Viscosity of Concentrated Polymer Solutions.

Molecular dynamics simulations of dielectric relaxation of concentrated polymer solutions

Molecular dynamics simulations are conducted for concentrated solutions of flexible polymers. The results are contrasted with literature dielectric spectroscopy data, in an attempt to elucidate the observed phenomena from a molecular level perspective. A bead-spring model is used and systems with chain sizes up to N5150 beads at reduced densities 0.5<r<0.8 are studied. The dimensions of the cha...

Entanglement-controlled subdiffusion of nanoparticles within concentrated polymer solutions.

We describe x-ray photon correlation spectroscopy (XPCS) experiments tracking the motion of gold nanoparticles within solutions of high-molecular-weight polystyrene. Over displacements from nanometers to tens of nanometers, the particles undergo subdiffusive motion that is dictated by the temporal evolution of the entangled polymer mesh in the immediate vicinity of the particles. The results th...

Concentrated polymer solutions in the presence of fixed obstacles

Viscosity Solutions for a Polymer Crystal Growth Model

We prove existence of a solution for a polymer crystal growth model describing the movement of a front (Γ(t)) evolving with a nonlocal velocity. In this model the nonlocal velocity is linked to the solution of a heat equation with source δΓ. The proof relies on new regularity results for the eikonal equation, in which the velocity is positive but merely measurable in time and with Hölder bounds...

Diffusion Coefficients in Polymer- Solvent Systems for Highly Concentrated Polymer Solutions

The Vrentas/Duda proposal for the diffusion of polymer-solvent systems, which is based on the free-volume theory, was employed in correlating and predicting mutual diffusion coefficients in highly concentrated polymer solutions. It has been observed that the predictive version of the model is capable of qualitatively representing the experimental data, while the use of an adjustable parameter g...