberg rheogoniometer and the Instron rheometer was not quantitative for many high-density polyethylenes studied here. For the low-density polyethylenes, it was shown that the agreement between the theory and the experiment was good even though the molecular weight distribution data were not corrected for long-chain branching. For these samples, the experimental relaxation time τ0 obtained by superposition of the data with the theoretical master curve was of the order of the Rouse relaxation time τR. The systematic increase in the ratio τR/τ0 was ascribed to the increase in the molecular weight or to the increased number of long-chain branches.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 51
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 226-232 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The mechanical performance of fiber glass epoxy, cross-plied laminates having either ductile or brittle matrices, was evaluated in tension. The laminates with ductile matrices have higher initial strength, slower crack propagation in the transverse layers and higher ultimate stress and strain. In both the ductile and brittle systems, the laminae have higher strength, stiffness and toughness than equivalent unidirectional composites. This improved performance results from the interaction between the perpendicular layers which gives them additional stiffness due to shear and transverse coupling effects and also increases the resistance of each individual layer to crack propagation and plastic flow.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 52
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 258-263 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A numerical method for analyzing the uniformity of flow from sheeting dies is presented. The method assumes that the flow is isothermal and that the material is a power law fluid. A uniformity index is defined and methods are presented which enable die dimensions to be established which will result in a specified uniformity at particular flow rates and pressure drops. The analysis shows that the flow index “n” of the power law is the key parameter determining the uniformity of flow from a sheeting die.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 53
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 289-294 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Fibrous structures of high complexity, as introduced by ply and twist, have been subjected to high and low speed tensile tests. The ratio of strength at high speed to low speed is always greater than one, but decreases with increasing complexity of fibrous structure. The ratio of elongation to break at high speed to that at low speed is always less than one and also decreases with increasing structure complexity. The ability to absorb energy markedly increases with increasing complexity of geometry at low strain rates, characteristic of an Instron. The reasons for this additional energy absorption are discussed. Tests at high rates of strain point out the inability of many complex textile structures to translate their superior energy absorption characteristics to high strain rates. The results obtained and the principles demonstrated are applied to the development of improved materials for use in aerial delivery and ballistic applications.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 54
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 312-319 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: 3,3,3-Trichloropropylene oxide (TCPO) is a monomer which has the combination of a highly reactive epoxide group and a stable trichloromethyl group. The epoxy group will undergo ring opening polymerizations with itself and with a host of other compounds to yield polymeric materials. Water, alcohols, phenols, amines, carboxylic acids and many other compounds react with TCPO with the aid of Lewis acid type catalysts. The electron-withdrawing influence of the trichloromethyl group, steric effects and the oxirane ring have a strong influence on the course of reactions, which are often radically different from that encountered with the simpler alkylene oxide monomers.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 55
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 324-334 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Ciné film was employed for recording the movement of tracer particles, thus directly determining the velocity profile in the capillary flow of model materials of polybutadiene over a range of shear stresses relating to (1.) flow conditions in which there is no distortion of the regular stream of melt emerging from a capillary, (2.) severe surface fracture, (3.) elastic turbulence, (4.) oscillatory flow of melts with discontinuous flow curves. No qualitative difference was found between the velocity profiles in conditions (1) and (2); surface fracture is not related to laminar flow disturbances and originates at the capillary exit. Surface fracture must be distinguished from elastic turbulence. The streamline velocities undergo both local and time variations within the capillary under conditions of developed elastic turbulence; the wall velocity is non-zero. A periodic pulsation of velocities occurs in the flow curve discontinuity region; it takes place throughout the capillary and is caused by stick-slipping of polymer on the capillary wall. The frequency of velocity pulsations coincides with the frequency of extrudate variations.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 56
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 369-376 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The dynamic mechanical properties of polyester and polyether urethane block polymers have been investigated at four frequencies (3.5, 11, 35 and 110 Hz) in the temperature range of  -  150 to 200°C. The existence of a two phase structure was demonstrated in these systems by the observation of two major transition regions corresponding to (1) the glass transition temperature (Tg) of the ester or ether soft segments, and to (2) the softening temperature of the aromatic-urethane hard segments. Several secondary relaxations were observed in addition to the two major relaxations. It was possible to assign molecular mechanisms to each of these relaxations. All relaxation phenomena were greatly influenced by the molecular weight of the prepolymer, weight percent of hard segments, and thermal history. An increase in the molecular weight of the prepolymer above 1,000 at constant hard segment content resulted in a semi-crystalline material, which possessed a lower Tg for the macroglycol segments. Annealing to enhance crystallinity increased the Tg of the soft segments, consistent with the usual observation in semicrystalline homopolymers. These findings suggest that the relaxation mechanisms of polyurethane block polymers are not only influenced by the degree of crystallinity, but also by the nature of the domain structure.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 57
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 395-400 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An experimental study has been carried out to investigate the influence of the reservoir-to-capillary diameter (DR/D) ratio on the elastic properties of polymer melts flowing through capillary tubes. For the study, a capillary rheometer, described in an earlier paper by Han, was used with DR/D ratios of 3, 6, 9 and 12. Measurements were taken of wall normal stresses in high density polyethylene along the axis of the capillary, and the axial pressure profile was used to obtain the “exist pressure,” which is believed to be an elastic phenomenon. The analysis of the experimental data indicates that, for a given capillary length-to-diameter (L/D) ratio, the exit pressures first increase and then level off, as the DR/D ratio is increased. This behavior of the exit pressure is in accord with that of extrudate expansion which has also been determined in the experiment. This dependence of the exist pressure and extrudate expansion ratio on DR/D ratio is explained with the concept that the amount of recoverable elastic energy stored in the melt flowing through the capillary depends on the strain history, which the melt experiences on entering the capillary.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 58
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971) 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 59
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 446-451 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Melt studies on PVC systems at elevated temperature or long times are difficult. One consequence is that measurements may be possible only in the non-Newtonian region. The results indicate that even in this case the melt viscosity can be related exponentially with the weight average molecular weight by the 3.4 power. Since literature data are scarce, attempts were made to extend the range by mixing polymers. This led to the complication of dispersity both on a molecular scale and on a macroscopic level. The latter point is particularly important for PVC studies since the polymers are frequently blended with materials having different viscosities.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 60
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 484-491 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The pressure distribution through the melting and melt zones of a plasticating extruder is discussed, and an analysis is described for predicting the pressure profile. In the stable melting zone, the pressure profile is calculated based on flow in the melt pool, and the pressure is strongly influenced by the flow of the solid bed of plastic. The solid bed flow is primarily determined by the polymer rigidity in the screw compression section. If the size (through a melting analysis) and the velocity (through a solid bed acceleration parameter) of the solid bed along the screw channel are reasonably approximated, the pressure profile is reasonably approximated by this analysis. Inaccurate representations of the size or velocity of the solid bed can yield inaccurate pressure profile prediction.In the unstable melting region, the assumption of a complete melt yields reasonable pressure predictions. The introduction of these concepts into an extrusion model permits a more accurate prediction of the operating RPM of a given screw design in a given machine.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 61
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971) 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 62
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 6-10 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The synthesis of graft copolymers by anionic polymerization techniques is reviewed. Two basic procedures are described. In one a polymer having a reactive end-group is prepared and allowed to react with another polymer having suitable functional groups. In the second procedure, anions are generated on a preformed polymer backbone and used to initiate the polymerization of subsequently added monomers.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 63
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 35-45 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A falling coaxial cylinder viscometer was used to measure the melt flow behaviour of a commercial polystyrene with Mw 260,000. The shear stress region extended down to 0.6 × 104 dynes/cm2 and shear rates were as low as 3 × 10-2 sec-1 at 186°C. The shear rate-shear stress plots were linear at low shear stresses with slopes (differential viscosities) of 3.3 × 105 poises at total shear less than 120 units and decreasing differential viscosity with higher total shear. The flow curves at relatively low total shear were initially dilatant and became pseudoplastic with increasing shear stress. The inflection point represents a Newtonian apparent viscosity, which agrees fairly well with literature values for polystyrenes of the same Mw. Newtonian apparent viscosity is characteristic of a point value of shear stress and shear rate and is not necessarily a plateau region. Observation of a Newtonian region with decreasing shear stress or shear rate does not prove that this flow regime persists unchanged to zero values of the experimental parameter. The existence and magnitude of the Newtonian apparent viscosity reflects shear history of the polymer as well as its constitution and molecular weight distribution.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 64
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 1-5 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The results of an experimental study of melt fracture using polystyrene samples of narrow and broad molecular weight distribution are presented. The weight average molecular weight (M̄w) ranged from 9.72 × 104 to 1.80 × 106 and the distribution breadth M̄w/M̄η from 1.06 to 9.21. The critical shear stress varies linearly with 1/M̄w, increases slightly with temperature and is independent of the distribution of molecular weights. This type of behavior is satisfactorily explained in terms of Graessley's entanglement theory.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 65
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 11-18 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The interactions of γ-aminopropyltriethoxy silane (A-1100), γ-methacryloxytrimethoxy silane (A-174), γ-glycidoxytrimethoxy silane (A-187), and ethyltriethoxy silane (A-15) with silica surfaces have been studied by means of infrared spectroscopy. The results indicate that the major force holding the silane to the silica surface after application from dilute solutions is primary chemical bonding. These bonds are formed by a condensation reaction between silanols on the hydrolyzed form of the silane and hydroxyl groups on the silica surface. In the case of the amino-silane (A-1100), hydrogen bonding was found to exist but was of minor importance in bonding the silane to the surface. In studying the effects of the addition of water, acetic acid, or n-propylamine to various silane treating solutions, it was found that n-propylamine has a unique catalytic effect on the condensation reaction. This catalytic effect explains the observation that γ-aminopropyltriethoxy silane is more reactive than the other silanes studied. It is felt that silanes not containing an amine group can be made more effective if they are applied in the presence of an amine catalyst.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 66
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 182-186 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Poly(vinyl chloride) was fractionated and its solution properties were studied. Calibration of the gel permeation chromatograph was carried out using poly(vinyl chloride) and polystyrene. Empirical correlations were established for the calibration plots.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 67
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 51-56 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The longitudinal strengths of unidirectional discontinuous fiber composites have been calculated based on the concept of perturbation effect and the distortional energy criterion, utilizing the finite-element method. The theoretical results thus obtained are compared with the experimental data as well as the results of shear lag analysis for tungsten-copper, boron-aluminum, glass-epoxy and boron-epoxy composites. Based on the Jackson-Cratchley equations, modified for discontinuous fibers, a formula is also proposed for calculating the strengths of randomly oriented discontinuous fiber composites. The results calculated from this formula are compared with the experimental data for aluminum oxide-aluminum-silicon and glass-epoxy composites.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 68
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 64-69 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A previous paper described the theory and equipment of Differential Thermal Analysis using High Frequency Dielectric Heating, DTA/HF. Curing studies using DTA/HF on cis-1,4-polyisoprene rubber filled with 50 phr of CaCO3 and containing from 1.5 to 4.5 phr of dicumyl peroxide (DCP) curative indicated that below about 185°C, the curing reaction was first order with respect to DCP; the mean activation energy was 32.6 kcal/mole; and the heat of reaction ranged from 60 to 80 kcal/mole DCP. These results are in agreement with published results. Above 185°C both thermodynamic and kinetic evidence implied that the reaction mechanism changed; the first order peroxide decomposition no longer controlled the overall rate of reaction.The curing of both stereo styrene-butadiene rubber (SBR) and cis-1,4-polybutadiene rubber (BR) containing 50 phr of CaCO3 and 0.5 phr of DCP was found to follow first order kinetics as expected. The magnitude of the heat of curing was used to determine the frequency of a vinyl propagation-type cross-linking reaction. Eight to 36 crosslinks per molecule of DCP were obtained. This reaction became more extensive at high temperature, in agreement with published results.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 69
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 99-108 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An experimental procedure is outlined to examine the potential of thermoplastic sheets in draw forming. Experiments carried out on a variety of materials indicate that the following requirements must be fulfilled for a thermoplastic sheet to be cold formable: (1) The glass transition of polymer should be above ambient temperature and above the temperature of forming, (2) tensile elongation at break should equal or exceed 30%, (3) ratio of tensile to compressive yield stress should equal or exceed 1.6 and (4) sheet must not yield locally (neck) when strained in tension.An experimental method has been developed to determine the compressive, friction and bending forces which oppose the drawing force exerted by the punch. It is shown that the compressive force is, in most cases, largest. A stress analysis is carried out leading to an expression correlating the maximum depth of draw as a function of basic properties of sheets such as tensile strength (St*) and compressive yield stress (Sc). The effect of rolling on drawability is examined and interpreted in terms of the ratio St*/Sc. The cold formed items have a lower heat distortion temperature than their thermoformed counterparts.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 70
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 139-151 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A theoretical model for a short fiber reinforced composite is proposed. The composite is assumed to consist of an aggregate of sub-units, each sub-unit possessing the elastic properties of a reinforced composite in which the fibers are continuous and fully aligned. The elastic constants of a partially oriented composite are then calculated by the Voigt and Reuss averaging procedures, giving upper and lower bounds respectively for the composite modulus. Comparison is made with experimental data for such composites. The measured modulus of glass and carbon fiber composites is found to be given by the Reuss or lower bound, to a good approximation compared with the difference between the bounds, for fiber orientations ranging from almost isotropic to highly aligned.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 71
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 284-288 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The utility of anisotropic ultrafiltration membranes in gas separation has been examined. These membranes consist of a thin (0.2-2μ) barrier layer supported upon a more porous supporting substructure. Gases permeate these membranes by a Knudsen diffusion mechanism. Permeabilities from 0.1 to 0.4 cm sec-1 cm Hg-1 were obtained. These values are 104 to 105 higher than most conventional gas separation membranes. These membranes may be useful in several gas separation processes.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 72
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 240-246 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Investigations on the extrusion characteristics of composite systems were performed on the Sieglaff-McKelvey capillary rheometer, with particular emphasis on the characterization of flow instability and “melt fracture” phenomena. The mechanisms of melt fracture appear to be identical for both the filled and unfilled polymers (1. Polyethylene with glass beads; 2. Ethylene-propylene copolymer with graphitized carbon black). In all cases, the flow curves exhibit a plateau at some value of the shear stress. Above this shear stress plateau, melt fracture occurs. Although slip flow is the dominant mode of transport during melt fracture, the slippage in the tube may not be a necessary condition for the subsequent severe melt fracture.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 73
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 507-511 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The properties of fluorocarbon plastics have made them desirable for numerous new applications. Poly(vinylidene fluoride) (PVF2) can be easily extruded into films or fibers or injection molded into a variety of shapes. It was found that crystallinity, molecular weight distribution and polymer structure are important in establishing resin properties. Highly crystalline PVF2 with a narrow Gaussian molecular weight distribution gives specimens with optimum physical and chemical properties.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 74
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 416-420 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: This article reviews recent developments in laser and UV source technologies that are potentially useful for photochemical processes and photopolymerization processes in particular. Methods for measurement and calibration of light energy are described. A few publications on newer photochemical processes are also briefly reviewed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 75
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 3-4 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Enthalpies of the coexisting equilibrium vapor and liquid mixtures of the ethane-n-butane-n-pentane system are computed at several pressures. Saturated liquid enthalpies are obtained by using a new multicomponent Clapeyron equation with the B-W-R equation of state and the experimental temperature-composition data for the ternary mixture. Saturated vapor enthalpies are calculated by applying the B-W-R equation to the vapor mixture. Ideal gas state enthalpies are used in both vapor and liquid enthalpy calculations.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 76
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 30-37 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: For certain classes of chemical reactions, it is possible to increase the yield of the desired products by choosing appropriate variable-volume operating policies. An analysis of the steady state and semibatch operation of a stirred tank reactor demonstrates operating policies for both the isothermal and adiabatic case to maximize the steady state yield and to produce an improved semibatch yield. Computations carried out by using an analogue computer with a digital logic expansion system demonstrate further relationships between yield increase and operating policy.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 77
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 51-56 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Models for the laminar sublayer of turbulent pipe flow are reviewed. The observations of the sublayer by Popovich and Hummel and the experimental fluctuation frequencies obtained by Shaw and Hanratty are used with the models to evaluate experimental heat and mass transfer data. The eddy diffusivity model and a parallel conductance model appear to be consistent with the experimental data.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 78
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 81-85 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effect of viscosity and diffusivity variations on concentration polarization during the ultrafiltration of protein solutions in two-dimensional stagnation flows is investigated by numerical integration of the equations of continuity and motion. It is found that these effects are surprisingly small and insensitive to the forms of concentration dependence postulated. The high Schmidt numbers and low permeation rates characteristic of these systems result in considerable simplification of the analysis and permit use of a modified Chilton-Colburn relation for predicting the onset of sludge formation at the membrane-solution interface. The predicted dependence on Schmidt number agrees with published experimental data for other boundary-layer flows and suggests the possibility of improved prediction of equipment performance.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 79
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 86-91 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Vapor-liquid equilibria data for the hydrogen-propane binary system and the hydrogen-carbon monoxide-propane system were taken at temperature of -185° to +75°. and under pressures as high as 3000 psi. Vapor-liquid data for the hydrogen-carbon monoxide-propane system are reported at -50°, 0°, and +50°. at pressures of 500, 1000, and 2000 lb./sq.in. abs. for each of the three temperatures. The Krichevsky-Kasarnovsky equation adequately correlated the solubility data of hydrogen in the liquid phase of the hydrogen-propane system. Hydrogen-propane data are compared with the data of two previous studies.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 80
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 226-234 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Two methods are presented for the treatment of the nonuniform systems. Both have as a starting point the approximation of the real system by a succession of uniform systems (cells). In one of them, the nonuniformity is taken into account by attributing a free energy to the separating surfaces between the cells, while in the other by considering that the cells are under the action of an “external field” created by the nonuniformity.A distinction between small and large nonuniform systems is made by comparing the thickness of the nonuniform system with the length of the interval in which the nonuniformity is decaying. For small systems the intensive properties depend on the thickness of the system and thus some supplementary effects, as for instance the disjoining pressure, occur.An expression for the “external field” based on the formalism of the radial distribution function is proposed.A large number of phenomena, such as surface tension, adsorption, disjoining pressure, nucleation, the vapor pressure of a liquid imbibing a porous medium, the influence of a solid surface upon a chemical reaction, are treated in a unitary manner by means of the present approaches.Some previous equations such as those of Cahn-Hilliard and of Hill are derived in a different manner or justified.The objections raised by Widom against the continuous approaches are discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 81
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 254-255 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 82
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 509-510 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 83
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 265-271 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Conversion data for the reduction of nitric oxide with C1 to C8 hydrocarbons over a bariumpromoted copper chromite catalyst were obtained in an integral flow reactor operated at atmospheric pressure and temperatures of 225°C to 525°C. In general, an increase in carbon number in the hydrocarbon studied resulted in a decrease in the required temperature for a given nitric oxide conversion. For a given carbon number the required temperature for a given nitric oxide conversion decreased with degree of saturation. The data were fitted to empirical rate expressions.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 84
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 300-308 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A general treatment is presented for mass transfer in turbulent pipe flow with special emphasis on the mass transfer entry region and the role of interfacial velocity on the rate of mass transfer. This study includes numerical solutions of the convective diffusion equation with an entering fully developed flow. Solutions for constant properties and a constant wall boundary condition are presented over a wide range of Reynolds numbers, Schmidt numbers, and aspect ratios.An expression was developed for predicting the entry region mass transfer coefficient in both gaseous and liquid systems at ordinary fluxes with negligible interfacial velocities and at small aspect ratios. The proposed equation for a binary system is \documentclass{article}\pagestyle{empty}\begin{document}$$ N'St_{{\rm ave}} \, = \,0.24\,(N_{{\mathop{\rm Re}\nolimits} })^{ - 0.4} \,(N_{Sc})^{ - 2/3} \,(z/D)^{ - 0.3} $$\end{document}Experimental concentration profiles have been reported on the vaporization of acetone into a turbulent air stream within a short cylindrical test section. Data are also reported on concentration measurements in an air-carbon dioxide gaseous mixture with a large interfacial velocity at the inner surface of a porous pipe test section.The numerical solutions of the diffusion convection equation have been compared with the experimental data in the mass transfer entry region, and a pronounced effect of the interfacial velocity on the mass transfer coefficient was found.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 85
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 313-322 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Analytical solutions are obtained for the transfer of an adsorbing solute across a liquid-liquid interface taking into account the effects of molecular diffusion in both bulk phases, adsorptive accumulation at the interface, and energy barriers to adsorption and/or desorption. These solutions show that while adsorptive accumulation alone affects the transfer rate but little, the presence of an adsorption or desorption barrier can significantly affect the bulk concentration profiles and decrease the mass transfer rate. The presence of a desorption barrier is shown to cause the dynamic interfacial tension to pass through a minimum below the steady state value. For some systems it is conceivable that the interfacial tension minimum would be sufficiently low that a slight agitation would result in spontaneous emulsification.Dynamic interfacial tension data for oil-water systems with interface ages from 0.05 to 1.5 sec. are obtained using a laminar contracting liquid jet. The data indicate the presence of a small net desorption barrier to the transfer of normal and isobutyric acids from oil to water and large barriers to both the adsorption and desorption of 1,5 pentanediol.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 86
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 104-110 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new model of packed-bed behavior based on a second-order stochastic process is developed and examined. The model takes as the basis process the transitions of fluid “packets” among allowed velocity states. The observable phenomenon, that is, the spatial distribution of packets, is a projection of the velocity state process.Results from the model compare well with results from experiments for mixing in packed beds. Model parameters are consistent, and correlate with the physical parameters of the systems. Present results under mass transfer conditions are inconclusive but encouraging.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 87
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 371-378 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Diffusion and either surface or gas-phase reaction in a ternary ideal gas mixture in steady fully developed laminar flow in a tube is considered. The linearized equations valid near equilibrium and under isothermal conditions are solved. Concentration profiles predicted using a multicomponent diffusivity matrix are compared to those predicted using more approximate diffusivities. Local overshoots past equilibrium occur, but oscillations (with axial position) are not possible. A simplified diffusivity expression is found which predicts cup-mixing mole fractions in good agreement with those predicted using the multicomponent diffusivities.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 167-170 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A theoretical approach to equilibrium calculations for homogeneous real fluid mixtures is presented. The overall approach is developed for, although not theoretically restricted to, a corresponding states equation of state, z(Tr, pr). The method is applied to the gaseous ammonia synthesis data of Larson and Dodge. Excellent agreement was attained with the data. Quite significant improvement was observed over the ideal gas and ideal solutions approximations.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 89
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 428-435 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Modification of parameters in the conventional controller equation usually is necessitated by uncontrollable process parameter drifts which occur during the operation of the large scale continuous processes typically found in the chemical industry. To this end, a normalized version of the model reference adaptive control system, including suitable procedures for adjusting the adaptive loop gains, was developed and demonstrated to provide excellent adaptive performance for a single concentration control loop for a simulated stirred-tank chemical reactor. The three constants in a conventional PID controller were simultaneously adjusted to accomplish this adaptation. Equally excellent adaptive performance was achieved in an interacting control loop scheme simulated by control of both the concentration and the temperature in the same stirred-tank reactor. In both cases adaptation was achieved in a time interval which was sufficiently short to make this method of adaptive control feasible for use in a real processing situation. Models needed for implementation of the model reference adaptive control scheme were easily developed. In a real application these models could be easily developed from studies which could take place during prestartup or early operations of the process; hence no a priori knowledge would be required. A wide range of adaptive loop gains was demonstrated to provide a stable overall control system. A high degree of stability was demonstrated for the overall system despite the initiation of large extraneous load upsets occurring during the operation of the adaptive control system.The method presented has not been rigorously proven to be applicable to every real control problem requiring adaptive control. However, the method was demonstrated to be highly effective over a wide range of required controller adjustments in cases similar to those encountered in large continuous processes. Thus the method merits serious consideration for possible implementation whenever adaptive control is required.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 90
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 464-469 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new technique is derived for determining the concentration dependence of diffusion coefficients from sorption experiments. In this analysis the diffusion equation including the effects of phase volume change and volume change on mixing is solved by a weighted residual method to produce approximate analytical expressions which describe the sorption process. It is possible to deduce the concentration dependence of the diffusion coefficient from a single sorption experiment without assuming the form of the diffusivity-concentration relationship. A direct evaluation of the technique is obtained from the analysis of test data generated by finite-difference solutions of the equations which portray the sorption process.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 91
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971) 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 850-853 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: No. Abstract.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 854-856 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: No. Abstract.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 856-866 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: No. Abstract.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 867-872 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: No. Abstract.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 899-902 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: No. Abstract.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 910-915 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: No. Abstract.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 920-926 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: No. Abstract.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 927-932 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: No. Abstract.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 947-958 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A single-pellet, stirred-tank reactor was used to measure temperatures, compositions, and rates of reaction for the hydrofluorination of UO2.14 at atmospheric pressure. By correlating the rate with conditions at the reacting surface, the activation energy of the first-order reaction was found to be 6,070 cal./g.-mole.Since the product forms an unreactive layer around the core of UO2.14, and since the heat of reaction is high, significant concentration and temperature differences develop between the gas phase and the reaction surface. The temperature and rate data were used to calculate the effective diffusivity and thermal conductivity of the product layer under reaction conditions.An adaptation of a pseudosteady state method was developed for predicting the conversion and temperature history of a pellet. Using rate constants for reaction and mass and energy transfer derived from the experimental data, this method gave good results. Predictions with estimated rate constants were poor, indicating that an accurate value was necessary for the effective diffusivity in the product layer.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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