EN ISO 1628-2:2020 PDF

Overview

EN ISO 1628-2:2020 - "Plastics - Determination of the viscosity of polymers in dilute solution using capillary viscometers - Part 2: Poly(vinyl chloride) resins" (CEN adoption of ISO 1628-2:2020) defines a standardized procedure for measuring reduced viscosity (viscosity number) and K‑value of PVC resins. The method uses capillary viscometers and cyclohexanone solvent to determine efflux times from which viscosity parameters are calculated. It applies to PVC powders (homopolymers and copolymers where vinyl chloride is the main constituent) that are fully soluble in cyclohexanone and have volatile matter ≤ 0.5 % ± 0.1 % (ISO 1269).

Key topics and technical requirements

• Measured properties: Reduced viscosity (viscosity number) and K‑value - indicators related to molecular mass but not direct molecular-weight equivalents (relationship depends on comonomer type and concentration).
• Principle: Calculate reduced viscosity and K‑value from efflux times of solvent and polymer solution in a capillary viscometer.
• Solvent: Cyclohexanone with a specified kinematic viscosity (2.06 × 10‑6 to 2.33 × 10‑6 m2/s at 25 °C) and boiling point ≈ 155 °C; store protected from light.
• Reference viscometer: Model 1C capillary (reference capillary diameter ~0.77 mm). Alternative viscometers require established correlation to the reference.
• Solution preparation: Document specifies preparing solutions at the standard concentration (document gives 5 kg/m3 ± 0.1 kg/m3 at 25 °C ± 1 °C) and prescribes dissolution, filtration and temperature‑controlled equilibration.
• Apparatus and controls: 50 ml class A volumetric flasks, fritted filter (40–50 µm), mechanical agitator/heating (80–85 °C) or oven agitation, analytical balance (0.1 mg), temperature bath maintained at 25.0 °C ± 0.5 °C (stability ± 0.05 °C), and timing device (0.1 s).
• Comparability caveats: Values are comparable only when identical solution concentrations and test conditions are used. Limiting viscosity number is not used for PVC.

Applications and users

• Quality control and lot acceptance testing of PVC resins for manufacturers and compounders.
• R&D and polymer characterization to monitor molecular-weight-related properties during polymerization or formulation changes.
• Material specification and supplier verification in industries using PVC (construction, tubing, profiles, cable insulation).
• Analytical laboratories, testing houses, and standards bodies performing standardized polymer viscosity testing.

Related standards

• ISO 1628-1:2009 - General principles for viscosity determination by capillary viscometers.
• ISO 1269 - Determination of volatile matter in PVC (relevant limit).
• ISO 3105 - Glass capillary viscometers specifications.
• ISO 1042 - One-mark volumetric flasks.

Keywords: EN ISO 1628-2:2020, PVC resin viscosity, reduced viscosity, K-value, capillary viscometers, cyclohexanone, polymer viscosity determination, ISO 1628 series.