Mechanical & Physical Testing

Izod Impact

Properties Measured

Measures the impact strength of a material, typically on rigid materials such as thermoplastics and composites. ISO standards report impact strengths in kJ/m2, where the impact energy is divided by the cross sectional area at the notch. ASTM standards call for values to be reported in J/m, where the impact energy is divided by the length of the notch.

Instrumental Capabilities

1 – 25 Joules

Sample Requirements

The standard specimen for ASTM D256 is 64 x 12.7 x 3.2 mm (2½ x ½ x 1/8 inch).  The most common specimen thickness is 3.2 mm (0.125 inch), but the preferred thickness is 6.4 mm (0.25 inch). The depth under the notch is 10.2 mm (0.4 inches).

The standard specimen for ISO 180 is a Type 1A multipurpose specimen with the end tabs cut off. The resulting test sample measures 80 x 10 x 4 mm. The depth under the notch of the specimen is 8 mm.

Typically five specimens are measured.

Example Test Protocols

ASTM D256 – Izod Impact (Notched)

Standard Test Method for Determining the Izod Pendulum Impact Resistance of Plastics

ISO 180 – Plastics — Determination of Izod Impact Strength

Method Used to Determine the Impact Resistance of a Plastic Specimen When Supported in a Cantilever Configuration


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