In situ observations of crack propagation mechanisms along interfaces between confined polymer layers and glass

This paper concentrates on microscopic observations of the propagation of cracks along polymer-glass interfaces and crack propagation mechanisms. The experimental set-up consists of an asymmetric double cantilever beam in an optical microscope. Image processing techniques used to isolate the crack fronts are presented. The fronts propagate inhomogeneously in space and time, i.e., in bursts that spread laterally along the front over a certain distance. It is interesting to note that two different cases are detected; one in which crack propagation is dominated by initiation of instabilities on the front, and another one in which it is dominated by propagation of existing instabilities. (c) 2006 American Institute of Physics