Structure and dynamics of breaking foams

Experimental results are presented for the relaxation of a two dimensional soap foam in which wall breakage is initiated through gentle warming of the foam cell. Significantly different phenomenology from the relaxation of nonbreaking foams is observed. At a critical ``break time,'' which depends on the temperature ramping rate and initial conditions, a large scale mechanical cascade of wall rupture sets in, leading to a rapid disintegration of the foam. In the cascade regime, whose behavior is essentially independent of the ramping rate, a dynamical scaling behavior, associated with the distribution of cell edge lengths, is proposed.