  We study experimentally the fracture dynamics during the peeling at a
constant velocity of a roller adhesive tape mounted on a freely rotating
pulley. Thanks to a high speed camera, we measure, in an intermediate range of
peeling velocities, high frequency oscillations between phases of slow and
rapid propagation of the peeling fracture. This so-called stick-slip regime is
well known as the consequence of a decreasing fracture energy of the adhesive
in a certain range of peeling velocity coupled to the elasticity of the peeled
tape. Simultaneously with stick-slip, we observe low frequency oscillations of
the adhesive roller angular velocity which are the consequence of a pendular
instability of the roller submitted to the peeling force. The stick-slip
dynamics is shown to become intermittent due to these slow pendular
oscillations which produce a quasi-static oscillation of the peeling angle
while keeping constant the peeling fracture velocity (averaged over each
stick-slip cycle). The observed correlation between the mean peeling angle and
the stick-slip amplitude questions the validity of the usually admitted
independence with the peeling angle of the fracture energy of adhesives.
