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  • 1
    Electronic Resource
    Electronic Resource
    SANS from hot-stretched polystyrene revisited (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 1607-1612 
    Details
    ISSN: 0887-6266
    Keywords: neutron scattering (SANS) from hot stretched polystyrene ; polystyrene, hot stretched, SANS study of ; chain deformation in hot stretched polystyrene, SANS study of ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Small-angle neutron scattering (SANS) has been used to investigate macromolecular orientation of uniaxially hot-stretched partially deuterated polystyrene. Principle radii of gyration and degree of eccentricity were measured over a range of hot-stretch temperatures, strain rates, and external draw ratios (EDR). Results show affine deformation for EDR 〈4 and an increase in the degree of local molecular orientation with increasing rate of strain and decreasing stretching temperature. It also is found that although the macromolecules follow the external stretching affinely on average, they do not deform uniformly.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090291306
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    In situ X-ray scattering studies of lyotropic liquid crystalline PBO and PBZT monofilament drawing (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 2567-2573 
    Details
    ISSN: 0887-6266
    Keywords: poly(cis-benzoxazole) ; poly(trans-benzothiazole) ; lyotropic ; liquid crystalline ; monofilament ; x-ray scattering ; compressive strength ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The results of a series of novel synchrontron-based in situ x-ray scattering experiments of monofilament fiber drawing from lyotropic solutions of poly(cis-benzoxazole) (PBO) and poly(trans-benzothiazole) (PBZT) are reported. The purpose of the study is to determine orientation and microstructure development in the draw zone as a function of shear rate in the capillary die, and spin draw ratio (SDR). The transition of the extrudate from opaque to the transparent is complete at about a SDR = 3 and f of 0.9. The filament orientation parameter (f) was found to depend strongly on spin draw ratio, but not shear rate. The orientation was found to increase down the extrudate toward completion of the draw down as one proceeds further from the die face up to an extrudate length of 3.8 cm. Coherence lengths on the order of 19 nm (axial), and 4.5 nm (lateral) have been observed. These “microdomain” sizes are consistent with the “crystallite” sizes typically observed in coagulated fiber. The occurrence of these microdomains in the draw zone as a precursor to the microfibrillar structure is believed to be the origin of low filament compressive strength. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090321602
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Coagulation of poly(p-phenylene benzobisoxazole) in polyphosphoric acid using aqueous and nonaqueous solutions (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1621-1626 
    Details
    ISSN: 0887-6266
    Keywords: poly(p-phenylene benzobisoxazole) ; PBO ; polyphosphoric acid ; diffusion ; fluorescence microscopy ; aqueous coagulants ; nonaqueous coagulants ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Diffusion of aqueous and nonaqueous coagulants into lyotropic/nematic solutions of poly(phenylene benzobisoxazole) in polyphosphoric acid using fluorescence microscopy is reported. The fluorescence microscopy technique offers advantages in that the experiment is independent of the coagulant and the experiments can be performed in a front surface mode so that optically thin samples are not required. The diffusion process is modeled as Case II diffusion as described by Crank and Park. The apparent diffusion coefficients are found to range from ∼ 2 × 10-6 cm2/s to ∼ 2 × 10-7 cm2/s for aqueous and nonaqueous coagulants. The apparent diffusion coefficients can be varied by several orders of magnitude (e.g., down to ∼ 3 × 10-10 cm2/s) by varying the concentration of polyphosphoric acid in the coagulant. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090331106
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of processing conditions on the fracture behavior of syndiotactic polystyrene films (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 1483-1490 
    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 fracture behavior map for syndiotactic polystyrene (sPS) film as a function of annealing temperature and the extension ratio has been developed. The fracture initiation and propagation processes of the film were characterized by a specialized video-based real-time thin-film fracture technique. An unusual layered complex deformation mechanism has been observed for the films fabricated at high extension ratios. This mechanism enhances the resistance to crack growth in sPS films. © 1996 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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