This standard provides a unified test method for determining the low-temperature brittleness of plastic films and sheets. It specifies that loop-shaped specimens are placed in a temperature-controlled cooling chamber and subjected to instantaneous folding impact by a free-falling impact block to determine the temperature at which 50% of the specimens rupture or become damaged under given conditions, known as the "cold-crack temperature." This method is applicable for evaluating the low-temperature performance of finished films and sheets made from different raw materials, with specified thicknesses and textures. It should be noted that the data obtained from this method are specifically intended for comparing the low-temperature brittleness of materials and should not be directly extrapolated to other application conditions.