Viscoelastic Properties of Entangled Polymer IV. Binary Blends of Monodisperse Homopolymers.

摘要

In a previous publication from this laboratory, the Rouse-Bueche-Zimm molecular theory of viscoelasticity has been extended by using a transient network model to apply to monodisperse polymers with chain entanglements. Effects of the entanglements were modeled both by the enhanced frictional coefficients and by the additional elastic couplings resulting from the transient entanglement network. For binary blends consisting of two monodisperse polymers with different molecular weights, additional modifications are now required to predict their linear viscoelastic behavior. It is recognized that entanglements not only may form between chains of the same lengths, but also between those of different lengths. For the latter case, the longer chain will in fact have the frictional coefficient of the shorter chain at the point of entanglements. The frequency of such interactions is assumed to be proportional to the weight ratio of the repective component chains in the blend. Equations of motion are formulated for each component and solved numerically for the relaxation spectra.