ISO 1628-3:2010定义了在135℃下在稀溶液中测定聚乙烯和聚丙烯的比浓粘度（也称为粘度数）和特性粘度的具体条件。 聚合物溶液的粘度可能受样品中存在的添加剂的影响。因此，如果样品含有填料或其他添加剂，则通过该方法测定的比浓粘度的值可能是不可靠的

ISO 1628-3:2010 defines particular conditions for determining the reduced viscosity (also known as viscosity number) and intrinsic viscosity of polyethylenes and polypropylenes at 135 °C in dilute solution. The viscosity of polymer solutions may be affected by additives present in the sample. The value of a reduced viscosity determined by this method may therefore be unreliable if the sample contains fillers or other additives.