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  • Chemical Engineering  (1,794)
  • 1970-1974  (1,794)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Viscosity of polypropylene oxide solutions over the entire concentration range (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 1-3 
    Details
    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: An empirical equation is presented which describes polymer solution viscosity, η, over the entire concentration range from a knowledge of intrinsic viscosity, [η], Huggins constant, k′, and bulk flow viscosity of polymer, η0. The equation is: \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{\eta _{sp}}}{{C[\eta]}} = \exp \left\{{\frac{{{\rm k'[}\eta {\rm]C}}}{{1 - bC}}} \right\} $\end{document} where solution viscosity, η, is contained in ηsp. No arbitrary parameters are invoked since b can be evaluated at bulk polymer (C = polymer density) where everything else is known. The equation accurately portrays the viscosity of polypropylene oxide (PPG 2025) from infinite dilution to bulk polymer in a very good solvent (benzene) and in a somewhat poorer (∼ θ) solvent (methylcyclohexane). The hydrodynamic consequences of the thermodynamic interactions between polymer and solvent are reflected in the constants. This equation should be applicable to other polymer/solvent systems, and thus be immediately useful to those working with concentrated polymer solutions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100102
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  • 2
    Electronic Resource
    Electronic Resource
    Entrance flows of polymeric materials: Pressure drop and flow patterns (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 24-31 
    Details
    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: Flow at the entrance of a tube or channel is of interest in many polymer processes. Except for mathematical treatments at high Reynolds numbers and in creeping Newtonian flow, one must turn to empirical correlating equations and qualitative observations. These are discussed in two parts, one on pressure drop and the other on flow patterns. The discussion of pressure drop is largely a review, dealing with inertial, viscous, and elastic contributions to the pressure drop in tapered and sharp-edged entrances; also presented are new data for a viscoelastic polymer solution in tapered cone entrances. In the section on flow patterns, stress birefringent data for a very elastic solution flowing into a channel entrance show an unusual effect: stress discontinuities, not unlike “shock waves,” upstream and downstream of the entrances. This is in contrast to Newtonian and less elastic materials in which the stress patterns change gradually between the developed flow region and the entrance region.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100106
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  • 3
    Electronic Resource
    Electronic Resource
    Compression, bending, and shear of bonded rubber blocks (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 48-53 
    Details
    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: An approximate theoretical treatment is given for small compressions of bonded rubber blocks. The component of the compressive force arising from the bonded condition at the loaded surfaces is obtained from a pressure distribution within the block, given by the solution of the corresponding torsion problem. The bending of blocks is treated in a similar way, the pressure distribution in this case being derived from the corresponding bending stress function. The apparent shear of relatively thick blocks is then treated as a combination of shear and bending displacements. The location of an internal rupture and the deformation at which it occurs are also derived from a critical (negative) value of the pressure developed within the block, at which a small cavity increases indefinitely in size. The corresponding critical deformations are calculated for extension and bending displacements. The shear stresses developed at the bonded surfaces under extension, compression or bending displacements are also evaluated.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100110
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  • 4
    Electronic Resource
    Electronic Resource
    The rheology of polypropylene - the influence of molecular weight distribution on melt elasticity (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 79-85 
    Details
    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 structure of isotactic polypropylene, obtained by means of Ziegler-Natta catalysis, can be characterized only by molecular weight distribution. The mechanism of stereospecific catalysis eliminates other variables, i.e., short and long branching. In this case it is possible to develop a rheological study dependent only by polydispersity. The spectrum of relaxation times of five samples of polypropylene have been calculated from swelling measurement in the molten state and from flow master curves. The molecular weight distribution of the samples has been calculated by means of the relaxation spectrum, as suggested by Ferry. This information has been compared with that obtained by a fractionation method. There is a good agreement between the calculated and measured polydispersity curves.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100205
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  • 5
    Electronic Resource
    Electronic Resource
    Description of tensile failure of viscoelastic materials under multiaxial loadingWork Performed under the auspices of the U. S. Atomic Energy Commission. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 102-107 
    Details
    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 description of tensile failure of polymeric materials under multiaxial loading has been formulated, based on a combination of ideas and implications derived from Smith's work on uniaxial tensile failure envelopes and the author's earlier theoretical work. Some simplification of the formal expressions was achieved by imposing restrictions that would assure that the uniaxial failure envelope is recovered under uniaxial tensile stress conditions and that the progression toward failure is monotonically increasing under monotonically increasing loads. The final result emerges as an extension of the uniaxial failure envelope applied to failure under multiaxial loads. Subsequently, the result is capable of describing rate effects to the same extent as can be described by the uniaxial failure envelope. This is an added capability over many of the existing multiaxial failure descriptions. Unfortunately, the result applied at best, only to those materials for which the uniaxial failure envelope applies; thus the generality is restricted. Some preliminary verification is presented for LX-04-1, a high-explosive material composed of 85% HMX and 15% Viton by weight, using Peterman's results from 68°F biaxial tests. Further experimental work is underway.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100208
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanism of ultraviolet degradation and stabilization in plasticsPaper presented at Plastics Institute of American Seventh Annual Conference, November 6, 1969, Hoboken, N. J. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 228-234 
    Details
    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: When plastics are used for outdoor applications, they often deteriorate fairly rapidly. Theoretical explanation is based upon absorption of ultraviolet energy, raising some bonds to an energy level which exceeds their stability, and thus initiating their breakdown, usually involving atmospheric oxidation and sometimes hydrolysis as well. This theory is satisfactory for many polymers, but does not explain the instability of some polymers which are transparent to ultraviolet, nor the stability of some polymers which contain ultraviolet-absorbing and/or unstable groups. Plastics are often stabiliized by addition of ultraviolet reflectors, absorbers, or deactivators, increasing stability sufficiently for outdoor use; theoretical explanation of their protective action is satisfactory when they work, but does not explain their specificity or their failures.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100408
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  • 7
    Electronic Resource
    Electronic Resource
    Mixing and residence time distribution in melt screw extruders (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 279-288 
    Details
    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 residence time distribution (RTD) functions were derived for screw extruders, based on the “parallel plate” and curved channel flow models. The results indicate a relatively narrow distribution, and they explain several characteristics of screw extruders. The strain distribution in the fluid across the channel was also derived. With the aid of these two functions an average strain of the fluid leaving the extruder was defined. The resulting weighted-average total strain (WATS) provides a quantitative criterion to the “goodness of mixing” in extruders.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100505
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  • 8
    Electronic Resource
    Electronic Resource
    Gel sensitivity of polybutadiene-based rubber subjected to thermal abuse (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 159-162 
    Details
    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 thermal instability of polybutadiene-based rubber used to improve the impact strength of vinyl-type polymers often presents processing problems. Rubber manufacturers have attempted to alleviate this situation by incorporating various types of stabilizers. However, this is not always successful. One of the consequences of using a rubber that is not sufficiently stable in the production of modified vinyl-type polymers is the formation of insoluble gel particles during processing. In an attempt to prevent this from occurring, a test was developed that can differentiate between rubbers of acceptable and non-acceptable thermal stability. In principle, the test consists of exposing the rubber in question to a controlled thermal abuse of such intensity and duration as to approximate the thermal abuse to which the rubber will be subjected in a normal processing sequence. (The extent of abuse will vary for different processes and must be empirically established for each system.) Following this controlled exposure, the rubber is tested for gel-particle content by filtration of a specific solution, much the same way that the rubber manufacturer tests for initial gel-particle content. Sufficient data have been compiled to statistically describe the validity of the test.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100306
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  • 9
    Electronic Resource
    Electronic Resource
    On the strength and stiffness of planar reinforced plastic resins (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 185-192 
    Details
    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 recent history of planar reinforced plastic resins, including glass flake, high modulus ceramic flake, and continuous vapor coated film composites, is reviewed. The theoretical mechanics of both continuous (film) and discontinuous (flake and ribbon) reinforcements are summarized in simple form. A novel set of design curves is presented from which the lower bound requirements for the flake composite constitutents may be read directly. At the same time, the dependence of the composite ultimate strength on the shear strength of the plastic resin matrix is demonstrated.The mechanical properties of experimental film and flake composites representative of recent work are reported and compared with the theoretical predictions. In conclusion, the potential of planar reinforced plastic resin composites is discussed and found to be significant for applications where low weight and high isotropic stiffness are required, for example in aero-structural, airfoil, or blade components.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100310
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  • 10
    Electronic Resource
    Electronic Resource
    Torque rheometer evaluation of polypropylene process stability (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 215-221 
    Details
    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 method of treating torque rheometer test data has been developed. First, it involves converting the torque values measured over a range of temperatures to torques corresponding to a constant reference temperature. Then the log of the calculated torques is plotted against time. The method has been applied to several polypropylene grades, and the effects of numerous test variables have been explored. Correlations have been developed between torque rheometer data and fundamental polymer properties of viscosity and molecular weight. The method should also be applicable to polymers other than polypropylene.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100405
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