ISO 21304-2:2021

Overview

ISO 21304-2:2021 - Plastics: Ultra‑high‑molecular‑weight polyethylene (PE‑UHMW) - Part 2 describes standardized procedures for preparing test specimens and determining the physical, mechanical, thermal and electrical properties of PE‑UHMW moulding and extrusion materials. The standard targets materials with a melt flow rate (MFR) less than 0.1 g/10 min (measured at 190 °C / 21.6 kg per ISO 17855‑1) and is intended to produce reproducible, comparable test data for specification, quality control and product development.

Key topics and technical requirements

• Specimen preparation
  • Compression‑moulded sheets produced per ISO 293 with specified moulding temperature (nominally 210 °C) and controlled preheating, pressure, cooling and demoulding steps (see Table 1 of the standard).
  • Machining or stamping of specimens in accordance with ISO 2818 or ISO 20753.
• Conditioning
  • Unfilled PE‑UHMW: condition at 23 °C ± 2 °C for at least 40 h (no RH requirement).
  • Filled/additive‑sensitive materials: condition at 23 °C ± 2 °C and 50 % ± 10 % RH for at least 40 h.
• Test methods and properties
  • Mechanical: tensile modulus, yield stress/strain, stress at 50 % strain, flexural modulus, tensile‑impact and Charpy double‑notched impact (Annex C).
  • Thermal: melting temperature, glass transition, heat deflection temperature, coefficient of linear thermal expansion.
  • Rheological/evaluation: melt volume‑flow rate (MVR) method (Annex A) and elongational stress (Annex B).
  • Electrical and flammability tests where applicable (references to relevant IEC/ISO methods).
• Data presentation
  • Properties and test conditions selected from ISO 10350‑1 for comparable single‑point data.
  • Notes that values are reproducible for the specified specimen geometry and preparation; different specimen dimensions or procedures can yield different results.

Practical applications and who uses this standard

• Materials and components manufacturers use ISO 21304‑2 to qualify PE‑UHMW grades for moulding and extrusion and to create material datasheets.
• Quality control and testing laboratories adopt these specimen preparation and conditioning rules to ensure consistent, comparable test results.
• R&D and product designers rely on the listed mechanical and thermal properties to select materials and predict component performance (wear parts, liners, gears, medical device components).
• Standards writers and procurement/specification teams reference the designation system (ISO 21304‑1) and test data compiled per this part for contractual specifications and regulatory documentation.

Related standards

• ISO 21304‑1 (designation system and basis for specifications)
• ISO 10350‑1 (single‑point data presentation)
• ISO 293 (compression moulding), ISO 2818 (specimen machining), ISO 291 (conditioning)
• ISO 1133‑1 / ISO 17855‑1 (MFR/MVR and MFR reference)

Keywords: ISO 21304-2, PE‑UHMW, ultra-high-molecular-weight polyethylene, test specimen preparation, compression moulding, conditioning, mechanical properties, melt volume-flow rate.