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  • 1
    Electronic Resource
    Electronic Resource
    Deuteron NMR analysis of the molecular origin of the thermal relaxations in polycarbonates (1988)
    s.l. : American Chemical Society
    Macromolecules 21 (1988), S. 2058-2063 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00185a030
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  • 2
    Electronic Resource
    Electronic Resource
    Monofilament drawing device for in situ x-ray scattering studies of orientation development in polymeric fibers (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 2652-2657 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The physical properties of polymer fibers are directly related to the development of orientation in the draw zone under extensional conditions. Although the final properties and microstructure of fibers can be evaluated after processing is completed, it is desirable to understand the development of orientation during drawing independently from the effects superimposed by subsequent unit operations. In situ x-ray scattering measurements of the extrudate in the draw zone provide an ideal means of accomplishing this goal. Depending on the polymeric system to be studied, rotating anode or synchrotron-based x-ray sources may be required, making portability of the fiber drawing device highly desirable. This paper describes an easily transportable in situ x-ray filament drawing device, and discusses typical data obtained using the device to produce filaments from a liquid crystalline nematic solution of poly(cis-benzoxazole) in polyphosphoric acid. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145604
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  • 3
    Electronic Resource
    Electronic Resource
    The inclination angle of nonisotropic inhomogeneities determined by SANS (1986)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 19 (1986), S. 320-323 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The angle between the axis of symmetry of nonisotropic inhomogeneities and the surface of a bulk sample is sometimes unknown. This angle may be determined by fitting small-angle neutron scattering (SANS) data taken at two or more different sample inclination angles. The feasibility of this technique is verified by analyzing SANS data taken at different tilt angles from a well characterized hot-stretched (partially deuterated) polystyrene sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S002188988608929X
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  • 4
    Electronic Resource
    Electronic Resource
    Treatment of SANS data from hot stretched polystyrene chains (1990)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 23 (1990), S. 1-5 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The small-angle neutron scattering technique is applied to a hot stretched 5% perdeuterated polystyrene sample in order to investigate the residual macromolecular orientation at various length scales. The observed orientation is left over after fast quenching (in ice water) of the hot stretched sample. Previous investigations focused on how much polymer chains follow the external stretching. It is found that, even when macromolecules follow the external stretching affinely on the average, they do not deform uniformly. Moreover, over the time scale of the temperature quench, small chain portions relax more rapidly than large ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889889008484
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  • 5
    Electronic Resource
    Electronic Resource
    Modes of deformation in rubber-modified thermoplastics during tensile impact (1991)
    Springer
    Journal of materials science 26 (1991), S. 6249-6259 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Real-time small-angle X-ray scattering (RTSAXS) studies were performed on a series of rubber-modified thermoplastics. Scattering patterns were measured at successive time intervals as short as 1.8 ms and were analysed to determine the plastic strain due to crazing. Simultaneous measurements of the absorption of the primary beam by the sample allowed the total plastic strain to be computed. The plastic strain due to other deformation mechanisms, e.g. particle cavitation and macroscopic shear deformation was determined by the difference. Samples of commercial thicknesses can be studied at high rates of deformation without the inherent limitations of microscopy and its requirement of thin samples (i.e., plane strain constraint is maintained on sample morphology). Contrary to the conclusions drawn from many previous dilatation-based studies, it has been demonstrated that the strain due to non-crazing mechanisms, such as rubber particle cavitation, and deformation of the glassy ligaments between rubber particles, occurs before that due to crazing mechanisms. Crazing accounts for at most only half of the total plastic strain in HIPS (high impact polystyrene) and ABS (rubber-modified styrene-acrylonitrile copolymer) materials. The proportion of strain attributable to crazing can be much less than half the total in thermoplastic systems with considerable shear yield during plastic deformation. The predominant deformation mechanism in polycarbonate-ABS blends is shear in the PC (polycarbonate) with associated rubber gel particle cavitation in the ABS. This cavitation means that there appears to be a direct relationship between gel particle rubber content in the ABS and toughness of the blend. The mechanism is the same whether the tensile stress is in the direction parallel or perpendicular to the injection-moulded orientation, with simply less total strain being reached before fracture in the weaker perpendicular direction. Crazing, although the precursor to final fracture, occurs after the predominant mechanism and contributes only a few per cent to the total plastic deformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02387801
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  • 6
    Electronic Resource
    Electronic Resource
    Modes of deformation in rubber-modified thermoplastics during tensile impact (1991)
    Springer
    Journal of materials science 26 (1991), S. 6249-6259 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Real-time small-angle X-ray scattering (RTSAXS) studies were performed on a series of rubber-modified thermoplastics. Scattering patterns were measured at successive time intervals as short as 1.8 ms and were analysed to determine the plastic strain due to crazing. Simultaneous measurements of the absorption of the primary beam by the sample allowed the total plastic strain to be computed. The plastic strain due to other deformation mechanisms, e.g. particle cavitation and macroscopic shear deformation was determined by the difference. Samples of commercial thicknesses can be studied at high rates of deformation without the inherent limitations of microscopy and its requirement of thin samples (i.e., plane strain constraint is maintained on sample morphology). Contrary to the conclusions drawn from many previous dilatation-based studies, it has been demonstrated that the strain due to non-crazing mechanisms, such as rubber particle cavitation, and deformation of the glassy ligaments between rubber particles, occurs before that due to crazing mechanisms. Crazing accounts for at most only half of the total plastic strain in HIPS (high impact polystyrene) and ABS (rubber-modified styrene-acrylonitrile copolymer) materials. The proportion of strain attributable to crazing can be much less than half the total in thermoplastic systems with considerable shear yield during plastic deformation. The predominant deformation mechanism in polycarbonate-ABS blends is shear in the PC (polycarbonate) with associated rubber gel particle cavitation in the ABS. This cavitation means that there appears to be a direct relationship between gel particle rubber content in the ABS and toughness of the blend. The mechanism is the same whether the tensile stress is in the direction parallel or perpendicular to the injection-moulded orientation, with simply less total strain being reached before fracture in the weaker perpendicular direction. Crazing, although the precursor to final fracture, occurs after the predominant mechanism and contributes only a few per cent to the total plastic deformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00551868
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Changes in yield and deformation of polycarbonates caused by physical aging (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1142-1148 
    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: Change in yield and deformation associated with physical aging was studied on a series of polycarbonates (bisphenol-A polycarbonate, polyestercarbonates, and phenolphthalein-bisphenol-A copolycarbonates) and a polysulfone. A combination of tensile and biaxial yield measurements, dynamical mechanical analysis, and high-resolution density measurements were performed. These data indicate that both free volume arguments and molecular entanglement arguments are inadequate for explaining the differences in large-scale deformation associated with physical aging for the polymers and the superiority of polyestercarbonates over the other resins. The local intramolecular and intermolecular conformation in the glassy state, as predicated by molecular structure, is apparently an important key to understanding physical aging in polycarbonate-type polymers.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241411
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  • 9
    Electronic Resource
    Electronic Resource
    Physical aging in thermosets of differing degrees of cure - master curve generation and the relation to mechanical properties (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1-5 
    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: Physical aging of a thermoset system based on bisphenol-A epoxy (DERTrademark of The Dow Chemical Company. 383) and tetrabromobisphenol-A cured with sulfanilamide and diaminodiphenylsulfone was studied as a function of cure history. Changes in the dynamic mechanical spectra for the thermoset system were correlated to changes in relative toughness associated with physical aging as determined by plane-strain biaxial tension-compression yield measurements. It was found that master curves, generated by using tan δ data obtained in the β relaxation temperature regime, are well related to the corresponding changes in mechanical properties and, hence, have predictive value. Relative toughness decreases and compressive yield increases with decreasing tan 5 because of decreased molecular segmental mobility. The relative extent of physical aging for the as-cast thermosets was shown to be linearly related to the cure time.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280102
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  • 10
    Electronic Resource
    Electronic Resource
    Environmental stress cracking in impact polystyrene (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 624-633 
    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: Environmental stress cracking (ESC) measurements for various impact polystyrenes were performed using a constant load technique with the specimens in contact with a 50/50 solution of cotton seed oil and oleic acid. It was shown that ESC in impact polystyrene is controlled by the transport of the aggressive liquid through a pre-established dry craze structure where capillary pressure is the driving force. At moderate stress levels just above the critical stress for environmental cracking, there is an apparent incubation time for the dry craze formation. The craze incubation time is strongly influenced by thermal stresses induced by the gel particles. As a consequence, ESC is two-stage process involving both an incubation time and actual crack growth. Control of the craze structure to maximize fibril content is essential for good ESC resistance. The craze fibril content can be altered by variables such as gel particle size, matrix molecular weight, plasticizer content, and rubber content.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760211009
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