Polymer Physics Prize Talk: Getting the kinks out: extensional flow in polymer solutions, melts, and glasses

Using molecular dynamics and Brownian dynamics, and “kink dynamics” simulations, polymer chains under extensional flow at high stress and strains are found to unravel through folded states, wherein highly stretched strands connected by kinks, or fold points, bear most of the stress. This process occurs universally at high stresses in polymer solutions, melts, and glasses, and is responsible for the strain hardening seen in extensional flows in all these states, regardless of whether the polymer is entangled or not. We show that experimental data for stress and local orientation can be explained semi-quantitatively or even quantitatively with models that capture these dynamics.