Dynamic fracture surface energy values and branching instabilities during rapid crack propagation in rubber toughened PMMA

An experimental device based on strip band geometry has been designed to ex plore the brittle behaviour of polymers during rapid crack propagation. The macroscopic crack speed is found to be quasi-constant along an entire RT-P MMA specimen. even in the case of crack branching and until arrest, if any. At the macroscopic branching velocity, the experimental fracture surface e nergy and the fracture surface roughness have no single values in RT-PMMA. In fact, the macroscopic fracture surface energy increases with the number of instabilities or frustrated micro-branches. (C) 2001 Academie des scienc es/Editions scientifiques et medicales Elsevier SAS.