ASTM D256 Izod Impact Strength


These test methods cover the determination of the resistance of plastics to "standardized" pendulum-type hammers, mounted in "standardized" machines, in breaking standard specimens with one pendulum swing. The standard tests for these test methods require specimens made with a milled notch. In Test Methods A, C, and D, the notch produces a stress concentration that increases the probability of a brittle, rather than a ductile, fracture. In Test Method E, the impact resistance is obtained by reversing the notched specimen 180 in the clamping vise. The results of all test methods are reported in terms of energy absorbed per unit of specimen width or per unit of cross-sectional area under the notch.