ISO 16770:2004

Plastics — Determination of environmental stress cracking (ESC) of polyethylene — Full-notch creep test (FNCT)

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ISO 16770:2004 specifies a method of determining the stress cracking resistance of polyethylene materials in any environment. The test is carried out on notched test specimens cut from compression-moulded sheet or finished products, as applicable. The test specimen is subjected to a static tensile load when immersed in an environment such as a surfactant solution held at a specified temperature, and the time to failure measured.
The method has been specifically developed for polyethylene materials but can be used to evaluate PE extrusions, such as pipe segments, PE fusion welds/fittings and blow-moulded PE containers to study the effect of aggressive environments, i.e. dangerous goods/chemicals. The method may also be adapted for other thermoplastic materials, e.g. polypropylene (PP). In this case, care must be taken in interpreting the results as the processing stresses/orientation in finished products may have an effect.