Specific gravity, or relative density, is the ratio of the mass of a given volume of the impermeable part of the material at 23 °C to the mass of an equal volume of gas-free distilled or de-mineralized water at the same temperature. Density is a cubic meter of impermeable part of the material at 23 °C.
This standard finds the specific gravity and the density of solid polymers. Specific gravity can be used to name a material, to follow physical changes in a sample, to indicate the degree of uniformity among the different specimens or to figure out the average density of a large item. Density is useful for calculating strength/weight ratios of a material. This standard has two test methods. Method A is for testing solid plastics in water. Method B is for testing solid plastics in liquids other than water.