Investigating Crack Resistance Behavior of Polypropylene Using <i>J</i> integral, <i>J‐R</i> Curve and Fractographic Analysis

ABSTRACT In this study, the fracture response of polypropylene (PP) was assessed using J ‐integral evaluation, J‐R curve construction, and fractography examination. J‐R and load–displacement curves were analyzed to determine critical loads and estimate J ‐integral values based on standards established for polymer fracture testing, which led to the evaluation of the J IC fracture toughness parameter. Numerical validation was performed to obtain dimensionless stress intensity coefficients and geometry‐dependent parameters, which resulted in J‐R curves and J IC values that were consistent with experimental observations. Experimental analysis indicated that the onset of plastic deformation at the crack tip leads to a significant increase in the J integral values compared with perfectly elastic behavior. Scanning electron microscopy revealed that as the crack propagated from the initiation point to the final fracture zone, both the magnitude and intensity of the surface peaks increased, indicating a rise in the material's resistance to crack propagation.