Parallel superposition experiments are used here for the linear and nonlinear rheological characterization of a commercial polydisperse polymer melt in the entangled state. In the limit of small amplitude of the oscillations, we focus (to our knowledge for the first time) on the time-temperature superposition principle. With increasing oscillation amplitudes, the storage and loss moduli become amplitude-dependent at amplitudes which vary with the strength of the background flow. Experimental results are compared with predictions of a recent molecularly based constitutive equation in order to validate the equation itself as well as to interpret the data in terms of the molecular mechanisms accounted for in the constitutive equation.
Parallel superposition in entangled polydisperse polymer melts: Experiments and theory
SOMMA, Elvira;TITOMANLIO, Giuseppe;
2007-01-01
Abstract
Parallel superposition experiments are used here for the linear and nonlinear rheological characterization of a commercial polydisperse polymer melt in the entangled state. In the limit of small amplitude of the oscillations, we focus (to our knowledge for the first time) on the time-temperature superposition principle. With increasing oscillation amplitudes, the storage and loss moduli become amplitude-dependent at amplitudes which vary with the strength of the background flow. Experimental results are compared with predictions of a recent molecularly based constitutive equation in order to validate the equation itself as well as to interpret the data in terms of the molecular mechanisms accounted for in the constitutive equation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
