Overview
ISO 22088-1:2006 - "Plastics - Determination of resistance to environmental stress cracking (ESC) - Part 1: General guidance" provides general guidance for selecting appropriate test methods to assess environmental stress cracking (ESC) of thermoplastic materials. It explains the phenomenon, lists parameters that influence ESC, and directs users to the specific test-method parts (Parts 2–6) for procedural details. ISO 22088-1 is intended primarily as a ranking and comparative tool, not for direct design or life‑prediction.
Key topics and requirements
- Scope and purpose
- Guidance for selecting ESC test methods for thermoplastics; tests are essentially for ranking materials.
- ESC phenomenon
- Describes mechanisms (microvoids, craze formation, crack initiation) and key influencing factors: specimen dimensions, orientation, thermal history, stress/strain, temperature, test medium, and failure criterion.
- Available test methods (summarized)
- Part 2: Constant tensile load method
- Part 3: Bent strip (fixed flexural strain)
- Part 4: Ball or pin impression (local deformation)
- Part 5: Constant tensile deformation
- Part 6: Slow strain rate method
- Specimen preparation
- Specimens must be prepared and handled consistently (references: ISO 293, ISO 294-1, ISO 2818). Machined surfaces must be free of visible flaws; orientation and molding effects must be reported.
- Conditioning and test conditions
- Default conditioning: at least 24 h at (23 ± 2) °C and (50 ± 10) % RH.
- Normal test temperature: (23 ± 2) °C; alternate temperatures include 40, 55, 70, 85, 100 °C (±2 °C) as agreed.
- Test medium: specified by the relevant material standard or chosen to represent service exposure; examples include 95% ethanol, a 1% nonylphenoxy-poly(ethylene-oxy)ethanol solution, or refined linseed oil.
- ESC index
- Defined as the ratio of a failure-indicative property measured in the test medium to that in a reference medium (usually air), used for comparative assessment.
Applications and users
- Who uses ISO 22088-1
- Materials R&D, quality control laboratories, test houses, product engineers, and manufacturers of thermoplastic articles.
- Practical uses
- Screening and ranking materials for resistance to chemical/stress environments.
- Comparing processing/molding effects (orientation, internal stress) on ESC susceptibility.
- Selecting the most relevant test method (constant load vs bent strip vs local impression) based on expected in-service stress/strain type.
- Limitations
- Results are comparative; short-duration specimen tests rarely predict complex in-service behavior directly. Careful matching of test conditions to application is essential.
Related standards
- ISO 22088 series: Parts 2–6 (specific test methods)
- Specimen preparation: ISO 2818, ISO 293, ISO 294-1
- Other referenced or comparable methods: ASTM D1693 (Bell/bent-strip), ISO 16770 (FNCT), ASTM F1473 (PENT) - useful cross-references when selecting test protocols.
Keywords: ISO 22088-1, environmental stress cracking, ESC testing, thermoplastics, test specimen preparation, ESC index, test medium, conditioning, ESC resistance.
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