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  • 1970-1974  (3,659)
  • 1965-1969  (2,967)
  • 1955-1959  (1,642)
  • 1920-1924
  • 1905-1909
  • Industrial Chemistry  (4,443)
  • Chemical Engineering  (3,825)
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Year
  • 201
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 191-193 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 202
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 228-238 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most models for fixed bed adsorbers have used either the homogeneoussolid or pore diffusion model for the pellets. When the adsorption isotherm is linear, the two models can lead to identical breakthrough curves. The conditions for this equivalence are presented here. It is shown that one of the bulk flow factors that was included in the formulation of one pore diffusion model will be significant only for feedstreams containing a relatively high concentration of adsorbate. The prosity factor of the pore model is shown to be very important, especially as the porosity decreases. The importance of the two diffusional models with respect to the predicted breakthrough curves is demonstrated. For comparable beds, it is shown that the breakthrough curve based on the homogeneous model is delayed with respect to that based on the pore model at early times, regardless of the shape of the isotherm. Finally, the various possible solutions for an irreverisble isotherm are reviewed for each of the models, and a solution is presented for the general case of a pore model with an outside film resistance.
    Additional Material: 9 Ill.
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  • 203
    Electronic Resource
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 238-244 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A calculation procedure for multicomponent distillation has been developed that is directly applicable to design problems. It is based on successive approximation methods with adjustment of the number of equilibrium stages in each column section between iterations to meet given reflux flow and feed stage composition conditions while maintaining specified key component recoveries. This procedure has been applied to a number of representative distillation design problems. It converges readily to proper column designs from initial estimates based on a noniterative stage-to-stage calculation. Moreover, the procedure is markedly superior in computational efficiency to solution of design problems by repeated application of operating calculations to assumed column configurations.
    Additional Material: 3 Ill.
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  • 204
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 263-272 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new correlation of second virial coefficients of both polar and nonpolar systems is presented. It uses the Pitzer-Curl correlation for nonpolar compounds, but in a modified form. The second virial coefficient of nonhydrogen bonding compounds (ketones, acetaldehyde, acetonitrile, ethers) and weakly hydrogen bonding compounds (phenol) is fitted satisfactorily with only one additional parameter per compound, which is shown to be a strong function of the reduced dipole moment. Two parameters are needed for hydrogen bonding compounds (alcohols, water), but for alcohols, one parameter has been kept constant and the other expressed as a function of the reduced dipole moment. The extension of the correlation to mixtures is satisfactory, direct, and involves only one coefficient per binary.
    Additional Material: 9 Ill.
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  • 205
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 294-300 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A continuous thermal parametric pumping system is compared to a conventional adsorption system with thermal regeneration. Well-defined mathematical models are used to find the operating conditions which maximize the separation and throughput of each system.Under practical operating conditions, the model equations indicate parametric pumping can process a larger volume feed stream at equivalent separations than conventional adsorption for the solute/adsorbent system studied. At equilibrium conditions equivalent results are obtained but parametric pumping requires more energy.
    Additional Material: 9 Ill.
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  • 206
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 320-325 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methods are developed for the computer-aided synthesis of sequences of valve operations to reach complex operation goals with safety. Given dangerous events which must not occur and operation goals to be reached, sequences of valve openings and closings are formed rapidly for industrially significant problems.
    Additional Material: 5 Ill.
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  • 207
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 340-346 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fully developed forced-convective heat transfer to viscous flow of a constant-property Newtonian fluid in curved circular tubes was studied theoretically for a uniform-wall-temperature boundary condition. Numerical solutions were obtained over a wide range of Prandtl numbers for Dean numbers as large as 1,200. The curvature ratio (radius of bend/inside radius of tube) was included as an independent parameter and, for values as small as 10, was found to have a negligible effect on the peripherally averaged Nusselt number. The average Nusselt numbers for the important Prandtl number range of 0.7 to 5 were correlated by NNu = 0.836 NDe0.5 NPr0.1 for NDe ≥ 80.
    Additional Material: 9 Ill.
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  • 208
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 362-368 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An analysis is presented which enables detailed description of solute concentration profiles for free-flow elecrophoresis in planar slit flows. This analysis is suitable for either batch or continuous operation with arbitrary variation of solute input rate, and it requires no seriously restrictive assumptions other than constancy of equilibrium and transport properties. It permits for the first time a systematic investigation of the effects of governing parameters and can be used to optimize operating conditions. The most significant finding is that Taylor dispersion, ignored in previous analyses, markedly reduces separability.
    Additional Material: 4 Ill.
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  • 209
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 959-966 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rate of secondary nucleation of ice, assumed to be proportional to the product of collision frequency and impact energy, has been quantitatively modeled using idealized representations of collisions between crystals and either other crystals or surfaces in the crystallizer. The crystal-crystallizer collisions were assumed to be driven by either steady or turbulent fluid motion and the crystal-crystal collisions were assumed to be driven by either gravitational forces or turbulent eddies. The models predict to a good approximation the experimentally determined dependence of the secondary nucleation of ice on crystal size, ice concentration, and agitation power.
    Additional Material: 6 Ill.
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  • 210
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 989-995 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extensive ternary ion-exchange rate data for cases where particle-diffusion is important are presented. Experimental rate data, using a single-particle radioactive-tracer technique, were obtained for the following systems in Dowex 50W-X8 resin: Mn-Cs-Na, Ba-Mn-Na, and Sr-Mn-Cs. Nernst-Planck equations have been used to describe the ternary ion-exchange kinetics. The Nernst-Planck model, when used for the correlation of binary and various types of ternary exchange data obtained under unfavorable equilibrium conditions, usually cannot afford to disregard liquid-film resistance. The model incorporating the film effects correlated satisfactorily most of the experimental data, and even in cases where the correlation was not good, it interpreted adequately the trend of the results.
    Additional Material: 11 Ill.
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  • 211
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1024-1025 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 212
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1027-1027 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 213
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1034-1036 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 214
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 485-491 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When ultrasound is applied to a liquid reacting system, the reaction rates are often increased. The application of ultrasonics, therefore, provides additional modes of accelerating the reaction rates which are usually not considered by conventional mechanisms. In an attempt to study the effect of ultrasonics on chemical reactions, experimental work was undertaken in which the reaction rates of the hydrolysis of methyl acetate were measured under the presence of ultrasound. The temperature, the vapor pressure with in the cavitating bubbles, the resonance characteristics, the volume of the reacting system, and the intensity and frequency of the ultrasound are all influencing parameters on the reaction rates.
    Additional Material: 5 Ill.
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  • 215
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 555-563 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methods for the solution of linearly constrained optimization of a nonlinear objective function are presented and compared. The methods of Fletcher-Reeves, Fletcher, and Powell are used to generate search directions in the decision variable space. Generalized Kuhn-Tucker conditions are presented and used to check for a local minimum.
    Additional Material: 1 Tab.
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  • 216
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 539-550 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mathematical models are developed to study the catalytic reduction of nitric oxide contained in automobile exhaust in which the temperature, flow rate, and concentrations of various species vary widely with time. The quasi-static approximation is compared to the fully dynamic model. In the quasi-static model all processes are steady state except for the solid temperature and inlet conditions. Suggestions are given for deciding a priori if the quasi-static model is appropriate. Suggestions are also given for integrating the quasi-static equations in order to minimize errors compared to the dynamic model. The performance of three different catalysts is examined with the mathematical model, when the inlet conditions correspond to typical values of temperature, flow rate, and concentration when the automobile is operated according to the Federal Test Procedure.
    Additional Material: 9 Ill.
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  • 217
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 571-581 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental study has confirmed a theoretical prediction that, when an exothermic mass transfer limited chemical reaction occurs on a single catalytic wire for which the parameter a [Equation (11)] is large, temperature fluctuations (flickering) of large amplitude must be induced by concentration fluctuations. A simplified model is presented for predicting the magnitude of flickering in industrial convertors for which the parameter a is usually large. The model should be useful in estimating the influence of improved mixing of the reactants on the reduction in precious metal loss from the gauze.
    Additional Material: 9 Ill.
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  • 218
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 581-591 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The growth rate of an ice crystal in the basal plane has been measured in subcooled water flowing at velocities of 0.04 to 1 cm/s to test a theory of Fernandez and Barduhn (1967). The theory fits the data in pure water at all velocities and subcoolings studied here and at velocities up to 46 cm/s studied previously. The interfacial tension between ice and water calculated from these data is 33 ± 6 ergs/cm2, a value in good agreement with those determined by others.Measured growth rates of ice from solution do not follow the theory and in fact are as much as 150% higher in 0.5 to 1% NaCl solution than in pure water. High subcoolings and low flow velocities accentuate this anomaly.
    Additional Material: 13 Ill.
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  • 219
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 600-602 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 220
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 221
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1079-1086 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: One challenging problem in liquid-gas, interfacial phenomena is the prediction of the size and location of a flowing meniscus because it involves surfaces which are highly curved. The paper presents one aspect of this problem. A numerical method is presented for predicting the dynamic meniscus profiles-specifically these distorted considerably by flow. The geometry considered to provide those free (liquid-gas) surfaces is coating of a moving sheet by upward withdrawal from a finite bath. The predicted profiles agree with data taken with a glycerine-water solution and with viscous oils.The method predicts the three parameters (coating thickness and two others) which are the minimum number of parameters necessary to describe the dynamic-meniscus profiles for this geometry. The numerical method is iterative, it simultaneously predicts the flow field in the bath, and it is based on the two-dimensional Navier-Stokes equations and appropriate boundary conditions. The interfacial boundary condition used for iteration is the normal stress condition which is composed of pressure, surface tension, and viscous terms.
    Additional Material: 4 Ill.
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  • 222
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 43-50 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental procedure based on continuous crystal seeding was developed which can explicitly determine the fundamental relationship between collision breeding and the leading moments of the crystal size distribution. For the aqueous, cooling crystallization of potassium dichromate, the analysis determined that only the mass moment was successful in correlating observations subject to crystal seeding.It was also observed that mixing may have a pronounced effect on the nucleation rate but that kinetic orders for collision breeding and growth rate were independent of mixing.
    Additional Material: 11 Ill.
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  • 223
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 94-103 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Temperature and concentration profiles are obtained by solution of the coupled nonlinear differential equations which describe transient operation of an adiabatic fixed bed reactor. The unreacted-shrinking core mechanism describes the multiple, irreversible, exothermic gas-solid reactions. Numerical integration is accomplished by a predictor-corrector scheme which is programmed in Fortran IV language. The influence of kinetic parameters, heat and mass diffusivities within pellets, temperature variation of properties, gas velocity, bed and particle dimensions, inlet gas temperature and composition, and initial bed temperature on reactor performance are studied for sulfur dioxide removal from flue gases by fixed beds of copper oxide. Comparison with commercial reactors is in qualitative agreement.
    Additional Material: 11 Ill.
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  • 224
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 713-720 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The utility of a new dynamic experimental technique is illustrated for the specific case of the vapor phase dehydration of ethanol over a hydrogen ion exchange resin. Adsorbed phase composition data are obtained simultaneously with complete vapor phase information, providing new insight into the catalytic behavior. A mathematical model, based upon Langmuir-Hinshelwood kinetics, comprises simply five first-order ordinary differential equations. The model describes all of the important transient and equilibrium characteristics of the reacting system qualitatively and most quantitatively. Experimental data alone are used to show that the surface reaction is the rate controlling step.
    Additional Material: 9 Ill.
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  • 225
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 189-190 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 226
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 889-900 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The packed bed model developed by Payatakes, Tien, and Turian (1973a, 1973b) is used as a basis for the study of particle deposition in deep bed filtration. The size of the particulate matters present in the suspension is assumed to be sufficiently large for Brownian motion to be negligible, but small enough for straining to be unimportant. The prediction of the rate of particle deposition is based on the one-step trajectory approach. The collector is represented by a unit bed element of the porous media model and the particle trajectory equation is formulated to include the gravitational force, the hydrodynamic force and torque (including the correction for the presence of the unit cell wall), the London force (including the retardation effect, which is shown to be of primary importance under conditions usually met in deep bed filtration systems), and the electrokinetic force. Sample capture trajectories, including the limiting capture trajectories, are given.Based on the limiting trajectories and the assumption of uniform particle distribution at the entrance of each unit cell, the number fractions (of suspended particles) impacted on each unit cell are determined and then used to calculate the fraction impacted on the entire unit collector and also the value of the filter coefficient for a clean bed. It is also shown how the capture trajectory calculation can be used to determine the local rate of deposition along the wall of a given unit cell.
    Additional Material: 5 Ill.
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  • 227
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 924-932 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When a periodic process is disturbed, control action may be necessary to maintain satisfactory performance. Regulating controls to achieve this objective can be synthesized by solving a linear-quadratic optimization problem with periodic coefficient's. Generalized proportional and proportional-integral feedback regulators developed in this manner are tested by simulating a cyclic reactor. Very satisfactory control is achieved for 10% step disturbances in reactor feed conditions although the results are sensitive to the choice of manipulated variables.
    Additional Material: 6 Ill.
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  • 228
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    AIChE Journal 20 (1974), S. 397-399 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 229
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 413-413 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 230
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 414-415 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 231
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    AIChE Journal 20 (1974), S. 416-416 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 232
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    AIChE Journal 20 (1974), S. 454-461 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Turbulent pipe flow was examined by measuring the radial dispersion of dyed fluid introduced at an axial point source within the flow. From the classical theoretical results of G. I. Taylor it was possible thereby to calculate various parameters that characterize the structure of the turbulent flow field. A comparison was made between water, and aqueous solutions of polyethylene oxide (Polyox) at concentrations up to 50 ppm (by weight). Results indicate that Polyox affects the turbulence in the following ways: (1) intensity is reduced, (2) the energy spectrum is shifted toward low frequency, (3) dispersion occurs largely through large scale motion, and intermittency is increased. Indication is also seen that a simple exponential form for the Lagrangian correlation coefficient is superior to other often recommended models.
    Additional Material: 10 Ill.
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  • 233
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    AIChE Journal 20 (1974), S. 933-940 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The industrially important reaction of phenol and acetone to give bisphenol A and water was catalyzed by beads of ion-exchange resin (sulfonated styrene-divinylbenzene copolymer) suspended in a batch reactor containing liquid reactants. The data are summarized by a rate equation accounting for reaction in the resin competitively swollen by water, acetone, phenol, and methylcyclohexane.The catalyst is modeled as two phases, each in equilibrium with the liquid: a polar phase consisting of sulfonic acid groups with hydrogeb-nonded acetone and water and a nonpolar phase consisting of the hydrocarbon matrix swollen with organic components. The rate determining step is the electrophilic attack on phenol in the nonpolar phase by a carbonium ion intermediate in the polar phase.Resin cross-linked with 4% divinylbenzene initially catalyzed acetone conversion at a rate of 5 × 10-4 (moles)/(equiv of acid groups s) at 364°K. An 8% cross-linked resin was much less active because the rigid polymer matrix was only slightly swollen by phenol, but a more highly cross-linked resin with macropores and accessible internal surface catalyzed reaction almost as rapidly as the 4% cross-linked catalyst.
    Additional Material: 7 Ill.
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  • 234
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    AIChE Journal 20 (1974), S. 974-980 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Through the statement of the Ergun equation in a vectorial form, a formulation is presented for three-dimensional flow of fluids through packed beds having a spatially variable resistance to flow. The equations were put in a form convenient for numerical solution by successive over-relaxation, and a selection of computed results is presented for cylindrical beds where the nonuniform resistance to flow obeys axial symmetry. The method outlined in the paper for calculating flow maldistribution in packed beds is thought to be a necessary first step in the representation of hot spot formation and flow nonuniformities in packed bed reactors.
    Additional Material: 6 Ill.
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  • 235
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    AIChE Journal 20 (1974), S. 1012-1014 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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  • 236
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    AIChE Journal 20 (1974), S. 1010-1011 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 237
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    AIChE Journal 20 (1974), S. 611-615 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 238
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    AIChE Journal 20 (1974), S. 622-622 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 239
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 623-623 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Tab.
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  • 240
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    AIChE Journal 20 (1974), S. 660-664 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two-phase solids-in-air flow was experimentally studied in a once through flexible wall tube flow system using nominal 25μm and 50μm spherical glass beads. For turbulent flow through the Silastic tube without a damping medium behind the wall, cases of true drag reduction and no drag reduction were found. The rate of addition of the glass beads was seen to be a correlatable parameter for both the flexible and rigid wall systems. A mechanistic model is proposed for interpretation of the results. It was qualitatively observed that the presence of an electrostatic charge on the particles at low relative humidities had a pronounced effect on increasing the drag in the system.
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  • 241
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    AIChE Journal 20 (1974), S. 688-695 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of nonuniform velocity distributions and retrograde flow on Murphree tray efficiency has been studied. Both types of nonuniformities were shown to substantially reduce the efficiency of the tray. The results show that the presence of flow nonuniformity alone may result in significant deviations from the efficiency predicted by the AIChE model.
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  • 242
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    AIChE Journal 20 (1974), S. 735-742 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: By means of infrared internal reflection spectroscopy we measured the time dependence of the surface concentration of stearic acid molecules over a well defined region of the surface. The molecules were diffusing into this region from a source comprising a compressed monolayer or bulk crystalline material outside the field of view. By these measurements in conjunction with solutions to the diffusion equations we determined the diffusion coefficient Ds of stearic acid on the (0001) plane of α-alumina. We also determined the dependence of Ds upon the amount of water coadsorbed on the surface. When the surface was free of reversibly adsorbed water, Ds had a value of about 2 × 10-7 cm2/s. As the surface coverage of coadsorbed water increased to about a monolayer Ds increased to a maximum value of about 4 × 10-5 cm2/s. With further additions of surface water Ds then decreased and became less than 10-8 cm2/s at coverages slightly less than about two monolayers. In the region of its maximum value the temperature dependence of Ds indicated an activation energy for the diffusion process of about 26 kcal/mole.
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  • 243
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    AIChE Journal 20 (1974), S. 776-784 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is suggested that chromatographic separations can be performed very effectively in the absence of a stationary sorbent phase by using small diameter tubes or tube bundles for the column and segregating the solutes radially into the slower moving fluid near the tube walls. Separation is achieved by differential solute retardation whenever the degree of segregation is different for the various solute species present.An approximate analysis and preliminary experimental studies demonstrate the feasibility of using ultrafiltration through the tube wall to achieve solute separation. Preliminary estimates based on our ultrafiltration analysis also show that segregation by electromigration is very promising for electrically charged solutes.
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  • 244
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    AIChE Journal 20 (1974), S. 803-814 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Adiabatic Joule-Thomson coefficients are presented for argon and two argon-carbon dioxide mixtures (46.4% CO2 and 75.4% CO2) in the single-phase part of the range: -120 〈 T 〈110°C, P 〈 190 atm. Results are analyzed in terms of the virial equation (including terms to account for the quadrupole moment of CO2), several forms of the Redlich-Kwong equation, and the Benedict-Webb-Rubin equation. In general, the best results were obtained by the Redlich-Kwong equation as modified by Barner et al. (1966).
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  • 245
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    AIChE Journal 20 (1974), S. 1027-1028 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 246
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    AIChE Journal 20 (1974), S. 1037-1037 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 247
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1038-1040 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 248
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    AIChE Journal 20 (1974), S. 1087-1096 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Simplified expressions to calculate the extent of reaction in a fluid bed show good agreement with the experimental data of Lewis et al. (1959) and Swaay and Zuiderweg (1972). The contribution of the dilute phase seems more important than that of the jetting zone or reaction factor (Hatta number) in usual fluid bed operations. The effect of the dilute phase is discussed. It is profitable to use the dilute phase for the consecutive isothermal and endothermic reaction, but unprofitable for the exothermic reaction. These characteristics depend upon the nature of reactions and careful considerations as to the choice of the gas velocity, particle characteristics, and reactor design will be necessary.
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  • 249
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 487-490 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The resistance of various linear condensation polymers to acid or base hydrolysis is dependent upon the nature of the linkages in the polymer chain. Aryl polysulfonates having a styrylketone sensitizing group have been shown to be particularly resistant to attack by strong bases. Similar phosphorouscontaining polymers have been prepared and those with the arylphosphonate, thiophosphonate, and phosphate linkages have been found resistant to attack by such acids as ferric chloride. Using a solution polymerization method, these phosphorous polymers and also those containing the phosphite, phosphonite, and phosphorane linkages may readily be prepared. A comparison has been made of the resistance of these polymers and of the corresponding polycarbonates, polysulfonates, and polyesters to various bases and to ferric chloride solutions.
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  • 250
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    Polymer Engineering and Science 14 (1974), S. 509-512 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The formation of an image in a photoresist during photolithographic processing requires the exposure of the photoresist through a mask to a light source in the spectral region to which the photoresist is sensitive. The functional advantage of the flash exposure of photoresist is presented, which includes the elimination of oxygen effects, the reduction of diffraction and standing wave effects, and the enhancement of pattern-edge acuity. The effects of both broad and narrow band sources are also shown with emphasis on proximity printing techniques. Finally, the optical, electrical and physical design parameters for a practical flash exposure system are discussed.
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  • 251
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 252
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    Polymer Engineering and Science 14 (1974), S. 560-566 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Based on the assumption of a constant critical shear strain, an expression for the critical stress at the onset of entrance fracture as a function of polymer concentration has been developed. Experimental results with 10-25 percent narrow distribution, high molecular weight polystyrene-benzene solutions show the critical stress to be much lower than that for the polymer melt and in agreement with predicted values. This result is all the more impressive when the contrast in flow behavior at the capillary entrance for melts and solutions is observed. Instead of the rotating toroidal vortices surrounding a 90-deg material entrance cone observed with polystyrene melt, cine movies of the solution flow birefringence patterns in the capillary entrance region reveal only a stagnant zone surrounding a narrow cone less than 20 deg. At fracture, the cone axis moves in a rotary path circulating about the capillary axis without undergoing the flow discontinuities typical of melt behavior.
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  • 253
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    Polymer Engineering and Science 14 (1974), S. 581-588 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A theoretical analysis using finite element methods has been applied to oriented short-fiber composites and spherical particle composites in order to predict the influence of a finite layer at the interface on mechanical properties. In this study the interfacial layer has been modeled by assuming that a layer surrounds the interface and that this layer has a modulus of elasticity different than both the fiber and the matrix. The stress distribution near the interface has been determined as a function of the elastic constants of the interface layer and the interface layer volume fraction. This analysis has also been performed for two volume fractions of fibers and two fiber length to diameter ratios. From this stress distribution, the composite modulus and toughness have been determined as a function of interface modulus. It is theoretically shown that the toughness, measured by amount of strain energy absorbed, can be maximized by controlling the interface modulus. Furthermore, recent experimental results appear to verify the theory.
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  • 254
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    Polymer Engineering and Science 14 (1974), S. 604-609 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Particulate-filled thermosetting composites are widely used, yet little systematic work has been done on their long-term strength characteristics. In this study short-term tensile, flexural, and impact tests as well as tensile creep-rupture tests were made for unfilled and filled epoxy to clarify the effects of filler size, filler content, and temperature. Fillers used were silica, alumina particles, and glass beads. Test temperatures were varied from 25 to 110°C. As a result of short-term testing, it was found that the Petch relation held between strength and filler size if brittle fracture occurred, while a strength and filler size if brittle fracture occurred, while a strengthening effect existed when ductile fracture occurred. On creeprupture testing, a strengthening is observed with filler size and content for silica and glass beads. The Arrhenius plot of rupture time for various filler sizes and contents converges to a characteristic point corresponding to the glass transition temperature of the material. Using this relation, a modified Larson-Miller master rupture curve is proposed which can predict the long-term strength of particulate-filled thermosetting composites as functions of rupture time, temperature, filler size, and content.
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  • 255
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    Polymer Engineering and Science 14 (1974), S. 616-620 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Detailed studies have been carried out on the anisotropy of creep and creep rupture behavior of thermoplastics oriented by the imposition of a large permanent deformation. This deformation is usually such as to produce simple fiber symmetry within the specimen. Experimental techniques have been devised for the accurate measurement of all three principal strains during tensile creep on small samples which are cut from the oriented specimens at various angles to the symmetry axis. In this way a full characterization of the creep behavior up to strains of 5 percent has been obtained at room temperature.Results are presented for work on rigid poly (vinyl chloride), poly(methyl methacrylate), and low density polyethylene. The results are discussed in terms of the time dependence and nonlinearity of the anisotropy. Creep rupture results on similar specimens are also presented and discussed. Anisotropy due to orientation is shown to be important in determining engineering properties and in understanding structure-properties relationships.
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  • 256
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    Polymer Engineering and Science 14 (1974), S. 120-123 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The porosity of poly (vinyl chloride) (PVC) resin particles produced in bulk polymerization is sensitive to polymerization conditions. Using scanning electron microscopy, 60μ spherical beads of PVC are shown to be composed of loosely packed 1μ spherical subparticles. This complex morphology is characterized by a variability in surface area. The surface area of bulk PVC materials can be measured by a chromatographic technique. The elution time of n-octane as a probe molecule on PVC packed columns is simply related to PVC surface area. At approximately constant particle size (measured by Coulter counter and optical microscopy), surface areas measured by argon adsorption are correlated to chromatographic elution times. The bulk density, plastisol viscosity and pore volume (from mercury penetration porosimetry) are determined and related to specific surface area.
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  • 257
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 258
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Plasticized poly(vinyl chloride) formulations were prepared in solid and foam form, and mechanical hysteresis was measured by low-speed tension and compression on an Instron tester and by high-speed rebound on a resiliometer. Hysteresis was greatest in copolymers with vinyl acetate, at low plasticizer concentration, with inefficient plasticizers, at high concentrations of reinforcing fillers, at high expansion to low density, and at high speed of testing. Conversely, resilience was greatest at high plasticizer concentration, with more efficient plasticizers, with non-reinforcing fillers, and at high density.
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  • 259
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    Polymer Engineering and Science 14 (1974), S. 401-412 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A concentric cyclinder dilatometer was designed and built to study the influence of shear on the crystallization kinetics of polymers. This instrument allows crystallization to be followed at both constant temperature and shear rate. Several samples of polyethylene oxide (Carbowax 4000, Carbowax 20-M, and WSR-205) were used. A low molecular weight fraction of the Carbowax 20-M, as well as the unfractionated material, was crystallized under shear. The WSR-205 was studied only in a mixture with Carbowax 4000. It was shown that the kinetics of crystallization of uncrosslinked melts of polyethylene oxide are altered by shear. The induction times for the appearance of crystallinity are shorter in the sheared systems than in the quiescent melts. The Avrami exponents are also higher for crystallization in sheared melts than in quiescent systems and increase with decreasing supercooling. The high values of the Avrami exponent are attributed to the disruption of crystalline aggregates into particles larger than the critical sized nucleus. These particles will persist in the melt and continue to grow spontaneously. A continuous infusion of growing particles into the melt occurs.At constant temperature and shear rate, the induction time of the crystallization curve is influenced by polymer molecular weight. In moderate to high molecular weight samples, the effect of shear becomes saturated at very low shear rates. Decreasing the molecular weight separates the crystallization curves. The curves from the higher shear rates appear at the shorter induction times. However, decreasing the molecular weight below that at the critical entanglement molecular weight allows the nucleation rate, strongly dependent upon the supercooling, to influence the relative positions of the sheared crystallization curves.
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  • 260
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    Polymer Engineering and Science 14 (1974), S. 478-480 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Chemical batch-to-batch variations of an acrylonitrile-modified epoxy potting compound were monitored by infrared spectroscopy and correlated to capacitance and hardness measurements of the cured product before and after exposure to high humidity. The reversion resistance of the cured material was dependent upon the amount of a carbonyl functionality in the uncured potting compound. This relationship is an approach to assess the reversion resistance of these types of potting compounds.
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  • 261
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    Polymer Engineering and Science 14 (1974), S. 482-486 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Classical photochemistry is an ancient branch of chemistry, but in the past its practitioners have restricted their interest primarily to studies in the gas or liquid phases. However the practical applications of photochemistry in recent years have led to an increasing interest in photoreactions which occur in the solid phase, particularly in polymeric systems. One of the first areas of practical interest has been in stabilizing plastic and other polymeric systems against photodegradative reactions initiated by solar radiation. More recently photoreactions in polymers have been used extensively in recording and reproducing photographic and other images.
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  • 262
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    Polymer Engineering and Science 14 (1974), S. 498-508 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Versatile computer programs capable of simulating near-contact images from arbitrary objects and illumination were reported. Their capability was demonstrated in examples of combinations of different types of object and illumination. From the specific examples, we were able to derive certain general rules: (1) Polychromatic illumination is always better than monochromatic illumination. (Besides observing the examples given above, polychromatic illumination also helps when standing waves in photoresist are considered.) (2) Negative masks are easier to print than positive ones. Note that a negative mask in the sense of optical diffraction means smaller dimension for transparent parts of the mask. (3) Some well designed irregularities in the mask pattern improves the image. (4) The effective depth tolerance is between the limits set by the focussing effect and the image spreading effect. (5) Holographic mask should relax flatness and exposure tolerance.
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  • 263
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    Polymer Engineering and Science 14 (1974), S. 525-528 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(2-methyl pentene-1) sulfone undergoes scission followed by rapid chain depolymerization when irradiated with 5-20 kV electrons. Several parameters which affect the rate of this process, termed vapor development, were evaluated, viz., molecular weight, dose rate, temperature, accelerating voltage and film thickness. While it was never really possible to remove 100 percent of the film, it was possible to remove 〉 99 percent at reasonably low doses (∼ 10-6 coul/cm-2) using high temperatures (∼ 100°C) and low accelerating voltage (5 kV). Some lithographic details of this process are also described.
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  • 264
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    Polymer Engineering and Science 14 (1974), S. 518-524 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(methyl isopropenyl ketone) (PMIPK) degrades upon exposure to 5 keV electrons. Using a scanning electron microscope to expose fine-line raster patterns in thin films of this polymer and subsequently solvent-developing the thus-degraded regions, sharp walled troughs are observed, the width of which is a measure of the sensitivity to degradation. Copolymers with several vinyl monomers were prepared and the sensitivities of these were similarly determined. Information relevant to the mechanism of depolymerization was obtained by comparing homopolymers with copolymers and by the use of additives in the irradiated polymer films. Examples of potential device-fabrication techniques using PMIPK resist are given.
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  • 265
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    Polymer Engineering and Science 14 (1974), S. 538-541 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the manufacture of electronic devices for integrated circuits, reducing the number of resist steps is desirable for a variety of reasons. We describe some experiments on a process aimed at reducing the number of resist and registration steps in electron beam lithography. The process involves locally varying the electron dose in an electron sensitive resist (in this case poly[methyl methacrylate]) so that the different levels of exposure can be distinguished by subsequent developing. Reliable results have been achieved with three levels: (i)Strongly exposed (resist removed after short immersion in developer).(ii)Partially exposed or “metastable” (resist removed only after prolonged immersion in developer).(iii)Unexposed.In strongly exposed regions, operations such as etching may take place while using the metastable and unexposed regions to protect the workpiece. Subsequently, the metastable region may be developed for further processing.
    Additional Material: 4 Ill.
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  • 266
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    Polymer Engineering and Science 14 (1974), S. 567-572 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Aspects of the present status of structure-property correlations for linear polycarboranesiloxanes which contain rigid carborane cages and flexible siloxane in-chain linkages are discussed. Low temperature secondary transitions, glass transitions, crystallization and melting transitions, and high temperature chemical transformations in inert and air atmospheres are emphasized. The linear polymers serve as the basis for new high-temperature elastomers.
    Additional Material: 8 Ill.
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  • 267
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    Polymer Engineering and Science 14 (1974) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 268
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    Polymer Engineering and Science 14 (1974), S. 621-626 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The morphology of isotactic polypropylene in molded plaques containing a knit line is described in detail. The effects of mold temperature and flow on the size and orientation of spherulitic and transcrystalline regions are discussed. Deformation at the weld line under uniaxial tensile stress is analyzed by optical microscopy.
    Additional Material: 14 Ill.
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  • 269
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    Polymer Engineering and Science 14 (1974), S. 435-440 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Techniques have been developed for measuring the strain and thermal histories of fluid elements as they move from the die lips to the freeze line. Motion pictures were analyzed to determine the rates of extension in the machine and transverse directions. A radiation pyrometer was used to measure the temperature of the film. These techniques were used to study the film blowing of polyethylene; a 2.5-in. diameter die was used, and blow-up ratios in the range of 1.8 to 3.4 were employed. Film thickness ranged from 2 to 4 mils. The maximum measured extensional strain rates in both the transverse and machine direction were in the range of 0.15 to 0.6 sec-1. Standard shrinkage and impact tests were performed on the finished films, and an attempt was made to correlate the results with several simple empirical norms of the strain history. No correlation could be discerned. The results of this study are inconsistent with some popular ideas about the origin of orientation in blow films, but they are consistent with some recently published data on the influence of deformation on orientation in melt-drawn capillary extrudate.
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  • 270
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    Polymer Engineering and Science 14 (1974), S. 464-471 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The general incompatibility and microheterogeneity of polymeric mixtures are discussed. The concepts are extended to elastic polyblends whose polymer constituents are polarizable, non-conducting and non-magnetic. A theory is then developed for the interactions of dynamic deformation fields in polyblends with applied electromagnetic fields. It is shown that certain electro- and magneto-acoustical and optical effects are the outcome of the above-mentioned interactions. Plane elastic as well as electromagnetic waves are shown to be generally dispersive in such media. We have employed an internal scale parameter, commonly called the couple stresses constant, which can be estimated by measuring the speeds of plane waves, thus enabling polymer engineers and scientists to evaluate incompatibility in elastic polyblends. The present work also establishes a generalized Faraday effect by showing that there exist three pairs of left and right circularly polarized plane waves traveling at different speeds in a polyblend. We also discuss a new phenomenon, i.e. “micromagneto-elastic dragging”, emerging from our analysis. This phenomenon asserts that the more profound the internal incompatibility of polyblends, the more depressed the speed of plane waves below their normal values observed in the absence of incompatibility. For convenience, we have called such materials elastic micro-dielectric polymers or, in short, EMDP.
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  • 271
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    Polymer Engineering and Science 14 (1974) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 272
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    Polymer Engineering and Science 14 (1974), S. 491-493 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The spectral sensitivity of bisazide sensitized rubbers has been extended to 5000Å by the addition of p-azidocinnamylidene derivatives of cyclohexanone. The photoresists were suitable for projection exposure at 4050 and 4350 Hg lines. The photospeed of the compositions is enhanced by increasing the unsaturation of the polymer component. Speed increase could also be obtained by exposure of the films at elevated temperatures.
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  • 273
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    Polymer Engineering and Science 14 (1974), S. 513-515 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 2 Tab.
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  • 274
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    Polymer Engineering and Science 14 (1974), S. 516-517 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper presents a review of electron-sensitive resists evaluated for electron beam exposure. This includes positive as well as negative resists and their relative merits and drawbacks. The paper also presents general guidelines that can be used in evaluating any electron resist system for performance and usefulness in electron beam microfabrication.
    Additional Material: 1 Tab.
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  • 275
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    Polymer Engineering and Science 14 (1974), S. 534-537 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In order to determine the effects of chemical structure on electron beam resist sensitivities, a series of polymers with different reactive components and additives has been investigated. The results, based on a larger number of exposures varying over five orders of magnitude, point out several interesting facts. The data indicate that the sensitivity of negative resists is not a linear function of molecular weight as previously supposed. Also, the negative electron resists tend to be more sensitive and cover a broader range of sensitivities than positive resists. The results further show that olefin and epoxy groups greatly enhance the crosslinking rate of these exposed polymers. However, additives, which are good energy transferring type sensitizers, have little effect on resist sensitivity. This last result is not surprising considering the nonselectivity of the exciting electrons.
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  • 276
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    Polymer Engineering and Science 14 (1974), S. 553-559 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A theoretical model for melting in reciprocating screw injection molding machines is proposed. The model permits the calculation of the solid bed profile as a function of time during the injection cycle. It consists of a dynamic extrusion melting model for the rotation period, a transient heat conduction model with a phase transition for the screw rest period, and a proposed model for the drifting of the beginning of melting during the injection cycle.
    Additional Material: 9 Ill.
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  • 277
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    Polymer Engineering and Science 14 (1974), S. 573-576 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The rheology of a high molecular weight polyisobutylene “Vistanex” L-80 is measured at 20°C under constant stress creep loading in simple shear and simple elongation and compared with published data for biaxial extension. These data can be reduced to a single curve by the application of simple geometric parameters and instability during extensional flows may be interpreted on the basis of the Considère construction. The results are further extended by dynamic measurements to estimate the viscoelastic response of this material over a time scale of nine orders of magnitude. The rheological response shows an approximately linear relationship with stress up to elongation strains of 1.0, and, because of this, the results do not illuminate the present controversy over the selection of different equations of state to represent non-linear polymer melt flow. However, this body of data, which the authors believe to be the most comprehensive presently available in terms of strain level and deformation geometry, does demonstrate that a viscoelastic polymer can respond to different deformation geometries in a simple manner.
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  • 278
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    Polymer Engineering and Science 14 (1974), S. 597-603 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Problems associated with single-lap shear testing of a structural epoxy adhesive are discussed relative to analyses of the epoxy by infrared spectroscopy, gel permeation chromatography, scanning electron microscopy and other instrumental methods. The value of analytical techniques for assessing the adhesive's cure are shown, including a peculiar correlation of lap shear bond strength with the adhesive's initial uncured state as defined by infrared spectroscopy and gel permeation chromatography. This resulted in the development of definitive batch-to-batch adhesive quality control methods and specifications involving the water content, curing agent, and oxirane concentrations of the uncured system.
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  • 279
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    Polymer Engineering and Science 14 (1974), S. 633-640 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mechanical properties of a series of thermoplastics reinforced with unidirectionally oriented short fibers are reported. Both organic and inorganic fiber reinforcements were used in fiber volume fractions of 0.10 to 0.50. A number of these composites were found to have excellent strength and stiffness properties combined with good toughness and low density. The dependence of composite properties on the properties of the constituent materials is discussed. Fiber efficiency factors for strength and modulus are presented and models for predicting composite mechanical behavior are reviewed.
    Additional Material: 8 Ill.
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  • 280
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    Polymer Engineering and Science 14 (1974), S. 677-677 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: No. Abstract.
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  • 281
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    Polymer Engineering and Science 14 (1974), S. 687-690 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Rigid, glassy plastics differ over a wide range in the amount of energy they can absorb before fracturing under the influence of an applied stress. It is here proposed that molecular structure influences energy absorption more significantly by determining the onset of fracture than by its effect on the energy-dissipating processes themselves. Emphasis has been placed, therefore, on finding a relationship between molecular structure and the onset of fracture. Since many relationships between molecular structure and bulk mechanical response have already been established, it should be a useful step to relate the onset of fracture to bulk mechanical responses. The hypothesis is developed that the appropriate bulk property is the stress-deformation function of the material. The observed stress-deformation function is of such a nature that a highly non-homogeneous deformation is produced at any point of stress concentration. Typically, this is a narrow region in which the material is highly deformed while the deformation in adjacent material is still slight. Fracture initiation is postulated to occur in such a region of high deformation. Differences among polymers in the shape of the stress-deformation function are demonstrated experimentally. These differences correlate with tough-brittle behavior. An explanation is proposed in terms of the probability of fracture initiation.
    Additional Material: 2 Ill.
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  • 282
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    Polymer Engineering and Science 14 (1974) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 283
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    Polymer Engineering and Science 14 (1974), S. 12-15 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: By incorporating the spectroscopic techniques of reflection-absorption and internal reflection in the infrared region, we have been able to define and characterize overall chemical changes occurring at a metal-polymer interface. Our initial studies have concentrated on the oxidative degradation of metal-polymer systems. These systems are of particular importance because of the common need to retard the metal-catalyzed degradation of the polymer. Preliminary results for copper-polyethylene interfaces, models for polyolefin-insulated cable, have shown the copper surface to be the site of the initial catalysis in the oxidation of the polyethylene. When copper deactivators are added to inhibit the oxidation, initial reactions between the copper surface and the inhibitor can be seen. The importance of these surface reactions highlights the necessity for studying the interface.
    Additional Material: 6 Ill.
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  • 284
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    Polymer Engineering and Science 14 (1974), S. 38-42 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A highly sensitive thickness sensor has been developed which may be used as a continuously recording extensometer for rubbery materials. The application of the sensor for measuring volume changes in dewetting filled rubbers is also discussed. Further possible applications include the determination of Poisson's ratio on plastics.
    Additional Material: 10 Ill.
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  • 285
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    Polymer Engineering and Science 14 (1974), S. 76-78 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Interpenetrating polymer networks of the SIN type (simultaneous interpenetrating networks) composed of a polyacrylate and a polyurethane were prepared. They were made by mixing several concentrations of the linear polymer and prepolymer in solution, together with their respective chain extending and crosslinking agents and catalysts, casting films and curing them in situ. The morphology was studied by differential scanning calorimetry and electron microscopy in order to determine the extent of chain entanglement of the two networks (interpenetration). It was found that little or no phase separation occurred, thus implying extensive interpenetration.
    Additional Material: 1 Ill.
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  • 286
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    Polymer Engineering and Science 14 (1974), S. 101-111 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A mathematical representation of the plasticating process in a reciprocating-screw injection-molding machine has been formulated as a design tool for simulating the effect of processing parameters on the melting performance, the melt temperature, and the pressure profile. Comparisons with experimental data on low density polyethylene (LDPE), acrylonitrile butadiene styrene (ABS), and polyvinyl chloride (PVC) under a wide variety of processing conditions are described.
    Additional Material: 21 Ill.
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  • 287
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    Polymer Engineering and Science 14 (1974), S. 124-136 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A rheological analysis of a wire-coating die is presented. The rheological forces which might play a role in the stability of the wire are estimated. In particular, consideration is given to lateral forces related to the secondary normal stress function acting on the wire which is in an eccentric position, and the hydrodynamic force related to the viscosity function acting on the wire which moves at an angle to the die axis. For the former a simple, yet general, expression was derived by solving the flow problem (without axial pressure gradient) with the Ericksen equation in bipolar coordinates. Results indicate that normal stresses stabilize the wire, i.e., tend to restore it to the central location, provided the secondary normal stress function is negative. The hydrodynamic effect tends to reduce the angle between wire and die axes, thus drawing attention to the need of perfect mechanical centering of the guider tip, since in this case this effect also reduces eccentricity. The need is stressed for further work, in particular, experimental measurement of the secondary normal stress function.
    Additional Material: 6 Ill.
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  • 288
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    Polymer Engineering and Science 14 (1974), S. 147-154 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The solubility parameters and molar volumes of substances can be used, in conjunction with suitable theory, to provide estimates of the thermodynamic properties of solutions; the solubility characteristics of polymer-solvent systems and the estimation of the equilibrium uptake of liquids by polymers are examples of the type of practical problems that are amenable to treatment.For low molecular weight liquids, the solubility parameter, δ, is conveniently calculated using the expression δ = (ΔEv/V)½, where ΔEv is the energy of vaporization at a given temperature and V is the corresponding molar volume which is calculated from the known values of molecular weight and density.For high molecular weight polymers, the volatility is much too low for ΔEv to be obtained directly and hence recourse must be made to indirect methods for estimating δ for these materials. One such widely used method is based on Small's additive group “molar-attraction constants” which when summed allow the estimation of δ from a knowledge of the structural formula of the material; however, the density must still be determined experimentally.The proposed method of estimating δ, also based on group additive constants is believed to be superior to Small's method for two reasons: (1) the contribution of a much larger number of functional groups have been evaluated, and (2) the method requires only a knowledge of the structural formula of the compound.
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  • 289
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    Polymer Engineering and Science 14 (1974), S. 189-192 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The flexural creep compliance of a propylene copolymer was determined as a function of time and temperature using stresses of less than 700 psi. Equilibrium compliances of 2.82 × 10-5, 3.80 × 10-5, and 4.47 × 10-5 in2/lb at 75, 140, and 168°F respectively, are predicted. The data are used to characterize a flanged pressure chamber. Deflections due to flange opening deformation modes predicted for life times in excess of 40 years indicate the need for flange reinforcement.
    Additional Material: 7 Ill.
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  • 290
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    Polymer Engineering and Science 14 (1974), S. 202-205 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Often the first step in the solution of problems concerning the use of plastics involves the detailed characterization of a particular resin. Typically, a commercial plastic is composed not only of the basic resin but also of many additional additives. These additives may be such things as impact modifiers, plasticizers, flame retardants, and molding lubricants. In our laboratory we have developed thermoanalytical techniques for the determination of the morphology and composition of these multiphase materials. Specifically, we have quantitatively analyzed an ABS resin for not only the amount of SAN and BD but also the concentration of a molding lubricant (ML) in the resin. The concentration of BD and SAN was estimated calorimetrically from ΔCp measurements at Tg, and the ML level was calculated from ΔHf determinations. In addition, the shifts in Tg of both the BD and SAN phases of the ABS were studied as a function of diluent concentration. The diluents in these resins are residual monomers or other “impurities”.
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  • 291
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    Polymer Engineering and Science 14 (1974), S. 240-245 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Batch-to-batch variations with boron/epoxy prepreg tape are described in terms of uncured and cured matrix chemistry. The effects of thermal and humidity aging on both the chemistry and tensile modulus characteristics of the epoxy matrix are also shown.
    Additional Material: 16 Ill.
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  • 292
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    Polymer Engineering and Science 14 (1974), S. 282-287 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Tensile yield, flow, and fracture mechanisms in styrene A (SA), a styrene-acrylonitrile copolymer rubber-modified styrene A (RMSA) have been studied and characterized into two basic types: tensile crazing and shear banding. Each can be represented by a master curve and equation over ranges of temperature and deformation rates. Each exhibits distinctive activation energy and volume values. Tensile crazing predominates in unoriented SA below 70°C, and in RMSA. Shear yielding predominates in oriented SA.
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  • 293
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    Polymer Engineering and Science 14 (1974), S. 308-314 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Commercial, suspension-type PVC resin, poly (vinyl chloride), molecular weight Mw × 10-4 = 8.6 ± 0.9, polydispersity Mw/Mn = 2.26, was mixed with plasticizer di(2-ethyl hexyl)phthalate (DOP) and organo-tin stabilizer in four different proportions. The mixtures were milled and pressed into sheets for testing. The polymer content in these samples was 97, 80, 60, and 40 wt percent. The viscoelastic properties of the materials were investigated using a Weissenberg rheogoniometer in a cone-and-plate, steady-state shearing mode. The viscosities and primary normal stress difference coefficients were measured at shear rates of 10-2 ≤ \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \gamma \limits^. $\end{document} (sec-1) ≤ 102 and at temperatures from 151 to 246°C. The zero shear viscosities, plotted as log η0 vs 1/T (T is the absolute temperature) did not follow either a straight line dependence, reported for PVC melts at low shear rates at 170-190°C, nor was any discontinuity found near 195°C as by others; the data follows a continuous concave curve. The apparent activation energy of flow increases steeply with decreasing temperature. The data can be represented by a WLF type of equation, but the magnitudes of the parameters of this relation differ from expected values. A crossplot of log η0 (T = const.) vs log w (where w is the polymer content) also demonstrates a faster increase of η0 with w than expected from the straight line dependence. The primary normal stress difference coefficient was found to increase with w and decrease with T, paralleling the observed dependencies of η0.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 295
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 332-337 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new particle size analysis of latexes has been developed using a disc centrifuge allowing a very fast zonal sedimentation of particles followed by an automatic optical device. This method, which involves 5-10 minutes, permits the routine control of fabrication for emulsions of PVC. Linked to a computer, it permits accurate determinations of particle sizes in terms of weight, surface or number averages. The complete operation for one latex requires less than 15 minutes. This technique has been used to follow the growth of particles in seeding operations, i.e., monosized seed latex and the competitive growth of 2 populations of seed particles. Some results have also been obtained by comparing accurate particle size analyses of latexes with rheological properties of plastisols obtained from these latexes.
    Additional Material: 7 Ill.
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  • 296
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 357-361 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of polymerization temperature on the melt flow behavior of PVC of varying molecular weights has been studied over a wide shear rate range. For the same molecular weight, higher melt viscosities are observed for polymers prepared at lower temperatures. The shear rate dependence of the viscosity vs molecular weight plot is shown to be nonlinear over the shear rates examined. The inability to achieve a limiting zero-shear viscosity is discussed.
    Additional Material: 6 Ill.
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  • 297
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 382-385 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A high-frequency alpha transition of some plasticized poly (vinyl chloride) compositions was measured at 4 MHz employing an ultrasonic pulse technique. The material property used to determine the transition region was the intrinsic loss, which is indicative of changes in both the storage and loss moduli. Four dicarboxylic esters were used as plasticizing agents. These were (1) butyl benzyl phthalate, (2) di-(2-ethylhexyl) phthalate, (3) dibenzyl sebacate, and (4) di-(2-ethylhexyl) sebacate. Compositions were prepared using 10, 20, and 30 parts by weight of plasticizer per hundred of polymer. A small quantity of thermal stabilizer was added to prevent degradation. Samples were produced by an extrusion process to promote a high degree of fusion and consolidation. Comparison of the data showed the usual decrease in the transition temperature with increasing concentration of the plasticizing agent. However, it was shown that the controlling factor of the transition response was the molecular structure of the plasticizer. Both the structure of the parent dicarboxylic acid and the ester side groups were controlling factors. This relationship was supported when a high-frequency storage and loss modulus (dilatational) was compared at 25°C to the molecular weight of the side chain. The dimethyl ester was included for both series for comparative purposes. These data showed that the storage modulus increased and the loss modulus decreased with increasing chain length and complexity. However, the factor contributing most was the complexity (steric hindrance) of the plasticizing molecule.
    Additional Material: 4 Ill.
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  • 298
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 299
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 420-428 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Crack velocity measurements and fracture toughness tests have been carried out on extruded sheets of bisphenol-A polycarbonate. Slow bend tests provided quasi-static K1c data while dynamic initiation values were obtained from instrumented Charpy impact tests. In both types of tests high-speed crack velocity measurements were made using conductive silver grids applied to the specimens. The variation of K1c with strain rate and temperature was found to be small and in general agreement with expectations from the relaxation properties of polycarbonate. Notch acuity was found to have little effect in that values of K1c and crack velocity from specimens having the standard Charpy notch were similar to values obtained from sharp-cracked specimens. Some anisotropy was present in the material and gave rise to a small variation in K1c values with direction of crack propagation. Crack velocity and also the fracture mode transition temperature showed considerable dependence upon orientation. It was thought that dynamic toughness Kd, was influenced more than K1c by partial orientation of amorphous regions in the material and that the relaxation time for re-orientation was probably significant here.
    Additional Material: 14 Ill.
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  • 300
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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