  This work proposes an investigation on the fracturing behavior of polymer
nanocomposites. Towards this end, the study leverages on the analysis of a
large bulk of fracture tests from the literature with the goal of critically
investigating the effects of the nonlinear Fracture Process Zone (FPZ). It is
shown that for most of the fracture tests, the effects of the nonlinear FPZ are
not negligible, leading to significant deviations from Linear Elastic Fracture
Mechanics (LEFM). As the data indicate, this aspect needs to be taken into
serious consideration since the use of LEFM to estimate mode I fracture energy,
which is common practice in the literature, can lead to an error as high as
157% depending on the specimen size and nanofiller content.
