Viscoelastic dynamic properties of meshlike polymer networks: Contributions of intra- and interchain relaxation processes

The theory of intra- and interchain relaxation processes for the local dyna mic characteristics of meshlike polymer networks has recently been proposed by the authors (Macromolecules 1998, 31, 5756). The extension of this theo ry to macroscopic viscoelastic characteristics is presented. A regular cubi c network consisting of "bead and spring" Rouse chains embedded in an effec tive viscous medium is considered. The viscoelastic response of the polymer network to an external stress producing a longitudinal velocity gradient i n the effective viscous medium is studied. The comparisons of contributions from intra-and interchain relaxation processes to the dynamic modulus and viscosity of the Gaussian network are made. The asymptotic behavior of dyna mic quantities considered is estimated for various limiting regions of freq uency,The possibility of a simplified description of the viscoelastic prope rties of a polymer network in terms of a coarse-grained network model and a melt consisting of un-cross-linked chains is demonstrated. The problem of hydrodynamic interactions in polymer networks is also discussed.