1.1本文件规定了PVC树脂的还原粘度（又称粘度数）和K值的测定条件。它适用于由单体氯乙烯的均聚物和氯乙烯与一种或多种其它单体的共聚物、三元共聚物等组成的粉末形式的树脂，但其中氯乙烯是主要成分。树脂可以含有少量的未聚合物质(例如乳化剂或悬浮剂、催化剂残余物等)和在聚合过程中加入的其它物质。然而，当根据ISO 1269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，但该关系根据存在的其它单体的浓度和类型而变化。因此，具有相同降低粘度或K值的均聚物和共聚物可能不具有相同的分子量。 1.3对于PVC树脂的特定样品，测定的降低粘度和K值的值受选择用于测定的溶液浓度的不同影响。因此，当所用溶液的浓度相同时，使用本文所述的方法仅给出可比较的降低粘度值和K值。 1.4极限粘度数不适用于PVC树脂。 1.5本文件中描述的实验程序也可用于表征在PVC组合物的化学分析期间获得的聚合物级分。然而，由于回收的聚合物级分的不纯性质，在这些情况下针对降低的粘度和K值计算的值可能不指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.