Dynamics and stress relaxation of bidisperse polymer melts with unentangled and moderately entangled chains

Stress relaxation in unentangled and entangled polymer liquids

We develop a stochastic model for the dynamics of a dense fluid of flexible linear macromolecules. A polymer is represented by a harmonic chain of beads whose mobilities fluctuate in time between two values. A bead in the low-mobility state does not execute local motions, but may move by a cooperative slithering process involving the entire chain. A bead in the high-mobility state may execute b...

Stress relaxation in entangled polymer melts.

We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements and into the terminal relaxation regime for Z=10. Using the known (Rouse) mobility of unentangled chains and the m...

Syddansk Universitet Stress Relaxation in Entangled Polymer Melts

Influence of polymer architectures on diffusion in unentangled polymer melts.

Recent simulations have indicated that the thermodynamic properties and the glassy dynamics of polymer melts are strongly influenced by the average molecular shape, as quantified by the radius of gyration tensor of the polymer molecules, and that the average molecular shape can be tuned by varying the molecular topology (e.g., ring, star, linear chain, etc.). In the present work, we investigate...

Stress relaxation in entangled melts of unlinked ring polymers.

Stress relaxation in unlinked ring polymer melts poses an important challenge to our theoretical understanding of entangled polymer dynamics. Recent experiments on entangled unlinked ring melts show power-law stress relaxation with no hint of a rubbery plateau, usually the hallmark of entangled polymers. Here we present a theory for stress relaxation in rings analogous to the successful approac...