Many polymers used in structural applications (vessels, pipes, etc? are crystalline thermoplastics like polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF). These biphasic materials are made of crystalline lamellae bonded to an amorphous phase. When highmy crystalline polymers like mentioned above are strained at a temperature higher than the glassy transition temperature (T
), the amorphous phase, softer than crystals, is very sensitive to cavitation. Depending on thermal and mechanical loading conditions, cavities nucleation occurs in a generalized or localized manner and lead to macroscopic plastic strain and ductile fracture or to a slow crack growth regime. The latter regime is crucial since industrial installations must be certified over decades. Mechanisms of damage and fracture in this slow crack growth (SCG) regime are expected to depend both on micro-scale gradients (resulting from processing and further thermal annealing) and on macroscopic gradients induced by structure shape and boundary conditions.