Abstract: The carbon-13 relaxation parameters were measured for star-shaped polystyrenes with different branch degree and different molecular weight of parent chain in a 20% (W/V) solution. The backbone segmental motion is interpreted in terms of the lg-X², Cole-Cole and a conformational jump model. The internal rotation motion of aromatic ring is analysed and the activation energies and jump rates are obtained. The results show that light chemical crosslinks has, to some extent, an influence on the distribution of correlation time, but no distinct effect on the potential for segmental motion. The dependence of carbon-13 relaxation on the molecular weight is similar to that of linear polymers.

Key words: Velaxation parameters, Activation energies, Jump rates