ISO 24483:2023

Overview

ISO 24483:2023 - Epoxidized natural rubber (ENR) - Specifications defines the physical and chemical requirements for epoxidized natural rubber (ENR) based on its epoxidation level. The first edition (2023) standard covers grade structure, material composition, sampling, packaging and the test methods needed to verify key properties of ENR grades (notably ENR 25, ENR 50 and their field-latex variants ENR 25 FL / ENR 50 FL). This standard provides a uniform reference for manufacturers, buyers and testing laboratories to specify and verify ENR quality.

Key topics and requirements

• Grades and identification
  • ENR 25, ENR 50 (centrifuged latex origin) and ENR 25 FL, ENR 50 FL (field latex origin).
  • Numerals indicate mole percentage epoxidation (25 mol% and 50 mol% ± 2 mol%).
• Chemical and physical limits
  • Epoxidation level: 25 ± 2 % or 50 ± 2 % (mole fraction) - ISO 5260.
  • Ring opening level (max): ENR 25 → 2.0 %; ENR 50 → 4.0 % (mole fraction).
  • Ash content (max): 0.25 % (mass fraction) - ISO 247-1.
  • Mooney viscosity (ML (1+4) at 100 °C): 70 to 100 - ISO 289-1.
  • Glass transition temperature (Tg): ENR 25: −45 ± 2 °C; ENR 50: −22 ± 2 °C - ASTM D3418.
  • Nitrogen content (field-latex grades only): max 0.15 % - ISO 1656.
  • Lovibond colour index (optional): max 4.0 - ISO 4660.
• Quality control
  • Sampling per ISO 1795; each lot must meet agreed grade requirements.
  • Packaging typically in bales of nominal 33.3 kg or 35 kg, identified and wrapped (ISO 20299-2 recommended).

Applications and users

ISO 24483:2023 is used by:

• Rubber compounders and product manufacturers specifying ENR feedstock for formulation control.
• Quality assurance and testing laboratories performing conformity checks (epoxidation, ring opening, viscosity, Tg).
• Procurement and specification engineers drafting material purchase requirements.
• Standards bodies and certification organizations harmonizing ENR specifications for trade.

The standard helps ensure consistent ENR quality and supports broader use of chemically modified natural rubber grades across rubber product applications where controlled epoxidation levels and reproducible physical properties are required.

Related standards

Relevant normative references cited in ISO 24483:2023 include:

• ISO 5260 (epoxidation by NMR), ISO 247-1, ISO 289-1, ISO 1656, ISO 1795, ISO 4660, ISO 20299-2; also ASTM D3418 and ISO 2000 for broader NR specification guidance.