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  • 1980-1984  (10)
  • Polymer and Materials Science  (10)
  • 1
    Electronic Resource
    Electronic Resource
    Rapid measurements of elastic modulus and density in polypropylene sheet during aging (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 1579-1584 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: New methods for rapidly obtaining elastic modulus and density measurements during isothermal polymer aging are given. The elastic measurements are performed using a Rockwell hardness tester. In this case, the elastic recovery is measured. Rapid density measurements are performed using a “double drop” density gradient columan method. Here, a fully aged and a freshly quenched specimen are dropped simultaneously into the column. Simultaneous column height differences directly measure the density difference of the two specimens. The results of these two experiments extend previously reported aging measurements to relatively low times of aging. A log (time) law for both properties is found to the smallest times measured.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260513
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  • 2
    Electronic Resource
    Electronic Resource
    Dependence of electrical breakdown on spherulite size in isotactic polypropylene (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 4183-4197 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 self-seeding technique, coupled with isothermal crystallization, was used to prepare isotactic polypropylene specimens of varying spherulite size, but of constant crystallinity and lamellar thickness. The latter quantities were also varied by changing the isothermal crystallization temperature. The electrical lifetime at constant applied voltage, in a point-plane geometry, was measured. It was found that the electrical lifetime decreased with increasing spherulite size and, more weakly, with decreasing crystallinity (at a given spherulite size).
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070291248
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  • 3
    Electronic Resource
    Electronic Resource
    Annealing of polypropylene films crystallized from a highly extended meltResearch sponsored by the Army Research Office (Durham) under Grant No. DAAG29-77-G-0201, by the U.S. Department of Energy, under Contract No. W-7405-eng-26 with Union Carbide Corporation, and by the Deutsche Forschungsgemeinschaft. (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 609-620 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin films of isotactic polypropylene were drawn from the melt at a very high rate of extension. Transmission electron micrographs of this material reveal fibrous crystals lying along the draw direction. The chain axis and fiber axis are identical. Dark field micrographs show a dark/light modulation along the fiber axis. Annealing at temperatures below 110°C produces no qualitative change in the electron microscope observations. Annealing between 110 and 150°C produces gradual dominance of lamellar crystals, oriented normal to the draw direction. Small-angle x-ray scattering (SAXS) data exhibit a strong streaking normal to the fiber axis, in broad agreement with the observed fibrosity. A Bragg peak along the draw directions shows that the modulation observed microscopically is a density modulation. The absence of second-order maxima and the dependence of the SAXS peak on treatment temperature strongly suggest that the axial modulation is a spinodal decomposition of the material into crystalline and amorphous regions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.180190405
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetics of microstructure rearrangement during annealing of cold-drawn isotactic polypropyleneSupported by the U.S. Army Research Office, under Grant No. DAAG-29-G-0187 and by Oak Ridge Associated Universities. (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 497-508 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The microstructure of polypropylene, annealed after cold drawing to an oriented state, was examined using density measurements and small- and wide-angle x-ray scattering (SAXS and WAXS) techniques. SAXS patterns were obtained after annealing (in an oil bath), and during annealing (of samples annealed in a furnace placed directly in the x-ray beam). Data, for isothermal annealing, showed an increase in SAXS intensity, in crystal perfection, and in density over the observed time range, but no change in long spacing during the same period. Long spacing, SAXS intensity, and density were all strongly dependent upon annealing temperature, increasing at higher temperatures. Upon annealing the elastic modulus and yield strength dropped below the as-drawn values in an immeasurably short time, and did not appear to change thereafter during the time range examined. The decrease was more marked for higher-temperature annealing. The kinetics of the micro-structural changes are compared qualitatively to the predictions of nucleation and growth theory and of spinodal decomposition. The defects in the microstructure are considered as the “solute molecules” of the spinodal model. The experimental results do not agree neatly with either model. However, a nonequilibrium thermodynamic approach appears to be the more promising. It is suggested that the kinetics of mechanical property change may be due to different rates of migration for different defect species.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.180200311
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  • 5
    Electronic Resource
    Electronic Resource
    Microstructure rearrangement during the heat-treatment of melt-drawn poly(ethylene terephthalate) fibers (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1927-1953 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Melt-spun poly(ethylene terephthalate) fibers were isothermally heat-treated at constant length. Microstructural changes occurring during the heat-treatment were monitored using specific gravity, wide-angle x-ray scattering (WAXS), small-angle x-ray scattering (SAXS), optical birefringence, and static mechanical testing. Major changes in the density of the most highly oriented fiber examined occurred in times below 100 ms. For less oriented fibers, the time scale for significant density change increases to the 1-10 s range. The course of birefringence increase approximates that of the density. WAXS measurements show that crystallinity develops at essentially constant crystal perfection, but that the orientation of the crystallites first decreases and then increases with time. SAXS results show development of a four-point pattern, the azimuthal angle of the lobes decreasing with initial orientation, with temperature, and with time. A streak transverse to the fiber axis develops more rapidly than do the lobes. A two-stage transformation process is envisaged, the first stage being the formation of defective crystal fibrils and the second being internal rearrangement of the fibrils to form more perfect crystallites, separated by more amorphous zones. Changes in the crystallite orientation are related to constraints of the noncrystalline material on the crystallites.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180211005
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  • 6
    Electronic Resource
    Electronic Resource
    Microstructural rearrangement during heat treatment of drawn nylon 66 fiberAccepted for publication November 23, 1984 (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 22 (1984), S. 781-792 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Melt-spun nylon 66 fibers were drawn and subsequently heat treated isothermally and quenched. The heat-treated fibers were then examined by wide-and small-angle x-ray scattering (WAXS and SAXS), by differential scanning calorimetry (DSC), and by static mechanical testing. These measurements allow one to follow microstructural changes taking place during the course of the heat treatment. WAXS results show that as the treatment progresses, the crystallites become both more perfect and more disoriented with respect to the fiber axis. SAXS results show crystallite thickening. DSC results show that the melting point increases, goes through a maximum, and then decreases as the heat treatment progresses. The tensile modulus decreases with time to an asymptotic level. The changes in crystallite perfection and thickness occur more rapidly than do the changes in crystallite orientation, modulus, and melting point. A model is proposed whereby the two time frames are related to intracrystalline and intercrystalline processes, respectively.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.180220501
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  • 7
    Electronic Resource
    Electronic Resource
    The kinetics of defect clustering in fibrillar polypropylene crystalsResearch sponsored by the Deutsche Forschungsgemeinschaft, by the Army Research Office under Grant No. DAAG29-79-G-0187, by the U.S. Department of Energy under Contract No. W-7405-eng-26 with the Union Carbide Corporation, and by Oak Ridge Associated Universities. Portions of this work were performed at the National Center for Small-Angle Scattering Research at ORNL, which is supported by NSF Grant No. DMR-77-24458 through interagency agreement No. 40-637-77 with the DOE. (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 523-534 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polypropylene films were produced by solidification during high-rate (〉104s-1) melt drawing. Small-angle x-ray scattering (SAXS) data were collected during interruptions of the annealing of these films. Fibrillar crystallization took place during the melt-drawing process. The fibrils exhibit an axial density modulation as determined by SAXS and transmission electron microscopy. Annealing increases the amplitude of the density modulation. Detailed examination of the SAXS curves shows that the modulation is approximately sinusoidal and that the amplification of the density modulation occurs with no change in periodicity. Comparison of SAXS curves taken at different times during annealing suggests a process similar to spinodal decomposition. It is proposed that the microstructural change within a fibril takes place by the axial motion and clustering of chain defects.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.180200313
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  • 8
    Electronic Resource
    Electronic Resource
    Absolute integrated SAXS measurements during the crystallization of linear polyethyleneResearch sponsored by the Army Research Office (Durham) under Grant No. DAAG 29-77-G-0201 and by the Department of Energy, Division of Materials Science, under Contract W-7405-eng-26 with the Union Carbide Corporation.Corrected proofs received April 29, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1365-1369 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Absolute intensity measurements of a dynamic small-angle x-ray scattering from a linear polyethylene were carried out during polymer crystallization from melt in a temperature range of 113.5° to 124.5°C. The mean-square modulation of the electron density over the irradiated volume was evaluated and the feasibility of dynamic experimentation for crystallization kinetic analysis was established. The results provide an absolute value of mass density of the amorphous phase of a semicrystalline polymer at the crystallization temperature.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.180200803
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  • 9
    Electronic Resource
    Electronic Resource
    Small-angle x-ray scattering studies of melting (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 239-245 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The course of melting of melt-crystallized polyethylene fractions and of a poly(ethylene oxide)-polystyrene-poly(ethylene oxide) triblock copolymer has been followed by small-angle x-ray scattering (SAXS). Changes in the intensity and shape of the SAXS curves indicated that both surface melting and melting over the full crystallite thickness (full-strand melting) take place. Full strand melting is the final, irreversible process. Comparison with an analytical model indicates that in the earlier stages of the irreversible, full-strand process the crystallites melt out randomly throughout the bulk. Later stages may occur by the simultaneous melting of a larger stack of crystallites.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180180207
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  • 10
    Electronic Resource
    Electronic Resource
    Crystallization of polymers under high tension: A dendrite model (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 22 (1984), S. 143-161 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystallization of highly oriented homopolymer melts (or glasses) is modeled. It is shown that in such cases heat flow controls the kinetics and microstructure of the transforming material. The situation is modeled similarly to the growth of a thermal dendrite, with the inclusion of large and variable concentrations of defects in the fibrillar crystals. Expressions relating the undercooling, growth velocity, filament tip radius, and defect concentration to a normalized tensile force are derived. Example predictions for the case of isotactic polystyrene are given.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.180220201
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