The fracture behavior of polypropylene has been examined with a granulator-like cutting test bench at rotor tangential velocities up to 40 m/s and rotor knife wedge angles of 30degrees, 55degrees and 80degrees. Depending on the wedge angle, the failure is either more due to tensile stresses or due to shear stresses. This has a significant influence on the necessary cutting energy. The fracture, surface shows different zones of failure, which can be related to the actual cutting energy.