This test is used to investigate the behaviour and for estimating the brittleness or toughness of
specimens within the limitations inherent in the test conditions.

PA6 - 4.0rv = High Viscosity Nylon
PA6 - 2.7rv = Medium Viscosity Nylon
PP - High Impact = Typical Polypropylene

The Izod Impact strength test of a notched specimen is an International Standard test. The test specimen, supported as a vertical cantilever beam is broken by a single swing of a pendulum, with the line of impact at a fixed distance from the specimen clamp and, in the case of notched specimens, from the centreline of the notch The Impact energy absorbed in breaking a notched specimen is referred to the original cross sectional area of the specimen at the notch. A pendulum strikes the face containing the notch. The result is expressed in Kilojoules per square millimetre.

Source:ISO 180 Plastics-Determination of Izod impact strength