Molten State Transition in Thermoplastic Rubber

Abstract

The flow characteristics of styrene-butadiene-styrene thermoplastic rubbers have been studied and the results compared with earlier static measurements. Computer best-fitting shift factors and inverse Melt Flow Index were plotted according to two mathematical models, Arrhenius and Vogel. Fulcher, Tamman and Hesse (VFTH). One transition was observed in both models, with appreciable reduction in the apparent activation energy of flow above this transition. This melt transition was associated with the temperature above which the PS chains can be removed from the PS rich phase by the rubbery chains. This allows rearrangement of the domain structure in a static condition or facilitates flow. Birefringence measurements support the model proposed.