TIME-TEMPERATURE SUPERPOSITION AND LINEAR VISCOELASTICITY OF POLYBUTADIENES

A series of monodisperse polybutadienes has been used to perform mecha nical relaxation measurements from the flow regime to the glassy state . Results on loss shear moduli have been analyzed within the framework of a coupling model. It has been found to represent well the frequenc y dependence in the glassy and terminal zones using a segmental motion coupling parameter beta(alpha) and an entanglement coupling parameter beta(eta). Moreover, our results on apparent shift factors resulting from time-temperature superposition are consistent with the lack of th ermorheological simplicity predicted by the coupling theory due to the difference between beta(alpha) and beta(eta).