What Is Environmental Stress Cracking?
Environmental stress cracking test, where the notched or stressed sample is held in a surfactant or chemical environment; It is the experiment in which the cracking onset time or the cracking sample rate is determined.
Purpose of Environmental Stress Cracking
The aim is to determine the resistance of polyolefin and other plastics to cracking in a chemical environment under stress.
Which Products Is Environmental Stress Cracking Applied To?
- Polyethylene pipes and bottles
- Detergent and chemical packaging
- Fuel system plastic parts
- Plastic components operating under tension
In Which Sectors Is Environmental Stress Cracking Used?
Standards Related to Environmental Stress Cracking
- ASTM D1693
- ISO 22088 serisi
- ISO 16770 (FNCT)
- ASTM F1473 (PENT)
Environmental Stress Cracking Conditions
- Environment
- Surfactant solution or service chemical defined in the standard
- Strain
- Notch and bend (ASTM D1693) or constant tensile load (FNCT)
- Temperature
- Defined in the standard; upgraded for acceleration
- Assessment
- Cracking time or the rate of sample cracking in a defined period of time
Equipment for Environmental Stress Cracking
- ESCR bending fixtures and tubes
- Constant load test setup (FNCT)
- Temperature controlled bath or oven
- Notching setup and stereo microscope
Sample Requirements for Environmental Stress Cracking
- Notch depth and smoothness must comply with the standard
- Sample thickness and preparation are defined in the standard
- The freshness of the media solution must be maintained
- The number of samples must be sufficient for statistical evaluation
Duration of Environmental Stress Cracking
Days to months depending on the method; FNCT experiments can take a long time.
Environmental Stress Cracking Procedure
- 1Samples are prepared and notched.
- 2The samples are put under tension.
- 3It is kept at defined environment and temperature.
- 4Cracking is monitored at regular intervals.
- 5The cracking time or rate is recorded.
- 6The result is evaluated.
Environmental Stress Cracking Acceptance Criteria
The acceptance criterion is given in the product standard or specification as the minimum cracking time or maximum cracking sample rate.
Evaluation of Results
Notch geometry is so influential that it determines the outcome; small deviations greatly change cracking time. Expedited results do not directly translate to service life, but are reliable for sorting materials.
Environmental Stress Cracking Report
- Standard and method applied
- Sample preparation and notch dimensions
- Environment, concentration and temperature
- Tensile or bending condition
- Cracking times or rate
Accreditation
EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.
Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.
Scope and authorisationsRelated Regulations
- Pipe and packaging product standards
Plastics Testing — What Does This Testing Field Cover?
The section below describes the field that the Environmental Stress Cracking test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.
Plastics testing determines the mechanical, thermal and burning behaviour of a polymer material. Unlike metals, plastics are VISCOELASTIC: their behaviour depends on loading rate, temperature and moisture. The same material therefore gives different results under different conditions, and the test conditions are an inseparable part of the result.
The practical consequence of viscoelasticity is this: a plastic part continues to deform over time under a constant load (creep) and the stress it carries at constant deformation falls over time (stress relaxation). A screwed joint loosens, a clamp loses its clamping force, a shelf sags over time. A short-term tensile test does not show this behaviour; a long-term test or an accelerated model is needed.
Thermal behaviour is the second main axis. Melt flow rate indicates the processability of the material and lot-to-lot consistency; heat deflection temperature and the Vicat softening point give a rough limit for service temperature. Thermal analysis (DSC, TGA, DMA) reveals the identity of the material: glass transition temperature, melting behaviour, crystallinity, filler content and decomposition temperature.
Burning behaviour is the third axis and ties directly into product standards. The UL 94 class and the limiting oxygen index are written into the material data sheet; a particular class is required for the housing of an electrical appliance, while a different classification system applies to a construction product.
Ageing is the most frequently skipped part of the field. Plastics degrade under UV, heat, moisture and oxygen: colour changes, the surface cracks, impact strength falls. For a part intended for outdoor use, what matters is not its values on day one but its values after ageing. Xenon arc and fluorescent UV equipment accelerate this degradation and allow comparison.
The output of this family is usually written into the material data sheet, and product standards refer to that sheet. But there can be a difference between the data sheet value and the behaviour of the actual part: orientation formed during moulding, weld lines and internal stresses make the part behave differently from the specimen.
The use of recycled content has added a new question to the field. Recycled resin varies from lot to lot; mechanical properties, colour and burning behaviour can shift between batches. For a manufacturer using recycled material, incoming material control is therefore not a choice but a necessity.
Method groups in this field
Mechanical
Tension, compression, bending, Charpy and Izod impact, hardness (Shore), creep and environmental stress cracking.
Thermal
Melt flow index (MFI), heat deflection temperature (HDT), Vicat softening temperature, linear thermal expansion.
Thermal analysis
Transition temperatures and crystallinity by DSC, composition and decomposition by TGA, dynamic mechanical behaviour by DMA.
Burning
UL 94 classification, limiting oxygen index (LOI), glow wire and needle flame tests.
Ageing
Accelerated ageing by xenon arc and fluorescent UV, hot air ageing, humidity and condensation.
Physical
Density, water absorption, ash content, gas and water vapour permeability of films and sheets.
Commonly confused in this field
- A plastics result without a stated test rate and temperature cannot be interpreted; viscoelastic behaviour depends on these parameters.
- A specimen result does not transfer directly to the actual part; moulding orientation and weld lines are decisive.
- HDT and Vicat values are NOT service temperatures; they are a rough indication of an upper limit and do not apply under load.
- The UL 94 class depends on thickness; a different wall thickness requires re-verification.
- For moisture-absorbing polymers (such as polyamide), results are misleading unless conditioning is carried out.
- ASTM D638 and ISO 527 results are not directly equivalent; the specimen geometries and rate definitions differ.
Which decisions these results support
- Material selection and supplier approval
- Meeting the flammability and thermal requirements of the product standard
- Verifying the use of recycled content and lot control
- Moulding process control and lot consistency
- Demonstrating ageing resistance for outdoor use
Related Tests
Frequently Asked Questions About Environmental Stress Cracking
According to which standard is Environmental Stress Cracking made?
Environmental Stress Cracking is executed in scope ASTM D1693, ISO 22088 serisi, ISO 16770 (FNCT) and ASTM F1473 (PENT). The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.
Which products does Environmental Stress Cracking apply to?
Mainly applied to Polyethylene pipes and bottles, Detergent and chemical packaging, Fuel system plastic parts and Plastic components operating under tension. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Environmental Stress Cracking done?
The determining parameters are: Environment — Surfactant solution or service chemical defined in the standard, Strain — Notch and bend (ASTM D1693) or constant tensile load (FNCT) and Temperature — Defined in the standard; upgraded for acceleration. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.
What kind of sample is needed for Environmental Stress Cracking?
Notch depth and smoothness must comply with the standard, Sample thickness and preparation are defined in the standard and The freshness of the media solution must be maintained. The number of samples is determined according to the product standard and the scope to be reported.
How long does Environmental Stress Cracking take?
Days to months depending on the method; FNCT experiments can take a long time. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.
What is the Environmental Stress Cracking result called "appropriate"?
The acceptance criterion is given in the product standard or specification as the minimum cracking time or maximum cracking sample rate.