Rheological and relaxation properties of MQ copolymers

The rheological properties of MQ copolymer melts are investigated under steady-state shear flow and dynamic oscillatory shear within a wide temperature range. The MQ copolymers are highly branched polycyclic compounds (densely crosslinked nanosized networks) incapable of further intermolecular interactions. The samples have identical chemical compositions, but their detailed molecular structures are different. The polymers under consideration show Newtonian behavior in a wide shear-stress range. The values of viscosity vary considerably with the molecular structure of the copolymers. The generalized frequency dependence of complex dynamic modulus components is constructed with the use of the temperature-frequency superposition method. In a first approximation, the viscoelastic behavior of the materials is satisfactorily described by the Maxwell model with a single relaxation time. In this respect, the studied materials are similar to micellar colloids. The relaxation spectra of the copolymers distinguished by narrow distributions are calculated.