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.
Open preview (PDF)Plastics — Ethylene/vinyl acetate copolymer (EVAC) thermoplastics — Determination of vinyl acetate content