The dynamic melt viscoelasticity of polystyrene (PS) was carefully measured and critically revised for temperatures up to 290°C (about T, + 185°C). It has been found clearly that the Williams-Landel-Ferry (WLF) free-volume description is obeyed in the whole temperature range investigated here, whereas, rather surprisingly, no evidence was found for Arrhenius-like behaviour at the highest temperatures. The size of the PS jumping unit was quantitatively assessed to be about three skeletal bonds (i.e. one and a half monomer units). This size is large enough to cause the free volume to be the rate-limiting factor in such a wide temperature range
Посилання на статтю:
Williams-LandeI-Ferry versus Arrhenius behaviour: polystyrene melt viscoelasticity revised / Paolo Lomellini // Polymer. – 1992. – Vol 33. – P. 4983-4989.