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Volumn 101, Issue 15, 1997, Pages 2745-2749

Structure of solid poly(tetrafluoroethylene): A computer simulation study of chain orientational, translational, and conformational disorder

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EID: 0001712066     PISSN: 15206106     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp963333k     Document Type: Article
Times cited : (42)

References (18)
  • 2
    • 36448999840 scopus 로고
    • Schwickert, H.; Strobl, G.; Kimmig, M. J. Chem. Phys. 1991, 95, 2800, 2807. For hydrocarbons, see e.g.: Sirota, E. B.; King, H. E., Jr.; Singer, D. M.; Shao, H. H. J. Chem. Phys. 1993, 98, 5809.
    • (1991) J. Chem. Phys. , vol.95 , pp. 2800
    • Schwickert, H.1    Strobl, G.2    Kimmig, M.3
  • 16
    • 4143057878 scopus 로고    scopus 로고
    • note
    • The assumption of a uniform helical ground state is a simplification since the experimental ground state consists of a mixture of right- and left-handed helices. In refs 5 and 8 it is argued that the average zero helicity of a bulk sample is achieved by organizing chains segments with equal handedness in domains separated by dislocation planes consisting of helix reversal defects. At low temperature the characteristic distance between these planes is at least as large as the length of a chain in our simulation.
  • 17
    • 4143113269 scopus 로고    scopus 로고
    • note
    • In ref 8 it is suggested that this correlation takes the form of coherent pairs of helix reversal defects. The distribution of defects in our simulation appears to be more disordered.
  • 18
    • 4143053350 scopus 로고    scopus 로고
    • note
    • In order to obtain an estimate of the effect of possible nonequilibrium states, we cooled the system again at the same rate as it was heated starting from a state just before the system displayed the first signs of melting. The phase I energies, lattice parameters, and dynamical properties were reproduced with satisfying accuracy. However, the spontaneous reestablishment of long range orientational order occurred at considerably lower temperature (425 K) compared to the disordering upon heating (575 K). This 150 K hystersis gives an estimate of the effect of superheating (and undercooling) that is caused by the rate of heating (cooling) used in the simulation. For similar reasons the onset of melting is observed at a higer temperature than the thermodynamic melting point of our model. Experimentally, the disordering transition occurs around room temperature. Finite-size scaling effects and deficiencies in the potential model are the likely cause of the higher transition temperature. These issues will be explored in more detail in ref 13.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.