Hostname: page-component-cd9895bd7-p9bg8 Total loading time: 0 Render date: 2024-12-27T23:46:04.343Z Has data issue: false hasContentIssue false
  • English
  • Français

A crystal structure of ultra-dispersed form of polytetrafluoroethylene based on X-ray powder diffraction data

Published online by Cambridge University Press:  06 March 2012

V. M. Bouznik ,
S. D. Kirik ,
L. A. Solovyov  and
A. K. Tsvetnikov
V. M. Bouznik
Affiliation:
Boreskov Institute of Catalysis, Russian Academy of Sciences, Siberian Branch, Novosibirsk 630090, Russia
S. D. Kirik*
Affiliation:
Institute of Chemistry and Chemical Engineering, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk, 660090
L. A. Solovyov
Affiliation:
Institute of Chemistry and Chemical Engineering, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk, 660090
A. K. Tsvetnikov
Affiliation:
Institute of Chemistry, Russian Academy of Sciences, Fareast Branch, Vladivostok, 690022, Russia
*
a)Electronic mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

An X-Ray powder diffraction study of ultra-dispersed polytetrafluoroethylene was carried out. As well as a regular polytetrafluoroethylene the ultra-dispersed form contents a high proportion of the crystalline phase. The X-ray diffraction pattern could be described with two-dimensional hexagonal unit cell [a=5.685(1) Å, symmetry group p6mm]. Structural modeling with a continuous electron density approach as well as with a discrete disordered atoms distribution was accomplished. The model was refined using the Rietveld method. The structure is characterized by a spiral arrangement of polymers (CF2-)n along the z-axis with complete mutual disordering by rotational displacement around z, as well as a partial molecular translation along the z-axis. Molecular disordering results in a systematic absence of reflections with 1≠0 and as a sequence in two-dimensional unit cell effect. The presence of complete rotational disordering distinguishes the ultra-dispersed form of polytetrafluoroethylene from the standard one (fluoroplast-4), where only partial disordering is observed.

Type
Technical Articles
Information
Powder Diffraction , Volume 19 , Issue 3 , September 2004 , pp. 219 - 224
Copyright
Copyright © Cambridge University Press 2004

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Allen, F. H. (2002). “The Cambridge structural database: A quarter of a million crystal structures and rising,” Acta Crystallogr., Sect. B: Struct. Sci. ASBSDK 58, 380–388. acl, ASBSDK CrossRefGoogle ScholarPubMed
Bunn, C. W.and Howells, E. R. (1954). “Structure of molecules and crystals of fluorocarbons,” Nature (London) NATUAS 174, 549–551. nat, NATUAS CrossRefGoogle Scholar
Clark, E. S.and Muus, L. T. (1962a). “The relations between Bragg reflections and disorder in crystalline polymers,” Z. Kristallogr. ZEKRDZ 117, 108–118. zek, ZEKRDZ CrossRefGoogle Scholar
Clark, E. S.and Muus, L. T. (1962b). “Partial disordering and crystal transitions in polytetrafluoroethelene,” Z. Kristallogr. ZEKRDZ 117, 119–127. zek, ZEKRDZ CrossRefGoogle Scholar
Clark, E. S. (1999). “The molecular conformations of polytetrafluoroethylene: forms II and IV,” Polymer POLMAG 40, 4659–4665. pol, POLMAG CrossRefGoogle Scholar
Cochran, W., Crick, F. H. C., and Vand, V. (1952). “The structure of synthetic polypeptides. I. The transform of atoms on a helix,” Acta Crystallogr. ACCRA9 5, 581–586. acc, ACCRA9 CrossRefGoogle Scholar
Ignatieva, L. N., Tsvetnikov, A. K., Lifshiz, F. I., Saldin, V. I., and Bouznik, B. M. (2002). “Spectral investigation of modified polytetrafluoroethylene” Zh. Strukt. Khim. (rus) ZZZZZZ 43, 69–75.Google Scholar
Holt, D. B.and Farmer, B. L. (1999). “Modeling of helix reversal defects in polytetrafluoroethylene. I. Molecular dynamics simulations,” Polymer POLMAG 40, 4667–4672. pol, POLMAG CrossRefGoogle Scholar
Kimmig, M., Strobl, G., and Stuhn, B. (1994). “Chain reorientation in polytetrafluoroethylene by mobile twin-helix reversal defects,” Macromolecules MAMOBX 27, 2481–2495. mml, MAMOBX CrossRefGoogle Scholar
Marega, C., Marigo, A., Garbuglio, C., Fichera, A., Martorana, A., and Zannetti, R. (1989). “Structural models for crystallographic disorder in polytetrafluoroethylene,” Makromol. Chem. MACEAK 190, 1425–1431. mkc, MACEAK CrossRefGoogle Scholar
Nakafuku, C.and Takemura, T. (1975). “Crystal structure of high pressure phase of polytetrafluoroethylene,” Jpn. J. Appl. Phys. JJAPA5 14, 599–602. jja, JJAPA5 CrossRefGoogle Scholar
Pierce, R. H. H., Jr, Clark, E. S., Whitney, J. F., and Bryant, W. M. D. (1956). “Crystal structure of polytetrafluoroethelene,” Abstract of Papers, 130th Meeting of the American Chemical Society, Atlantic City, NJ, p. 9S.Google Scholar
Powder diffraction file, sets 1–50. JCPDS-ICDD, Pennsylvania 19073-3273.Google Scholar
Rietveld, H. M. (1969). “A profile refinement method for nuclear and magnetic structures,” J. Appl. Crystallogr. JACGAR 2, 65–71. acr, JACGAR CrossRefGoogle Scholar
Solovyov, L. A., Blokhina, M. L., Kirik, S. D., Blokhin, A. I., and Derikova, M. G. (1996). “Powder diffraction solution of the crystal structure of [Pd(NH3)4]C2O4,” Powder Diffr. PODIE2 11, 13–16. pdj, PODIE2 CrossRefGoogle Scholar
Solovyov, L. A., Kirik, S. D., Shmakov, A. N., and Romannikov, V. N. (2001). “X-ray structural modeling of silicate mesoporous materials,” Microporous Mesoporous Mater. MIMMFJ 44–45, 17–23. a9k, MIMMFJ CrossRefGoogle Scholar
Tsvetnikov, A. K. and Uminskii, A. A. (1997). “The way of polytetrafluoroethylene processing,” Patent RF 1775419.Google Scholar
Vainshtein, B. K. (1975). “X-ray diffraction on chain molecules,” Moscow, 372.Google Scholar
Wiles, D. B.and Young, R. A. (1981). “A new computer program for Rietveld analysis of x-ray powder diffraction patterns,” J. Appl. Crystallogr. JACGAR 14, 149–151. acr, JACGAR CrossRefGoogle Scholar