The fracture behavior of two series of polyethylene (PE) films, both the unreinforced and reinforced with different amounts of nanoscale calcium carbonate (CaCO3) particles was investigated in this research work by means of the essential work of fracture (EWF) approach under the loading condition of mode I. For this purpose, EWF test was conducted on deeply double edge notched tension (DDENT) specimens; and the essential and non-essential components of fracture work, were estimated using the plots representing the variation of the specific total work of fracture (wf) versus the ligament length of the specimen. The results showed that the crack resistance for the PE/CaCO3 nanocomposites was lower than that of the unreinforced PE, and for the case of nanocomposite samples, the total plastic energy absorbed during fracture increased with increasing CaCO3 content up to 2.5 wt-% and then decreased for nanocomposite samples containing 5 wt-%CaCO3. The plastic zone size decreased with increasing CaCO3 content, whereas the specific plastic work per unit volume increased with increasing weight percent CaCO3. The observed trends were rationalized using the fracture and deformation mechanisms of nanocomposites.

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