Falling Plastic Drops and Sound Name: Eve W. Last week I saw a
demonstration where a newspaper plastic bag was suspended and
burned. Hot droplets would fall from the suspended plastic bag.
During this process there different noises made. I was wondering
what would cause this sound. Without actually being present, it
is hard to say with certainty. Assuming the sound was not just
the usual sounds that accompany flames that are caused by the
rapid implosion of hot air pockets, one possibility comes to
mind. Newspaper plastic bags are low density polyethylene (it is
the least expensive). When the molten drop of polymer falls, it
leaves a thread of fluid polymer because the time required for
the chains to untangle is long compared to the rate at which the
molten drop is falling. This thread cools. The cooling comes
from two effects. First, the thread is thin compared to the
"blob" as so heat is dissipated more rapidly. Second, the
polymer chains are being stretched and aligned along the axis of
fall. This stretchi