Fracture mechanisms and micromechanical deformation processes of polyethylene/calcium carbonate nanocomposite films

Abstract The fracture behavior of medium density polyethylene/calcium carbonate (MDPE/CaCO₃) nanocomposites was evaluated using the essential work of fracture (EWF) test. Fracture surfaces and the deformation zone in front of the precrack were studied using different microscopy techniques. Microscopic observations proved that extensive shear deformation of matrix due to debonding of nanoparticles plays the most important role on deformation mechanism of polyethylene nanocomposite. Large quantities of energy can be absorbed by plastic deformation of matrix polymer. This is why the specific plastic work (w_p) of nanocomposites is higher than that of polyethylene. The presence of voids formed due to debonding of nanoparticles, reduces the load carrying capacity of the matrix and consequently leads to the reduction of the specific EWF (w_e). Besides, it causes easily crack propagation that may restricts the area where plastic deformation takes place and results in the reduction of plastic zone shape factor (β).