A MODIFIED FRACTIONAL MODEL TO DESCRIBE THE ENTIRE VISCOELASTIC BEHAVIOR OF POLYBUTADIENES FROM FLOW TO GLASSY REGIME

The dynamic mechanical behavior of a series of monodisperse polybutadi enes has been investigated from the flow regime to the glassy state. A ssuming a linear superposition of the entanglement and glass behavior a mathematical model of the spectrum of relaxation times is developed. It consists in a selfsimilar spectra for the entanglement contributio n and a Fractional Maxwell Fluid (FMF) for the glassy contribution. Th e model closely represents the master curves of dynamic moduli over 15 logarithmic decades of frequency with three parameters for the flow r egime (G(N)(o), eta(o) and a cut-off parameter lambda(max)) and four p arameters for the FMF. It is shown that one of the parameter of the FM F is similar to the power-law exponent of a self-similar spectra previ ously proposed in the literature to model the transition to glass.