标准编号:ISO 1628-2:2020
中文名称:塑料 使用毛细管粘度计测定稀释溶液中聚合物的粘度 第2部分:聚(氯乙烯)树脂
英文名称:Plastics — Determination of the viscosity of polymers in dilute solution using capillary viscometers — Part 2: Poly(vinyl chloride) resins
发布日期:2020-06
标准范围
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.