Advertisement

Journal of Materials Science

, Volume 28, Issue 19, pp 5199–5206 | Cite as

On-line ultrasonic monitoring and modelling of radiation-induced structural changes in polymethyl methacrylate

  • B. Bridge
Papers
  • 26 Downloads

Abstract

Structural changes in polymethyl methacrylate (PMMA, monomer formula C2H2CH3COOCH3) induced by60Co radiation have been detected by means of on-line monitoring of increases in the attenuation of 10 MHz longitudinal ultrasound. Attenuation changes first became noticeable at a dose of 15 kGy and had increased by 75% at the maximum dose of 36.5 kGy. A theoretical upper bound to structural relaxation loss induced by radiation has been calculated. As a consequence it was then possible to show that at the dose levels encountered, the additional loss was attributable mainly to collective motions involving many atoms and of low attempt frequencies, rather than to the relaxation of individual atoms or structural groupings. The theory proposes an attenuation change proportional to the 5/3th power of the dose, which is in excellent agreement with experiment. It is suggested that on-line monitoring of ultrasound loss could be a sensitive diagnostic test of the onset of unwanted structural change during the practice of food preservation by the use of irradiation.

Keywords

Attenuation Structural Change PMMA Polymethyl Methacrylate Dose Level 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    I. G. Ritchie, J. F. Dufresne andP. Moser, in “Internal Friction and Ultrasonic Attenuation in Solids”, edited by C. C. Smith (Pergammon Press, 1979) pp. 43–7.Google Scholar
  2. 2.
    D. Beretz, M. Halbwachs andJ. Hillairet,ibid., pp. 131–8.Google Scholar
  3. 3.
    P. B. Fraser, in “Physical Acousticsed”, Vol. V, edited by W. P. Mason (Wiley, 1972) Ch. 2, pp. 59–109.Google Scholar
  4. 4.
    R. E. Strakna,Phys. Rev. 123 (1961) 2020–6.CrossRefGoogle Scholar
  5. 5.
    A. Callens, R. De Batist andR. Givers, in “Internal Friction and Ultrasonic Attenuation in Solids”, edited by C. C. Smith (Pergammon Press, 1979) pp. 255–60.Google Scholar
  6. 6.
    B. Bridge, F. Harirchian, D. C. Imrie, Y. Mehrabi andA. R. Meragi,NDT Int. 20 (1987) 339.Google Scholar
  7. 7.
    R. A. Bolz andG. L. Tuve, (eds), “Handbook of tables of Applied Engineering Science”, 2nd Edn (CRC Press, Boca Raton, FL) Table 4.32, Section 4.2, p. 441.Google Scholar
  8. 8.
    G. W. C. Kaye andT. H. Laby (eds), “Handbook of Physical and Chemical Constants”, 14th Edn (Longman, London, New York) Section 3.4.2, p. 277.Google Scholar
  9. 9.
    B. Bridge,J. Photographic Sci.,34 (1986) 95.CrossRefGoogle Scholar
  10. 10.
    Idem, Brit. J. NDT 28 (1986) 216.Google Scholar
  11. 11.
    B. Bridge andA. A. Higazy,J. Mater. Sci. 23 (1988) 1995.CrossRefGoogle Scholar
  12. 12.
    B. Bridge andN. D. Patel,ibid. 21 (1986) 3783.CrossRefGoogle Scholar
  13. 13.
    K. S. Gilroy andW. A. Phillips,Phil. Mag. B 43 (1981) 735CrossRefGoogle Scholar
  14. 14.
    B. Bridge, B. Gabrys, S. Joshi andJ. Higgins,J. Mater Sci. 24 (1989) 3295.CrossRefGoogle Scholar
  15. 15.
    R. Halmshaw, in “The physics of industrial radiology”, edited by R. Halmshaw, (Heywood, London, American Elsevier, New York, 1966) Ch. 1, p. 16.Google Scholar
  16. 16.
    Idem, “NonDestructive Testing”, (Edward Arnold 1987) Section 3.3.4, p. 31.Google Scholar
  17. 17.
    A. Brynjolfsson, in “Concise Encyclopaedia of Science and Technology”, edited by S. B. Parker (McGraw-Hill, New York, 1982) pp. 740–1.Google Scholar

Copyright information

© Chapman & Hall 1993

Authors and Affiliations

  • B. Bridge
    • 1
  1. 1.School of Electrical, Electronic and Information EngineeringSouth Bank UniversityLondonUK

Personalised recommendations