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  • 1
    Electronic Resource
    Electronic Resource
    Monte Carlo simulation of the order–disorder transition of a symmetric cyclic diblock copolymer system (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 1712-1720 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The microphase separation of symmetric cyclic diblock copolymer with decreasing temperature is simulated using the Monte Carlo method. In order to investigate the effect of the ring-shape chain architecture on order–disorder transition (ODT), the microphase separation of the cyclic diblock copolymer is compared with that of a symmetric linear diblock copolymer with the same chain length. For both systems, the ODT is observed as a first-order transition, and the ordered structure formed through the ODT is lamellar. The ratio of the domain spacing in the cyclic diblock copolymer to that in the linear one is 0.7 at the ODT, and the scattering intensity of the former is weaker than that of the latter. The ring-shape chain architecture suppresses the random thermal force, so that the cyclic diblock copolymer still shows a mean-field behavior at the temperature at which the linear diblock copolymer does not obey the mean-field prediction. The value of (χeffN)ODT of the linear diblock copolymer is calculated to be in the range of 25.36〈(χeffN)〈26.04, which is in good agreement with the theoretical prediction, (χeffN)ODT=25.61, indicating that this simulation properly describes the ODT of the diblock copolymer. The value of (χeffN)ODT of the cyclic diblock copolymer is predicted to be in the range of 40.83〈(χeffN)〈43.02. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479431
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of the mechanical behavior of poly(trimethylene terephthalate) in an amorphous state under uniaxial extension–compression condition through atomistic modeling (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 7524-7532 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The mechanical behavior of poly(trimethylene terephthalate) (PTT) in an amorphous state was simulated under uniaxial extension–compression conditions through atomistic modeling. The elastic properties obtained from the well-defined structure were comparable with those obtained from experiments. Typical stress–strain curves showing yielding and plastic behaviors were obtained under both extension and compression conditions. It was observed that the stress under uniaxial compression is higher than the stress under uniaxial extension with the same strain. The absence of structural defects in samples for simulation leads us to conclude that the difference of stress levels between two conditions is not intrinsically related to structural defects. Various analyses of chain conformation such as bond orientation, the dihedral angle, and Voronoi volume tessellation shows that the PTT chain under extension undergoes conformational changes different from those under the compression condition. When the change in the energetic state of PTT is calculated as a function of strain, it is revealed that the dihedral angle torsion energy and the van der Waals interaction energy play more important roles in deformation under extension than under compression. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478655
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Monte carlo simulation of copolymerization by ester interchange reaction in miscible polyester blends (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1637-1645 
    Details
    ISSN: 0887-6266
    Keywords: ester interchange reaction ; Monte Carlo method ; copolymerization ; degree of randomness ; miscible polyester blend ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of reaction variables on the degree of randomness in copolymers formed by ester interchange reaction in miscible polyester melt blends were systematically investigated using a Monte Carlo method. Three reaction variables such as the molecular weight difference between two component polymers, the blend ratio, and the reaction ratio of end attack to bond flip, were particularly considered on the cubic lattice model. Ester interchange reactions were assumed to take place during reptational chain motions. It was found that the copolymerization was dependent upon the molecular weight difference and reaction ratio: As the molecular weight difference becomes smaller and when both end attack and bond flip reactions are involved simultaneously, the copolymerization is accelerated. However, the blend ratio does not affect the copolymerization process. This result is discussed in relation to the polymer chain conformation for the ester interchange reaction. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1637-1645, 1998
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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