ISO 21304-1:2019

Overview

ISO 21304-1:2019 defines a standardized designation system and the basis for specifications for ultra-high-molecular-weight polyethylene (PE‑UHMW) moulding and extrusion materials. It applies to PE‑UHMW with a melt mass‑flow rate (MFR) < 0.1 g/10 min (190 °C, 21.6 kg) and covers homopolymers and selected copolymers supplied as powder, granules or pellets. The standard provides a concise code-based format for identifying material type, fillers, intended application/processing, key designatory properties and optional specification requirements.

Key topics and requirements

• Designation structure (individual-item block): Five comma‑separated data blocks following the identity block:
  • Data block 1: Identification symbol “PE‑UHMW” (per ISO 1043‑1).
  • Data block 2: Filler/reinforcement type, form and nominal content using code letters and numeric content.
  • Data block 3: Intended application/method of processing (position 1) and up to seven positions for properties, additives and colour.
  • Data block 4: Three designatory properties coded by ranges:
    • Viscosity number (determined per ISO 1628‑3, nitrogen atmosphere) coded into seven ranges.
    • Elongational stress (determined per ISO 21304‑2, Annex B) coded into six ranges.
    • Charpy double‑notched impact strength (per ISO 21304‑2, Annex C) coded into five ranges.
  • Data block 5 (optional): Additional requirements to transform a designation into a formal specification (e.g., reference to national standards).
• Format rules: Hyphen starts the individual-item block; data blocks separated by commas; empty blocks shown by consecutive commas.
• Scope limits & notes: MVR can be useful for characterizing some PE‑UHMW (see ISO 21304‑2); identical designations do not guarantee identical performance - test data or additional specifications may be needed.

Applications and who uses it

ISO 21304‑1 is intended for:

• Material manufacturers and compounders to label and market PE‑UHMW grades.
• Product designers and OEMs to identify candidate materials for moulding, extrusion, pipes, films, fibres and sintering.
• Procurement and quality engineers to create unambiguous purchase specifications and quality acceptance criteria.
• Standards writers and testing labs as a basis for consistent specification and communication of PE‑UHMW properties.

Practical benefits include streamlined grade selection, clearer supplier communication, and a standardized starting point for application‑specific material specifications.

Related standards

• ISO 21304‑2: Test specimen preparation and determination of properties (referenced for elongational stress, Charpy tests and MVR guidance).
• ISO 1043‑1: Symbols and abbreviated terms for plastics (used for the PE‑UHMW symbol).
• ISO 1628‑3: Determination of viscosity number for polyethylenes (test method referenced).
• ISO 5834‑1: Ultra‑high molecular weight polyethylene - powder form (related medical implant material reference).