1.1本文件规定了测定PVC树脂的还原粘度（也称为粘度值）和K值的条件。适用于单体氯乙烯均聚物、氯乙烯共聚物、三元共聚物等与一种或多种其他单体组成的粉末状树脂，但氯乙烯是主要成分。树脂可能含有少量未聚合的物质（如乳化剂或悬浮剂、催化剂残留物等） 以及聚合过程中添加的其他物质。然而，当根据ISO 1269进行测定时，本文件不适用于挥发物含量超过0.5%±0.1%的树脂。除此之外，它不适用于不完全溶于环己酮的树脂。 1.2特定树脂的还原粘度和K值与其分子量有关，但这种关系因其他单体的浓度和类型而异。 因此，具有相同的比粘度或K值的均聚物和共聚物的分子质量可能不同。 1.3对于特定PVC树脂样品，测定的还原粘度值和K值受所选溶液浓度的不同影响。因此，本文件中所述程序的使用仅给出当所用溶液浓度相同时具有可比性的还原粘度值和K值。 1.4限制 PVC树脂不使用粘度值。 也可在该实验文件中描述聚氯乙烯的化学成分。然而，由于回收的聚合物部分的不纯性质，在这些情况下计算的还原粘度值和K值可能并不表示用于生产组合物的树脂的实际值。

1.1 This document specifies conditions for the determination of the reduced viscosity (also known as viscosity number) and K-value of PVC resins. It is applicable to resins in powder form which consist of homopolymers of the monomer vinyl chloride and copolymers, terpolymers, etc., of vinyl chloride with one or more other monomers, but where vinyl chloride is the main constituent. The resins may contain small amounts of unpolymerized substances (e.g. emulsifying or suspending agents, catalyst residues, etc.) and other substances added during the course of the polymerization. This document is not applicable, however, to resins having a volatile-matter content in excess of 0,5 % ± 0,1 %, when determined in accordance with ISO 1269. In addition to this, it is not applicable to resins which are not entirely soluble in cyclohexanone. 1.2 The reduced viscosity and K-value of a particular resin are related to its molecular mass, but the relationship varies depending on the concentration and type(s) of other monomer(s) present. Hence, homopolymers and copolymers having the same reduced viscosity or K-value might not have the same molecular mass. 1.3 The values determined for reduced viscosity and K-value, for a particular sample of PVC resin, are influenced differently by the concentration of the solution chosen for the determination. Hence the use of the procedures described in this document only gives values for reduced viscosity and K-value that are comparable when the concentrations of the solutions used are identical. 1.4 Limiting viscosity number is not used for PVC resins. 1.5 The experimental procedures described in this document can also be used to characterize the polymeric fraction obtained during the chemical analysis of a PVC composition. However, the values calculated for the reduced viscosity and K-value in these circumstances might not indicate the actual values for the resin used to produce the composition because of the impure nature of the recovered polymer fraction.