GB/T 1632.2-2025 Active National standards

GB/T 1632.2-2025 Plastics—Determination of the viscosity of polymers in dilute solution using capillary viscometers—Part 2:Poly(vinyl chloride) resins

Publish Date: 2025-10-05 Implement Date: 2026-05-01 For services related to genuine standard inquiry, procurement, translation, and other related services in China, please Contact Us

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Basic Information

Standard Code: GB/T 1632.2-2025

Standard Type: National standards

Standard Status: Active

is_force_gb: no

CCS Name: Basic standards and general methods for synthetic resins and plastics

ICS Name: Thermoplastic plastics

Publish Date: 2025-10-05

Implement Date: 2026-05-01

Pages: 28 pages

Scope

1.1 This document specifies the determination conditions for the specific viscosity (also known as viscosity number) and K value of polyvinyl chloride resins, and is applicable to homopolymers of vinyl chloride and binary and ternary copolymers composed of vinyl chloride and one or more other monomers (with vinyl chloride as the main component) in powder form. The resins may contain a small amount of unpolymerized substances (such as emulsifiers or dispersants, residual initiators, etc.) and other substances added during the polymerization process. However, this document is not applicable to resins with a volatile content exceeding 0.5% as measured by GB/T 2914, or resins that cannot be completely dissolved in cyclohexanone.
1.2 The specific viscosity and K value of a particular resin are related to its molecular weight, but this relationship can vary depending on the type and concentration of other monomers present. Therefore, homopolymers and copolymers with the same specific viscosity or K value may have different molecular weights.
1.3 For a specific polyvinyl chloride resin sample, the concentration of the selected determination solution has a different impact on the measured values of specific viscosity or K value. Therefore, only when the solution concentration used is the same, can the values of specific viscosity and K value obtained according to the steps described in this document be compared.
1.4 The limiting viscosity is not used for PVC resins.
1.5 The test steps described in this document can be used to characterize the polymer components obtained during the chemical analysis of a polyvinyl chloride composite. However, since the obtained polymer components are impure, the calculated specific viscosity and K value in such cases do not represent the true values of the resin used in the composite.