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  • 1
    Electronic Resource
    Electronic Resource
    Theory of crystallization in high-speed spinning (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 661-666 
    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: Removal of the heat of fusion during steady-state crystallization in a high-speed spinline places restrictions on the morphology of the crystallites. An appropriate model is that of a thermal dendrite. It is shown that for this case there exists at each temperature along the threadline a limiting growth velocity, beyond which heat cannot be conducted away fast enough to permit growth. It is suggested that crystallization occurs when a fluid element reaches a temperature at which heat can just be conducted away rapidly enough. Comparison of dendrite theory predictions with experimental values of crystallite diameter and crystallization temperature shows satisfactory agreement. Poly(ethylene terephthalate) has been taken as the example.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310907
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  • 2
    Electronic Resource
    Electronic Resource
    Structure and mechanical properties of highly oriented poly(ethylene terephthalate) films (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 964-970 
    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 relationships between the supermolecular structure of poly(ethylene terephthalate) films subjected to cold drawing and subsequent zone annealing and their mechanical properties are investigated. The effectiveness of zone annealing is compared to that of annealing with fixed ends. Microstructural changes occurring during heat treatment and zone annealing are monitored using wide angle X-ray scattering, small angle X-ray scattering, infrared spectroscopy, differential scanning calorimetry, and static mechanical tests. The very high modulus and strength of the zone-annealed films are directly attributed to the large number of the molecules connecting the crystallites.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760321408
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  • 3
    Electronic Resource
    Electronic Resource
    Confinement orientation (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 785-786 
    Details
    ISSN: 0887-6266
    Keywords: crystal orientation induced by confinement ; polypropylene, confinement orientation of ; poly(ethylene oxide) confinement orientation of ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090300717
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  • 4
    Electronic Resource
    Electronic Resource
    Structure and property development in poly(p-phenylene terephthalamide) during heat treatment under tension (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1-14 
    Details
    ISSN: 0887-6266
    Keywords: poly (p-phenylene terepthalamide) ; Kevlar® ; heat treatment ; structure development ; mechanical properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The evolution of several structural characteristics during isothermal heat treatment of poly(p-phenylene terephthalamide) was studied. In this work, heat treatment was interrupted after different treatment times, with the specimens immediately quenched to room temperature. These specimens were then characterized by tensile testing, wide- and small-angle x-ray scattering, and optical microscopy. Structural parameters obtained from these measurements relate to crystal perfection (via the paracrystalline axial distortion parameter), axial crystallite size, transverse crystallite size, degree of chain misorientation, and degree of pleating. Structural and mechanical parameters were then plotted against heat-treatment time to obtain kinetic isotherms for each parameter. The kinetics of the removal of chain misorientation parallels that of tensile modulus increase under all conditions. Of the other structural parameters, only the kinetics of pleat removal mimics that of modulus change, indicating that pleat removal is the effective cause of increased chain alignment and thereby of increased axial stiffness. ©1995 John Wiley & Sons, Inc.
    Additional Material: 27 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330101
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of bond interchange reactions on mechanical behavior of solid poly(ethylene terephthalate) (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2307-2316 
    Details
    ISSN: 0887-6266
    Keywords: ester interchange ; small-angle neutron scattering ; poly(ethylene terephthalate) ; creep ; stress relaxation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reported are a pair of studies exploring the possible role of transesterification during the deformation of poly(ethylene terephthalate) (PET) near its glass transition temperature. SANS experiments on PET-D/PET-H blends were carried out on films drawn according to the method of Petermann and Gohil at 70 and 90°C. In order to avoid effects of orientation on the SANS pattern, the measurements were made on liquid solutions made from the drawn material. The results show a decrease in the D-sequence length upon deformation, while the molecular weight of the chain is unchanged. This result indicates that bond exchange has taken place. Based upon the SANS results, an approximate activation energy in the 8-24 kcal/mol range is reported for bond interchange. To test the hypothesis that transesterification may play a role in the mechanical behavior of PET near Tg, creep measurements were carried out over a temperature range on either side of Tg. Activation energies obtained from time-temperature superposition shift factors showed a dual behavior: above Tg the activation energy matches those for diffusive processes in PET; below Tg the activation energy coincides with activation energies reported for exchange reactions in this material. The role of annealing prior to deformation is also reported, and it is shown that the activation energy increases rapidly with increasing annealing temperature. © 1996 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Interatomic correlation in partially oriented polymer fibers (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 883-888 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The atomic ordering in materials possessing cylindrical symmetry can be investigated by an approximation of the cylindrical distribution function in a given direction. The approximation gives correctly the extent of the interatomic correlation for a wide class of polymer fibers and reduces considerably the amount of the experimental and computational times.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090290713
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  • 7
    Electronic Resource
    Electronic Resource
    Rapid mechanical deformation of poly(ethylene terephthalate) fibers at temperatures above the glass transition (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 125-133 
    Details
    ISSN: 0887-6266
    Keywords: mechanical deformation ; PET ; high-temperature deformation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanical properties of poly(ethylene terephthalate) (PET) fibers at temperatures above the glass transition are investigated by means of a specially constructed device. Measurements of the deformation rate and of the “dynamic” stress-strain curves of the fibers are performed in nearly isothermal regime (after initial rapid heating) in a temperature interval 100-200°C. The results reported in the present work demonstrate that the high-temperature mechanical characteristics of rapidly crystallizing polymers can be deduced to a satisfactory precision, while keeping the crystallinity development at low level. Our investigations indicate that if the high-temperature deformation is sufficiently fast, the polymer behavior is similar to the deformation at sub-Tg temperatures. Based on this similarity, a qualitative model of the deformation in the high-temperature region is proposed. The proposed model is fundamentally equivalent to the models describing mechanical deformation of glassy polymers at temperatures below the glass transition. ©1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330113
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  • 8
    Electronic Resource
    Electronic Resource
    Thermal response and structure of PET fibersWork supported in part by the National Science Foundation under Grant No. CPE8304058 (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 1647-1663 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The structure and the thermal response of polyethylene terephthalate (PET) fibers, melt-spun at speeds of 3 to 6 km/min, are investigated in the temperature region 0-200'C. Differential scanning calorimetry thermograms, and radial distribution functions from wide-angle x-ray scattering are used. Interpretation of multiple glass transition and crystallization peaks and of the range of structural coherence is interpreted in terms of a nonhomogeneous molecular arrangement for fibers melt-spun at intermediate spinning speeds. A three-phase model of the molecular structure of these fibers is used to explain the results. An important feature of the model is the existence of a threadlike, interconnected, highly oriented noncrystalline phase, coexisting with a more unoriented amorphous phase. The model can qualitatively explain a number of experimental observations.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090281001
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  • 9
    Electronic Resource
    Electronic Resource
    Consolidation of high-modulus PET laminates and the role of chemical healing (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 113-126 
    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: In this work, a process for making high-modulus (8GPa) laminates of poly(ethylene terephthalate) (PET) has been developed. Oriented films of the polymer were produced by a technique utilizing a very high extension rate, and these films were crossplied and consolidated to form the product laminates. The procedures for drawing the original film lamina and consolidating the laminates were optimized with respect to the material properties. Further, the possibility of chemical healing-bonding of the lamina together by chemical reaction, not diffusion-was investigated for these materials. It was found that laminates could be formed with both high moduli and strong interply bonding and that the moduli actually increase due to crystallization during pressing. Longrange diffusion during bond formation was ruled out, since crosslinked polyesters were found to bond as readily as uncrosslinked. Chemical reactions between contacted surfaces appear to be a likely mechanism of bonding.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070400110
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  • 10
    Electronic Resource
    Electronic Resource
    Processing, microstructure, and failure behavior in short-fiber-reinforced poly(ether ether ketone) composites (1990)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 11 (1990), S. 126-132 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Short-fiber-reinforced poly(ether ether ketone) (PEEK) composites were prepared by a specially designed mold. Both compression- and extrusion-molded plaques were obtained under the same thermal history. The fiber length distribution, fiber volume fraction, and fiber orientation are characterized. The fibers show an in-plane random orientation in compression-molded plaques, but they exhibit a 3-layer fiber orientation well-known for injection moldings in extrusion-molded composites. It is the final aim to simulate the rheological and morphologic behavior in injection moldings by using the laboratory designed extrusion/compression mold. Static compact tension (CT) specimens and electron microscopy (EM) were used to investigate the failure behavior. Results showed that crack initiation is the dominant failure energy absorption process in a brittle fracture, whereas crack propagation is dominant in a ductile failure. The extruded composites were mechanically characterized in two orthogonal directions (T- and L-type). The anisotropy factor is reported as 1.2.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750110209
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