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  • Articles  (1,845)
  • Chemical Engineering  (1,845)
  • 1980-1984  (1,410)
  • 1970-1974  (435)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (1,845)
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  • Articles  (1,845)
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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of polymer conformation and morphology through small-angle neutron scattering - A literature review (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1-21 
    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: Small-angle neutron scattering, SANS, stands forth as one of the most important of the new tools for evaluating polymer chain conformation and morphology. This paper reviews the SANS literature through 1982, with a few early 1983 references added. The theory of SANS is outlined and compared to light scattering. SANS values of polymer molecular weights and radii of gyration obtained in the bulk state were found to be in agreement with values obtained from dilute solutions by light scattering. In each case, deuterated fractions of polymer were inserted into the hydrogeneous matrix, or vice versa, to provide contrast. Several new research areas are then discussed, including unidirectional stretching of elastomers, stress-relaxation, polymer-polymer miscibility, crystallization from the melt compared with crystallization from dilute solutions, nonclassical aggregation during bulk polymerization of thermoset systems, morphology of polymer blends, block copolymers and ionomers, the core-shell structure of latexes and polymer blocks, and grafts as surfactants in emulsions and latexes. Much new and sometimes unexpected information is being provided by the SANS research now in progress.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240102
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of pressure and temperature on time-dependent changes in graphite/epoxy composites below the glass transition (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 57-66 
    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: Effects of pressure and temperature on time-dependent changes in physical/mechanical properties of graphite/epoxy composites were investigated. Samples were cut from the eight-ply-thick laminates of commercially used composites, post-cured, and then quenched to environments of various temperature and pressure. Time-dependent changes in their properties were analyzed by thermal and thermomechanical (dynamic mechanical) measurements. An increase in the glass-transition temperature was found to occur as a function of time. The rate of this process was enhanced by an increase in temperature and/or a decrease in pressure. An explanation was offered in terms of types and mechanisms of molecular events that occur in the glassy state. Time dependent decrease in free volume (and enthalpy) takes place but is not the sole mechanism responsible for the observed increase in Tg. After a certain period of time (which depends on T and P of the environment), additional crosslinking appears to take place.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240107
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  • 3
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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.760240301
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  • 4
    Electronic Resource
    Electronic Resource
    The properties of mica-filled polypropylenes (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 169-174 
    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: Water-ground Phlogopite micas were classified into narrow particle-size distributions containing flakes with well-defined diameters and thicknesses in order to evaluate the influence of particle size and flake aspect ratio on the mechanical properties of mica-filled polypropylenes, For the purposes of comparison, most of the injection-molded specimens contained 40 percent (by weight) mica. As expected, the flexural and tensile modulus values increased in proportion to the aspect ratio over the range from 30 to 60 to a maximum of 8 GPa. The measured tensile strengths of the mica-filled polypropylenes increased substantially as the flake diameter became smaller, but did not correlate with the flake aspect ratio. The attainable properties were frequently dependent upon the method of mixing, and considerable care was necessary to ensure proper dispersion and adequate coupling. Intensive mixing, as in a Gelimat Mixer, may cause in situ delamination and particle-size reduction of the mica filler particles, leading to a marked increase in tensile strength of the resulting composite. The mica-filled compounds could be reprocessed many times without significant loss of properties, particularly compounds having mica particles less than 40 μm in diameter. The fracture energies (notched Izod) and the heat-distortion temperatures were not appreciably influenced by the size or aspect ratios of the mica within this range. Increased fracture toughness could be achieved by reducing the mica concentration or employing a polypropylene copolymer. Guidelines are presented to indicate the preferred characteristics of mica fillers and the influence of mixing conditions on performance.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240303
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  • 5
    Electronic Resource
    Electronic Resource
    Rheological properties of blown film low-density polyethylene resins (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 259-263 
    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: Three blown-film-grade low-density-polyethylene (LDPE) resins were studied using different rheological techniques. Eccentric rotating disks (ERD), cone-plate viscometry, capillary rheometry, annular die extrusion, and non-isothermal stretching of a filament were used. The viscoelasticity of the melts was found to play a dominant role in the observed behavior. Extrudate appearance in annular flow, melt strength, and extensibility are affected by melt elasticity. A correlation was found between the maximum draw ratio of a filament stretched under non-isothermal conditions and minimum film thickness.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240405
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  • 6
    Electronic Resource
    Electronic Resource
    Linear-low-density polyethylene melt rheology: Extensibility and extrusion defects (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 268-274 
    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 investigates three aspects of linear-low-density polyethylene (LLDPE) rheological properties: shear viscosity variations with shear rate and temperature, tensile behavior determined with an extensiometer, and extrusion defects. The differences in shear viscosity variation with shear rate and temperature between LLDPE and LDPE (low-density polyethylene) are shown. These differences, attributed to wider molecular weight distribution and to long chain branching (LCB) in LDPE, involve different extrusion behaviors. The lack of LCB in LLDPE can be demonstrated by comparison of the measured Newtonian viscosity with the value of the same parameter calculated from molecular weight distribution and composition law of Newtonian viscosities. The lack of LCB leads to good melt extensibility, which is shown by tensile properties of polyethylene melts determined with a non-isothermal extensiometer. The melt fracture phenomenon is studied because it promotes surface defects on bubbles in film application. Extrudate distortions are examined at the laboratory extruder outlet. This test shows differences between LLDPE and LDPE, but also between some LLDPE samples.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240407
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  • 7
    Electronic Resource
    Electronic Resource
    Gas chromatographic determination of the interaction parameter of poly(ethylene oxide)/poly(methyl methacrylate) blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 287-290 
    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: Inverse gas chromatography (IGC) has been used to investigate thermodynamic miscibility of a molten poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blend. Toluene, benzene, and chloroform have been employed as probes in pure and mixed stationary phases of these polymers. Experimental measurements have been taken over a narrow range of temperatures because of the high PMMA glass transition temperature as well as the degradation of the PEO. The interaction parameter χ23 determined at 150°C is slightly negative and dependent on the interacting probe, as has been also noted in previous chromatographic studies on polymer-polymer miscibility. The last section is devoted to a model calculation, using Flory's equation of state theory. Different χ23-concentration curves have been simulated, with the interaction energy parameter X23 as an adjustable parameter.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240410
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  • 8
    Electronic Resource
    Electronic Resource
    A quantitative description for the optical properties of crystalline polymers applied to polyethylene (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 328-344 
    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 quantitative model which described the microscopic and macroscopic refractive index properties of uniaxially oriented crystalline polymers has been extended in relation to molecular bond polarizabilities in this work. Application of this extended modeling methodology in analyzing measured refractive index data for a series of unoriented and oriented samples of linear polyethylene provided Δco = 0.0585 and Δao = 0.194 as the most probable crystalline and noncrystalline intrinsic birefringences for samples exhibiting spherulitic morphology. With these intrinsic birefringences, noncrystalline orientation functions were determined from the optical measurements coupled to the model and the results compared to values obtained from infrared measurements. This comparison of noncrystalline orientation functions, as well as from low density polyethylene reported by other investigators, provided experimental justification for our modeling methodology to examine the possibility of changing intrinsic birefringences for polyethylene as a function of orientation and morphology. The results of this examination demonstrated that values for Δco = 0.0585 and Δao = 0.12 should be used for both low and high density polyethylene samples oriented above the spherulitic to fibrillar transition region.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240507
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  • 9
    Electronic Resource
    Electronic Resource
    “Living” anionic polymerizations in a continuous stirred-tank reactor under sustained feed oscillations (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 391-397 
    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: “Living” anionic polymerizations carried out in a continuous stirred-tank reactor (CSTR) and operated under forced-feed oscillations are theoretically studied to investigate the effects on time average values of average chain lengths, polydispersity, and reagent conversions. The instantaneous mean residence time is maintained constant. The period of the oscillations is varied between 60 and 0.05 mean residence times, and various amplitudes are considered. Some advantages are observed with the periodic forcing as compared to the steady operation; polymers with average polydispersities above 10 may be produced at low frequencies, with polydispersities below the steady-state value of 2 at intermediate frequencies, and with polydispersities of 2 but with increased monomer conversion at fast cycling.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240602
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  • 10
    Electronic Resource
    Electronic Resource
    Applications of a reaction-injection-molding process model in the analysis of premature gelling, demold time, and maximum temperature rise (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 428-434 
    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 this paper, we discuss a way to present results or practical interest for the reaction injection molding (RIM) process, such as guidelines to avoid premature gelling and to control demold time and maximum temperature rise. The results are presented as a set of graphs correlated using the relevant dimensionless groups of the process. Examples of applications of these graphs are given and discussed. The numerical calculations are done using the RIM process model developled by Castro and Macosko, which has been shown to agree with experimental results.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240607
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  • 11
    Electronic Resource
    Electronic Resource
    High-temperature electrical conductivity and thermal decomposition of Sylgard® 184 and mixtures containing hollow microspherical fillers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 435-441 
    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 high-temperature electrical conductivity and thermal decomposition characteristics of Sylgard® 184 with and without hollow microspheres of glass, silica, and ceramic have been determined to 600 to 700°C in air and nitrogen environments. The materials are silicone-based dielectrics and are used as electronic encapsulants. Results show that a peak in the conductivity temperature dependence at ∼300°C results principally from volatilization of [Si(CH3)2O]n with some evolution of water, that oxygen accelerates decomposition, and that the microspheres may help form a network of interconnected conductive pathways in the residual material. There is a good correlation between thermal stability and temperature-dependent electrical properties.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240608
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  • 12
    Electronic Resource
    Electronic Resource
    Modeling of polyethylene terephthalate reactors: 7. MWD considerations (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 30-41 
    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 mathematical model has been developed to compute the molecular weight distribution (MWD) in the polyethylene terephthalate (PET) manufacturing process. Unlike the previous efforts, this model takes into account the influence of side reactions and various interchange reactions on MWD. The process of blending of molten polyester chips has also been simulated with a view to calculate the equilibrium MWD as well as the time required to reach the equilibrium MWD. The1 significance of the results has been discussed in terms of industrial operations involving PET polymerization and PET blending.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240104
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  • 13
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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.760240201
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  • 14
    Electronic Resource
    Electronic Resource
    On the nature of polymer interfacesd and interphases (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 79-86 
    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 abbreviated review of the current state of knowledge of polymer interfacial phenomena is given. Classical thermodynamics treats the interfacial zone (the interphase) as a “black box” and yields rigorous relationships among interfacial quantities. A recent reformulation of interphase thermodynamics, which eliminates the use of a Gibbs dividing surface, is shown to be an invaluable tool for investigating interfacial properties. Microscopic theories, such as the gradient theory, yield more details about what is in the black box, but the information is only approximate. The gradient theory has been used to: (1) relate the surface tension of a polymer liquid to its isothermal compressibility, (2) develop a quantitative theory of polymer liquid surface tension, and (3) determine the interfacial tension between two immiscible polymer liquids. The gradient theory will be shown to be in harmony with the microscopic theory of Helfand and co-workers although the latter treats polymer interfaces from a completely different point of view.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240204
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  • 15
    Electronic Resource
    Electronic Resource
    Thermally stimulated creep of polyethylene, polypropylene, copolymers, and blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 127-134 
    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 technique of Thermo Stimulated Creep (TSC) has been applied to the study of anelastic properties of polyethylene, polypropylene, their copolymers and blends. In the temperature range -200 to 100°C, complex TSC peaks were observed in all samples, namely around 0°C, about the same temperature as for the homopolypolymer polypropylene. By applying “fractional stresses”, with a convenient choice or the loading program, these peaks have been experimentally resolved. Two components can be distinguished: 1. The “low temperature” component is characterized by mechanical retardation times following a compensation law. It has been attributed to microbrownian motions of polypropylene sequences liberated at the glass transition of the “true” amorphous regions. 2. The “high temperature” component which is influenced by thermal treatment has been assigned to microbrownian motions of polypropylene sequences liberated at the glass transition of the “constrained” amorphous regions. In block polymers, an additional TSC peak is observed around -50°C: it has been associated with the glass transition of ethylene-propylene-rubber (EPR) interphase. The coupling of this interphase with polyethylene and polypropylene phases is insured by diffusion of some ethylene and propylene sequences in-EPR. At about -140°C, a TSC peak associated with the low temperature component of the glass transition of polyethylene can be distinguished in all the materials studied.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240210
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  • 16
    Electronic Resource
    Electronic Resource
    Water-soluble copolymers VIII. Synthesis and dilute solution rheological studies of dextran-g-poly(acrylamide-co-sodium acrylates) (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 163-168 
    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: Dextran-g-poly(acrylamide-co-sodium acrylates) were prepared by partial hydrolysis of dextran-g-poly(acrylamides) with controlled numbers and lengths of grafted chains. This hydrolysis route proved to be more effective than Ce(IV)-induced cografting of acrylamide and sodium acrylate comonomers onto dextran in producing the desired graft-copolymer structures. The resulting copolymers were characterized and the effects of composition, temperature, ionic strength, and shear rate on dilute solution rheological properties were studied.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240302
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  • 17
    Electronic Resource
    Electronic Resource
    Solution of final stages of polyethylene terephthalate reactors using orthogonal collocation technique (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 194-204 
    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 formation of polyethylene terephthalate (PET) has been modeled to have reactions with monofunctional compounds, redistribution, and cyclization reactions in addition to the usual polycondensation step. In the final stages, the overall polymerization is mass-transfer controlled and solution of the reactor performance equations have been determined through the orthogonal collocation technique. This technique is found to be considerably more efficient for PET reactors compared to the finite difference method; the use of ten collocation points gives results which are close to the exact solution.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240306
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  • 18
    Electronic Resource
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    Theoretical investigations on some rigid-rod polymers used as high-performance materials (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 218-225 
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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 review focuses on a new type of para-catenated aromatic polymer being used in the preparation of high-performance films and fibers of exceptional strength, thermal stability, and environmental resistance, including inertness to essentially all common solvents. Polymers of this type include cis and transpoly(p-phenylene benzobisoxazole) (PBO), and the cis and trans forms of the corresponding poly(p-phenylene benzobis-thiazole)(PBT). The purpose of this paper is to summarize the authors' theoretical work on the structures, conformational energies, intermolecular interactions, and electronic properties of PBO and PBT chains, including the protonated forms known to exist in strong acids. The emphasis is on how such studies provide a molecular understanding of the unusual properties and processing characteristics of this new class of materials.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240309
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  • 19
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    Foreword (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 843-843 
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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.760241102
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  • 20
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    Analysis of the evolution of microcreep during physical aging and mechanical deformation in poly(methyl methacrylate) using a microstructural model (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 921-929 
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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 evolution of poly(methyl methacrylate) (PMMA) during physical aging at 90°C is followed by torsional microcreep tests. On the aged specimen a longitudinal stress is applied which induces a strain of 5 percent after 30 days of creep. The torsional microcreep tests are performed during the longitudinal creep in order to compare the structure evolution of PMMA caused by straining with its evolution measured during aging. The microcreep, for the first 800s, follows a reversible logarithmic law. In this stage the mobile defects achieve their activated form which is perfectly reversible when unloaded. The physical aging reduces this logarithmic part of microcreep. This is due to the decrease of either the number or the volume of the mobile defects. Beyond a critical elongation ∊ = 1 percent, the longitudinal straining has just the opposite influence, i.e., the logarithmic part of microcreep increases. This critical elongation ∊ = 1 percent corresponds to the beginning of the steady state longitudinal creep. The transient that precedes this steady state has no detectable influence on the structure of the specimen.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241112
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  • 21
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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.760241201
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  • 22
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    Orientation in amorphous polymers II. Characterization of orientation (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 965-973 
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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 based on network theory is developed for characterizing molecular orientation in amorphous polymers. The proposed procedure gives not only the orientation distribution function for the chain segments in the polymer network (and hence the average orientation) but also a quantitative measure of how this orientation is distributed among the various types of entanglement junctions. The orientation of chain segments can be characterized by two parameters, one which gives the average orientation and another which reflects how much orientation is concentrated in long time entanglement junctions. The new method of characterizing orientation is used to interpret tensile strength data for both brittle and ductile failures.
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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
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    URL: http://dx.doi.org/10.1002/pen.760241301
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    Correction (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1025-1025 
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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
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    URL: http://dx.doi.org/10.1002/pen.760241305
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    An investigation of optical clarity and crystalline orientation in polyethylene tubular film (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1035-1042 
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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 study of the crystalline orientation, light transmission, and surface roughness of polyethylene tubular film prepared in our laboratories is presented. The present studies were primarily carried out on low-density (LDPE) and linear-low-density (LLDPE) polyethylene films. The optical properties of a few films of high-density polyethylene (HDPE) prepared for a previous study of morphology were characterized for comparison to the LDPE and LLDPE films. Wide angle X-ray diffraction and birefringence were used to characterize orientation. Both the LDPE and LLDPE films exhibited crystalline texture in which the b-axes tended to be perpendicular to the film surface and the a-axes had some tendency to align with the machine direction. The c-axes tended to be concentrated in the plane of the film with nearly equal biaxial orientation with respect to the machine and transverse directions. Little variation in the crystalline orientation was found with changes of process conditions in the range studied. Birefringence results indicate that the amorphous regions developed an orientation in which the chains tend to be normal to the film surface. The majority of light scattering from these films and a series of HDPE films was from the surface and not from the film interior. The transmission coefficient for the surface contribution was found to be a monotonic decreasing function of the standard deviation of the surface height obtained from surface profiles measured by profilometer. The surface asperites were largest for the HDPE and smallest for the LDPE samples. The intensity of both the surface and interior contributions to the scattering increased with increasing frostline height, i.e., a slower cooling rate. As draw-down ratio and blow-up ratio increase the scattering contribution from the film interior decreases but the contribution from the surface increases somewhat. These effects are discussed in terms of the changes in crystalline morphology and surface roughness produced by flow defects generated during extrusion.
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    Physical aging of poly(methyl methacrylate) in the nonlinear range: Torque and normal force measurements (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1138-1141 
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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: Cylindrical specimens of poly(methyl methacrylate) (PMMA) were quenched from above the glass transition and subsequently tested in torsion. Torque and normal-force relaxation responses were recorded simultaneously. The experiments were performed at 40, 60, and 80°C, at increasing aging times and at deformations ranging from γ = 0.0027 to γ = 0.074. It was found at 40 and 60°C, that, contrary to the classical picture of aging, the small-deformation torque-relaxation curves could not be superposed by any combination of vertical and horizontal shifts. On the other hand, at 80°C, and in the nonlinear deformation range even at lower temperatures, the relaxation curves are superimposable simply by horizontal shifts, but as γ increases they involve decreasing values of the double-logarithmic shift rate. At the same deformation level, however, the shift rate for the normal force is significantly higher than is that for the torque over most of the γ range investigated.
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    Correction (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1165-1165 
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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.760241503
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    Wood fibers as reinforcing fillers for polyolefins (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1166-1171 
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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: Wood pulp fibers possess strength and modulus properties which compare favorably with glass fibers when the differences in fiber densities are considered. Softwood pulp fibers with fiber aspect ratios near 100 are readily dispersed into high-density polyethylene or isotactic polypropylene with the aid of carboxyic dispersing agents to form mixtures containing 50 weight-percent wood pulp which can be readily injection molded. The mechanical properties of the molded specimens were similar for all types of pulp including Kraft (bleached and unbleached), mechanical and chemical-mechanical pulps, waste pulps, and reclaim newspapers. Comparisons of the stiffness/weight efficiencies revealed that pulp composites equal or exceed the stiffness of most traditional materials of construction including steel, aluminum, glass-fiber composites, and talefilled polyolefins, while retaining a major material cost advantage. The measured strength values of the pulp composites were less than the theoretically predicted values due to the presence of voids created by the formation of volatiles during processing. Mechanical pulps which were available in dry form were preferred because of lower cost and ease of handling. Wood fibers are non-abrasive so that relatively large concentrations may be incorporated into polyolefins without causing serious machine wear during mixing and fabrication.
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    Effect of the cooling rate in the formation of glass on the α and β relaxations of some amorphous polymers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1202-1204 
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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: It has been observed in dynamic mechanical measures that the range of temperatures in which relaxation properties are affected by the diminishing of the free volume has, as a lower limit the temperature at which the maximum of G″ or tgδ, corresponding to the β relaxation, occurs. In dielectric measures on polymers in which the β relaxation is not predominant over the α relaxation, this temperature range is scarcely affected by changes in frequency, whereas the peak shifts according to its activation energy. This fact leads to the conclusion that the decrease in free volume due to a slow cooling from a temperature above Tg mainly affects mobility of the main chains under Tg, without disturbing the groups that give rise to the secondary relaxations.
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    Dynamic and steady-state rheological properties of linear-low-density polyethylene melt (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1215-1218 
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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: Linear-low-density polyethylene (LLDPE) is steadily gaining importance in a wide variety of applications due to its excellent performance characteristics in the final product. The rheological properties of LLDPE in the dynamic and steady state are of great pragmatic importance and these have been studied in the present work. A correlation between the dynamic and steady-state rheological properties has been attempted and good agreement has been found.
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    Thermal catalytic polymerization of mortars impregnated with styrene-acrylonitrile (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1240-1244 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Standard test specimens of mortar were cured under water for 15 days to achieve satisfactory strength. They were dried without allowing dehydration reactions to occur, evacuated to 40 millimeters (mm) Hg, and impregnated with a styreneacrylonitrile comonomer, which gives the highest strength after polymerization. Positive pressure of 0.6 N/mm2 was applied and thermal catalytic polymerization was carried out. Optimum initiator concentration was found to be 2 percent. Strength (compressive and tensile) increases with polymerization temperature up to 120°C, above which rapid deterioration occurs due to monomer loss, production of short chains with high polymerization rates, and the possibility of polymer degradation at high temperature. Optimum polymerization period of' 10 hours was selected. Inexpensive methods for field polymerization were tried at 95°C. Hot water yields a strength more than double that obtained with a, flow of hot air and about 80 percent of that obtained radiolytically. While hot air accelerates evaporation, hot water forms a hydraulic head above the capillaries and decreases the monomer losses tremendously.
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    Free radical solution oligomerization of styrene in a continuous-stirred tank reactor train (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1253-1259 
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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: For free radical oligomerization of styrene, a scheme for calculating the molecular weight distribution and conversion in a continuous-stirred tank reactor (CSTR) train is developed, which also allows the calculation of molecular weight distribution (MWD) for batch reaction. Calculations show that under conventional or near dead-end condition: (1) increasing initial initiator concentration, reaction time and reaction temperature, and decreasing initial monomer concentration cause P̄n and P̄w to decrease and MWD to narrow; (2) increasing initial initiator concentration, reaction time and reaction temperature, and increasing monomer concentration cause monomer conversion to increase; (3) a single CSTR gives a lower rate of oligomer production, but a narrower MWD than does a batch reactor.
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    Torsional braid analysis of bitumen-liquid rubber mixtures (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 252-258 
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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 performance of liquid rubbers as low-temperature plastcizers for bitumen was evaluated by the torsional braid technique developed by Gillham. The low-temperature dynamic mechanical properties of bitumen-liquid rubber mixtures were measured from ambient to -100°C and compared with the corresponding fracture behavior using a modified Fraass test. Microscopic observation of the mixture revealed that the liquid rubber was partially soluble in the bitumen at 23°C and at concentrations greater than 10 percent tended to form colloidal dispersions of rubber particles having mean diameters of approximately 10 μm. The loss tangent maxima shifted to lower temperatures and became less pronounced as the concentration of liquid polybutadiene increased. The colloidal rubber dispersion further contributed to the ductility and reduced the brittle temperature of the bitumen at -30°C at 20 percent liquid rubber concentration. The reduction in the brittle temperature of the bitumen is related to the glass-transition temperature of the added rubber, those rubbers having, the lowest glass-transition temperatures being most efficient. Such modifications are necessary to reduce the tendency of asphaltic paving materials to crack in cold climates.
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    The influence of high storage humidity on some properties of solid propellantsThis paper is based on part of the work undertaken for a thesis for an M.Sc. degree in chemical Engineering by the first author under the supervision of the second author. (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 275-277 
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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 absorption of water vapor by propellants based on hydroxy-terminated polybutadiene and an isocyanate from atmospheres of increasing relative humidities, and the swelling index of the propellant which had absorbed various proportions of water, were measured in an attempt to establish the extent of hydrolytic damage. The method was found incapable of assessing such damage, but it was shown that there was no measurable absorption of vapor below 92 percent relative humidity (RH). The MEK/polymer and toluene/polymer interaction parameters were determined.
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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.760240501
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    Microphase structure and properties of polyurethane/polyvinyl interstitial composites (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 293-310 
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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 morphology of two series of polyurethane/polyvinyl interstitial composites is characterized by scanning electron microscopy, small-angle light scattering, and small-angle X-ray scattering. Thermal and mechanical properties are measured using differential scanning calorimetry and dynamic mechanical analysis. The polyurethane networks examined are microphase separated segmented block copolymers. A variety of linear and network vinylic components are studied including polymethacrylonitrile homopolymer and copolymer, and polyacenaphthalene homopolymer and copolymer. The polyurethane and polyvinyl components phase separate during the in situ polymerization resulting in a three-phase morphology. Detailed small-angle X-ray scattering analysis provides measurements of phase mixing, domain spacings, and diffuse phase boundary thicknesses. A comparison of these parameters for parent polymers and composites reveals only slight differences; indicating that the microdomain structures of the phase-separated polyurethane networks are preserved in the composite. Appreciable molecular interpenetration of components is not observed. Dynamic mechanical loss measurements for several of the composites demonstrate the presence of loss processes occurring over extremely broad ranges of temperature. The strong mechanical interaction between components observed suggest that the urethane and vinyl phases may be bicontinuous in these materials.
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    Panel and general discussion (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1359-1365 
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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.760241714
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    A basic study of orientation in poly(ethylene terephthalate) stretch-blow molded bottles (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1390-1395 
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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 series of stretch-blow molded poly(ethylene terephthalate) bottles were investigated using measurements of birefringences (in plane and out of plane) and wide angle x-ray diffraction (WAXS) pole figures. Both bottles prepared in our laboratories and commercial bottles were investigated. Birefringences Δn13 and Δn23 of inside and outside surfaces of bottles were determined as a function of position along the length of the bottle (1-bottle axis, 2-hoop direction, 3-thickness direction). The Δn13, Δn23 for the inside surface of the bottles were found to be greater than those for the outside surface indicating heterogeneity through the thickness of the bottles. The WAXS studies indicate that the benzene rings in the polymer align parallel to the bottle surface. The chain axis in crystalline regions exhibit orientations close to equal biaxial orientation. Both Δn13 and Δn23 increased with inflation pressure.
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    Predicting water diffusivity in elastomers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1417-1420 
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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: By the use of water absorption data (rate and equilibrium), the diffusivity of distilled and salt water through Neoprene, styrene-butadiene, and ethylene-propylene-diene elastomers was predicted. Activation parameters were calculated from the Arrhenius plots and were used to calculate heats of solution (all negative). Solubility coefficients (S) were calculated from permeability (P) and diffusion (D) coefficients. For all materials salt water showed a lower D than distilled water but a higher S and P.
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    Small angle scattering from ampholytic styrene ionomersSome of these results were presented at the American Physical Society March Meeting, Dallas, 1982, and at the IUPAC Macro 82 Meeting, Amherst, July, 1982. (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 385-390 
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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: Small angle neutron scattering experiments were made on an ionomer synthesized from perdeuterostyrene and an ion pair comonomer. A Debye plot based on data from the sample with lower ion concentration gave a correlation length of 5.3A. Clustering is not significant in this sample. With a higher concentration of ionic groups a peak in the scattering curve is interpreted as due to clusters about 20A in diameter. These studies along with X-ray scattering and electron microscopy also indicate the presence of larger ion rich domains.
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    Flow analysis of rubber transfer molding (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 403-414 
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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: An experimental study has been carried out on rubber I transfer molding. It reveals that the filling is frequently limited more by the resistance of flow across the transfer pot than by resistance of flow through the sprue holes into the cavities. A mathematical model has been derived, which predicts semi-quantitatively the molding behavior observed. The mode1 predicts that fill time is proportional to the ratio of compound viscosity divided by molding pressure raised to about the fourth power. For the common cases where most of the fill time is from the resistance to the transverse flow on the top of the sprue plate, the fill time is proportional to about the fifth power of the ratio of transverse distance divided by the charge thickness. Experimental results showed that preheating and mastication of the compound reduced transfer time substantially. The charge pattern did not seem to have a major influence on transfer time.
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    Drying of plastics with time-varying surface concentration: Experiments on slabs and application to equipment analysis (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 460-468 
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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: Drying of hygroscopic plastics in preparation for molding or extrusion is characterized by very low moisture levels in the polymers and by very low humidity in the drying air. In these circumstances, diffusivity is essentially independent of moisture concentration but surface concentration will vary with time in the general case. An exponential surface concentration/time function is derived from fundamentals and applied to the solution of the diffusion equations for slabs and spheres. Under ideal drying conditions, the solutions reduce to the elementary case in which cs = cf for θ 〉 0. For non-ideal drying, the exponential factor b̃ in the surface concentration function appears in the solutions of the diffusion equations. Experiments on slabs were used to verify the analysis since ideal or non-ideal drying conditions could readily be set up with molded slab samples. Experimental drying curves are in agreement with theory. To complete the analysis for engineering applications, equations for counter flow heat transfer in the dryer hopper are derived and combined with the diffusion solutions to generate dryer performance data.
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    Morphology of polyethylene-polypropylene blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 488-492 
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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 morphology of blends of high-density polyethylene (PE) and isotactic polypropylene (PP) was studied by mesans of optical and scanning-electron microscopy. In the range of 10 to 90 percent by weight PE, these blends are two-phase systems, the components of which crystallize separately into discrete phases. The presence of PE has a definite and pronounced effect on the crystalline structure of the PP, whose spherulitic structure becomes increasingly irregular and coarse with increasing PE content. The light transmission of these blends during melting and crystallization was also studied in an attempt to characterize them.
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    Isothermal swell of extrudate from annular dies; effects of die geometry, flow rate, and resin characteristics1Some of the results contained in this paper were presented at the October 1982 meeting of the Society of Rheology in Evanston, Illinois.2The data in this paper are from the doctoral dissertation of N. Orbey, submitted in May of 1983. (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 511-518 
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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: An experimental study was made of the effects of die geometry and extrusion velocity on parison swell for three high-density-polyethylene blowmolding resins. Four annular dies were used: a straight, a diverging, and two converging dies. Diameter and thickness swells were measured as functions of time under isothermal conditions and in the absence of drawdown. This was accomplished by extruding into an oil having the same density and temperature as the extrudate. It was observed that 60 to 80 percent of the swell occurs in the first few seconds and that equilibrium swell is attained only after 5 to 8 minutes have elapsed. The diameter and thickness swells appear to be independent phenomena, as the relationship between them depends strongly on die design. The ranking of the resins in terms of the magnitude of the swell was found to be the same for all die geometries and extrusion rates used.
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    A novel hysteresis test for studying crazing and shear yielding in rubber-toughened polymers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 535-540 
    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, tensile impact, compact tension, and fatigue tests were carried out on ABS (acrylonitrile-butadiene-styrene), HIPS (high impact polystyrene), and toughened PMMA (poly(methyl methacrylate)). Dumbbell specimens machined from test pieces were then subjected to sinusoidal tension-compression cycling at low stress amplitudes. The HIPS specimens produced asymmetrical hysteresis loops characteristic of multiple crazing, whereas PMMA gave more symmetrical, regularly shaped, loops. The behavior of the ABS polymers varied with loading history. It was concluded that the hysteresis test provides a useful additional technique for studying deformation mechanisms, especially under conditions that do not readily permit volumetric measurements.
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    URL: http://dx.doi.org/10.1002/pen.760240805
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    Mathematical modeling of melting of polymers in a single-screw extruder (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 988-999 
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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 addresses the apparent controversy surrounding the role of the solid bed mechanics in the Maddock melting mechanism. It is demonstrated that the inability of the melting models based on the freely deformable solid bed concept to predict accurately the pressure gradients in the melting zone is not exclusively due to the highly simplified isothermal Newtonian treatment of the melt pool as presumed previously. This study has shown that when using a non isothermal non-Newtonian flow model for the melt pool, the freely deformable solid bed concept still results in unrealistically low pressure gradients while it may give good predictions of the melting rates. To the contrary, when a rigid solid bed is assumed, the pressure predictions tend to represent the experimental data more closely, whereas the theoretical melting rates seems to become less realistic. In view of the fact that both the freely deformable and the rigid solid bed concepts show such inconsistencies, it has been concluded that the mechanics governing the solids and melt transport in the melting zone require some additional examination, most notably, the influence of the constitutive behavior of the solid bed and of the cross-channel melt circulation around the solid bed, and possibly of the melting kinetics for semicrystalline polymers.
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    Mechanical properties and molecular aggregation of soluble aromatic polyimide (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1021-1025 
    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: Dynamic and static mechanical properties of a soluble aromatic polyimide (PI 2080) were investigated. It, unlike poly(pyromellitimide) (PI), was essentially amorphous in X-ray diffraction and did not exhibit any heterogeneous two-phase structure having ordered phases after annealing at temperatures around its glass transition temperature. The mechanical properties including thermal-distortion temperature and elastic recovery were not much affected by the annealing. The difference in molecular aggregation and mechanical properties between PI 2080 and PI may be due to their different chemical structures. The flexible carbonyl group and the statistical distribution of copolymeric repeating units in the main chain of PI 2080 seem to prevent the formation of molecular order.
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    URL: http://dx.doi.org/10.1002/pen.760241304
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    A Wide-angle X-ray diffraction method of determining chopped fiber orientation in composites with application to extrusion through dies (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1051-1055 
    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 method of determining fiber orientation in composites using wide-angle X-ray diffraction (WAXS) is described. Oriented crystalline fibers are suspended in an amorphous polymer matrix. The WAXS reflects characteristics of the fiber are used to determine the mean orientation and orientation distribution of the crystallographic axes representing the polymer chain relative to preferred axes located in the test specimen. The chain direction crystallographic axis is taken as representing the fiber axis, and the orientation of this axis to represent the orientation of the fibers. Experimental studies were carried out using Kevlar (poly(p-phenylene terephthalamide)) fibers suspended at a 20 volume percent loading in a polymethyl methacrylate matrix. The Kevlar fibers had Hermans orientation factors of 0.92. Specific attention is given to how through circular dies. We have examined both extrudates and the material frozen-in when the composite in the reservoir and die is cooled to room temperature. Fiber orientation factors, corresponding to Hermans orientation factors, 0.3 to 0.38 were obtained for the extrudates. Orientation factors for fibers within the die is about 0.45. Specially prepared completely oriented samples had orientation factors of 0.93, which closely corresponds to the orientation of the fiber.
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    Numerical simulation of entry and exit flows in slit dies (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 707-715 
    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 general-purpose finite element program has been used to simulate the flow of Newtonian, power-law, and viscoelastic fluids in the entry and exit regions of a slit die. It was found that shear-thinning increases the entrance correction while it decreases the exit correction. Shear-thinning reduces the size of the small corner vortex that forms in the entry flow of a Newtonian fluid. The swelling ratio had a value of 1.196 for Newtonian fluids and decreased as the value of the power-law index decreased. Viscoelastic calculations were performed using the Criminale-Ericksen-Filbey (CEF) constitutive equation. Convergence of the iterative scheme was unattainable for Deborah numbers above 1.0. The results showed a decrease of the entrance correction and an increase of the exit correction with elasticity. Extrudate swell first decreased slightly and further increased with the Deborah number.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240913
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    Craze fibril formation and breakdown (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 761-769 
    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 crazes grow in areal extent they also increase in width. The areal growth involves craze tip advance which has been shown to occur by the Taylor meniscus instability. Craze widening, at least for air crazes, occurs by drawing more fibrillar material from the craze-bulk polymer interfaces at essentially constant extension ratio. Simple arguments will be given to predict the scale of the fibrillation in terms of the stress S at the craze tip and interfaces and an effective polymer surface energy (Γ) where:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\Gamma = \gamma + {\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 4$}}d \cdot v_E U_b} $$\end{document} which assumes that all entangled chain crossing the surface are broken [γ represents the van-der-Waals (intermolecular) surface energy, d is the entanglement mesh size, vE is the entanglement density, and Ub is the energy required to break a single backbone bond]. These arguments also give the rate of fibrillation as a function of S, a nominal plastic resistance σy and Γ and can explain the fact that the stress for crazing increases relative to that for shear deformation as the entanglement density of the polymer is increased. The geometrically necessary entanglement loss (either by scission as assumed above or by disentanglement- at temperatures just below Tg) that accompanies fibril formation has important consequences for fibril stability. The probability p that a given entangled chain is lost can be computed from simple geometrical considerations knowing the fibril diameter D, its extension ratio λ and the mesh size d; p increases rapidly as Dλ½ becomes comparable to or less than d. These concepts can be tested in blends of high molecular weight polymer with chains of the same polymer that are too short to entangle.
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    Effects of stress and vapor exposure before and during aging on enthalpy relaxation of poly(vinyl chloride) (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1123-1129 
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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: Enthalpy relaxations in glassy poly(vinyl chloride) following varied pre-aging treatments and under varied aging conditions have been compared through observations of sub-Tg endothermal DSC (differential scanning calorimetry) aging peaks. The extent of enthalpy relaxation for a fixed time and temperature of aging is progressively enhanced by the imposition and release of increasing mechanical stress before aging. The same effect is produced by sorption and desorption of increasing amounts of CO2 or CH3Cl vapor before aging. In contrast, the continued application of mechanical stress, or the presence of vapor, during the aging period suppresses enthalpy relaxation. The extent of suppression increases with increasing vapor pressure and solubility or increasing stress. These effects are interpreted as consequences of an increase in the enthalpy of the polymer under mechanical or sorptive stress and an enthalpy relaxation following the release of this stress. In addition to these effects on the DSC endotherm, a pronounced exotherm between the aging peak and Tg is observed for samples which have undergone shear yielding or orientation either before or during aging. This exotherm may be the result of release of stored strain energy during the DSC scan.
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    Relaxation induced changes in electrical behavior of glassy chalcogenide semiconductors (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1149-1154 
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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: Effects of structural relaxation and the glass-transition process are clearly manifested in the electrical behavior of glassy-chalcogenide films. Analysis of the transport and trapping of photoinjected carriers and of the thermal generation of free carriers in the bulk reveal that in chalcogenides each of these processes is mediated by a specific manifold of localized electronic states residing in the mobility (forbidden) gap. It is demonstrated that in the vicinity of Tg the population of these states varies systematically with the structural state of the glassy film always tending toward a temperature-dependent quasi-equilibrium. The present-observations thus clearly establish the structural origin of key electronic-gap states and simultaneously reveal the mechanism by which relaxation impacts electrical behavior.
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    Spherulite growth in isotactic polypropylene-based blends: Energy and morphological considerations (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1155-1165 
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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 kinetics of isothermal crystallization of polymer blends in which the matrix is a crystallizable polymer is considered. It is shown that depending on the difference in interfacial energies the inclusions are rejected or engulfed by the growing spherulite. Other factors influencing rejection, engulfing, and/or deformation of dispersed particles of the second polymer are the viscosity of the melt, the spherulite growth rate, and the size of dispersed particles. If the difference in interfacial energies is positive, then rejection or engulfing requires additional work to be done by the crystallization front. This dissipation of energy decreases the spherulite growth rate. It is estimated that the rejection of the second component is the most important phenomenon in the crystallization of blends. The spherulite growth rate of isotactic polypropylene in blends with low-density polyethylene and several elastomers was studied as a function of crystallization temperature and concentration. The comparison of growth rate data with morphological changes occuring during crystallization of blends studied shows very good agreement with the theoretical predictions based on energetics considerations.
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    Anisotropic aspects of the environmental stress cracking of acrylonitrile-butadiene-styrene and styrene acrylonitrile copolymers in methanol (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1174-1179 
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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: Critical strains causing environmental stress cracking of injection-molded poly(acrylonitrile-butadiene-styrene) (ABS) and poly(styrene-acrylonitrile) (SAN) plaques were determined upon exposure to methanol. Measurements were obtained for samples strained either parallel or perpendicular to the melt flow direction and for samples located at various distances from the mold gate. Critical strains were significantly higher in the direction parallel to the melt flow compared to the transverse direction. The degree of anisotropy increased with increasing rubber content. For ABS containing 46 percent rubber, the critical strain at one point was determined to be 2.99 percent in the direction of melt flow, but only 0.47 percent in the orthogonal direction. For this material, critical strains determined parallel to the melt flow decreased with distance from the gate; whereas, critical strains for SAN and ABS containing 30 percent rubber remained essentially constant. Orientation of the plaques was assessed using shrinkage determinations and a thermal conductivity technique. Though a straightforward correlation of orientation with critical strain is observed for ABS, a similar relationship is not observed for SAN. These results suggest that although stress cracking occurs in the glassy matrix of ABS, it is the dispersed rubbery phase which controls the magnitude of strain required to initiate cracking.
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    Kinematics, dynamics and stability of the tubular film extrusion of various polyethylenes (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1185-1201 
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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 basic study of the kinematics, dynamics, and heat transfer occuring during tubular film extrusion of polyethylene is outlined. Three rheologically characterized polyethylenes, a low-density polyethylene (LDPE), a linear-low-density polyethylene (L-LDPE), and a high-density polyethylene (HDPE) were used in this study. The kinematics and stability of the tubular film process were investigated over a wide range of blow-up ratios, drawdown ratios, and frost-line heights. Local deformation rates along the bubble have been determined. Regions of stability and instability are described. Tensions and inflation pressures have been measured and expressed in terms of locol elongational viscosities. Temperature profiles along the bubble were determined and interpreted in terms of local heat transfer coefficients. Positions of crystallization and temperature profiles have been noted and used to estimate rates of crystallization. The characteristics of the LDPE, LLDPE, and HDPE are contrasted.
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
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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.760241601
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    Thermodynamics of polymer solutions, especially poly(dimethyl siloxane) solutions (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1219-1226 
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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: An improved non-random free-volume theory of polymer solutions is presented. It is based on Flory's Equation-of-State theory which is modified to account for differences in the size of core volumes of segments in pure liquids and in solution. In addition, it is corrected for non-randomness through Guggenheim's Quasi-Chemical approach. The theory is tested against experimental results on heats of mixing, volumes of mixing, and χ interaction parameters of poly (dimethyl siloxane), polyisobutylene and natural rubber solutions with gratifying results. Relations with existing similar theories are discussed.
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    Manufacture of urea-formaldehyde concentrates using a gas-liquid technology (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1245-1248 
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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 performance of a laboratory packed-column for the manufacture of urea-formaldehyde (UF) concentrates is analyzed. Gaseous formaldehyde was generated by the thermal decomposition of paraformaldehyde in a carrier nitrogen stream. The UF solution was continuously recirculated through a glass column filled with Raschig rings. No pH control was necessary when the operation was started using a solution with a F/U molar ratio higher than 3.5 to 4. Otherwise, insoluble resins appeared during the operation. The formaldehyde absorption rate was controlled by the gas phase resistance. The vapor composition in equilibrium with a typical UF concentrate is provided as a function of temperature.
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    Molecular kinetic theory of the glass transition (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1079-1086 
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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: An overview of a new molecular kinetic theory of glass-transition phenomena is presented and experimental comparisons of its prediction for a variety of thermal and stress histories reviewed. The theory, which was developed in accordance with the balance of nonequilibrium statistical entropy, is shown to provide a unified interpretation of some recent models. The volume-relaxation process in amorphous polymers over the glass-transition region is regarded as the result of the collapse of a series of free volumes having different levels of energies of hole formation. An applied stress is shown to contribute to the variation of the entropy. An activation volume is introduced as a new tensorial extensive variable. The theory is applied to the phenomenon of physical aging in polymer glasses and shown to provide good quantitative agreement with the results of a well-known experiment on volume recovery of poly(vinyl acetate). This supports the underlying postulate of a fundamental link between the apparent relaxation time and the mean energy of hole formation, the distribution of relaxation times and the free-volume fractions. In contrast to the prevalent thinking toward free volume theories, an explicit expression between Tg and stress is presented and reveals that Tg does not continue to increase at all pressures but levels off to a semi universal asymptote at very high pressure. The calculated effect of stress rate is found to be in good agreement with dynamic viscoelastic measurements.
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    Physical aging of heavy metal fluoride glasses - sub-Tg enthalpy relaxation in a ZrF4-BaF2-LaF3-AlF3 glass (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1117-1122 
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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 enthalpy changes during structural relaxation or physical aging of a 58ZrF4-33BaF2-5LaF3-4AlF3 (ZBLA) glass during annealing well below the glass-transition temperature have been studied using differential-scanning calorimetry at several sub-Tg temperatures. Substantial relaxation within the course of several hours was detected at temperatures as low as sixty degrees below Tg (585K). The relaxation process is extremely nonlinear and self-retarding. The time dependence of the enthalpy during the initial stages of annealing was modeled approximately using the Narayanaswamy-Tool approach. The structural-relaxation parameters obtained from this fit were used to predict rates of physical aging for rapidly cooled ZBLA glass at temperatures close to ambient.
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    A simple test method for the response of materials to large bending deformations (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1172-1173 
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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 simple test device is described for subjecting bars to large bending deformations and simultaneously monitoring the bending moment. Examples are given of the elastic bending of a bar of a natural rubber vulcanizate and of the maximum bending moment that molded bars of polyethylene and polypropylene can withstand before the fully-plastic state is attained.
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    Fatigue life prediction of filled polypropylene based on creep rupture (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1180-1184 
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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: To predict the fatigue performance of talc-filled polypropylene in engineering applications, a simple relationship using constant stress data to predict the cycles-to-failure (Nf) was developed:\documentclass{article}\pagestyle{empty}\begin{document}$$ N_f = kv\sigma ^{ - n} f(n) $$\end{document} where k and n are constants from creep rupture tests, v is the cyclic frequency (≤1 Hz to avoid self-heating), f(n) is a function that accounts for the wave form, and a is the peak cyclic stress with a zero minimum stress. For stress concentrations produced by central holes, σ is taken as the average net section stress and the effect of the stress concentration is ignored. Extensive tests were used to verify this expression for cyclic frequencies of 1.0 and 0.1 Hz, sinusoidal and triangular waveforms, stress concentrations produced by small and large holes, and 20 and 40 percent talc filler content.
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    Optimization of the polycondensation step of polyethylene terephthalate formation with continuous removal of condensation products (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1205-1214 
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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 polycondensation step of poly(ethylene terephthalate) (PET) formation is assumed to include various side reactions in addition to the usual polymerization reaction. Polymerization in the batch reactor at constant pressure has been modeled to flash volatile components at the end of small discrete time intervals with polymerization occurring during the interval. The Hamiltonian has been written for the time interval and optimum temperature history computed for batch reactors for various reactor pressures. For low pressures, computed optimum temperature history is found to be of similar nature as that used in industry.
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    Confined parison inflation behavior of a high-density polyethylene (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1232-1239 
    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 analysis of the confined parison inflation step associated with the extrusion blowmolding of a high-density polyethylene is presented. Based upon simple geometrical considerations and material conservation principles, relationships describing the wall thickness variation have been obtained for various mold configurations. The experimentally measured part thickness distribution is found to be in good qualitative agreement and reasonable quantitative correspondence with the theoretical predictions. Furthermore, the expressions for the thickness variation have been utilized in order to estimate the confined inflation time for the case of a power-law constitutive equation. In addition, a brief discussion of some practical mold design considerations is given based upon the theoretical analysis.
    Additional Material: 16 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241604
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    Thermal energy storage in columns packed with crosslinked polyethylene tubes (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1227-1231 
    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 energy storage system based on solid-solid phase transition of crosslinked polyethylene was constructed and tested. The energy storage unit consisted of a column packed with crosslinked polyethylene tubes. The solid-solid phase transition enables heat transfer by direct contact between the form-stable polymer and the hot (cold) fluid. A theoretical model for the simulation of this system was developed. The heating-cooling characteristics of the energy storage system were simulated by the model, using measured thermodynamic properties of the crosslinked polyethylene. The potential of various crosslinked polyethylene materials for energy storage applications will depend on sufficient high-temperature stability.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241603
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    A note on the role of diffusion during the inflation of a tubular viscoelastic film (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1249-1252 
    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 mathematical simulation of the effect of diffusion on the inflation of a cylindrical polymer film has been developed. The rheological constitutive equation of polymer was assumed to obey an Oldroyd fluid B type. Calculated results indicate that the diffusion coefficient and solubility of the gas have a profound influence on the film or membrane expansion.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241607
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    Measurement of mixing in polymer melts by focused ultrasound (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1277-1282 
    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 outlines the development of an acoustical technique for measuring the dispersion of an additive in a polymer melt. It included a justification of the use of sound over other interrogating methods and an analysis of the acoustical system's operation. Results for dispersions of liquid or solid additives were shown. It was demonstrated that this system could detect the presence or absence of large particles in melts filled with small particles.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241611
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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.760241701
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    Statistical thermodynamics of blends: Equation of state and phase relations (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1284-1290 
    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 discuss the free-energy expressions for homogeneous melts and their blends, based on our hole theory. Equation of state (PVT) and free energy of mixing (ΔGm) are considered from a common point of view without the introduction of additional parameters to pass from the first to the second set of properties. Practical problems arise from the fact that ΔGm represents a difference between large quantities. As illustrations we analyze two typical systems. One is the n - C6 + n - C16 pair where PVT and ΔGm, the latter at atmospheric pressure only, have been studied experimentally. The other is n - C6 with a low and high molecular weight respectively of polyethylene as solute. Here the PVT relations of the components only are known. The effects of intercomponent attractions, temperature, pressure, and molecular weight on phase behavior are investigated. Critical coordinates, lower critical-solution temperatures (LCST) and their pressure dependence are computed. An iso-free volume condition obtains for this dependence where free volume is defined by the hole fraction inherent in the theory. Comparisons with experimental observations and other theoretical computations for different molecular weights are limited by the effect of polydispersity. Moreover, cloud point curves are shown. We finally compute the composition and pressure dependence of the χ-parameter which is implicit in the theory. We conclude with some comments regarding polymer blends.
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    Polycarbonate blends with polystyrene and polypropylene (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1312-1318 
    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 polycarbonate/polystyrene (PC/PS), polycarbonate/polypropylene (PC/PP) and ternary blends of the three components (PC/PS/PP) were studied. Extrudate swell of the molten blends increased with increasing concentrations of the minor components and leveled off at characteristic blend compositions. These compositions corresponded to the limits of compatibility as judged by the onset of brittleness in tensile tests. Both PS and PP appear to have some limited practical compatibility with PC. The change in extrudate swell behavior with concentration may be a rapid and convenient test for the effective concentration limits of partially miscible polymers.
    Additional Material: 17 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241708
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    Development of phase morphology in incompatible polymer blends during mixing and its variation in extrusionThe experimental studies described were carried out at the University of Tennessee as part of the Ph.D. Dissertation of K. Min. (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1327-1336 
    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 development of phase morphology in incompatible polymer melt blends of polyethylene/polystyrene (PE/PS), polyethylene/polycarbonate (PE/PC), and polyethylene/nylon-6 (PE/N6) is presented. Different temperatures (180°C, 240°C) of mixing and polyethylene molecular- weight levels were used in the PE/PS studies. Little variation in the cross-sectional phase morphology of the PE/PS extrudates was observed with these variables, though the morphology became finer with increased shear rate/stress in capillary die flow. Variations in the longitudinal morphology are observed with continuous filaments of dispersed phase only arising when the dispersed phase has an equal or lower viscosity than the continuous phase. The PE/N6 and PE/PC, especially the former, give coarser morphologies when the N6 and PC are the continuous phases. This was attributed to larger inter-facial tensions. The effect of viscoelasticity was also discussed.
    Additional Material: 24 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241710
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    Ultrasonic velocity measurement for the determination of density in polyethylene (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1354-1358 
    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 ultrasonic immersion method is presented for the rapid and accurate measurement of longitudinal sound velocity (v) in polyethylene (PE). The method is based solely on the measurement of time delays and can be automated. The samples are the same press-molded plaques that are prepared for the standard-density (ρ) determination using a density-gradient column, Our measurements on a representative group of various types of PE with densities in the range 0.92 to 0.96 g/cm3 show without ambiguity that v is proportional to ρ. The degree of correlation is such that we come to suggest that the acoustic method be used for the characterization of density. We show that the accuracy is good and compares with that of the density-gradient column and we then conclude on the practical advantages of the ultrasonic method.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241713
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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.760241801
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    Processing of composites with titanate coupling agents - a review (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1369-1382 
    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 proposed that titanium-derived coupling agents react with free protons at the inorganic interface to form organic monomolecular layers on the inorganic surface, which causes inorganic/organic phase compatibilization resulting in new composite property, catalysis, adhesion, and rheology performance standards. Processing techniques and rheology effects using titanates are discussed. The injection pressures of CaCO3, carbon black filled polystyrene, and glass-fiber, talc-filled poly(phenylene sulfide) are shown to be reduced 50 percent by use of cumyl phenyl type titanate. Adhesion effects are discussed in many composites such as epoxy/aluminum, acrylic/slate, carbon fiber/polyester, etc., followed by data showing significant property improvements in 1/16 inch milled glass fiber and Wollastonite RRIM urethane, printed circuit boards and amide and anhydride cured aramid fiber-reinforced epoxy.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241802
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    General treatment of polymer crystallization kinetics - Part 2. The kinetics of nonisothermal crystallization (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1402-1408 
    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 isothermal macrokinetic equation of polymer crystallization has been generalized to cover nonisothermal situations as well. The process of nonisothermal crystallization of poly(caproamide) has been studied experimentally. It is shown that the macrokinetic equation of the autocatalytic type can be used to solve both direct and inverse problems of nonisothermal polymer crystallization. Use of the inverse approach has made it possible to establish the value of the constants of the new kinetic equation. The general statement of the problem of nonisothermal crystallization of polymers in an inhomogeneous temperature field is considered. Inhomogeneous temperature and conversion fields have been calculated for model products of different sizes and configurations.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241806
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    Chemiluminescence apparatus and method for studying thermal oxidative stability of polymers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1421-1428 
    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 chemiluminescence multi-sample apparatus and method are described for determining polymer stability by measuring the intensity of the light emitted during thermal oxidation. Depending on the nature of a material analyzed the experiments are performed either under O2 atmosphere at a constant temperature or under N2 atmosphere at a constant heating rate. In the former case applicable to polypropylene (PP) and acrylonitrile-butadiene-styrene copolymers (ABS), parameters such as induction time and oxidation rate can be evaluated. In the latter case applicable to nylon and polyethylene terephthalate (PET), the extent of oxidation in a certain temperature region can be evaluated by measuring the area under the intensity of light - temperature curve. Along with providing a great deal of knowledge on thermal oxidative stability, the chemiluminescence approach gives the additional information concerning polymer quality. The appearance of the low-temperature pulses on the chemiluminescence curve observed before the onset of autocatalytic oxidation is associated with the history and processing of the sample and with the natural aging of the polymer.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241809
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    The effect of a temperature gradient on residual stresses and distortion in injection moldings (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 227-241 
    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: Distortion of bars injection-molded from polystyrene, polypropylene, and glass-fiber-filled polypropylene and subsequently placed in a temperature gradient has been examined. Residual stress distributions have been measured both for the as-molded state and after annealing in a temperature gradient. In the as-molded state all moldings showed the usual residual stress distribution with compressive stresses near the surface and tensile stresses in the interior. In all three materials it was found that tensile stresses could be developed near to the warmer surface on gradient annealing and that tensile stresses still remained at this surface when the bar was cooled and permitted to bend to restore internal equilibrium. It is shown therefore that in addition to the dimensional changes which occur and which may render the molding unserviceable after temperature gradient annealing, another undesirable change takes place, leaving the molding much more susceptible to fracture from a surface flaw. Uniform annealing is found to be much less likely to cause stress reversal and the stresses remain balanced so that distortion is minimal.
    Additional Material: 18 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240402
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    Necking behavior of low-density polyethylene-isotactic polypropylene blends: A morphological investigation (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 264-267 
    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 tensile behavior of low-density polyethylene-isotactic polypropylene blends was investigated at room temperature. Neck formation and propagation along the whole length of the samples were observed for the whole range of composition. This behavior, which is not indicated by most data available in the literature, was examined in relation to sample morphology by scanning electron microscopy. The results of this investigation indicated some differences between the morphology of these materials and the morphology of blends which do not undergo necking propagation.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240406
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    Preface (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 291-291 
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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.760240502
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    The crystalline morphology of poly(vinylidene fluoride)/poly(methylmethacrylate) blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 311-318 
    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(vinylidene fluoride), PVF2, as well as blends of PVF2 with poly(methyl methacrylate), PMMA, develop a variety of crystalline morphologies at low undercoolings. Both the α and γ crystal forms grow from the melt and the former undergoes a solid-solid phase transition to the latter, though its morphology remains unaltered. Three melting temperatures which decrease with increasing PMMA content are observed. Hoffman-Weeks analysis shows the equilibrium melting points of the blends to be depressed. Using these equilibrium values, the thermodynamic interaction energy density is calculated to go from -5.40 × 106 to -2.96 × 107 j/m3 as the blend composition goes from 40.1 volume percent to pure PVF2. The band periodicity in the α form spherulites increases with crystallization temperature and PMMA content and it appears to be from a lamellar reorientation process with an apparent activation energy of 322 cal/mole. Electron diffraction patterns taken along the radial direction in a given spherulite reveal lamellar twisting which causes the banded appearance. Light scattering results suggest that the lamellar are formed into rod-like structures on a local scale but that on a larger scale they develop a disoriented spherulitic morphology.
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    Positional small angle X-ray scattering from flaws (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 373-375 
    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 simple theory of PSAXS (positional small angle X-ray scattering) has been developed and used to aid in the interpretation of PSAXS data from flaws. The importance of the various experimental parameters has been studied and an explanation offered for apparent magnification. A comparison between images created by assumed flaw structures and from actual flaws has been made. It is proposed that three dimensional imaging of flaws can be performed.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240512
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    Poly(p-phenylene terephthalamide) films formed from extrusion and coagulation of liquid crystalline sulphuric acid solutions: Characterization of orientation and void structure, annealing, and upgrading of film mechanical properties (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 242-251 
    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(p-phenylene terephthalamide) (PPD-T) films have been prepared by continuous extrusion of liquid crystalline 17 percent PPD-T/sulphuric acid solutions through an annular die followed by coagulation, Films extruded without drawdown exhibit some polymer chain orientation in the machine direction. This is increased by uniaxially drawing down films. Films produced with a lubricated conical mandrel sitting between the die and the coagulation bath exhibit an equal biaxial orientation. The uniaxially oriented films exhibit highly anisotropic mechanical properties, while the mandrel-produced film exhibits balanced properties. Heat treatment at 350°C results in significant enhancement of the tensile strength of the mandrel film. Void structures in the films have been investigated by mass density, scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS). Density measurement indicate a void content decreasing with decreasing film thickness and heat treatment. SEM locates micron-size voids in the thickest films, apparently caused by rapid coagulation. SAXS indicates much smaller void sixes which are roughly prolate ellipsoids (long axis in machine direction) for uniaxial films and oblate ellipsoids (short axis in thickness direction) for the mandrel produced films. Various techniques are used to estimate mean void size.
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    URL: http://dx.doi.org/10.1002/pen.760240403
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    Photodegradation of some poly(vinyl chloride) (PVC) blends: PVC/ethylene-vinyl acetate (EVA) copolymers and PVC/butadiene-acrylonitrile (NBR) copolymers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 278-286 
    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(vinyl chloride) (PVC) and its blends with polybutadiene-acrylonitrile (NBR) (containing 21.7 weight-percent acrylonitrile (AN), a heterogeneous two-phase system; and containing 41.6 weight-percent of AN, a homogeneous one-phase system) and with polyethylene-vinyl acetate (EVA) (containing 45 weight-percent of vinyl acetate (VA), a heterogenous two-phase system; and containing 65 weight-percent VA, a homogeneous one-phase system) were UV-irradiated (at 3500 Å UV-light (solar spectrum)). After UV irradiation the kinetics measurements were made of the formation of hydroperoxy (OOH) and carbonyl (CO) groups and the changes of mechanical properties: tensile strength, elongation to break, and impact energy. As a result of the photooxidative degradation of PVC blends, decreases of mechanical properties were observed. The effects are more severe in PVC/NBR blends, which contain unsaturated bonds (polybutadiene segments) than in the case of PVC/EVA. The phase structure plays an evident role on the UV degradation only of PVC/NBR blends. The photostability of PVC blends can be slightly improved by introducing Tinuvin P or Ni-chelates photostabilizers.
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    URL: http://dx.doi.org/10.1002/pen.760240409
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    Biographical sketch of professor Richard S. SteinDepartment of Chemistry and Director of Polymer Research Institute, University of Massachusetts, Amherst, Massachusetts 01003 (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 292-292 
    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.760240503
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    Effect of prestrain on the subsequent thermal crystallization of a copolyester of lactic and glycolic acid (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 319-327 
    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 investigation was carried out in order to study the effect of prestrain on the subsequent crystallization of a specific copolyester based on lactic and glycolic acid. This polymer, which can be easily quenched into an amorphous glass, has a Tg of 43°C and when in crystalline form has a melting point of 210°C. Using amorphous films, samples were prestrained to various levels at temperatures not far above Tg. In some cases films were immediately quenched at the prestrain level so as to retain the elongation while others were allowed to immediately retract whereby they showed a relatively small degree of permanent Set. Utilizing birefringence, quenched samples whose initial elongation was maintained showed linear behavior with prestrain while those that retracted showed essentially zero birefringence until a prestrain of about 150 percent after which a small degree of positive birefringence resulted. Wide angle x-ray diffraction (WAXS) showed no signs of crystallinity in all cases. These same films were then quickly taken to 150°C and rapidly crystallized. Again, one series of the prestrained samples were in the elongated state during crystallization whereas the second series was unrestrained during crystallization. Using microscopy and small angle light scattering (SALS), the morphological textures of these crystallized films were investigated. In all cases, spherulitic textures were observed of equivalent size up to a value of about 200 percent elongation the spherulite size systematically decreased with the prestrain an increase in clearly showing that prestrain had a pronounced effect upon the nucleation density. Increasing draw rate displayed a similar effect on nucleation density. Since spherulite size was noted to be the same in either series, it indicated that nucleation was induced as a result of the prestrain and remained irrelevant of whether the sample was allowed to relax or not. The morphology above the transitional state was similar to row structure common to polymers crystallized in the oriented state. WAXS and birefringence was applied to the crystallized materials and it was found that up until the transitional zone, no crystal orientation was observed in either series indicating that although nucleation density was strongly affected up until that point, no orientation was retained within the sample upon crystallization. A simplified model is used to explain the observed results.
    Additional Material: 16 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240506
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    Concerning voids in polyimide (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 345-349 
    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: Small angle X-ray scattering (SAXS) has been used to evaluate the size and concentration of voids in poly(N,N′-bis-(phenoxyphenyl)pyromellitimide), PMDA-ODA. Analysis of the angular dependence of the scattering indicates the presence of voids ranging from 50 to 150 Å in radius. Integrated SAXS demonstrated that the volume fraction of voids was 7 × 10-4. These results were supported by measurements of the attenuation factor as a function of the sample thickness.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240508
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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.760240601
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  • 88
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    Dynamic X-ray diffraction studies of spherulitic poly-alpha-olefins in relation to the assignments of alpha and beta mechanical dispersions (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 361-372 
    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 dynamic tensile deformation mechanism of spherulitic poly-alpha-olefins, high-density polyethylene, isotactic polypropylene, and isotactic polybutene-1, was investigated by dynamic X-ray diffraction at various temperatures and frequencies in order to assign the α and β mechanical dispersions explicitly. The uniaxial orientation distribution function qj(ζj, 0) of the j-th crystal plane and its dynamic response Δqj′(ζj, 0) in-phase with dynamic strain were observed for several crystal planes, and then the orientation distribution function ω(§, 0, η) of crystallites (crystal grains) and its dynamic response Δω′(§, 0, η), also in-phase with the dynamic strain, were determined by a mathematical transformation procedure proposed by Roe and Krigbaum on the basis of the Legendre addition theorem. The temperature and frequency dependences of Δω′(§, 0, η) were analyzed in terms of a spherulite deformation model combining affine orientation of crystal lamellae with several types of preferential reorientation of the crystal grains within the orienting lamellae. The following assignments are made: (1) the a mechanical dispersion must be assigned to the dynamic orientation dispersions of crystal grains within lamellae involving two types of preferential rotations of the grains associated with lamellar detwisting mostly in the equatorial zone of uniaxially deformed spherulites and with lamellar tilting mostly in the polar zone of the spherulites. Both processes are intralamellar grain-boundary phenomena, and the former process of lamellar detwisting is hardly activated for polypropylene and polybutene-1 spherulites in contrast to polyethylene spherulites. (2) The β mechanical dispersion must be assigned to the dynamic orientation dispersion of the crystal lamellae behaving as rigid bodies unaccompanied by reorientation of crystal grains within the orienting lamellae. This process is an interlamellar grain-boundary phenomenon.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240511
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    Preamble (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 69-69 
    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.760240202
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  • 90
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    Fluorescence techniques in the study of polymer colloids (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 87-97 
    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: Applications of fluorescence techniques to the study of polymer colloids are reviewed, with emphasis on excimer and exciplex forming probes and fluorescence energy transfer processes. In these experiments non-aqueous dispersions covalently labelled with naphthalene or anthracene were examined by a variety of techniques in order to elucidate aspects of core morphology with a resolution of about 10Å. The current “concentric sphere” or “core-shell” model of colloid structure was found to be inconsistent with the results of the luminescence experiments. A new “microphase” model is proposed which overcomes these difficulties. In this model, the core structure is seen to be made up of phase-separated microdomains of core and stabilizer chains.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240205
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    Rheological and mechanical behavior of the UHMWPE/MDPE mixtures (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 117-126 
    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 attempt was made to melt incorporate ultra high molecular weight polyethylene, UHMWPE, into medium density polyethylene, MDPE. The behavior of the mixtures, containing up to 6 wt percent of UHMWPE, was examined using mechanical and rheological testing. The mechanical test results were found to contain large experimental errors, which makes interpretation very difficult. On the other hand, melt rheology studies, using dynamic and extensional deformations, gave direct insight into the extent and effect of blending. Degradation during the processing was evaluated by size exclusion chromatography. The degree of dispersion of the UHMWPE was examined under the optical microscope.
    Additional Material: 25 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240209
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    Some observations on kinetic and steric limitations to specific interactions in miscible polymer blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 112-116 
    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 note describes the application of infrared spectroscopy to determine the proportion of ester groups of poly(∊-caprolac-tone) which are involved in specific interactions with the hydroxyl groups of the poly(2-hydroxypropyl ether of bisphenol A) (Phenoxy, Union Carbide) in a series of miscible blends of the two polymers, Even with a fifteen-fold excess of hydroxyl groups, only about 50 percent of the ester groups of poly(∊-caprolactone) are hydrogen-bonded, presumably reflecting steric restrictions to the ester-hydroxyl interactions. Partially miscible blends of these two polymers may also be prepared by a suitable choice of casting solvent, and infrared spectroscopy may then be used to follow the kinetics of miscibility when the partially miscible blend is heated.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240208
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    Analysis of transient sorption and permeation of small molecules in multiphase polymer systems (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 153-162 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The transport of small molecules (gases) in incompatible polymer blends, semi-crystalline polymers, and filled polymer systems is usually examined in terms of transient sorption and permeation experiments which yield effective values of diffusivity and permeability. From a modeling standpoint these complex systems can be regarded as composites with complex morphology whereas the gas can be considered as a molecular probe of the morphology and especially its connectedness. In this paper we present a brief review of transport descriptions in prototype ordered and disordered systems with special emphasis on simulation of transient measurements. The simulations presented are selected in such a way as to aid in the interpretation of experimental results obtained by sorption and permeation and in the construction and evaluation of morphologies with desired effective transport properties.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240213
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  • 94
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    Optimization of the transesterification stage of polyethylene terephthalate reactors (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 185-193 
    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 tranesterification step of the polyethylene terephthalate (PET) formation consists of several side reactions in addition to the main ester interchange, transesterification, and polycondensation reactions. The side reactions considered in this work are acid end group, acetaldehyde, diethylene glycol, water, and vinyl end group formations. The objective function of the batch esterinterchange reactor is assumed to consist of maximizing the conversion and simultaneously minimizing the formation of side products. The control vector iteration procedure has been used to optimize the esterinterchange reactor and the temperature-time profile that gives the best performance has been found. It is found that the reactor should be operated at a high temperature initially to obtain high conversion of dimethyl terephthalate (DMT) first, but then it should be lowered to reduce the formation of side products.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240305
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  • 95
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    Hot water aging of polycarbonate (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 211-217 
    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: Internal cracking and microvoids are shown to form during room temperature storage of polycarbonate samples that have previously been exposed to boiling water. These microcracks or microvoids are actually disc-shaped pockets filled with water. This formation occurs due to the creation of water super-saturation conditions by cooling water-saturated specimens from 100°C to room temperature. As a result, water phase-separation, clustering, and microvoiding result and lead to deterioration of the mechanical properties. Visual healing of the microcracks is also sometimes observed at room temperature, especially under a dry atmosphere. Water from the water-filled pockets diffuses through the polycarbonate matrix to the external dry environment; the very thin emptied pockets then close and visually heal. This paper provides experimental data for the microvoiding process and clarifies the special mechanism of cracking/healing in polycarbonate samples.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240308
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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.760240401
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  • 97
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    The plasticization of an epoxy resin by dibutylphthalate and water (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1270-1276 
    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 glass-transition temperature of an epoxy resin cured at two different temperatures and plasticized with water and dibutylphthalate has been studied. Both modulus of elasticity and yield stress were measured as a function of temperature to determine the glass-transition temperature. Drying a saturated material appeared to restore the glass-transition temperature to its original value but some broadening of the transition occurred. The behavior of an undercured epoxy when saturated with water could not be predicted by theory. A substantial increase in the transition temperature was observed which may have been caused by the presence of water and an expanded structure.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241610
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    Correction (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1290-1290 
    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.760241704
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  • 99
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    Compatibilization of polyester/polyamide blends via catalytic ester-amide interchange reaction (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1300-1305 
    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 a series of publications we reported on melt rheology, morphology, and mechanical properties of the poly(ethylene terephthalate)/poly(amide-6,6) blends (PET/PA). The non-oriented samples had poor interphase bonding resulting in low impact and tensile strengths. To improve these properties the ester-amide interchange reaction was carried out in solution and in melt. In the latter case a Brabender Plastograph was used in the mixing chamber or twin-screw extruder configurations with p-toluenesulfonic acid as a catalyst. The interchange reaction was followed by 400 MHz proton and 13C nuclear magnetic resonance spectroscopy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241706
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  • 100
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    Rheological and mechanical properties of ternary blends of linear-low-density polyethylene/polypropylene/ethylene-propylene block polymers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1319-1326 
    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 addition of an ethylene-propylene block polymer on rheological and mechanical properties of a linear-low-density polyethylene/polypropylene blend was examined. The samples were prepared by melt blending in a twin-screw extruder followed by injection molding. The single-, two- and three-component systems were treated the same way. The mechanical behavior of the blends was evaluated by means of tensile, and flexural, tests at 23 and -40°C. The capillary, elongational, and dynamic-flow measurements were performed at 190°C.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241709
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