| Abstract: | Using a light scattering photometer we investigated the orientation- and density fluctuations in the amorphous polymers “polycarbonate” (poly(oxycarbonyloxy-1,4-phenylene-isopropylidene-1,4-phenylene)) and polystyrene as a function of temperature. In addition to this, we performed supplementary measurements on oligomers of polystyrene and on the liquid-crystal compound 4-butyl-N-(p-methoxybenzyliden)aniline (MBBA) in the isotropic phase. From the amount of depolarized light scattering it is evident that an orientation correlation, as suggested for some bundle models, does not exist. As far as polystyrene is concerned, we were able to draw particularly detailed conclusions. The depolarized light scattering was constant in the whole angular range and independent of temperature. The anisotropy per monomeric unit of the oligomers already has a similar value to that of the polymer, consequently no additional orientation fluctuations are present in the polymer. The orientation correlation of the monomeric units in the polymer could be totally attributed to that in a random coil. The amount and temperature dependence of the light scattering of polystyrene caused by density fluctuations agreed with the results of the fluctuation theory. Consequently, light scattering due to density fluctuations of a specific macromolecular species did not occur. |
