本文件规定了一种梯度柱法，用于测定无空隙形式的非泡沫模制或挤压塑料或颗粒的密度。密度梯度柱是含有两种液体混合物的柱，柱中的密度从上到下均匀增加。 注:密度通常用于跟踪塑料材料物理结构或成分的变化。密度也可用于评估样品或试样的均匀性。塑料材料的密度取决于试样制备方法的选择。在这种情况下，试样制备方法的准确细节应包含在适当的材料规范中。

This document specifies a gradient column method for the determination of the density of non-cellular moulded or extruded plastics or pellets in void-free form. Density gradient columns are columns containing a mixture of two liquids, the density in the column increasing uniformly from top to bottom. NOTE Density is frequently used to follow variations in physical structure or composition of plastic materials. Density can also be useful in assessing the uniformity of samples or specimens. The density of plastic materials can depend upon the choice of specimen preparation method. When this is the case, precise details of the specimen preparation method are intended to be included in the appropriate material specification.