Failure of time-temperature superposition in dilute miscible polymer blends

The dynamic viscosity for miscible blends of 1,4-polyisoprene and poly(vinyl ethylene) (PVE) at the extremes of composition (1% tracer in 99% matrix) has been measured as a function of temperature. Time-temperature superposition failure is observed in these tracer blends. This observation indicates that intramolecular contributions are crucial in defining the local environment experienced by a polymer segment, as anticipated by self-concentration models. The temperature dependence of the dynamics of the PVE tracer has been extracted, and compared with the model of Lodge and McLeish. The selfconcentration effect was found to be even stronger than predicted.