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  • Articles  (1,125)
  • Chemical Engineering  (1,125)
  • Inorganic Chemistry
  • Animals
  • 1975-1979  (887)
  • 1960-1964  (238)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (1,125)
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  • Articles  (1,125)
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  • 1
    Electronic Resource
    Electronic Resource
    Composites with planar reinforcements (flakes, ribbons) - A reviewAn extended version of “Composites with Two-Dimensional, Planar Reinforcements” in “Adv. Comp. Materials,” edited by G. Piatti, Applied Science Publishers (1978). (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 1-11 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Unlike fibers, planar reinforcements, such as flakes and ribbons, provide reinforcement in two directions. If such reinforcements are arranged parallel to their principal plane in a composite material, they thus provide a distinctly higher performance than fiber reinforcements for two-dimensional loading conditions. This higher performance amounts to about a factor three for the Young's modulus and a factor two for the tensile strength. However, in spite of this obvious advantage, composites with planar reinforcements are as yet relatively unknown. This is mainly due to the fact that planar reinforcements are not as readily available as fiber reinforcements and therefore not much work has been done on them. The present article gives first a short outline of the theory of the elastic and tensile properties of composites with planar reinforcements. Then, a non-exhaustive review is presented of the work on composites with planar reinforcements, with particular attention given to recent developments. A final aim of this article is that by showing the merits of planar reinforcements as compared to presently existing fiber reinforcements, it may contribute to their use in the design of composite structures.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190102
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  • 2
    Electronic Resource
    Electronic Resource
    Aspects of the yield behavior in poly(ethylene terephthalate) fibers (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 18-23 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The yield behavior during cold drawing of commercially spun poly(ethylene terephthalate) (PET) filament yarn was investigated. Microscopic examination revealed the presence of inherent flaws within the spun filaments; these act as points for localized stress concentration. These inhomogeneities appear to be either internal cracks or crazes developed during the fiber melt spinning process. During elongation, stress magnification at these flaws results in shear band formation, indicating the onset of inhomogeneous yielding. At the yield bend in the load-elongation curve a circumferential crack propagates within these shear band regions. This yield crack develops into the classical neck geometry which further localizes additional plastic deformation within the sample at the neck.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190104
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  • 3
    Electronic Resource
    Electronic Resource
    Application of small system thermodynamics to polymer molecules. I. The entropy barrier between liquid and crystalline state (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 40-44 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The methods of small systems thermodynamics have been applied to the calculation of the entropy barrier to the growth of polymer crystals. The height of this barrier at the equilibrium melting point of polyethylene molecules of typical lengths (X = 4,000 to 10,000 segments) is estimated to be of the order of 4 to 5 Kcal per molecule. This barrier increases linearly with ln X if the crystal is very large but retains the approximate values mentioned for crystals with the lamella thicknesses usually found. This entropy change causes the free energy to go through a maximum as in a nucleation phenomena but no new surface formation is involved. The existence of such a barrier explains why crystallization (or melting) never occurs at the equilibrium melting temperature.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190107
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  • 4
    Electronic Resource
    Electronic Resource
    Application of small system thermodynamics to polymer molecules. II. Secondary nucleation (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 45-50 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Statistical mechanical methods can be used to relate not only structure and thermodynamics but also structure and kinetics. Methods are developed for calculating the crystal growth rate kinetic models. When the usual macroscopic thermodynamics are applied, the resulting surface energies, σ and σe extracted from the experimental growth rates are quite comparable to those obtained from kinetic models. However, when one applies small system thermodynamics, a substantially smaller σ is obtained. This latter assumption has the advantage of explaining why extended chain seed crystals do not promote crystal growth and why folded chain crystals grow on such seeds. The statistical mechanical methods in both of these cases predict the observed decrease in the rate constant, Kg with decreasing molecular length without the necessity of a separate theory for varying σe with molecular length.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190108
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  • 5
    Electronic Resource
    Electronic Resource
    Introductory remarks (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 65-65 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190202
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  • 6
    Electronic Resource
    Electronic Resource
    An anomaly in the necking behavior of polyethylene (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 77-81 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Tensile creep measurements at constant load on nonoriented polyethylene have shown a marked transition at a certain stress level from a neck formation followed by instantaneous fracture to the formation of a neck which resists fracture for a considerable time. The transition, which shifts towards shorter time and higher nominal stress with increasing molecular weight, has been studied for 16 polyethylenes of different molecular weights, degrees of branching and crystalline structures. The marked. transition has only been observed for high density polyethylene of high molecular weight. Deformation measurements show a more distinct necking for the high density than for the medium density polyethylenes. This is consistent with current molecular deformation theories. A hypothesis for the transition is proposed based on the distinctness of the neck process in the high density polyethylene and the large difference in strength between the spherulitic structure and the fibrillar structure. The dependence of the transition on molecular weight is expected since the number of tic chains incrcrtses with increasing molecular weight.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190204
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of crosslinking on the tensile strength and fractography of poly(methyl methacrylate) (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 95-98 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Glassy crosslinked networks were prepared by copolymerization of methyl methacrylate with up to 4.7 mole-percent ethylene dimethacrylate. These networks were degraded by exposure to γ-rays and the solubilized fraction estimated by benzene extraction using the analysis of A. R. Schultz. The efficiency of the Crosslinking agent was found to be 0.5 and this value was used to calculate the molecular weight between crosslinks. The molecular weight of the primary molecules in the network, M, was estimatfrom the radiation dose using the known fact that one fracture requires an energy deposition of 59 ev. Crosslinking was found to have little influence on the tensile strength of networks of primary molecular weight 〉 105. In contrast. crosslinking raised, the strength of polymers of M 〈 105 to, a value approaching that of a high molecular weight linear polymer (ca. 70MN/m2). Crosslinking was found to have only a small influence on the gross morphology of fracture surfaces.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190207
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  • 8
    Electronic Resource
    Electronic Resource
    Polymer applications in three dimensional linear fracture mechanics analysis (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 108-111 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A discussion is given of three types of experimental techniques which make use of polymers for the verification of theoretical solutions to three-dimensional linear fracture mechanics problems. The three techniques discussed are designated as the fatigue method, the photoelastic stress-freezing method and the static fracture method. These techniques employ poly(methyl methacrylate) sheets which are cut into appropriate fracture mechanics specimen geometries or castable epoxies which may be cast into flat plates or other appropriate shapes for investigation. The suitability of these materials for linear fracture mechanics testing is discussed and the quality of results obtained is described.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190210
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  • 9
    Electronic Resource
    Electronic Resource
    Elastic modulus and strength of fibrous material (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 118-124 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: As a rule, the large increase of elastic modulus with increasing draw ratio obtainable in highly-drawn or extruded semicrystalline polymers is not reflected in a similarly large increase of strength. This is closely connected with the wellknown fact that with increasing plastic deformation one obtains fibrous material with decreasing strain to break. The axial elastic modulus is mainly caused by the taut tie molecules which bridge the amorphous layers between consecutive crystal blocks and thus provide an efficient axial force transmission through the sample. The defects at the ends of microfibrils interrupt this transmission because they contain few if any taut tie molecules connecting the end of microfibril with adjacent fibrillar elements. As a consequence of the small number of such ends, they only marginally reduce the elastic modulus. But as the mechanically weakest areas of the fibrous material, they drastically depress the strength. They fail as soon as the strain concentration upon them reaches their strain to break. The growth and coalescence of resulting microcracks finally lead to bulk fracture as the growing crack reaches critical dimensions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190213
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  • 10
    Electronic Resource
    Electronic Resource
    Failure sensitivity of high density polyethylene in compressionWork performed in conjunction with Stanford University, Department of Materias Science, Stanford, CA. (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 136-139 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: As part of an investigation of the compressive mechanical behavior of high density polyethylene between room temperature and the crystalline melting temperature, the strain-to-failure as a function of temperature and strain rate was studied. The two resins studied in applied-strain-rate tests were found prone to fail, as judged by decreased strain-to-failure, at temperatures from 70 to 88°C. The strain-to-failure decreased as the temperature was increased or as the strain rate was decreased. This behavior is opposite to that observed in tension at lower temperatures. At temperatures just below melting, the strain-to-failure apparently began to increase again. By analogy to the results of tearing experiments on polyethylene and other thermoplastics, the findings are explained in terms of the influence of the α relaxation in polyethylene. Differences in the behavior of the two polyethylene resins were also examined.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190216
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  • 11
    Electronic Resource
    Electronic Resource
    Barrier and surface properties of polyurethane-epoxy interpenetrating polymer networks. II (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 294-296 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We have measured the advancing contact angles of drops of methanol-ethylene glycol mixtures on films of previously studied polyurethane-epoxy interpenetrating polymer networks. The extrapolated critical surface tensions were in excellent agreement with those obtained from advancing contact angles of drops of water-methanol mixtures. A sharp minimum is observed in the critical surface tension at network compositions where we have previously found maxima in ultimate mechanical properties. We advance a physical explanation based on unrelieved surface strains. We have also measured the toluene vapor transmission (permeability, diffusion and sorption coefficients) in these films. These results, together with the previously obtained water vapor permeabilities, are in complete accord with the expected morphologies of these networks.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190411
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  • 12
    Electronic Resource
    Electronic Resource
    Thermochemical characterization of some thermally stable thermoplastic and thermoset polymers (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 24-29 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (a) thermomechanical properties such as glass transition and melt temperature; (b) dynamic thermogravimetric analysis in anaerobic environment; (c) flammability properties such as oxygen index, flame spread and smoke evolution; and (d) selected physical properties. The thermoplastic polymers evaluated included polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated included epoxy, bismaleimide, a modified phenolic and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190105
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  • 13
    Electronic Resource
    Electronic Resource
    Masthead (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190201
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  • 14
    Electronic Resource
    Electronic Resource
    Dynamic mechanical and broad line nuclear magnetic resonance behavior of some aromatic polyamidesPaper presented at the Joint Meeting of the British, Netherland and Italian Societies of Rheology, Pisa, April 1977. Work carried out with financial support of Italian C.N.R. (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 56-62 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The results of dynamic mechanical and broad-line proton magnetic resonance studies carried out over a broad, temperature range on a series of aromatic polyamides are presented. At temperatures lower than 300 K, the NMR data show no relaxation for the all-meta linked benzene rings polyamide, whereas processes for the other polyamides are found, the magnitude of which is dependent on the polymer structure. Between 400 and 500 K further decreases in the second moment take place for all materials. Two secondary mechanical loss peaks are evident in these polymers, one in the 200-380 K region (β) and one in the 380-500 K region (β*), at about 104 cps. In particular, the relaxation strength of the β* peak depends on the conditions of isolation of the polymers from solution. The results are discussed in terms of possible motional processes of these polymers characterized by a long range intramolecular uniaxial order. An attempt is made to correlate the relaxational properties of aromatic polyamides to the existence of a phase of low regularity such as the nematic or smectic mesophases.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190110
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  • 15
    Electronic Resource
    Electronic Resource
    Radical formation and deformation in poly-p-(2-hydroxyethoxy) benzoic acid fibers (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 89-94 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Radical generation during tensile deformation of poly-p-(2-hydroxyethoxy) benzoic acid (PEOB) fibers was studied by electron spin resonance techniques under various stretching conditions. Primary phenoxy radicals were detected at room temperature, indicating main-chain rupture during mechanical loading. The kinetics of phenoxy radical formation were observed at constant strain, constant load, constant strain-rate, and in constant load rate experiments. The effect of strain rate on the radical formation was found to be larger in this sample than was observed in Nylon 6. These results coupled with other experimental observations have yielded information on a basic structural model and improved insight into the basic molecular mechanism responsible for deformation and fracture.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190206
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  • 16
    Electronic Resource
    Electronic Resource
    Creep failure and fracture of polyethylene in uniaxial extension (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 99-103 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is shown that under conditions of uniaxial creep the fracture of high density polyethylene can be categorized as one of three types, depending upon the magnitude of the applied load, molecular architecture, and environment. When subjected to relatively large loads, the specimens neck and then fracture almost immediately. At the other extreme of very small initial loadings, the specimens fracture in a brittle fashion through crack formation and growth. In the intermediate range of loadings the specimens neck and, depending upon the molecular weight and molecular weight distribution, may then elongate substantially before fracture. It is shown that the uniaxial creep behavior for the region where drawing occurs, when plotted in terms of isochrones, represents a type of phase diagram, one boundary of which describes the fracture enelope. In addition, experiments employing different constant rate of loading histories are described and an additivity of damage criterion used to predict the time to failure under constant load conditions, and visa versa.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190208
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  • 17
    Electronic Resource
    Electronic Resource
    Role of bond thickness on adhesive failure (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 114-117 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An analytical, numerical and experimental program is described which establishes the basic fracture mechanics properties of an adhesive joint. A finite element analysis of a homogeneous finite tapered double cantilever beam is first presented and the results compared with elasticity and strength of materials solutions. Using analytical results developed in another paper, a finite bond line thickness correction factor is introduced to determine the crack tip stress intensity factor as a function of crack length. An experimental program is described wherein the crack tip stress intensity factor for the cantilever beam adhesive joint is measured by the compliance method and the results compared with those obtained by analytical and numerical methods. Finally, the critical value of the adhesive crack tip stress intensity factor is determined using the analytical and experimental techniques presented.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190212
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  • 18
    Electronic Resource
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    Evaluation of resin-glass fiber interface under environmental stress (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 350-352 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A test method has been developed to evaluate resin-glass composite materials for their resistance to environmental, thermal and hydrolytic stresses, humidity, radiation, and immersion in aggressive fluids. The advantages this method offers are ease of specimen preparation, small specimen size, and maximum exposure of resin, glass and interface to the test environment.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760190505
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  • 19
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    A study of chain-addition polymerizations with temperature variations. IV. Copolymerizations - Experiments with styrene-acrylonitrile (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 190-197 
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    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: Free-radical copolymerizations were studied under nonisothermal conditions with emphasis on their thermal runaway and ignition behavior. Computational models are presented in generalized form and compared with experiments on the system styrene-acrylonitrile. A new, useful method is proposed for the evaluation of runaway parameters from scant kinetic data.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760190305
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  • 20
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    Finite element analysis of polymer melt flow in cable-covering crossheads (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 203-209 
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    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 finite element method is presented for the analysis of isothermal non-Newtonian polymer melt flow in narrow channels of complex shape. The particular application considered is flow in cable-covering crossheads. The geometric flexibility of the finite element method allows a mesh of triangular elements to be constructed to suit the shape of the flow channel. Computed results obtainable from the analysis include the distribution of polymer layer thickness on the finished cable, together with the extrusion pressure required to maintain a given flow rate of melt. Some typical thickness distribution results are presented as an introduction to experimental verification of the method and its application to crosshead design.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760190307
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  • 21
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    Processability of raw elastomers and its relation to deformational and failure behaviorPresented at the US-Japan Joint Semina on Elastorners at the Institute of Polymer Science, The University of Akron, Akron, Ohio (October 17-21, 1977). (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 215-222 
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    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 method was proposed for a scientific description of processability of raw elastomers involving a master curve representing deformation behavior and a failure envelope representing the ultimate properties. When a specific machine is given, the mechanical and environmental conditions may be defined from the geometry and operating condition of the machine. Matching these conditions, specific information on processability may be extracted from the master curve and failure envelope. In constructing the master curve, we have proposed to use the strain-time correspondence principle including the behavior at both small and large deformation. The necessary measurements may be considerably simplified; for example, the Rheovibron and the Mooney rheometer provide necessary data over the entire range of the rubbery behavior. The latter instrument may be operated at a slow speed, i.e., 0.05 RPM and the torque-rise curve is used. With the rotational viscometer, the stress often reaches a maximum before reaching steady state, particularly with rubbers. We have shown that the curve leading to the peak is the shear stress-strain curve. The maximum was found to correspond to the failure point in the tensile deformation. The stress-time correspondence principle is not applicable to some rubbers. In these cases, the same calculation may still be conducted to evaluate the deviation from the master curve. Then, the extent of deviation may be used to represent the degree of long chain branching.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760190309
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    Stress-strain isotherms for polymer networks at very high elongations (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 254-259 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Some polymer networks show an anomalous increase in the modulus or reduced stress at very high elongations. This behavior has now been investigated definitively by determining stress-strain isotherms for both crystallizable and noncrystallizable networks, prepared using several curing techniques (carried out so as to yield a wide range in degree of cross-linking). The networks were studied unfilled at a number of temperatures, and at several degrees of swelling. The results clearly implicate strain-induced crystallization as the origin of the upturn in the modulus, and thus demonstrate that the wide spread interpretation of this upturn in terms of limited chain extensibility is incorrect.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760190405
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    Entanglement and excluded volume effects in rubber elasticity (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 263-266 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The role of interchain excluded volume and entanglement in the elastic behavior of polymeric networks is theoretically examined. A three-chain network model is used, with each chain confined within an infinite, rectangular cylinder. The cylinders and the network crosslinks, are assumed to deform affinely. When the cross sections of the cylinders are small, the network elastic free energy equation has the form \documentclass{article}\pagestyle{empty}\begin{document}$$ \Delta F_e = A[\lambda _x^2 + \lambda _y^2 + \lambda _z^2 - 3] + B[\lambda _x^{ - 2} + \lambda _y^{ - 2} + \lambda _z^{ - 2} - 3] + C{\rm }\ln [\lambda _x \lambda _y \lambda _z] $$\end{document} The λs represent the macroscopic deformation ratios. The constants A, B and C are functions of the number of each type of network chain (i.e., A contains the number of tie chains; C contains the number of loops and tie chains; B contains the number of dangling chain ends, unattached chains, loops and tie chains), their unperturbed dimensions and the sizes of the cylinders which confine them.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760190407
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    The isothermal crystallization of crosslinked polyethylene under uniaxial extension (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 406-408 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An experimental study of the crystallization of chemically crosslinked polyethylene at constant strain under isothermal conditions was carried out. Changes in the stress and birefringence were measured simultaneously as a function of time. Both the stress and the birefringence behavior are consistent with previous work carried out under constant rate of cooling conditions. This indicates that the cooling conditions do not affect the structural features of the crystallization process. A comparison of the stress and birefringence curves shows that there are periods off time during which both stress and birefringence increase; stress increases and birefringence decreases; stress decreases and birefringence increases; and both stress and birefringence decrease. None of the crystal morphological models proposed to date for the strain-induced crystallization of crosslinked polyethylene appear to be able to account fully for this behavior.
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    URL: http://dx.doi.org/10.1002/pen.760190607
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    Fiber growth in tubular flow (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 414-421 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Data are presented for the seeded growth of polyethylene fibers from solutions undergoing laminar flow in tubular geometry. Radial growth rates are reported for solutions of high and low molecular weight fractions for the second stage fiber thickening process which occurs in the tube entrance region. Results are also shown for high molecular weight growth from fiberglass seeds which indicate an enhanced growth rate at elevated temperatures. A two-stage growth pattern documented earlier for the high molecular weight fraction is shown to occur for the lower molecular weight material. The Discussion includes an analysis for the tapered fiber geometry in the second stage of growth and calculations for stress-induced, diffusion-limited growth in the first stage downstream from the tube entrance.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760190609
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    High modulus through lamellar structures nucleated by flow induced fibrous substrates (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 433-435 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Extremely high modulus (up to 1011Nm-2) strands of poly ethylene have been prepared by the controlled crystallization of lamellar overgrowths onto a small quantity of preformed flow-induced microfibrils. The requirements for achieving a high modulus from a lamellar system are considered, and indicate that high chain extensions may not be needed. The lamellae satisfying these requirements possess a unique taper, the outer edges having a fold length of less than 40Å. This raises new issues relating to crystallization in confined spaces, and space filling by lamellae in bulk samples in general.
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    URL: http://dx.doi.org/10.1002/pen.760190612
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    Factors affecting the formation of hard elastic fibersWork done at Celanessse Ressearch Company, Summit, New Jerssey 07901. (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 427-432 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Factors affecting the formation of hard elastic polypropylene and nylon 6,6 are described. In the case of polypropylene, it is shown that the morphology of the stress spin-oriented fibers depends on the molecular weight, the molecular weight distribution, and the cooling rate. Narrow molecular weight distribution and/or fast cooling rate can lead to a smectic, essentially fibrillar morphology in contrast to the normally observed crystalline, essentially lamellar structure. Hard elastic nylon 6,6 fibers are produced by drawing regularly spun nylon 6,6 yarn to draw ratios in the range of 1.6-3 and annealing the resulting fibers in phenol solutions (cone. 1-5 percent). By this method, a highly increased crystalline order is created, simultaneously transforming the original morphology to a lamellare one or superimposing a lamellar morphology on the poorly organized fibrillar base. Some tensile and elastic characteristics of polypropylene and nylon 6,6 yarns as. functions of spinning and annealing variables are presented.
    Additional Material: 8 Ill.
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    On the conformational behavior and solid-state extrudability of crystalline polymers (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 450-455 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Extrusion experiments on thirteen polymers in our laboratory and extrusion and forging studies on nine polymers in other laboratories reveal that solid-state extrusion and malleability occur in semi-crystalline polymers that have a crystalline relaxation, αc at the temperature Tαc, and do not occur in semicrystalline polymers devoid of αc. The solid-state extrusion takes place in the temperature range of Tαc ≤ T 〈 Tm with Tm being the melting point. In this temperature, range, the polymeric crystals show a measure of disorder, observed by several techniques and by small heats and entropies of fusion. A survey of the literature indicates that, in general, polymers which have a αc and are solid-state extrudable have shallow and broad bottoms to the energy-wells describing their most stable crystalline conformations, and polymers showing no αc have steep-walled energy-wells for the same conformations.
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    URL: http://dx.doi.org/10.1002/pen.760190615
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    Poly(ethylene terephthalate) nucleation as studied by shrinkage of film of low orientation level (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 456-461 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(ethylene terephthalate)s of weight average MW 74,000 and 30,000 have been uniaxially stretched, cooled under restraint, reheated, and shrunk unrestrained. Five stretch temperatures between 80 and 120°C and elongations up to 280 percent have been employed. Density and wide-angle X-ray diffraction results indicate conventional crystallization to have occurred only for the highly oriented samples, e.g., stretching above 200 percent at 90°C. The majority of stretching conditions studied produced only nucleated polymer. A sensitive, qualitative measure of nucleation is the degree of stretch imposed. Sufficiently high stretch temperature and low stretch rate lead to negligible nuclei formation. Nucleation in stretched, unshrunk films correlates with relatively high shrinkage, low orientation, low density and the absence of crystallinity until after the film has been shrunk. Crystallization on the other hand correlates with relatively high density, relatively low shrinkage and high orientation.
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    URL: http://dx.doi.org/10.1002/pen.760190616
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    Masthead (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190701
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    Critical parameters for thermoset curing in heated molds (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 835-840 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The change in temperature and conversion during the curing of a thermosetting resin in a slab-shaped heated mold is analyzed theoretically. Results show that there is a critical value of β = AL2/k, for which the maximum center exotherm takes place (A = Arrhenius pre-exponential factor, L = slab thickness, k = thermal conductivity). Beyond this value, increasing β decreases the center exotherm. The temperature rise at the slab center may be substantially greater than under adiabatic conditions. Wall temperature has a great effect on the process behavior, implying the need of an adequate control system. A description of the temperature profiles and conversion rates is provided and some criteria for the process design are stated.
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    Application of a chemical group contribution technique for calculating solubility parameters of polymers (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 858-863 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A chemical group contribution technique, based on the principle of additivity of molar attraction constants for groups in a molecule, has been used for determining the solubility parameters for several polyesters, polyethers and a few other types of polymers. The solubility parameter for a polymer is calculated by using the contributions for chemical groups reported in the literature with the resultant values found to compare favorably. For geometrical isomers of polymers, the calculated solubility parameters are identical but differ for positional substitution.
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    Masthead (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191301
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    Simultaneous interpetrating network based on castor oil elastomers and polystyrene. III. Morphology and glass transition behavior (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 869-877 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Electron microscopy and dynamic mechanical spectroscopy (DMS) techniques were used to study the morphology and glass transition behavior of simultaneous interpenetrating networks (SIN's), based on three different castor oil derived elastomers, and polystyrene (PS) plastic erosslinked with 1 percent divinyl benzene. The castor oil elastomers consisted of either the sebacic acid polyester, 2,4-tolylene diisocyanate polyurethane, or the mixed poly(ester-urethane). Emphasis was placed on two compositions having 10 and 40 percent elastomer contents by weight of each type, the remainder being PS. In all cases, a two-phase morphology emerged. With the 10 percent elastomer composition, the use of vigorous stirring during the early stages of reaction resulted in materials having the crosslinked polystyrene as the continuous phase and elastomer domains (ranging from 100 to 8000 nm in size) as the discontinuous phase. The elastomer domains contained a polystyrene cellular structure, with the polystyrene cell sizes ranging from 50 to 300 nm size. Several examples showed morphologies resembling high impact polystyrene. Materials having a 40 percent elastomer content always showed a continuous phase of castor oil elastomer, with the PS displaying a bimodal size cellular structure. Domain sizes ranged from 10 to 860 nm. The DMS studies showed two well-defined glass transitions near their respective homopolymer glass transitions, but shifted inwards to greater or lesser extents indicating some molecular mixing between the two polymers. The glass transition of the pure elastomer phase occurred at -66°C for the castor oil polyester elastomer, -4°C for the castor oil polyurethane elastomer and -50°C for the castor oil poly(ester-urethane) elastomer. Phase separation in these materials is postulated to occur by two mechanisms: (1) multiple precipitation of polystyrene chains at progressive levels of polymerization and (2) microsyneresis processes. The thermodynamics of mixing and phase separation in polymerizing SIN's is examined in some detail.
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    Effects of dispersion on flow and mechanical properties of polymer blends (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 900-906 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of linear polyethylene and ethylene-propylenediene elastomer, representing the entire composition range, were prepared under various conditions of shear intensity. It was found that both viscoelastic flow parameters and mechanical properties at large deformation respond strongly to variations in shear history of material preparation. Mechanical degradation of the polymers not being detected, it is postulated that property variations are due to morphological effects related to domain sizes of the two components and to the ease of molecular diffusion across domain boundaries. Thus, mechanical properties develop over finite times of mixing, consistent with the attainment of steady states in domain sizes. Maximum sensitivity of mechanical properties to mixing variables is found for 50/50 blends of the polymers, which have maximum interdomain contact areas. It appears feasible to develop desired balances of flow and mechanical properties in such polyblends through the close control of component dispersion processes.
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    Aluminum/carbon fiber hybrid composites (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 917-922 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An effective, economic way of using carbon fiber is to combine it with a resin and another material, either a fiber or a metal, to produce a hybrid structure. Some of the properties of a hybrid beam made by attaching carbon composite to either side of an aluminum channel section are described here. The structure has considerable potential in the orthotics field; the aluminum core assists in the forming of, for instance, orthoses (calipers), modifies the failure characteristics of the carbon fiber composite, and eases the problem of jointing and adjustment of finished articles. Difficulties can arise when combining carbon composites and metals because of differences in thermal expansion behavior. To alleviate these effects a urethane modified epoxide resin matrix, which has very good adhesive properties, was employed. The work covers measurements of strength and modulus, evaluation of the aluminum/aluminum bond strength, and the flexural fatigue performance.
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    URL: http://dx.doi.org/10.1002/pen.760191307
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    Wall thickness distribution in thermoforming (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 946-951 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper presents an isothermal, one-dimensional model predicting wall-thickness profiles of vacuum- or pressure-formed products. After formulating a set of simplifying assumptions theoretical analyses of forming into conical and truncated (deep and shallow) molds are presented and discussed. Fair agreement is found between previously reported experimental results and the proposed theoretical models.
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    Amorphous control of solid state properties (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 953-954 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191402
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    Coupling of optical and mechanical properties in crystalline polymers (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 975-994 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The modules and birefringence of oriented polymers are known to couple through the structural and intrinsic properties of the polymer. Recent developments in both optical and mechanical theories have allowed this coupling to be expanded so that it includes predictions of modulus and refractive indices of uniaxially-oriented polymer films at various angles to the draw direction. The validity of these theories has been tested in this study by predicting the angular dependence of the optical and mechanical properties of seven uniaxiallyoriented films of isotactic polypropylene. The present study also provides intrinsic material properties associated with the crystalline and noncrystalline components of the polymer, and consequently allows the identification of the structural parameters that control the properties of ultra-high oriented isotactic polypropylene.
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    URL: http://dx.doi.org/10.1002/pen.760191405
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    Prediction and measurement of the thermal expansion coefficient of crystalline polymers (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 1000-1009 
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    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: Among the increased structural demands now being made on both unfilled and reinforced plastics is that of dimensional stability under various performance environments. Crystalline polymers are heterogeneous materials consisting of two distinct phases and, as such, can be treated as molecular versions of engineering composites. This paper first outlines the general physical model whereby a crystalline polymer is considered to be a multi-ply laminate of unidirectionally reinforced plies. The calculational format is then detailed for the prediction of the stiffness and thermal expansion coefficient of an isotropic sheet of crystalline polymer and a sample calculation is given for quenched high density polyethylene. A data base is presented for the stiffness and thermal expansion coefficient of low and high density polyethylene having quenched, slowcooled, and annealed thermal histories. Comparison between experimental and predicted results yields good agreement in all cases to better than 25 percent. Implications and limitations of the predictive technique are discussed.
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    The effect of hot drawing on the properties of short fiber reinforced extruded sheets (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 1046-1053 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The hot drawing of extruded composite sheets can be used to control the orientation of both matrix and reinforcing fibers. A study was made of the effect of draw ratio on the properties of an extruded polystyrene sheet containing 0 to 1 percent of short glass fibers. An increase in draw ratio resulted in an increase in fiber orientation. A model of a rigid fiber rotating in an elongational flow field was used to describe the effect of draw ratio on the final orientation distribution. An increase in draw ratio also caused an increase in the amount of fiber breakage. A shear-lag analysis was used to estimate the extent of damage as a function of draw ratio. It was also found that the mechanical properties were dependent upon both the draw ratio and fiber concentration.
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    URL: http://dx.doi.org/10.1002/pen.760191413
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    Masthead (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191501
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    An experimental study of the influence of carbon black on the rheological properties of a polystyrene melt (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 617-624 
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    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 broad range of experiments on carbon black filled polystyrene melts shows the reinforcing effect of the filler. This study represents one of the most extensive investigations of a series of highly filled polymer melts. Stress relaxation and dynamic experiments characterize the small strain behavior while the steady state shear viscosity, normal stresses, and elongational flow experiments describe the large strain deformation rate response. Extrudate swell and unconstrained shrinkage of extrudates are also measured. Highly filled systems exhibit yield values. This is seen in the dynamic experiments and in the shear and elongational viscosities. Viscosity does not level off at finite values with decreasing deformation rate but continues to increase in an approximately inverse manner. This corresponds to yield values of order 5 × 105 dynes/cm2. The storage modulus also does not tend to zero at low frequencies. The small strain dynamic properties and stress relaxation results suggest high memories for small strain experiments. Txtrudate swell values are however small and the systems exhibit minimal delayed recovery. The implications of this are considered. Generally it is argued that at volume loadings between 10 and 20 percent, the system takes on the characteristics of a gel and the response is similar to that of a Schwedoff body.
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    URL: http://dx.doi.org/10.1002/pen.760190905
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    Order-disorder transitions in the extrusion of fiber-filled poly (ethylene terephthalate) and blendsContribution No. 2608 (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 638-650 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Order-disorder transitions occur in fiber orientation and distribution during extrusion of fiber-filled poly (ethylene terephthalate) and its blends with other polymers. Associated with these transitions are three characteristic regimes of extrudate surface morphology, cross-sectional structure and fiber distribution. Low wall shear rates result in a “smooth porcupine” surface, polygonal cross section, and uniform fiber distribution. Medium wall shear rates produce a “rough porcupine” surface, irregular cross section and tubular depletive fiber distribution with fibers depleting at a relative radial position r/R of 0.63 and accumulating at the surface and the axis. This is exactly opposite to the tubular pinch effect observed for neutrally buoyant rigid spheres which accumulate at r/R of 0.63 and deplete at the surface and the axis. High wall shear rates give a “shorn porcupine” surface, rounded or distorted polygonal cross section and radial migration of fibers toward the axis. The extant of disorder decreases with increasing pseudoplasticity, of the fluid, suggesting that the characteristic fiber orientation, distribution and transitions arise from normal stress effect and/or the eccentric rotation of fibers dictated by the complex velocity profile of the flowing fluid. These phenomena have not been previously reported.
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    Torsional braid analysis: Historical remarks (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 662-663 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191003
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    Effect of cure history on dynamic mechanical properties of an epoxy resin (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 683-686 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of cure history on the dynamic thermomechanical properties of a high temperature curing epoxy resin has been studied using torsional braid analysis. In isothermal cures “full cure” is not possible except at temperatures above the maximum glass transition temperature (Tg) of the cured resin, hence the necessity of a “post-cure” after lower temperature isothermal cures. The highest Tg and maximum cross-linking in the cured resin was for a linear heating rate of 0.05°C/min from 30 to 200°C; higher heating rates lead to lower glass transition temperatures.
    Additional Material: 8 Ill.
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    Pyrolysis-molecular weight chromatography-vapor phase infrared spectrophotometry: An on-line system for analysis of polymers - a review (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 699-708 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An instrumental system consisting of a combination of a programmable pyrolyzer, a thermal conductivity detector, a mass chromatograph, a gas chromatograph, a fast-scan vaporphase infrared spectrophotometer and a computer is reviewed with examples which show the utility of the system in the analysis of decomposition phenomena in polyolefins, polyolefinsulfones, polymethacrylates, polystyrenes, and polybutadienes. The system records the thermal history before and during pyrolysis of the sample and provides chromatographic retention times, infrared spectra, mass numbers and relative amounts of the volatile products of pyrolysis. Identification of the constituents is thus facilitated and mechanisms for decomposition become easier to estimate and verify.
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    Linear decomposition of thermomechanical relaxations in polymers (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 728-731 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The methodology of linear decomposition of thermomechanical relaxation phenomena in polymers is outlined. Experimental data obtained from Torsional Braid Analysis (TBA) experiments for tactic poly(methyl methacrylate) are analyzed and the physical significance of the results is discussed.
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    URL: http://dx.doi.org/10.1002/pen.760191013
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    Masthead (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191101
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    Fourier transform infrared spectroscopic study of transitions above Tg in atactic polystyrene (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 756-759 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fourier transform infrared spectroscopy (FT-IR) has been applied to the study of the molecular mechanisms of transitions of atactic polystyrene above Tg. Intensity measurements of vibrational modes as a function of temperature revealed two transitions above Tg, which are designated as Tu and T′u. T′u is independent of molecular weight as opposed to the molecular weight dependent Tu whose behavior is similar to Tg. Infrared measurements are more sensitive to T′u than Tu. Conformationally sensitive bands show that T′u may be related to disruption of local order where there is a negligible barrier to conformational change.
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    URL: http://dx.doi.org/10.1002/pen.760191016
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    Influence of molecular weight on crystallization rate of oriented, glassy nylon 6 (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 779-786 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Differential scanning calorimetry and wide angle X-ray diffractometry were used to investigate the effects of molecular weight and molecular weight distribution on the crystallization kinetics of oriented, glassy nylon 6. The samples had number average molecular weights ranging from 10,000 to 42,000 and polydispersity indices ranging from 2.0 to 3.1. Noncrystalline films were prepared by quenching molten films between plattens chilled with liquid nitrogen. These films were drawn 4X and 5-1/3X, and the resultant uniaxial orientation was observed to enhance markedly the room temperature crystallization kinetics. Although macroscopic deformation can be assumed to be affine at the molecular level, it is hypothesized that wholechain molecular relaxation occurs at rates inversely proportional to the square of molecular weight, thereby creating a distribution of extension ratios which reflect the actual molecular weight distribution. Thus, the crystallization rate and the degree of crystallinity depend on the fraction of high molecular weight molecules present in the sample. Given two samples with the same molecular weight, the one with the broader distribution crystallizes more rapidly. Similarly, samples having the larger molecular weight crystallize to a greater extent when two samples have the same molecular weight distribution.
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    URL: http://dx.doi.org/10.1002/pen.760191104
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    Influence of molecular weight on the creep behavior of undiluted polyisobutylenes (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 800-804 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The elongational behavior in constant force experiments has been considered for three samples of commercial polyisobutylene. The results compare favorably with the predictions of two existing non-linear theories as long as the samples deform homogeneously. Some qualitative observations have been made with reference to the “failure point”, i.e., the point where a non-homogeneous deformation begins.
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    URL: http://dx.doi.org/10.1002/pen.760191107
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    Masthead (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191201
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    Impregnated concrete. I: Characterization of poly (methyl methacrylate) prepared in concrete matrices (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 825-828 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Concrete specimens were impregnated with methyl methacrylate and after polymerization in situ, the extraction of polymer was carried out using appropriate solvents. The molecular weight and the stereochemical configuration of extracted polymer were determined by viscosity measurements and NMR spectroscopy respectively. The results obtained are discussed in relation to the increase of glass transition temperature of poly(methyl methacrylate) when the polymer is inside the concrete.
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    An approach towards the reduction of sink marks in sheet molding compound (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 829-834 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Sink marks are shallow depressions normally observed above reinforcing ribs in molded Sheet Molding Compound (SMC) parts. In this paper, the effect of mold geometry, particularly the rib entrance shape, on the flow pattern of molding compound and the resulting sink marks in molded parts is presented. Flat plate specimens with a single reinforcing rib in the center were used in this work. Rib entrance shape was varied and its effect on both sink depth and fiber orientation measured. A reduction in sink depth from 0.0007 in. to less than 0.0001 in. was observed when comparing rounded and protruding rib entrances, respectively. The effect of inducing unequal flow rates from the two sides of the rib was also investigated and found to give a reduction in sink depth of about one-third. A computer simulation of the flow during molding was, used to compare observed flow patterns with simple theoretical predictions. The SMC was modeled as a highly viscous Newtonian fluid and finite difference methods were used to solve the Navier-Stokes equations. Extension of this modeling procedure to more complex geometries will aid in the design of nearly sink free molds.
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    Laser degradation of polymer coatings on reflective heat sinks (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 864-868 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 10.6 μm laser-induced degradation and volatilization of thin non-char forming organic polymer coatings on aluminum heat sinks has been investigated. Volatilization rates were determined from coating absorptivities measured as a function of irradiation time at 110 W/cm2. First order volatilization rate constants (kJ-1) were: poly(ethylene-co-ethyl acrylate) 0.30, polystyrene 0.85, poly(ethyl methacrylate) 1.6, poly(methyl methacrylate) 2.1, and nitrocellulose 3.1. Residual coating thicknesses at infinite irradiation time are reported. Degradation results from exposure to the thermal environment provided by the heat sink as well as by the direct absorption of laser radiation. Relative polymer thermal stabilities measured at this laser irradiance level and by conventional heating methods are in agreement.
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    Equation of state of cis-1,4-polybutadiene melt (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 845-848 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Recent equation of state data are analyzed in terms of the hole theory of polymer melts. The good agreement between experimental and theoretical volume-temperature curves at atmospheric pressure, observed previously for a number of amorphous and crystallizable polymers, is again confirmed. Similarly, satisfactory theoretical results for the isotherms ensue, with deviations however becoming noticeable at elevated pressures and low temperatures. The linearity of the isochores observed experimentally is confirmed by the theory, however with somewhat different slopes. Departures of maximally 10 percent from the thermal pressure coefficients derived from the experimental PVT data are noted. Significant differences between theory and experiment apper only in the third derivatives of the partition function, as has also been observed with other pollymers. The characteristic scaling parameters of volume, temperature and pressure show the expected similarity with hevea rubber. Earlier correlations for scaling entropy and segmental volume with scaling temperature are found to be valid within the scatter of these relations. Finally, the applicability of the empirical Tait equation in the form applied to the equation of state in other polymer melts is confirmed. Although the resulting thermal pressure coefficient exhibits an explicit even if smal dependence on temperature, in disagreement with experiment or theory, the Tait equation remains a useful relation for the representation of PVT information.
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    A simplified method for analyzing mold filling dynamics. Part II: Extensions and comparisons with experiment (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 849-857 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A dimensional analysis based on four parameters has been developed previously to predict injection pressure; clamp force, and bulk temperature for the injection molding of amorphous materials in center-gated disk-shaped cavities. In this paper geometric and semicrystalline-materials approximations are introduced and tested for extending the previous analysis to include multigated thin cavities and semicrystalline materials. The combination of these approximations and the previous analysis, known hereafter as the Radial Flow Method (RFM), greatly simplifies the analysis of mold filling. The geometric approximation, which is based on a simple model for the axial stress distribution in the cavity, is shown to give reasonable predictions when compared with experimental data and a numerical two-directional flow simulation for the filling of an off-center-gated rectangular cavity with acrylonitrilebutadiene-styrene copolymer (ABS). The semicrystallinematerials approximation, in which heat capacity and viscosity changes during crystallization are neglected, is shown to give good agreement with experimental data for the filling of a center-gated disk-shaped cavity with polypropylene. As an illustration, the Radial Flow Method is used to analyze the molding of a large, thin-wall automobile interior trim panel. The inlet melt temperature, mold-wall temperature, part thickness, injection rate, viscosity and gate locations are varied in a series of calculations to determine the relative effectiveness of these variables in lowering the injection pressure and Clamp force. The results obtained with the Radial Flow Method are in good agreement with those obtained by a finiteelement simulation of two-directional flow.
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    Sintering behavior of poly(methyl methacrylate) particles (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 889-892 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The sintering behavior of poly(methyl methacrylate) (PMMA) particles was studied by photographic, means and mechanical testing. Interpretation of the data gives the sequence of events taking place during high temperature sintering (without pre-compaction). Optical observations, show essentially two main sintering regions while mechanical studies also give an intermediate transition zone separating these two regions. It is suggested that the flow mechanisms involved in the sintering process are viscoelastfc flow in the lower temperature range and shorter times and non-Newtonian viscous flow in the higher temperature range and longer times.
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    The effect of moisture on the mechanical behavior of a nylon-epoxy adhesive (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 940-945 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mechanical properties of a commercial nylon-epoxy resin have been studied using a sensitive creep apparatus which employs a frictionless levitation magnetic bearing. Isothermal creep measurements over a temperature range of 30-170°C and covering a time scale of five decades were made on the wet and dry state of the material. Following the usual time-temperature reduction scheme, master curves for each state were constructed from the experimental data. The effect of moisture was found to be more than that of a simple plasticizer. The steepness of the reduced curves in the transition region was determined and the distribution function of retardation times of the two states of the sample were calculated. The problem of predicting the physical state of the bulk adhesive at higher temperatures was found to be complicated, possibly due to the presence of nylon crystallites.
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    Chemorheology of crosslinked epoxy resins subjected to large strains (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 923-928 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The previously reported work on chemorheological changes occurring in two epoxy resins when aged under large strains at temperatures above their Tg was extended. Ageing times up to 100 h were applied and the phenomenon of orientation occurring in these samples was investigated, mainly by measurements of their birefringence index. It was found that the orientation of the air-aged samples, when studied at room temperature, depended on the ageing conditions (strain, temperature, time) and was not uniform throughout the bulk of the samples, being higher in two narrow external layers and lower in the core layer. After reheating oriented samples in air without strains for different lengths of time at temperatures above Tg, disappearance of the orientation in the external layers was observed. This is probably due to oxidation and degradation occurring in the network and scission of part of the network links, mainly those strained due to orientation. The decrease of orientation, especially in the inner layers of the polymer samples, was much slower when the reheating of the oriented- and unstrained samples took place in an inert atmosphere, this showing again the great influence of oxygen when it participates in ageing and heating processes of epoxy resins.
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    Masthead (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191401
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    Some relationships between injection molding conditions and the characteristics of vitrified molded parts (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 1081-1091 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The various mold filling phenomena influencing the characteristics of fabricated parts are surveyed. The phenomena leading to jetting in injection mold filling are considered. These are associated with the magnitude of swell by the melt as it exits the gate into the mold. Special attention is given to the influence of non-isothermal runner flow. A theory of extrudate swell of polymer melts with temperature profiles is developed using Tanner's unconstrained recovery theory. In the. absence of jetting, mold filling by a simple advancing front takes place. The hydrodynamics of the advancing front and the stress fields in the flowing melt are determined. Analysis and modeling are presented based on the use of hydrodynamic lubrication theory involving a solid layer along the mold wall and a hot isothermal melt core. This theory is compared with experimental measurements of pressure losses in mold filling. The development of birefringence in injection molding processes is analyzed. Birefringence distributions are due to frozen-in flow birefringence. A new experimental study is presented and its results compared with theoretical predictions. The problem of thermal stresses in injection molded parts is considered.
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    An improved concept in solubility parameter theory applied in amorphous polymers. I. Poly(ethyl methacrylate) (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 1174-1177 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Gas-liquid chromatography has been used to estimate thermodynamic parameters of a variety of aromatic and aliphatic solvents at infinite dilution in poly(ethyl methacrylate). Heats of solution, Flory-Huggins interaction parameters, and specific interaction parameters were calculated from specific retention volumes. Comparative interpretation of these thermodynamic quantities has led to the establishment of a solvent selectivity scale for poly(ethyl methacrylate). Limitations of the threedimensional solubility parameter theory on the systems tested here are demonstrated. A significantly improved concept is developed and tested.
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    Fiber-foam: A rheological phenomenon and a novel product (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 12-17 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: When certain molten thermoplastics containing glass fibers up to 20 mm in length are extruded through an orifice, the extrudate has a frothy texture and solidifies into an irregular open-cell structure. The effect is apparently caused by the recovery of the fibers from distortions arising in the region of converging flow near the entry to the orifice. The effect is particularly pronounced in systems with melt viscosities between 50 and 500 Ns/m2. Polypropylene, as an example, containing weight fractions of about 0.25 of glass fibers can be extruded through a zero-length die 2 mm in diameter to give “ropes” that can be readily formed into flat sheets or three-dimensional shapes because of adhesion between the still molten polymer in the newly extruded rope. Such sheets can then be bonded to other materials to make a variety of laminates. A range of bonding techniques is available and the rough surface texture of the ropes provides a useful mechanical key for bonding with grossly dissimilar materials. Fiber-foam is highly resistant to fracture and has a modulus in the range expected by a simple model for the foam.
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    URL: http://dx.doi.org/10.1002/pen.760190103
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    Mineral fillers in low density-polyethylene films (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 30-39 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The use of fillers is an established method of modifying the properties of plastics. The recent increase in prices of plastic raw materials and the new developments in compounding technology have heightened the interest of the plastic industry in compounds of fillers and polyethylene. This article discusses briefly the literature dealing with the effect of fillers on the properties of polyethylene, and research carried out on the effects of different mineral fillers, talcs, micas, clays, wollastonite and dolomite on the many properties of low density polyethylene films. The fine grade talcs have proved to be better than the other fillers with respect to most film properties. The platy talcs decreased the oxygen permeability by as much as 80 percent and the water vapor transmission rate by as much as 70 percent. With talcs, clays and dolomite the yield strength increased but with all fillers the tensile strength at break weakened with increasing filler content. A low elongation at break and a low tearing, resistance indicate the brittleness of the films especially at high filler contents (over 30 wt percent). The coefficients of friction decreased considerably with all fillers and a significant improvement in printability was achieved. However, none of the fillers had more than a very minor effect on the heat sealability of low density polyethylene.
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    Application of small system thermodynamics to polymer molecules. III. Molecular fractionation and tertiary nucleation (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 51-55 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The statistical mechanical methods developed in Parts I and II in this series permit the postulation of a thermodynamic criterion for the molecular fractionation which occurs during crystallization. Using this criterion we define a “local equilibrium” melting temperature as that temperature at which a polymer molecule (considered as a small thermodynamic system) has the same free energy when crystallized into the lowest possible free energy conformation on a given crystal surface (or surfaces) as it does in a completely molten state but still in contact with the same surfaces. This temperature will be a function not only of molecular length but also of the nature of the crystal surfaces to which it is exposed. Lowest “local equilibrium” melting temperatures occur on large flat crystal surfaces (secondary nucleation sites), higher temperatures result from the intersection of two crystal surfaces (tertiary nucleation sites). A number of such potential tertiary nucleation sites have been investigated and the resulting temperatures satisfactorily cover the range over which molecular fractionation has been observed.
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    The influence of structure on the failure of isotactic polypropylene films (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 66-76 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The failure behavior of uniaxially-oriented isotactic polypropylene films has been examined over a wide range of rates and temperatures. Above the glass transition temperature the failure behavior is observed to be a direct function of the initial noncrystalline orientation state of the film. Below the glass transition temperature (-80°C, -196°C), both the crystalline and noncrystalline regions contribute to the failure.
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    URL: http://dx.doi.org/10.1002/pen.760190203
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    Effect of molecular weight distribution on fatigue crack propagation in poly(methyl methacrylate) (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 145-150 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is well established that both molecular weight (M) and its distribution (MD) affect many polymer properties such as mechanical behavior. Thus studies have shown that fatigue life is enhanced by increases in M. Research here has shown that with notched specimens fatigue crack propagation (FCP) rates are dramatically decreased by increasing M, even when the M is high enough that the static fraeture energy has essentially reached its asymptotic limit. In this study, specimens of poly(methyl methacrylate) containing either high- or low-M tails were prepared and characterized. The earlier finding that FCP rates are inversely related to average M was confirmed, but specific effects of M distribution were observed. At constant Mn, a low-M tail had little effect on FCP resistance, while a high-M tail improved FCP resistance of polymers whose average M was too low for effective entanglements. Thus with high-M tails, it was possible to test specimens whose average M's were too low to permit machining. It is proposed that the effects noted are due to relative stabilization or destabilization of crazes ahead of the crack.
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    Geometry design of a coat-hanger die with uniform flow rate and residence time across the die width (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 169-172 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This article provides an approximate but sufficiently practical method of geometry design of a coat-hanger die having both uniform flow rate and residence time across the full width of the die. Such a die is often needed when a heat-sensitive resin such as poly(vinyl chloride) is sheeted, because different residence times across the die width are apt to cause a sheet defect in the transverse direction of the sheet. Although some assumptions were made facilitating mathematical analysis, an application of this method to a sheeting die 1 m wide gave good uniformity of flow rate and residence time.
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    URL: http://dx.doi.org/10.1002/pen.760190302
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    The load-bearing capability of short-fiber thermoplastics composites - A new practical system of evaluation (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 173-180 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The load-bearing capabilities of short-fiber reinforced thermoplastics composites can be evaluated, in principle, by the methods known to be satisfactory for unreinforced thermoplastics, but in practice the cost of a comprehensive evaluation of a composite would be prohibitive because of the anisotropy of the properties and its variation from point to point. For the same reasons the properties measured on a specimen cut from a molding may have little relevance to its overall performance. This paper describes recent experiments that could lead to a radical change in testing strategy. Instead of the classical method in which standard specimens cut from moldings are assumed to provide the various stiffness coefficients needed for anisotropic stress analysis, simple moldings such as discs or plaques are tested directly. The sacrifice of precision in the measurements and the loss of rigor in the definition of the measured quantities is more than compensated for by a gain in the general utility of the data and the substantial reduction in the cost of evaluations. The mechanical properties of shortfiber thermoplastics composites are particularly sensitive to mold geometry and the new methods of testing enable the effects to be assessed readily, whereas the information generated by the classical method is virtually indecipherable in that context. Examples are given in the paper.
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    URL: http://dx.doi.org/10.1002/pen.760190303
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    Viscoelastic measurements of PVC plastisol during gelation and fusion (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 210-214 
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    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 work is concerned with the change of viscoelastic properties of poly(vinyl chloride) (PVC) plastisol during heating. The system changes from a suspension of solid particles in a liquid medium to a swollen gel and further to a fused state as the temperature is raised. The Rheometrics mechanical spectrometer was used in the oscillatory mode at 0.1 Hz. The temperature of the sample was raised in a controlled manner to 195°C. During gelation, the viscosity increased rapidly about three decades. There was a similar increase of the elastic modulus. After reaching a maximum, both viscosity and elastic modulus decreased rapidly with the progress of fusion. The viscoelastic properties depended somewhat on the heating rate. At 170-195°C, it took a few minutes for the moduli to reach steady values. Continued heating, for several minutes at 195°C, did not change the moduli any further. The temperature range of the decomposition of a blowing agent in the plastisol foam formulation was determined. Over this temperature range, the viscoelastic properties change very rapidly. Quantitative estimates were made for the decrease of moduli during this period.
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    URL: http://dx.doi.org/10.1002/pen.760190308
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    Masthead (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190401
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    Thermal response of composite panels (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 226-231 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The thermochemical and flammability characteristics of laminating resins and composites currently in use and others being considered for use as aircraft interior panels are described. The properties studied included: (a) limiting oxygen index of the composite constituents; (b) fire containment capability of the composite; (c) smoke evolution from the composite; (d) thermogravimetric analysis; (e) composition of the volatile products of thermal degradation; and (f) relative toxicity of the volatile products of pyrolysis. The performance of hightemperature laminating resins such as modified phenolics, polyimides and bismaleimides is compared with the performance of epoxies. The relationship of increased fire safety with the use of polymers with high anaerobic char yield is shown. Processing parameters of the state-of-the-art epoxy resin and the advanced resin composites are detailed.
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    URL: http://dx.doi.org/10.1002/pen.760190311
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    Introductory remarks (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 233-233 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190402
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    Problems of structural characterization of polymer networks (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 246-253 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Problems of the characterization of network structure by investigating the network formation and its response to mechanical stress have been analyzed. Attention has been devoted to the effect of reactivity of functional groups and cyclization on the formation of network structure and to problems of obtaining the equilibrium modulus and its relation to the concentration of elastically active network chains (EANCs). It has been demonstrated that a theoretical description of network formation must be based on reliable information on the rules of joining of functional groups and on their relative reactivity; the tree-like approximation offers a number of structural parameters of the sol and gel including, e.g, chemical clustering of units of a certain type. The main obstacles to reaching the equilibrium modulus are long relaxation, times of lightly crosslinked networks and the occurrence of secondary relaxations. In correlating the equilibrium modulus and the concentration of EANCs, it is necessary to find conditions under which the Mooney-Rivlin constant C2 can be neglected and to carry out the required corrections of the modulus, if experimental conditions differ from those of network formation.
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    Calculation of molecular parameters for stepwise polyfunctional polymerization (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 272-283 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Our recursive method is extended to calculate several new parameters for stepwise polyfunctional polymerization. In the pregel region we calculate weight average molecular weight, Mw, for polydisperse reactants and effective average functionality, fe, of a reacting mixture. These quantities are useful for systems employing reactive oligomers. We also calculate weight average number of branches per molecule, Bw, and the weight average of a longest chain. These should be useful for viscosity relations. In the postgel region we give relations for the extent of reaction in the soluble fraction. This result can be used to calculate sol properties directly from existing pregel relations. We also calculate the weight fraction of pendant chains on the gel, wp, and the average molecular weight of the elastically effective network chains, Mc,w.
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    Entanglement networks of 1,2-polybutadiene cross-linked in states of strain. V. Relaxation phenomena and calculations of entanglement trapping (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 267-271 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Linear 1,2-polybutadiene is cross-linked near its glass transition temperature by γ-irradiation while strained in simple extension with a stretch ratio λo. After release, the sample retracts to a state of ease (λs). From λo, λs, and stress-strain measurements in extension from the state of ease, the concentrations of network strands terminated by trapped entanglements (vN) and by cross-links (vx) can be calculated. For vx/vN ≡ R′o 〉 1, retraction to the state of ease is rapid. For R0o ≃ 0.3 or less, retraction is slow and extends over many logarithmic decades of time scale. When an eased sample is stretched to λo where the cross-links do not contribute to stress, the subsequent stress relaxation of the entanglement network toward equilibrium is also very slow if R′o is small. The slow timedependent processes are attributed to a high proportion of untrapped entanglements on dangling branched structures. The concentration of trapped entanglement strands, vN, can also be calculated from the equilibrium stress at λo. The fraction of trapped entanglements agrees rather well with the predictions of the theory of Langley.
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    Synthesis, characterization, and viscoelastic behavior of single-phase interpenetrating polystyrene networks (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 284-293 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Single phase interpenetrating polystyrene networks were synthesized using a room temperature photopolymerization method. Divinylbenzene was used for crosslinking both networks in most cases; a few IPNs were prepared using acrylic acid anhydride to provide labile crosslinkages in the primary network. The IPNs were characterized by means of equilibrium swelling in toluene. The results of these experiments closely approached the predictions of a swelling equation derived under the assumption that the two networks were elastically independent. Deviations from the swelling equation predictions could be explained in terms of contributions from internetwork entanglements. Small amplitude dynamic mechanical measurements indicated that the presence of the small amount (∼10 percent) of tight primary network chains had no perceptible effect on the linear viscoelastic properties.
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    Studies on poly(vinyl chloride)-copper composites. Part 1: State of segregation of filler particles, electrical and mechanical properties in presence of plasticizer and stabilizer (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 533-539 
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    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 presence of additives influences the state of segregation of filler particles in the polymer matrix which in turn controls the electrical and mechanical properties of poly(vinyl chloride)-copper composites. The liquid plasticizer seems to form a coating on the filler surface which introduces quasirandomness in the segregated network. In accordance with the mathematical model proposed earlier, the strength properties were found to be proportional to dm-½ where dm is the mean free path between the filler particles. Calculations of dm were based on two different models, one for segregated network (unplasticized and low plasticized composites) and the other for quasi-random distribution of filler particles (plasticized composites). Extruded samples in general show more randomness in the filler distribution than the compression molded samples.
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    Impact behavior of nylon-66 compositions: Ductile-brittle transitionsPresented at the Plastics and Rubber Institute Confernce on Toughening of Plastics, London, England (July 5, 1978). (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 564-571 
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    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 ductile-brittle transitions of nylon-66 compositions were studied by Izod and falling weight tests. Samples included unmodified and impact modified compositions. Brittle breaks did not occur in the toughest resin with changes in rate of loading, notch radius, thickness, or distance and orientation to the gate. A fracture mechanism is proposed.
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    A simple procedure of accounting for physical aging in the prediction of the modulus of glassy plastic materials (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 579-584 
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    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 basic relationships are presented for predicting the creep and stress relaxation as a function of physical aging, loading time, and temperature of amorphous polymers processed under such conditions that their thermal treatment amounts to a quench from the melt to the glassy state. A nomogram construction, based on these relations, is proposed and developed for a particular polymer, namely an extrusion type acrylonitrile-butadiene-styrene (ABS), RONFALIN EST. The applicability of the procedure is restricted to the isothermal viscoelastic behavior at low stresses and strains of unplasticised amorphous plastic materials quenched from the melt to the glassy state.
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    Poly(vinyl chloride), Part II: Effect of polymerization temperature and molecular weight on the glass transition and melting point of poly(vinyl chloride) (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 585-589 
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    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 detailed study was made of the thermal behavior of poly(vinyl chloride) (PVC) homopolymers, whose chain length and structure were independently manipulated. Normal PVC polymerizations are made at temperatures, the selection of which determines the polymer chain length. In the case of PVC, this choice of temperature also determines its syndiotacticity, and so, its glass transition temperature, and in many ways, its processibility. The ability to understand how to control chain structure and length in PVC is critical in designing polymers for selected specific end use conditions. The thermal spectrum is known to be one measure of how polymers will perform. This study reveals how such controlled chain length/structure PVCs are characterized by thermal methods, and how one can separate individually the effects of syndiotacticity and molecular weight on thermal properties of poly(vinyl chloride).
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    Fracture toughness testing of dental biomaterialsPresented at the 175th meeting of the American Chemical Society, Division of Organic Coatings and Plastics Chemistry, Anaheim, California (March 1978). (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 607-608 
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    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 adaptation of a cylindrical geometry fracture toughness test specimen to testing of polymeric dental biomaterials is demonstrated. The specimen configuration facilitates the fabrication of small specimens and simplifies the experimental study of environmental effects on properties of dental biomaterials. The test method is used to measure critical stress intensity factor, KIC for poly (methyl methacrylate) (PMMA), particulate composite restorative materials, and dental polymers. Values obtained are in agreement with data reported for other specimen configurations.
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    The classification of solvents for bis-phenol-a polycarbonate (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 625-637 
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    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 procedure is described which permits the classification of solvents according to their effect on polycarbonate (PC):Class I - dissolve amorphous or crystalline PCClass II - dissolve only amorphous PCClass III - convert amorphous PC to crystalline PCClass IV - none of the above.This classification is achieved by comparing solvents to CH2Cl2 with respect to the exotherm and rate of crystallization observed when the solvents are brought into contact with PC under controlled conditions.
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    Introductory remarks (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 661-661 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191002
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    The torsion pendulum in the investigation of polymer (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 664-675 
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    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 early history of the use of the torsion pendulum in the investigation of polymers is described together with the development of dynamic mechanical testing at TNO. Examples are listed of studies of structure-property relationships by means of the torsion pendulum. Techniques using supported. Samples are compared with those using unsupported samples, particular attention being paid to the advantages and restrictions of torsional braid analysis (TBA). The comprehensive application of TBA by Professor Gillham is reviewed; a few TBA results are compared with our torsion pendulum measurements. A rheologist's view on the so-called liquid-liquid transition (Tn) in polymer melts, as observed by TBA, is presented.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191004
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    An ultrasonic-acoustic technique for nondestructive evaluation of fiber composite quality (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 373-376 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This report describes an ultrasonic-acoustic technique used to measure a “stress wave factor” in order to nondestructively assess the quality of composite structures. In a prior study this factor was found effective in evaluating the interlaminar shear strength of fiber-reinforced composites. Details of the method used to measure the stress wave factor are described. In addition, frequency spectra of the stress waves are analyzed in order to indicate the nature of the wave phenomena involved. The stress wave factor can be measured with simple contact probes requiring only one-side access to a part. This is beneficial in nondestructive evaluations because the waves can run parallel to fiber directions and thus, in many cases, measure material properties in directions assumed by actual loads. Moreover, the technique can be applied where conventional through transmission techniques are impractical or where more quantitative data are required. The stress wave factor was measured for a series of graphite polyimide composite panels and results obtained are compared with through transmission immersion ultrasonic scans.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190509
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    Masthead (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190601
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  • 90
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    Viscoelastic properties of epoxy polymer concrete (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 795-799 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The viscoelastic nature of polymer concrete was investigated utilizing an epichlorohydrin/bisphenol A-type epoxy resinaggregate system. Compression specimens were tested for linearity of viscoelastic behavior, the effect of size of mass on creep, and for determination of the specific creep compliance and the associated elastic modulus. The creep compliance was determined by least squares curve fitting of the experimental creep data. Collocation, a numerical Laplace transform inversion routine, was used to develop the equation for the relaxation modulus.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191106
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  • 91
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    Effect of bonding temperature on the joint strength of polyolefln/butyl rubber and polyolefin/ethylene-vinylacetate copolymer (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 810-814 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of bonding temperature on the peel strength of adhesive joints, polyolefin/butyl rubber and polyolefin/ethylene-vinylacetate copolymer, has been investigated. The peel strength, measured at room temperature, undergoes a sharp transition from its low values to higher values as the bonding temperature is changed from below to above, the melting point of the substrate. This increase in peel strength is accompanied by changes in failure mode from the apparent interfacial failure to cohesive failure through the adhesives. Investigation of the interface using Fourier Transform Infrared Internal Reflection spectroscopy and interference microscopy indicates that the sharp increase in the peel strength at the melting temperature of substrate is associated with the presence of an interdiffused layer at the interface.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191109
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  • 92
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    Rheological and energetic considerations of the fluid dynamics and scale-up of mixing small particles into polymer melts in an internal mixer (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 818-823 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A basic theoretical investigation is made of the fluid mechanics of mixing of particulates into a polymer melt in an internal mixer. It is shown how increasing levels of viscoelasticity, especially with non-linear, strain rate hardening character, should deteriorate mixing. he characteristics of internal mixers are discussed in terms of dimensionless groups. Rational scaling procedures based on considerations of viscoelastic fluid mechanics and energy balances are critically investigated and their limitations considered.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191111
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    Review of forging, stamping, and other solid-phase forming processes (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 474-481 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the last ten years, a considerable amount of work has been conducted on many different processes distinct from common plastics processing methods such as injection molding, extrusion, and compression molding. Perhaps the most common feature of these new techniques is that they resemble more the methods used for fabricating metallic materials in solid phase. However, there is a lack of uniform terminology. More importantly, the commercial acceptance and applicability of these processes have been slow. This review attempts to summarize the important findings of various publications and, whenever possible, to give information about potential or actual industrial applications. The purpose is to provide a brief overview of the state-of-the-art of the whole technology. Advantages, disadvantages, and the need for more work are pointed out as they relate to different processes and to crystalline and amorphous materials. A few instances where material was heated beyond the melting temperature by a small amount are included in the review when the processing method was similar to solid-phase forming.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190703
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    Ultradrawing of thermoplastics by solid state coextrusion illustrated with high density polyethylene (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 441-449 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Ultra-thin films of high density polyethylene of high orientation have been produced by the recently developed technique of solid state coextrusion. The films were prepared under moderate conditions, without lubricant in continuous lengths by extruding through conical dies of extrusion draw ratio up to 36. This is a draw ratio higher than achievable by conventional solid state extrusion at comparable processing conditions through slit dies. The ultra-thin films of high orientation were transparent and exhibited dead bend. The physical and mechanical properties were evaluated and compared with the properties of the same high density polyethylene extruded through a slit die. The increase in the melt point, crystallinity, tensile modulus, and birefringence indicates that the method is very efficient for the production of ultra-thin and highly oriented films. An experimental technique is also presented for preparing billets of controlled and uniform initial morphology and free of voids.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190614
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    Young's modulus of uniform density thermoplastic foam (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 493-499 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A comparison of experimental data for zero strain Young's modulus of uniform density thermoplastic foam for short times has been made with several theoretical and empirical correlations. An analysis of the variance of the data with the predicted values from the many models indicated that the simplistic density squared relationship adequately described the modulus of the foam for basic engineering calculations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190706
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  • 96
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    Fatigue crack propagation in, graphite fiber reinforced nylon 66 (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 512-518 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The rate of fatigue crack propagation in graphite fiber reinforced nylon 66 was measured. A model of the form å = β [Kmax1-γ ΔKγ]r was used to correlate the rate of crack propagation å with the maximum stress intensity Kmax and the amplitude of the stress intensity ΔK experienced by the notched specimen during the fatigue test. The quantities β, γ and r were constant at fixed temperature and frequency of the test. It was also found that there exists both an upper and a lower threshold of stress intensity for the slow ropagation of damage during fatigue. The mechanism of crack propagation in the short graphite fiber reinforced nylon was found to be similar to the growth and fracture of crazes in thermoplastics. The propagation of damage at the crack tip is controlled by matrix deformation, cavitation, fiber breakage and fiber pullout. Damage can propagate in the absence of crack growth until a critical point is reached at which time the material fractures catastrophically.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190709
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    Compatible glassy polyblends based upon poly(2,6-dimethyl-1,4-phenylene oxide): Tensile modulus studies (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 519-524 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mechanical behavior of compatible glassy polyblends based upon poly(2.6-dimethyl- 1,4-phe nylene oxide) (PPO) was investigated. In particular, the influence of composition, molecular weight, and molecular weight distribution upon the tensile modulus of the blend was assessed. Various possible correlations between the experimentally determined moduli and theory are considered. Included are correlations with density, packing density, composite theory, and lattice fluid theory. The modeling of the properties of mixtures via Simplex lattice design is also presented. Finally, attention is given to the development of compatibility criteria based upon tensile modulus and density measurements.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190710
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  • 98
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    Time constants for moisture diffusion through a permeable barrier into an airspace (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 525-529 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper arose from a study of the use of polymeric materials to protect humidity-sensitive items from damp ambient conditions. A one-dimensional model for the Fickian diffusion of moisture through a permeable wall into a volume of air is considered. The humidity in the airspace asymptotically approaches equilibrium with the exterior, and the time constant is defined as the time to reach 1-1/e of its ultimate value. Exact and approximate solutions are considered. Depending on the system geometry and properties, the time constant is either permeability-controlled or diffusivity-controlled, or somewhere in between. Under certain conditions, there exists an optimum combination of airspace depth and wall thickness that maximizes the time constant.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190711
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  • 99
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    Predicting the creep rupture life of polyethylene pipe (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 590-595 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A number of techniques have been developed in the past for the prediction of the dependence of the creep rupture life of polyethylene pipe on applied stress and temperature. It is now proposed that, using a modified form of the activated rate procss equation in which the activation volume varies predictably with temperature, a generalized equation may be derived which describes the “brittle” creep rupture curve over a range of temperatures, and also allows the use of a Larson-Miller type equation. Since the known “ductile” creep rupture curve at 20°C can be extrapolated from measurements carried out over a short period at room temperature in the laboratory, the intersection point between the extrapolated “ductile” curve and the calculated “brittle” curve can easily be calculated. If the proposed method is applied to creep rupture data obtained from Hoechst AG (GM5010, HDPE pipe) as an example, a transition at about 11 years is predicted.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190811
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  • 100
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    The selection and use of free radical initiators (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 597-606 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: There are over 50 different organic peroxides and azo compounds (in over 100 different formulations) produced commercially as free radical initiators (curing agents) for the polymer and resin industries. Thus, the user has many initiators to choose from and has usually relied on the resin and/or initiator producer to select his initiator system. This paper will discuss these initiators in general showing the different types- of initiator classes; how and why the activity of each class of initiator is varied by structure changes; how different initiators and/or promoter levels affect the curing process; and present guidelines that an end user might use to choose the right initiator for his resin system.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190902
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