  The dynamics of elastocapillary thinning in high molecular weight polymer
solutions are re-examined using high-speed digital video microscopy. At long
times, the evolution of the viscoelastic thread deviates from self-similar
exponential decay and competition of elastic, capillary and inertial forces
leads to the formation of a periodic array of beads connected by
axially-uniform ligaments. This configuration is itself unstable and successive
instabilities propagate from the necks connecting the beads and ligaments. This
iterated process results in the development of multiple generations of beads in
agreement with predictions of Chang et al. (1999), although experiments yield a
different recursion relation between successive generations. At long times,
finite extensibility truncates the iterated instability and axial translation
of the bead arrays along the interconnecting threads leads to progressive
coalescence before rupture of the fluid column.
