ISO 1431-1:2024

Overview

ISO 1431-1:2024 - Rubber, vulcanized or thermoplastic - Resistance to ozone cracking - Part 1: Static and dynamic strain testing - specifies laboratory procedures for estimating the ozone resistance of vulcanized or thermoplastic rubber when exposed under static or dynamic tensile strain. Tests are performed in controlled ozone atmospheres (fixed ozone concentration, defined temperature and, if required, relative humidity) that exclude direct light. Evaluation is by visual observation, image analysis, or by measuring changes in physical/chemical properties.

Keywords: ISO 1431-1:2024, ozone cracking, rubber testing, static strain, dynamic strain testing, ozone resistance.

Key technical topics and requirements

• Test principle: Expose prepared rubber test pieces in a closed ozone chamber under static tensile strain, continuous dynamic strain, or alternating dynamic/static conditions.
• Test pieces & conditioning: Requirements for wide strip, narrow strip and dumb-bell specimens, including conditioning in strained or unstrained state per ISO 23529 guidance.
• Test conditions: Controlled ozone concentration, temperature and optional relative humidity settings; exclusion of direct light to avoid UV effects.
• Evaluation methods: Crack formation and growth assessed by visual ratings or image analysing techniques; alternative evaluation through changes in physical/chemical properties.
• Procedures: Multiple procedures (A, B, C, D etc.) for static and dynamic exposure, including continuous and intermittent dynamic regimes; procedures define exposure periods, elongation protocols and evaluation steps.
• Calibration & equipment: Calibration schedules for ozone generator, sensors and chambers, with reference methods for ozone concentration measurement referenced in ISO 1431-3 and guidance from ISO 18899.
• Terminology & metrics: Definitions such as threshold strain and limiting threshold strain describe the strain levels associated with onset of cracking.
• Safety & environment: Warnings about laboratory safety and potentially hazardous by-products or wastes generated during tests.

Practical applications and users

ISO 1431-1:2024 is used to:

• Assess material selection and formulation changes for resistance to ozone cracking.
• Support quality control in rubber manufacturing (seals, hoses, gaskets, tyres, automotive components).
• Provide comparative R&D data for new elastomers and protective additives (antiozonants).
• Verify product durability for suppliers, test laboratories, OEMs and regulatory/standards bodies.

Primary users: rubber compounders, polymer laboratories, automotive and aerospace materials engineers, standards and certification labs.

Note: The standard cautions that laboratory ozone chamber results may not directly predict in-service performance because ozone resistance depends strongly on test conditions (ozone level, temperature, humidity) and geometry/strain in actual parts.

Related standards

• ISO 1431-3 - Reference and alternative methods for determining ozone concentration in test chambers.
• ISO 1382 - Rubber - Vocabulary (terms and definitions).
• ISO 18899 - Guide to calibration of test equipment.
• ISO 23529 - Procedures for preparing and conditioning test pieces.

This standard provides a robust, repeatable framework for evaluating ozone cracking resistance and is essential for anyone specifying or testing elastomers for service in ozone-containing environments.