Overview
EN ISO 20568-2:2017 (ISO 20568-2:2017) specifies procedures for the preparation of test specimens and the determination of properties of thermoplastic fluoropolymer dispersions, and moulding and extrusion materials. The standard defines test methods and conditioning requirements whose results can be used as the basis for material designation, supplier specifications and quality control of fluoropolymer resins (for example PTFE and melt-processable fluoropolymers).
Key topics and technical requirements
- Preparation of test specimens: Follow applicable ISO procedures for specimen preparation; the standard gives special procedures where needed (e.g., PTFE preforming and sintering).
- Conditioning and test conditions: Conditioning per ISO 291; laboratory test temperature typically 23 °C ± 2 °C. Note: PTFE exhibits a first‑order transition just below 22 °C, so testing and conditioning near 23 °C are emphasized to avoid density/structure variations.
- Determination of properties: Tests referenced to international standards or procedures in the document for use in designation/specification.
- PTFE-specific tests:
- Standard specific gravity (SSG): Preforming mould details and sample handling are specified (e.g., 28.6 mm internal diameter tube; weigh 12.0 g ± 0.1 g; pressures 34.5 MPa for granular PTFE and 14 MPa for coagulated dispersion resins).
- Bulk density, particle size and distribution, dispersion testing: Methods for granular and dispersion PTFE, including percent PTFE and surfactant determination for dispersions.
- Melt-processable fluoropolymers:
- Tests include melt mass‑flow rate (MFR) (ISO 1133-1 referenced) and melting-peak temperature (DSC per ISO 11357-3).
- Polymer-specific tests: PCTFE zero‑strength time, glass-transition measurement for certain copolymers (DSC per ISO 11357-2).
- Safety note: Users should follow laboratory safety practice; the standard points out specific hazards in PTFE testing sections.
Applications
- Establishing material specifications and designations for fluoropolymer resins.
- Incoming quality control and acceptance testing for PTFE powders, dispersions and melt-processable fluoropolymers.
- R&D and process development for extrusion, molding and sintering of fluoropolymers.
- Supplier qualification, procurement contracts and regulatory/compliance documentation.
Who uses this standard
- Materials and polymer engineers, quality assurance laboratories, test houses, fluoropolymer manufacturers, compounders, and OEMs specifying fluoropolymer resins for industrial, chemical processing, electrical or high-performance sealing applications.
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