ASTM D256-23e1 is a standard test method for determining the impact resistance of plastics to an Izod pendulum. It is suitable for evaluating the impact resistance of plastic materials under high-speed impact. The standard specifies detailed procedures for testing specimens with notches using a standardized pendulum impact tester, including specimen preparation, equipment requirements, and test steps. A variety of test methods (e.g. Methods A, C, D, and E) are provided in the standard for different impact strength ranges and material properties, such as notch sensitivity testing and notch-free impact strength assessment. Test results are expressed in terms of energy absorbed per unit width or cross-sectional area under the notch. The standard also emphasizes the effect of test parameters (e.g. specimen preparation, environmental conditions, etc.) on the results, and provides SI units as standard units of measurement.