Overview
EN ISO 3451-5:2025 - Plastics - Determination of ash - Part 5: Poly(vinyl chloride) (ISO 3451-5:2025) specifies laboratory methods to determine the ash (inorganic residue) of poly(vinyl chloride) (PVC). The standard defines three procedures: Method A (direct calcination) for unsulfated ash and Methods B and C (sulfated ash) for situations where lead-containing compounds are present. It follows the general procedures of ISO 3451-1 and adds updated test conditions (including thermobalance use) and guidance for common fillers such as calcium carbonate (chalk).
Key topics and requirements
- Scope and applicability
- Applies to PVC resins, compounds and finished products.
- Methods B and C are applicable when lead-containing compounds are present.
- Three test methods
- Method A (direct calcination): Burn organics, heat residue to constant mass. Accepts muffle or microwave furnace or thermobalance as alternative.
- Method B: Calcination followed by sulfuric acid treatment after combustion, then heating to 950 °C.
- Method C: Sulfuric acid added before combustion; recommended over B for better reproducibility.
- Temperature guidance (Method A)
- Unfilled PVC: 950 °C ± 50 °C
- Glass fibers/bubbles: 600 °C ± 25 °C
- Talc and most fillers: 950 °C ± 50 °C
- Calcium carbonate (CaCO3) and mixtures containing it: 1 100 °C ± 50 °C
- Thermobalance tolerance: ±5 °C
- Apparatus and reagents
- Crucibles (alumina, silica, platinum, porcelain), muffle/microwave furnace or thermobalance, analytical balance (±0.1 mg).
- For Methods B and C: concentrated sulfuric acid (100 %, density 1.84 g/ml) and acetic acid; pipettes and strict acid-handling safety.
- Safety
- PVC releases hydrogen chloride (HCl) on thermal decomposition; take precautions for fumes and acid handling.
Applications
- Quality control and specification testing of PVC raw materials, compounds and finished articles.
- Filler and ash-content determination (e.g., to quantify CaCO3 content or glass-fiber loadings).
- Regulatory and compliance testing when assessing the presence/effect of lead-containing additives.
- Research and failure analysis in polymer formulation development and recycling streams.
Who should use this standard
- Polymer testing laboratories, manufacturers of PVC resins and compounds, compounders, quality assurance teams, material scientists, and regulatory testing bodies.
Related standards
- ISO 3451-1 - Plastics - Determination of ash - Part 1: General methods (normative reference)
- ISO 11358-1 - Thermogravimetry (TG) of polymers - Part 1: General principles (thermobalance guidance)
Keywords: EN ISO 3451-5:2025, ISO 3451-5:2025, plastics determination of ash, PVC ash determination, sulfated ash, method A B C, thermobalance, muffle furnace, calcium carbonate, lead-containing compounds.
