ISO 8985:2022

Overview

ISO 8985:2022 specifies validated analytical procedures for determining the vinyl acetate content (VAC) of ethylene/vinyl acetate copolymer (EVAC) thermoplastics. It defines two categories of methods: reference methods (used for calibration and as primary measurement procedures) and test methods (alternative procedures that may be used when calibrated against a reference method and meeting repeatability requirements). The standard supports material designation and quality control per ISO 21301-1 and includes safety and laboratory practice guidance.

Key Topics

• Scope and purpose: Procedures to determine vinyl acetate content in EVAC for classification and product specification.
• Reference methods (Clause 4): Primary methods required for calibration, including:
  • Hydrolysis and back titration - dissolution in xylene, hydrolysis with alcoholic KOH, acidification and back titration.
  • Saponification and potentiometric titration - saponification followed by potentiometric endpoint detection.
  • Measurement of oxygen - oxygen-based measurement technique for VAC calculation.
• Test methods (Clause 5): Example methods that must be calibrated against reference methods and meet repeatability criteria, such as:
  • Fourier-transform infrared (FTIR) spectrometry
  • Acidimetric and iodometric titrations
  • Thermogravimetry (TG) for mass-loss-based estimates
• Calibration and repeatability: Test methods are permissible only when calibrated using one of the reference methods and when they demonstrate specified repeatability.
• Sampling, apparatus and reagents: Standard specifies required laboratory equipment, reagent quality, sample-mass guidance and reporting formats.
• Safety: Users must follow normal laboratory safety practices; the standard does not cover all safety issues.

Applications

• Quality control and incoming inspection of EVAC raw materials and compounds.
• Product specification and material designation in plastics manufacturing and polymer supply chains.
• Laboratory accreditation and method validation for chemical analysis of copolymers.
• Research and development when tracking composition-performance relationships (e.g., flexibility, adhesion, barrier properties tied to VAC content).

Who would use it:

• Polymer manufacturers and compounders
• Analytical and QC laboratories
• Regulatory and conformity assessment bodies
• Standards organizations and testing service providers

Related Standards

• ISO 21301-1 - designation of EVAC copolymers (uses VAC results)
• ISO 472 - plastics vocabulary and definitions referenced
• ISO 4799 - laboratory condensers (apparatus)
• ISO 11358-1 - thermogravimetry principles (relevant for TG test method)

ISO 8985:2022 is essential for consistent, traceable determination of vinyl acetate content in EVAC materials and for ensuring comparability across laboratories and suppliers.