The notched Izod impact test has become the recognised standard for comparing the impact resistance of plastic materials. However, like many tests, they have little relevance to how a moulded part will perform. Materials vary in their notch sensitivity so this test will penalise some materials more than others. There is also an unnotched Izod test which always gives superior results due to the absence of a stress concentrator.
Izod impact strength is the energy used to break a specimen divided by its cross-sectional area at the notch.
ISO 180 Izod differs in that there are two possible notch configurations, Notch A is the most commonly used:
A | Notch base radius 0.25mm |
B | Notch base radius 1.00mm |