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  • Chemical Engineering  (17,979)
  • Atomic, Molecular and Optical Physics  (6,266)
  • Wiley-Blackwell  (24,240)
  • American Association for the Advancement of Science (AAAS)  (5)
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  • 101
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 203-212 
    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: Tangential flow of a “power law” model fluid between two concentric cylinders is analyzed. A constant angular pressure gradient is imposed and one of the cylinders is rotating at a constant angular velocity. This type of flow is of interest in screw extrusion theory. The error in the superposition, i.e., linear addition of tangential pressure and drag flows, for a “power law” model fluid, is quantitatively calculated and plotted in the form of a correction factor. Tangential pressure flow is compared to a pressure flow between parallel plates and additional correction factor to account for the curvature is derived and plotted. The applicability of the “power law” model for flow of polymer melts in extruders is also discussed.
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  • 102
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 198-202 
    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 article describes a general mathematical model summarized in the form of a computer program for the plasticating extruder. The model combines features of the metering-zone model previously published, the melting-zone model described in paper No. I of this series, and a feed-zone model based on an extension of known theories. It is based on theoretical models for each zone unified and improved by non-linear estimation to accurately describe the extrusion experiments.The mathematical model predicts temperature, pressure, and melt channel width profiles of the plastic being processed in the plasticating extruder as a function of design and operating variables of the machine. It enables for the first time the design of the whole machine based on temperature and pressure profiles, including new combinations of cylindrical and tapered roots.
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  • 103
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 213-216 
    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 development of a fractional crystallization technique for characterization of polypropylenes with respect to stereoregularity is described. It is a simple technique which is attractive for routine analysis and under suitable conditions yields quantitative data with good reproducibility. Separation by fractional crystallization from hot xylene solution is shown to take place according to polymer crystallizability and is relatively independent of molecular weight. It thus represents an alternative and in some ways superior approach to the more commonly used fractional extraction method. Preliminary work indicates that the fractional crystallization method may prove of value in establishing correlations between the stereoregular nature of polypropylenes and their physical properties.
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  • 104
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 244-247 
    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 density and tensile property changes in polypropylene resulting from various post-crystallization aging procedures are investigated with the aim of (1) establishing standard procedures for the evaluation of these properties and (2) determining which conditioning treatment will provide optimum tensile properties. The morphology and resultant tensile behavior of polypropylene are particularly sensitive to conditioning treatments in the temperature range 145-160°C. A procedure for compression molding plaques, carrying out isothermal annealing treatment in the 100-170°C range and gradual cooling is described. The dependence on annealing temperature of the density, elongation, tensile modulus and yield stress is given.
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  • 105
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 260-262 
    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: Some earlier observations on the influence of molecular weight, plasticizer, and irradiation on the thermal conductivity of polymers is reviewed. Also some new data on polystyrene and some new calculations based on the theory of Hansen and Ho are presented. These data show almost a two fold increase in the thermal conductivity of polystyrene as the molecular weight goes from 900 to 100,000. Data on the moleculer weight effect on thermal conductivity appear to be consistent with the theoretical calculations.
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  • 106
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 273-278 
    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: Thermal oxidation in linear polyethylene is mainly confined to disordered regions in which scission reactions cause crystallization and eventual deterioration of mechanical properties. Gel formation is negligible at 100°C. As degradation proceeds, comparable changes occur in the intrinsic viscosities of melt and solution-crystallized liner polymers, indicating that chain folds are regularly arranged and are resistant to oxidative scission. Breakdown is much more extensive in branched and crosslinked polymers since crosslinking retards oxidative crystallization and branching increases the volume fraction of substrate ultimately accessible to oxygen.
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  • 107
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 295-298 
    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: For a system of equivalent bonds undergoing random bond scission it is reasonable to assume that the rate of bond breaking (hence the rate of creation of new molecules) reported in the literature and data presented here demonstrate that the number of molecules created is not proportional to the time of thermal treatment hence they seem to belie this reasonable hypothesis. Other authors have adduced the presence of some non-equivalent bonds in order to account for the observed cruvature and still retain the hypothesis. Implicit in these arguments is the assumption of a steady-state concentration of reactive fragments. Our analysis explores the consequences of abandoning the steady-state assumption and shows that a quantitative explanation of the observed degradation behavior may be had by this means wihile still retaining the hypothesis of a constant probability of a bond being broken per unit time.
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  • 108
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 248-254 
    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: Most polymers exhibit a very fluid melt rheology during extrusion and can be distorted, drawn down, and cooled without building excessive residual stresses into the product. In contrast, rigid vinyl is usually extruded as a stiff, almost selfsupporting mass. Care must be taken to prevent the formation ot oriented stresses in the product which will be relieved during long periods of exposure resulting in dimensional instability and related loss of physical properties. A newly developed method of in-line annealing has shown to be an effective means of relieving oriented stresses developed during extrusion. By use of this instrumented technique, rigid vinyl products can be controlled to much tighter shrinkage specifications in a single step process, thereby eliminating post-annealing treatments.
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  • 109
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966) 
    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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  • 110
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 282-284 
    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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  • 111
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 299-305 
    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: Residence time distribution (RTD) is a spectral property of contiuous chemical reactors. Batch reactors may be viewed as having “monodisperse” residence time distributions. This article discusses molecular weight distributions (MWDs) of polymeic materials formed in continuous and in semicontinuos process and how they are affected by reaction time distributions. All synthetic high polymers, even those Prepared in batch reaction, possess a MWD which may sometimes, for a given monomer, be altered chemically by a proper choice of catalyst and diluent. An interesting concept suggested by the present work is the prospect of “tailoring” the MWD for a given monomer-catalyst-diluent system physically by selecting appropriate reactor conditions. Hence, althought this work involves analysis the results may provide a guide to synthesis.
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  • 112
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 369-372 
    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 films, elastomers, and fibers have valuable in-use properties below 300°C. Astronautic requirements, however, may evaentually call for materials that withstand 500 hrs at 300°C or 100 hrs at 500°C while fully retaining their useful properties. The most significant advances in the synthesis and preparation of heat resistant polymer have been made since 1959 with new synthetic methods such as interfacial polymerization, cyclopolymerization, and intramolecular polymer post-cyclopolymerization, and intramolecular olymer post-cyclization reactions. It is the purpose of this paper to discuss the structural relationships among those heat resistant, orgainc polymers that were reported to give strong films and fibers. Those heat resistant polymers, which have not yet been fabricated into films and fibers are not included in this review.
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  • 113
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 7 (1967) 
    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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  • 114
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 373-376 
    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: Monodisperse and polydisperse polystyrenes of equal weight average molecular weight (Mw) are evaluated for melt flow behavior in an Instron capillary rheometer and for injection molding behavior in a 12 ounce in-line reciprocationg screw injection molding machine. The influence of molecular weight distribution on the shape of the flow curves is deconstrated over a wide range of shear rate and temperature. The influence is also reflected in injection molding behavior as defined by pressure to fill or flash the mold at a given melt temperature. Studies of capillary rheometer data for correlation with injection moling beghavior indicate poor agreement when low shear rate viscosity data are used. Good agrement is foun using high shear rate viscosity data in the range 103 to 104 sec-1 Striking crossover points on melt rheology and injection colding area diagram curvs are found with the monodisperse and polydisperse polystyrenes of the same M These crossovers shift with melt temperature and make possible the determination of a “controlling shear rate” for the injection molding process. This is found to be 3500 sec-1 for short shot and 6200 sec-1 for flash with the ASTM test specimen mold used in this study.
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  • 115
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 7 (1967), S. 24-25 
    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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  • 116
    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: 9 Ill.
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  • 117
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 7 (1967), S. 45-51 
    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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  • 118
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 7 (1967), S. 58-62 
    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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  • 119
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    Polymer Engineering and Science 7 (1967), S. 253-256 
    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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  • 120
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 7 (1967), S. 264-268 
    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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  • 121
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 2 (1962), S. 326-330 
    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 adsorption of triethoxysilylpropylamine and its polymer onto 325 mesh E-glass from both aqueous and non-aqueous systems has been investigated. The amount adsorbed from an aqueous solution onto an E-glass surface corresponds to that obtained by others workers using different techniques. Solid preformed A-1100 polymer (II) was found to be unstable. Upon prolonged standing a basic gas, identified as ammonia, was liberated. Experimental results indicate that the amount adsorbed is related to the number of ethoxy groups on the molecule. However, the mechanism of silane attachment is still not completely understood.
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  • 122
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    Polymer Engineering and Science 7 (1967), S. 222-223 
    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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  • 123
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 2 (1962), S. 332-336 
    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 technique of testing resin/glass laminates has been extended to include three alkali-containing glasses. NOL rings have been made by a direct filament drawing technique using an epoxide resin system. In each case the strength developed is less than with “E” glass.
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  • 124
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    Polymer Engineering and Science 2 (1962), S. 353-353 
    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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  • 125
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 2 (1962), S. 339-353 
    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 assertion was checked that alkali containing glass fibers, which evolve caustic bases when attacked by water, are, by this fact, responsible for the mechanical deterioration of reinforced plastics. Glass fibers of different chemical composition, when extracted with water, showed no correlation between amount of alkali in the glass and alkali leached out. Tensile strength of glass fibers is not a function of alkali content. Subjected to water, all types of glass fibers keep their strength except when boiled. This applies to fibers coated with coupling agent or in the native state. Deterioration of laminates under the influence of water seems to be primarily a function of the interface.
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  • 126
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    Polymer Engineering and Science 8 (1968), S. 89-100 
    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 stress-strain characteristic of polymeric binders and solid propellants are dependent on the crosslink density, molecular weight between crosslinks, molecular weight distribution in the binder formulation, volume fraction of filler, and the interaction between the binder and filler particles. This investigation is directed toward elucidation of solid propellant microscopic response and failure mechanisms through characterization of the constitutive effects of crosslink density, molecular weight distribution and curing agent ratio in the binder formulation, and filler fraction. This was accomplished on the ERLA/PBAA propellant system through investigation of three binder formulations with the same curing agent ratio but different crosslink densities; five binder formulations with different curing agent ratios; and four formulations with up to 69.9% by volume of filler.Uniaxial stress-strain characteristics were determined on each formulation at displacement rates of 0.2 to 20.0 in/min at isothermal test conditions ranging from 75 to -90°F. The failure characteristics of a viscoelastic material represent a curve in the three-dimensional space of stress, strain, and time. The ultimate property data on each formulation are presented as projections of this failure curve on the stress-strain, stress-time, and strain-time planes, respectively. Relationships are developed for the dependence of the stress-time, strain-time, and stress-strain failure envelopes on the volume fraction of bound rubber, crosslink density, molecular weight distribution and curing agent ration in the binder component, and the volume fraction of filler.
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  • 127
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    Polymer Engineering and Science 8 (1968), S. 58-63 
    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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  • 128
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    Polymer Engineering and Science 8 (1968), S. 82-88 
    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: Two independent methods for predicting the deformation of free openings of arbitrary shape in a viscoelastic plate are illustrated.The first method is experimental and is based on the interference of two systems of lines representing the initial and final positions of the material. To demonstrate the moire method, the creep compliance function for polymethylmethacrylate is determined as preliminary information. This function is used as input data in the ensuing theoretical analysis to insure realistic viscoelastic behavior.The second method involves techniques to approximate viscoelastic displacements from known elasticity solutions and known material properties.The methods are applied to two examples: (1) The square hole - to determine the motion of an opening of complicated shape; and (2) an ellipse loaded at 45° - to indicate qualitative agreement with an existing prediction of the motion of cracks in a viscous plate.
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  • 129
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    Polymer Engineering and Science 8 (1968), S. 116-125 
    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 simple, versatile biconical rehemoter has been developed. This device provides shear creep and creep recovery data for polymer melts over a temperature range of 200-500°F. and a range of applied shear stresses from 2 × 103 to 9 × 105 dynes/cm2.Extensive reheological data have been obtained for two samples each of polyisobutylene and high-density polyethylene. These illustrate the value of the device in obtaining data useful for predicting and understanding the processing properties of polymer melts.
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  • 130
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    Polymer Engineering and Science 8 (1968) 
    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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  • 131
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    Polymer Engineering and Science 8 (1968), S. 161-185 
    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: Considerable progress has been made in the past 20 years in the synthesis, characterization and fabrication of plastics. Previous SPE Award winners, such as Mark, Natta, and Marvel dealt largely with synthesis; Flory with characterization; Alfrey and Du Bois with fabrication. One of the still unsolved problems lies in the realm of relating mechanical properties, such as impact strenght and creep to molecular structure.The design enginner who wishes to use a plastic part is concerned primarily with how some property such as impact strenght varies with temperature, speed of test, test method, etc. The polymer scientist must know why. Through knowing why, he may be able to design better plastics.This paper attempts to survey some of the world-wide progress made in this area in the past 10 years. The ultimate goal is to understand these mechanical properties in terms of internal molecular motions which occur in solid polymers. Internal motion can be detected by electrical, electromagnetic and dynamic mechanical measurements. When these three methods are applied on a given polymer over a range of temperatures, insights can be gained as to the variation of impact strength and other properties with temperature and frequency for that same polymer. These three fundamental methods, which require very small samples (less than 50 grams), can provide insight into the practical behavior of plastic materials over the wide range of temperatures and frequencies encountered in the real world.
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  • 132
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    Polymer Engineering and Science 8 (1968), S. 235-240 
    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 knowledge of the variation of melt viscosity of thermoplastic polymers with both shear rate and temperature is of considerable importance to plastics engineers as well as to polymer rheologists. The actual measurement of melt viscosity at a large number of temperatures and shear rates is frequently a tedious and time-consuming task. A technique has been developed, based upon the applicability of shear rate-temperature superposition, for predicting the flow curves of a number of olefin polymers and copolymers at various temperatures from experimental data obtained at one temperature for the material in question. The experimental validity for superimposing log shear stress - log shear rate curves at different temperatures along the log shear rate axis has been established for both high and low density polyethylenes, polypropylene, polybutene-1, and poly (ethylene vinyl acetate) copolymers. The temperature dependence of the resultant shift factors has been determined for each system, and the method of utilizing this information to predict viscosities as a function of temperature and shear rate is discussed.
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    Polymer Engineering and Science 8 (1968), S. 245-245 
    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
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  • 134
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    Polymer Engineering and Science 8 (1968), S. 267-271 
    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 dynamic mechanical study has been made of an ethylenemethacrylic acid copolymer containing 4.1 mole per cent of methacrylic acid units and its sodium, lithium and calcium salts. On the basis of the results and related physical chemical studies it is proposed that the structures of the ionized copolymers consist of three distinct phases - a crystalline polyethylene phase, an amorphous polyethylene phase, and an ionic phase consisting of ionic domains. It is further proposed that the unionized acid copolymer consists of two phases - a crystalline polyethylene phase and an amorphous phase consisting of polyethylene crosslined with hydrogen bonded, carboxylic acid dimers.
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  • 135
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    Polymer Engineering and Science 8 (1968), S. 290-301 
    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 true stress-true strain behavior of polyoxymethylene, n(-CH2O), as an example of a bulk semi-crystalline polymer, has been investigated for constant hydrostatic environmental pressures from 1 atmosphere to 8 kilobars with the principal objectives of elucidating the factors controlling flow and fracture. Experiments were conducted in uniaxial tension at room temperature and constant strain rate. The tensile observations were supplemented by measurements of bulk compressibility and stress relaxation behavior at pressure.In contrast with metals and inorganic compounds, the modulus, yield stress and fracture stress of POM increase strongly with pressure by a factor of approximately three at 8 kilobars. The modulus increase is shown from the stress relaxation measurements to be associated with a pressure-induced increase in the β-transition temperature which points to the potential usefulness of the concept of pressure-temperature super-position of mechanical behavior. The characteristics of the pressure dependence of the yield stress demonstrate that yield criteria based on continum mechanics considerations, including the Mohr or Coulomb-Navier criterion, are not valid for general deformation (non-plane strain) conditions in this polymer. The concept of a critical volume change determining the initiation of yielding is suggested to be applicable to semi-crystalline polymers. Comparison with analogous changes in yield stress with temperature points to an increasing contribution to the control of yielding by the initially disordered regions with increasing pressure or decreasing temperature. The fracture behavior observed at pressure eliminates the concepts of a critical stress as a fracture criterion for POM and of a simple reduction in normal stress at points of stress concentration as the principal effect of the applied pressure on fracture.
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  • 136
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    Polymer Engineering and Science 9 (1969), S. 90-99 
    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 investigation considers a hypothetical three-phase ordered composite to permit the design of a new material both stiffer and tougher than the matrix phase alone. The required elastic solution is greatly simplified and was based on a single layered inclusion in an otherwise infinite matrix under uniaxial tension. The solution presented is exact and generalized to accommodate any number of concentric layers of different thickness and composition.
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  • 137
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    Polymer Engineering and Science 9 (1969), S. 121-130 
    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: Attempts to use low-cycle fatigue techniques derived from the work of Coffin and Manson to predict the fatigue performance of six diverse structural plastics are discussed. Through an analysis of dynamic property and thermal behavior studies of polymer samples in reversed-tension fatigue, an improved model for the polymer fatigue process has been proposed. Laboratory test data are presented illustrating the relationship between the various models.
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  • 138
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    Polymer Engineering and Science 3 (1963), S. 67-70 
    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: Methacryloyl chloride was polymerized in a number of solvents, and the polyacid chloride was converted into the methyl ester. The yield and viscometric molecular weight are given for each sample, whereas the osmometric molecular weight is given for selected samples. The choice of solvent controls the degree of polymerization between the limits of 500 and 8,800. Polymer yields were about 20% and the degree of polymerization was 1500 when dioxane was used as a solvent, whereas the yield increased to 45% and the DP was very high when such solvents as cyclohexane and n-hexane were used. Polymerization in solvent mixtures gave intermediate molecular weight values. Infrared analysis showed the presence of anhydride.
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  • 139
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    Polymer Engineering and Science 3 (1963), S. 71-71 
    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 water immiscible liquid is encapsulated in a thin skin of an insoluble copolymer by dissolving a difunctional acid chloride in said liquid and spraying the solution in fine droplets into a dilute aqueous solution of excess glycol or diamine. The polymer, which is not hygroscopic, forms as an insoluble film on the periphery of each drop. The microcapsules may be separated from the aqueous phase and dried without coalescing. Dyes, pigments, stabilizers, and other materials may be incorporated within the capsules.
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  • 140
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    Polymer Engineering and Science 9 (1969), S. 100-104 
    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: It is postulated that property gradients exist at the interface forming an “interphase” between the insert and the matrix. Such gradients might be caused by partial solubility and diffusivity of the two phases comprising a composite. For simplicity, the “interphase” is replaced by a shell exhibiting averaged properties (Eshell = 1/2 Einsert + 1/2 Ematrix, etc.). An exact linear elastic solution was employed to evaluate stress fields throughout all regions. The possible effect of the “interphase” and its thickness on several physical properties of the composite are evaluated in terms of the particular stress fields.
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  • 141
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    Polymer Engineering and Science 9 (1969) 
    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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  • 142
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    Polymer Engineering and Science 9 (1969), S. 159-163 
    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 investigation of the dynamic mechanical properties of several molten polymers was performed using the Maxwell Orthogonal Rheometer. Relaxation spectra derived from experimental data for the terminal region of viscoelastic response indicate that as molecular weight distribution broadens, terminal relaxation phenomena associated with molecular disentanglement and translation extend over a corresponding wider frequency range. The same data indicate that a true maximum relaxation time beyond which no elastic response is observed exists for the materials studied. Moreover, the maximum relaxation time corresponds to the reciprocal of the frequency where the dynamic viscosity deviates from its zero-shear value. Thus an estimate of the time necessary for complete elastic recovery in polymer melts is readily obtained experimentally.
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  • 143
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    Polymer Engineering and Science 9 (1969), S. 190-196 
    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 creep measurements were carried out on a commercial ABS polymer over a temperature range from 40 to 100°C at stress levels from 0.6 to 1.8 × 108 dynes/cm2. Experiments were conducted in a prototype of an apparatus designed to be compatible with digital acquisition systems. Analysis of the data indicated that application of the time-temperature super-position principle was of limited value due to the use of test temperatures near and below the effective glass transition temperature of the acrylonitrile-styrene component of the polymer. A strong stress dependence of the compliance was observed, even at relatively short times after loading. This was analyzed in terms of a model in which the height of the potential energy barrier to motion of the molecular flow unit is lowered by the application of stress. Analysis of the temperature dependence of the compliance at low stress levels indicated that the effective Tg of the acrylonitrile-styrene phase is about 85°C. The temperature dependence of the magnitude of the activation energy is considered as is the stress dependence of the glass transition temperature. Implications of short-time response in creep with regard to response under impact loading are pointed out. Practical application of results to the prediction of dimensional stability of molded parts is discussed as well as the limitations involved in extrapolation of experimental data to long times and high stress levels.
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  • 144
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    Polymer Engineering and Science 9 (1969), S. 197-205 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Fine structures of several plastic/rubber two -phase polymer systems were studied by means of direct observations of ultrathin sections under the electron microscope using osmium tetroxide staining and a hardening procedure developed recently by Kato. Samples used are several types of both ABS polymers and high -impact polystyrenes, and several PVC/rubber blends and the results were discussed in relation to their dynamic viscoelastic properties. It is suggested that these studies may fruitfully be extended to clarify the structure -to property relationships by use of this method.
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  • 145
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    Polymer Engineering and Science 9 (1969), S. 250-254 
    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 purpose of this paper is to describe a new deformation calorimeter, which is based on differential thermometry and uses a flowing gas stream as a heat transfer medium which allows it to operate under near-isothermal conditions. Also presented are some preliminary test measurements with a crosslinked polyurethane elastomer and crystalline polybutene-1.
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  • 146
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    Polymer Engineering and Science 9 (1969), S. 277-281 
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    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: Antiplasticizers are considered to be diluents which when added to polymers result in mechanical property behavior opposite to that of plasticization. The addition of antiplasticizers to certain polymers such as Bisphenol A polycarbonate, polysulfone, and polyvinyl chloride results in the elimination of the secondary loss transitions of these polymers. As a drop in modulus accompanies these transitions, their elimination results in higher tensile strength and tensile modulus. As secondary transitions are commonly associated with ductility and impact strength, their elimination also results in the observed embrittlement characteristics. The addition of anti-plasticizers to polymers also restricts the diffusion of penetrants resulting from the decrease of molecular flexibility in the polymer matrix.
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    Polymer Engineering and Science 9 (1969) 
    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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  • 148
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    Polymer Engineering and Science 9 (1969), S. 331-338 
    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 useful concept in polymer science is the degree of crystallinity - the fraction of the polymer that exists in a relatively ordered state. Methods of determination of the degree of crystallinity using density, infrared, thermal, N.M.R. and X-ray measurements are examined in light of modern notions of the structure of semi-crystalline polymers.
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  • 149
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    Polymer Engineering and Science 9 (1969), S. 405-414 
    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 changes occurring when polythene melts are subjected to shear, have been investigated using a rotating bob fitted into a ram extruder. In addition to chain scission, low density polythene exhibits reversible changes in mechanical and viscoelastic properties. The magnitude of the changes is controlled by total shear strain, and is related to molecular weight and long chain branching. The mechanism appears to be one of reversible disentanglement operating mainly on the large highly branched molecules. The work is relevant to various extrusion processes and to other long-branched polymers.
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    Polymer Engineering and Science 9 (1969), S. 434-444 
    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 investigation deals with the fatigue behavior of a group of thermoplastics fortified with discontinuous glass fibers dispersed by an injection molding process. The thermoplastics included nylon, polystyrene and polyethylene reinforced with short (1/8 in.) and long (1/2 in.) glass fibers.Several aspects of the fatigue behavior are included in the study. First, classical S-N curves were generated under fluctuating tension with R = 0.05 to show the loss of strength due to cyclic load application. Next, the extent of progressive fatigue damage was established by measuring the residual strength after cyclic loading. Finally, hypotheses pertaining to the fatigue mechanisms operative in all four materials were made based on microscopic examinations of sections removed from fatiguedamaged specimens.
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  • 151
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    Polymer Engineering and Science 10 (1970), S. 1-3 
    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.
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  • 152
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    Polymer Engineering and Science 10 (1970), S. 24-31 
    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.
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    Polymer Engineering and Science 10 (1970), S. 48-53 
    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.
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  • 154
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    Polymer Engineering and Science 10 (1970), S. 79-85 
    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.
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    Polymer Engineering and Science 10 (1970), S. 102-107 
    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.
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  • 156
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    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.
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    Polymer Engineering and Science 10 (1970), S. 279-288 
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    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.
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    Polymer Engineering and Science 10 (1970), S. 159-162 
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    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.
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    Polymer Engineering and Science 10 (1970), S. 185-192 
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    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.
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  • 160
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    Polymer Engineering and Science 10 (1970), S. 215-221 
    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.
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  • 161
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    Polymer Engineering and Science 10 (1970) 
    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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  • 162
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    Polymer Engineering and Science 10 (1970), S. 305-308 
    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 use of a commercially available thermomechanical analyzer (TMA) operated in its isothermal mode is illustrated for studies of penetration of a hemispherically-tipped probe into a material sample. Two amorphous copolymers were studied at various temperatures above their softening points. Kinetics of penetration are compared with tensile creep measurements for these viscoelastic materials. A simple semi-empirical relationship between creep and penetration at small strains is applied and found to yield approximate although not exact agreement with experiment. It is thus possible that for homogeneous materials of this type creep data might be easily predicted with a fair degree of accuracy from penetration data and vice versa. Experimental problems involved in the TMA penetration technique are discussed.
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  • 163
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    Notes: A mathematical model has been developed to predict radial temperature gradients in polymers during dielectric heating. The time-temperature model includes parameters for rate of dielectric heating, thermal conductivity, density, heat capacity, surface coefficient of heat transfer, and sample radius. The application of this model was checked experimentally on a 2-in. cylinder of cured polyisoprene.
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  • 164
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    Polymer Engineering and Science 10 (1970), S. 289-292 
    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 dynamic mechanical properties of blends of polymer melts were measured using the orthogonal rheometer. Two-phase blends, polyethylene-polystyrene, polyethylene-poly-(methylmethacrylate), and polystyrene-polymethylmethacrylate, were studied. The in-phase and out-of-phase moduli were measured over the range of composition and at frequencies between 10-4 and 10 revolutions/sec.The out-of-phase modulus increases in a monotonic manner with composition. The in-phase modulus, however, shows a maximum with composition in two cases. Examination of the relaxation spectra of these blends shows that when no maximum occurs it can be written as an additive function of the spectra of the components. In the case where a maximum is observed in the modulus the measured spectrum of the blend is shifted in frequency relative to the calculated one. This is tentatively attributed to slight interpretation and solubility of one phase in the other in these cases.
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  • 165
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    Polymer Engineering and Science 11 (1971), S. 129-138 
    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 crosslinked epoxy resin consisting of a 60/40 weight ratio of Epon 815 and Versamid 140 and composites of this material with glass beads, unidirectional glass fibers and air (foams) were tested in tension, compression and flexure to determine the effect of time and temperature on the elastic properties, yield properties and modes of failure. Unidirectional continuous fiber-filled samples were tested at different fiber orientation angles with respect to the stress axis. Strain rates ranged from 10-4 to 10 in./in.-min and the temperature from -1 to 107°C.Isotherms of tangent modulus versus strain rate were shifted to form master modulus curves. The moduli of the filled composites and the foams were predictable over the entire strain rate range. It was concluded that the time-temperature shift factors for tangent moduli and the time-temperature shift factors for stress relaxation were identical and were independent of the type and concentration of filler as well as the mode of loading.The material was found to change from a brittle-to-ductile-to-rubbery failure mode with the transition temperatures being a function of strain rate, filler content, filler type and fiber orientation angle, indicating that the transition is perhaps dependent on the state of stress.In the ductile region, an approximately linear relationship between yield stress and log strain is evident in all cases. The isotherms of yield stress versus log strain rate were shifted to form a practically linear master plot that can be used to predict the yield stress of the composites at any temperature and strain rate in the ductile region. The time-temperature shift factors for yielding were found to be independent of the type, concentration and orientation of filler and the mode of loading. Thus, the composite shift factors seem to be a property of the matrix and not dependent on the state of stress. The compressive-to-tensile yield stress ratio was practically invariant with strain rate for the unfilled matrix, while fillers and voids raised this ratio and caused it to increase with a decrease in strain rate. The yield strain of the composites is less than the unfilled matrix and is a function of fiber orientation and strain rate.
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  • 166
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    Polymer Engineering and Science 10 (1970), S. 358-363 
    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 a thin-walled rubber tube containing an incompressible fluid is compressed between two parallel plates the internal pressure rise depends on the restraints in the contact regions. When there is no friction in the contact zone the pressure rise is lower than when slip is prevented, so that the tube, regarded as a spring, has a compression stiffness which depends on the frictional conditions. The same considerations apply to the inflation of a tube between fixed parallel plates. In this case unstable inflation sets in at a critical pressure when the interfaces are frictionless; the tube develops a pronounced bulge when this pressure is approached. Simple theoretical relations are derived for the internal pressure and compressive force for both these deformations, and for both boundary conditions, assuming that the rubber is Neo-Hookean in elastic behavior. Experimental measurements on tubes of different dimensions are shown to be in reasonably good quantitative agreement with these theoretical predictions in all cases.
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  • 167
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    Polymer Engineering and Science 10 (1970), S. 364-368 
    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 diffusional model was established to study the kinetics of thermally-induced solid state polycondensation of poly(ethylene terephthalate). Diffusion through solid polymer is the rate controlling step when temperature is higher than 210°C and particle size is no smaller than 100 mesh. The activation energy is 30 Kcal/g mole. In polymerizing powders (20-200 mesh), the crystallinity of prepolymer and its changes during the polymerization affect the diffusivity and thus the polymerization rate. The diffusivity was found to be linearly proportional to the mass fraction of the amorphous phase in PET polymer.
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  • 168
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    Polymer Engineering and Science 10 (1970), S. 383-387 
    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 object of measurement was the diffusion of elemental sulphur labelled with the radioisotope S35 in typical representatives for various types of rubber. The highest values of diffusion coefficient have been found in cis 1,4 polybutadiene. The lowest measured value was found for butyl rubber. The activation energy, expressing the temperature dependence of the diffusion coefficients, ranges from 4 to 10 kcal mol-1. For some rubbers studied, the activation energy is to a certain degree dependent upon temperature. The values of the diffusion coefficients and the characteristic constants for their temperature dependence are related to the mobility of the macromolecular segments.
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  • 169
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    Polymer Engineering and Science 11 (1971), S. 247-257 
    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 plasticating extruders is described. Compared to previous models, this model introduces more accurate and less restrictive assumptions, adds a mass balance on the entire channel, and replaces certain approximate solutions by exact solutions. Flow of the solid bed is represented by a solid bed acceleration parameter, SBAP, which permits solid bed acceleration in a screw compression section. New experimental melting data for a variety of screw designs, polymers, and extruder sizes are presented and compared to the theoretical predictions. With the optimum SBAP, reasonably accurate model prediction of the melting profiles is observed for a wide variety of cases.
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  • 170
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    Polymer Engineering and Science 4 (1964), S. 34-38 
    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: Dielectric measurements made at 60 cycles per second over a temperature range of -40 to 200°C on small (0.2 g) samples arc most useful in studying acrylic polymers. Not only has this method elucidated structure, but the study of some structures has led to new interpretations emphasizing the value of this type of measurement. Data on a number of acrylic polymers are shown. Several copolymer systems are discussed. It is suggested that 60 c/s measurement of stereospecific PMMA samples can show more about molecular arrangements than has previously been revealed.
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  • 171
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    Polymer Engineering and Science 4 (1964), S. 39-44 
    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 investigation of the effect of sample dimensions on the oxidation of polypropylene is described. The results are used to select testing conditions. Two examples of the utility of the method are presented. First, a control method for uninhibited polypropylene and, secondly, an investigation of the synergistic effect between 2,6-di-t-butyl-p-cresol and dilaurylthiodipropionate.
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  • 172
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    Polymer Engineering and Science 4 (1964), S. 45-55 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Chemical structures limited to phosphines and their derivatives, including phosphine oxides, phosphonium salts and halogen-phosphorus compounds useful for fireproofing are discussed. In addition to these P-C bond containing compounds, structures containing P-O-C bonds are mentioned only if they are directly formed from halophosphorus substances. The general approaches to fireproofing are described. They include physical changes, unreactive additives, reactive comonomers, substitution of other functional groups and addition to a preformed polymer. Much of the literature is reviewed and the commercial importance of certain methods for both cloth and plastics are indicated.
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  • 173
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    Polymer Engineering and Science 4 (1964), S. 72-72 
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    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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  • 174
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    Polymer Engineering and Science 4 (1964), S. 66-71 
    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: Much past confusion has originated from attempts to describe the complete optical properties of a plastic in terms of a few ill-defined parameters. Simple light-scattering theory and studies of morphology have been combined in this article to suggest the causes of polymer opacity; methods cited for the improvement of transparency and properties of reflectance have been re-examined in this light. It is concluded that the optical properties displayed by a polymer which is allowed to crystallize without external stress depend on fundamental molecular and morphological parameters. The extent to which these inherent characteristics can be modified depends on such widely different factors as the Tg of the polymer and the physical form of the desired article.
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  • 175
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    Notes: Four new fluoropolymers were pyrolyzed in a vacuum to study rates of volatilization and to identify decomposition products. The polymers thus studied were polyperfluoropropylene, polyperfluoroheptene, poly-4-chloroperfluoroheptadiene-1,6 and poly (1,2,2-triflluorovinyl phenyl ether). Polyperfluoropropylene yielded 100% monomer at temperatures of 300 to 400°C gave an activation energy of 56.6 Kcal/mole. Polyperfluoroheptenes of different molecular weights also yielded 100% monomer on heating. However, they had lower thermal stability than polyperfluoropropylene, but a higher activation energy and a higher pre-exponential factor. Poly-4-chloroperfluoroheptadiene volatilized at a rate of approximately 1% per minute at 380°C. There was very little monomer produced on thermal decomposition and an activation energy of 60 Kcal/mole was obtained from rates of volatilization at 362, 374, and 381°C. Poly (trifluorovinyl phenyl ether) showed a 25% carbonized residue at 500°C pyrolysis. The polymer decomposes into fragments containing very little monomer. Undesirable low molecular weight components in the polymer are still to be eliminated.
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  • 176
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    Polymer Engineering and Science 11 (1971), S. 295-304 
    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 torsional pendulum which operates throughout the temperature range  -  180° ⇄ +650°C, and permits the examination of specimens which conform to ASTM standard D2236 is reported. The same apparatus is used for torsional braid analyses for which a composite specimen is prepared by impregnating a multifilament glass braid with a solution of polymer and thermally removing the solvent. A linear-with-angle no-drag optical transducer which employs the linear transmission region of a pair of polarizers is described. The apparatus has been used for examining thermo-hysteresis effects in polymers. Hysteresis can arise in polymers from physical time-dependent phenomena such as crystallization ⇄ fusion, dry atmosphere ⇄ water vapor, annealing ⇄ cracking, and from chemical reactions. Thermally-induced chemical reactions can be regulated so as to freeze out preferentially longer range relaxations, thereby extending the glassy state behavior to higher temperatures. A comparison of the thermomechanical behavior of a commercially available polyimide film and of a polyimideforming varnish is reported using torsional pendulum and torsional braid analyses.
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  • 177
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    Polymer Engineering and Science 11 (1971), S. 211-219 
    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: Glass-reinforced thermoplastics are being considered in many structural applications and fabricators require design information on these materials. Basic creep data are, in many cases, the most useful for design purposes. The work reported here concerns the development of methods of increasing our efficiency in generating creep data. The methods developed are applicable to polypropylene and coupled, glass-reinforced polypropylene. A stress-time superposition procedure has been found valid for extending creep data generated on coupled glass-reinforced polypropylene at several glass levels and at temperatures of 23 and 80°C.
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    Polymer Engineering and Science 4 (1964), S. 77-78 
    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
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    Polymer Engineering and Science 11 (1971), S. 353-360 
    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: Experimental studies were performed with low density polyethylene, acrylonitrile-butadiene-styrene polymers and on polyvinyl chloride to elucidate the nature of the plasticating process in a reciprocating-screw injection molding machine. Melting data, obtained by use of the “cooling experiment,” and plastic temperature data reveal that the screw recharge process is a transient plasticating extrusion process which gradually approaches the equilibrium extrusion behavior as the screw rotates. If the screw rotation time is a high percentage of the total cycle time, the plasticating behavior is very similar to steady-state extrusion behavior, but if the screw rotation time is a small percentage of the total cycle time, the plasticating behavior is significantly different. Furthermore, better plasticating is obtained by use of a low RPM and high percentage rotation time than by a high RPM and low percentage rotation time.
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    Polymer Engineering and Science 11 (1971), S. 381-384 
    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 peculiar behavior of thermoplastic elastomers in molding suggested that the processing steps (mainly shearing) to which the material had been submitted had a great influence on the morphology. Experiments were carried out on two polysstyrene-polybutadiene-polystyrene elastomers. The effects of melt-shearing and cooling were examined both by mechanical testing and low angle X-ray scattering. Melt-shearing creates a marked morphological anisotropy but a form of annealing can occur at sufficiently high temperatures.
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    Polymer Engineering and Science 12 (1972), S. 34-40 
    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 describes the use of an electron microprobe for characterizing filler and polymer dispersios in polymer composites. Examples described are: filler distribution in sisal reinforced polyester; aggregation of titanium dioxide in glassreinforced polyester; mixing behavior in a blend of silicone rubber, natural rubber, and titanium dioxide; and distribution of silica in a low-gloss paint on an ABS plastic surface. The limitations of electron microprobe analyses for qualitative and quantitative studies, the use of back scattered electrons for surface topography, and techniques for preparing specimens are mentioned.
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    Polymer Engineering and Science 11 (1971) 
    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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  • 183
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    Polymer Engineering and Science 11 (1971), S. 361-368 
    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 the transient melting behavior in a reciprocating-screw injection molding machine is proposed. The model is based on a steady state extrusion model, Neumann's melting problem, and a heuristic postulate for the transient behavior. The model predictions are compared to experimental melting data for low density polyethylene, acrylonitrile-butadiene-styrene polymers and polyvinyl chloride for a variety of operating conditions and two screw designs. A useful degree of correlation is demonstrated for all experimental cases.
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  • 184
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    Polymer Engineering and Science 11 (1971), S. 385-394 
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    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 experimental study is carried out to elucidate the melt fracture mechanism. For the study, the electrical outputs of the melt pressure transducers, mounted on the wall of a circular tube, are recorded on a Sanborn recording system. It has been observed from this study that the wall pressures start to fluctuate prior to the inception of visible melt fracture. The frequency and amplitude of the excursion signals are increased as the shear rate is increased up to and beyond the critical value. This behavior has been observed for three polymer samples tested: polystyrene, high density polyethylene, and low density polyethylene. The fluctuations of wall pressures are interpreted as due to an irregular flow of polymer melts at the tube wall. It is further investigated to find the effects of the die entry angle of a capillary, and capillary length-to-diameter ratio on the critical shear rate. A correlation between exit pressure and shear stress has been found for polystyrene and low density polyethylene. It is found that at and above the critical stress, the exist pressure increases abruptly. This is interpreted to be a sudden change in the elastic properties of the materials above melt fracture since Han et al have shown that the exist pressure is a measure of the elastic properties.
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  • 185
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    Notes: The current art for image-wise photopolymerization is reviewed and the prospective future developments are briefly assessed. Photomechanics, photoengraving, gravure, lithography, chromophores, dye sensitization, cyanine photopolymerization, bathochromy, and phototanning are covered. Primary photoprocesses, their sensitization by cyanines, Oster photopolymerization, photovinyls, diazo and diazido-sensitized systems, and secondary photoprocesses are discussed. A bibliography is provided.
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  • 186
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    Notes: The processing of polymers and other solids, such as waxes and acids, often requires the melting of a bulk or granular charge before its introduction into a process stream. Two approximate techniques for relating heat transfer and melting rates are presented here and the shielding effect of the melt formation is considered. The heat available for melting is sometimes remarkably decreased by the heat carried away by the flowing melt. Means are presented for quantitatively determining the shielding or sensible heat effect of the film. The thermal efficiency of the phase transformation process is discussed, and the effects of heat loss to both increased bulk temperature of the flowing melt and conduction in the solid are demonstrated. A comparison with experiment is made using temperature and melt flow data for polyethylene and polyoxymethylene. Heat transfer coefficients and melting correlations useful in practice are presented.
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    Polymer Engineering and Science 4 (1964), S. 133-136 
    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: Unstable flow involving extrudate distortion have been observed in the extrusion of PVC. Two types of distortion have been isolated and the factors which are operative have been examined. These Factors are discussed in the light of existing knowledge of “melt fracture”.
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  • 188
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    Polymer Engineering and Science 4 (1964), S. 136-138 
    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 post extrusion swelling behavior of PVC has been studied as a function of the rheological flow variables and as a function of the molecular weight of the polymer. An expression which correlates the swelling with the apparent non-Newtonian viscosity has been found for each of the five molecular weight samples studied. No mechanism for this elastic effect was proposed.
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  • 189
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    Polymer Engineering and Science 4 (1964), S. 146-148 
    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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  • 190
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 12 (1972), S. 101-108 
    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 (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepared using both random (containing 36% cis, 55% trans, and 9% 1,2 vinyl) PB and high-cis PB. For both series, a wide range of PB/PS compositions were synthesized. Using samples stained with osmium tetroxide, electron microscope studies revealed an irregular cellular structure of a few hundred Ångstrom diameter with the first component, PB, making up the cell walls. The size of the cells was found to depend on the PB crosslink density for the random materials. Modulus-temperature data revealed two distinct glass transitions, confirming the microscopy finding of two phases. However, the transition temperature and transition slope varied with composition, and with the microstructure of the polybutadiene, giving evidence of significant molecular mixing. Stress-strain data on the IPN's showed that materials rich in PB behave like self-reinforced elastomers. Charpy impact resistance experiments on materials rich in PS indicated values of 5 ft-lb/in. of notch, which compares well with graft-type polyblends of similar PB/PS composition. The results were interpreted in the light of the recent theoretical work of Bragaw, who considered the importance of the distances between domain boundaries with respect to crack acceleration mechanics. Although the IPN's considered herein exhibited somewhat less than the predicted optimum phase dimensions, the arrangement of the domains is different from ordinary impact resistant plastics.
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  • 191
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    Polymer Engineering and Science 4 (1964), S. 151-156 
    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: Investigation of the crystallography of the thin platelike polymer crystals precipitated from dilute solution has led to the concept of chain folding in polymer crystallization. This unexpected and unusual phenomenon has produced much speculation about both its origin and its implications concerning the morphology of the polymer crystals. The theories which have been proposed to account for the observed effects fall into two categories: (a) equilibrium theories; and (b) kinetic theories. At the moment the kinetic theories appear to be the more successful in explaining the observed morphology and behavior of the polymer crystals. Essentially it is proposed that the plate-like habit of the crystals results from the formation of crystal uncleii from single polymer molecules followed by a growth process whose rate is controlled by nucleation of new crystal layers on existing completed crystal faces. Quantitative observations of crystal growth rates and of the influence of supercooling on the thickness of the crystals are consistent with the predictions of these theories.
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  • 192
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    Polymer Engineering and Science 4 (1964), S. 165-168 
    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: Studies of polymer morphology under ideal conditions approaching equilibrium structures have been shown to be valuable in the development of an understanding of the relationship of properties to structure. Practical fabrication operations do not permit the achievement of equilibrium structures in commercial products and its is therefore necessary to study the effects of processing on the actual structures that result. In addition, an understanding of the effects of processing variables on properties permits the development of fabrication operations which can be directed toward the improvement of properties. Topics covered include the effects of hydrostatic pressure during processing, effects of combinations of pressure and thermal history, relationships between thermal history and crystallization rates in isotactic polymers and the kinetic and morphological effects of flow deformation on crystallizable plastics.
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  • 193
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    Polymer Engineering and Science 4 (1964), S. 157-164 
    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 relationship between crystallization and deformation is two-fold: (1) deformation or flow in polymers prior to crystallization has an important influence on the resultant crystalline morphology and (2) the morphology in turn largely determines the response of the structure to further deformation after crystallization. Thus, an understanding of deformation processes in crystalline polymers is intimately related to the crystallization processes and vice versa. The crystallization process may be approached by considering the observed morphological structures as being analogous to the usual crystal habits with the addition of various crystal-defects which add bending and twisting to the more common crystallographic variations. The crystal habit or morphology may be characterized by its surface to volume ratio. Crystallization of polymers may be considered as three steps (1) the formation of primary nuclei (2) crystallographic growth (also a nucleation controlled process) and (3) the introduction of crystal-defects which cause bending and twisting.
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  • 194
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    Polymer Engineering and Science 4 (1964), S. 169-177 
    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: Mechanical and dielectric relaxation as related to the morphology of crystalline polymers is reviewed. The behavior with temperature of the imaginary part of the complex dielectric constant and the mechanical loss factor, tan δ, at constant frequency is discussed in detail for two typical crystalline polymers: poly(chlorotrifluoroethylene) and polypropylene. Three relaxations are typically observed: a low temperature relaxation occurring at temperatures below the dilatometric glass transition temperature; a glass temperature relaxation occurring near the glass transition temperature; and a high temperature relaxation occurring between the glass temperature and the melting point. The activation parameters are given for these relaxations, and the influence of morphology on them is discussed along with possible molecular interpretations.
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  • 195
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    Polymer Engineering and Science 4 (1964), S. 178-186 
    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: Structural changes are considered in light of the two differing views of the structure of crystalline polymers involving either a two phase structure or a single phase structure involving detects. A compromise picture is proposed which appears consistent with existing experimental evidence. Optical methods are described for analyzing structural changes accompanying deformation of these polymers. These include x-ray diffraction, static and dynamic birefringence measurements and dynamic light scattering studies. The results are consistent with a two stage deformation process involving first the elastic deformation of a spherulitic or crystalline structure followed by an internal rearrangement of crystals within this structure, taking place by a number of mechanisms such as recrystallization, defect migration, plastic flow and crystal rotation. The time dependence of some of these processes is studied and related to structural features.
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  • 196
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    Polymer Engineering and Science 12 (1972), S. 193-198 
    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 rapid increase in the rate of application of thermoplastics in engineering design problems and the interest in the structural use of these materials have resulted in the requirement of comprehensive information about the behaviour of thermoplastics when subjected to cyclic loading conditions. In addition to the “total fatigue life” data already available for many materials, attempts have been made to analyse the crack initiation and steady crack growth processes and determine the effects of parameters such as mean load, frequency and crack geometry on the rate of crack propagation. The results of an investigation of these aspects of fatigue crack growth in a brittle thermoplastic, polymethylmethacrylate (PMMA), have already been reported. In this paper, the results of a test program devised to study the behaviour, at room temperature and in air, of a polycarbonate, (PC), under similar loading conditions, are presented. Fracture Mechanics concepts have been used to analyse the results. It was found that a relationship of the form ȧN = β λn already shown to predict the cyclic fatigue crack propagation rate in PMMA, is also applicable to polycarbonate. However, when the effects of frequency and loading rate were studied, it was found that after the magnitude of parameter K̇( = ΔK/half the periodic time) exceeded 4000 lbf in. -3/2 s-1, the influence of the mean level of stress intensity factor, Km, became negligible in comparison to the effect of ΔK.
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  • 197
    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 rubber particle size on the tensile properties of rolled and unrolled acrylonitrile-butadiene-styrene has been studied by considering model systems consisting of mixtures of a small particle (0.1 micron diam) rubber, S, and a large particle (0.56 micron diam) rubber, L, in an SAN matrix. Before rolling, tensile toughness is characterized by crazing. While both rubber induce matrix crazing, ABS systems containing only the S rubber exhibits early failure due to crack formation, before crazing is propagated very far along the tensile axis. The inefficiency of the small particle rubber is interpreted in terms of high composite yield stress and insufficient distance between particles to allow craze branching. The efficiency of the small particle rubber is improved via the addition of a small amount of large particle, L, rubber to the composite or by a slight degree of cold rolling, both of which enhance craze propagation in the tensile direction. With further rolling, the tensile deformation mode changes from one of localized crazing, which is propagated, to one of uniform deformation, which occurs without crazing.
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  • 198
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    Polymer Engineering and Science 13 (1973), S. 1-9 
    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 various structures encountered in block and graft polymers are reviewed and a nomenclature useful for the description of these macromolecules is proposed. The concept of living polymers is elucidated and its ramifications discussed. It is shown how greatly the control of polymerization and the uniformity of the products is improved when living polymers are used as the reagents. Their application in the synthesis of block and graft polymers is illustrated by numerous examples. Other synthetic techniques yielding block and graft polymers are briefly sketched, their advantages and shortcomings being considered. Properties of block and graft polymers are described, special attention being devoted to the problems of mesomorphic phases and to the morphology of block polymers. The incompatibility phenomena observed in block and graft polymer systems are compared with those encountered in studies of the polymeric blends.Finally, the present and future applications of block and graft polymers are considered and their potential evaluated.
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  • 199
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    Polymer Engineering and Science 4 (1964), S. 236-240 
    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 work carried out at Picatinny Arsenal on the weathering of plastics over the lat 15 years is briefly described. Although the perid of work was 15 years, individual systems were exposed for only three years. The need for running parallel tests on materials stored indoors for the three years is pointed out as a means of separating the effects of daging from weathering. Also brielfy discussed is the influence which the test method chosen can have on the judgment reached. The requirements of the application are as important as the inherent durability of the material. Improved compounds are becoming available and complete reporting of both favorable and unfavorable resuts is urged as a means of lending guidance in the search for still better compounds.
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  • 200
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 13 (1973), S. 65-73 
    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 study presents a mechanical analysis of the deep drawing of thermoplastics in the glassy state. A theoretical stress analysis is conducted by applying principles of classical plasticity together with several assumptions. A simple model is presented relating drawing performance with the mechanical properties of the plastic measured under the conditions of the fabrication operation. An experimental procedure is described for evaluating the drawability of a plastic. Data on thirteen thermoplastics are used to demonstrate the applicability of the theory developed.
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