Fracture Toughness Characterization of Nanocomposites

Several experimental procedures are employed in order to give an estimation of the fracture toughness of nanocomposites, which makes it sometimes difficult to assess this feature. The simplest ones are those that employ either analogical or instrumented impact tests (Charpy, Izod, and falling weight), and the impact strength is 

More specific values of the fracture toughness are obtained by the application of the experimental procedures derived from the fracture mechanics theories. In the case of no plastic deformation in front of the crack tip, the LEFM is employed, obtaining the values of the stress critical intensity factor (fQ) or critical stress energy release rate (G,.). On the other hand, when there is plasticity in front of the crack tip, we must use the principles of the elastoplastic fracture mechanics in this sense, two experimental procedures are widely employed the J-integral analysis and the EWF. 

Zhao et al. [193] found in composites with AI2O3 nanoparticles that at quasi-static loading rate the fracture toughness was found nearly unvaried with the filler content. Under impact loading rate, the notched Izod impact strength and the impact 

Maspoch et al. [209] added organomodified montmorillonite to poly(ethylene-vinyl alcohol) (EVOH), studying the fracture behavior of 400 [xm thick cast films. The presence of the montmorillonite particles promoted an increase in 

Testing conditions DDENT specimens cut out from extrusion-calendered films (400pm thick) crosshead speed = 10 mm/min Data adapted from Ref. [209]. 

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