B. Large amplitude oscillatory
Equally interesting is the response of these entangled polymer solutions to large-amplitude oscillatory shear (LAOS). Conventionally, LAOS was thought produce pendulum like uniform deformation across the sample thickness. Appearance of sub-harmonic frequencies and distortion of sine waves were thought to reflect constitutive behavior. Instead we observed shear banding and elastic disintegration.
shows the same sample (as studied in Movies 1 and 2) turning into something more liquid like over time in a spatially inhomogeneous way 300% and 1 rad/s. See Phys. Rev. Lett. 96, 196001 (2006) for details (PDF). The specific feature of a growing “water like” layer is apparently associated with the fact that the sample is highly polydisperse.
indicates different characteristics for a monodisperse PBD solution at 325 % and 0.25 rad/s.