NON-LORENTZIAN RAYLEIGH SPECTRA OF BULK HOMOPOLYMERS FAR ABOVE THE GLASS-TRANSITION

Non-Lorentzian depolarized Rayleigh-scattering spectra have been clear ly observed by Fabry-Perot interferometry in bulk homopolymers, polyis oprene and 1,4-polybutadiene, far above the glass-transition temperatu re. We have developed two alternative phenomenological methods for ana lyzing this kind of spectra. First of all we have used a scattering mo del function based on the Havriliak-Negami relaxation function which, in fact, is compatible with a Kohlrausch-Williams-Watts relaxation fun ction in the time domain. In the case of polyisoprene, the results obt ained by this method are in good agreement with the obtained ones thro ugh other different relaxation techniques when a similar method of ana lysis is applied. Besides, we have extended to the frequency domain th e CONTIN algorithm which calculates an apparent distribution function of relaxation times from nonexponential time domain relaxation functio ns. The results obtained as well as the applicability of both methods are discussed.