What Is Chemical Resistance?
Chemical resistance test is a test in which the sample is immersed in a defined chemical liquid at a defined temperature and time; It is an experiment in which the change in mass, size, appearance and mechanical properties is measured.
Purpose of Chemical Resistance
The aim is to verify that the material retains its properties against chemicals in the service environment.
Which Products Is Chemical Resistance Applied To?
- Chemical plant pipe and tank materials
- Automotive engine compartment parts
- Gaskets and sealing elements
- Coatings and primers
In Which Sectors Is Chemical Resistance Used?
Standards Related to Chemical Resistance
- ISO 175
- ASTM D543
- ISO 4599 (under tension)
- ISO 22088 (environmental stress cracking)
Chemical Resistance Conditions
- Kimyasal
- Liquid representing the service medium; defined in specification
- Temperature
- Service temperature or accelerated temperature defined in the standard
- Time
- Defined in the standard; typically days to weeks
- measured change
- Mass, size, hardness, appearance and tensile properties
Equipment for Chemical Resistance
- Dip pots and temperature-controlled baths
- Analytical balances and measuring instruments
- Tensile tester (post-exposure)
- Fume hood and chemical storage
Sample Requirements for Chemical Resistance
- Sample dimensions and surface condition must comply with the standard
- All measurements should be recorded before exposure
- Control samples (unexposed) should be kept together
- Chemical freshness and concentration should be monitored
Duration of Chemical Resistance
1–6 weeks depending on duration.
Chemical Resistance Procedure
- 1Samples are measured and weighed.
- 2The chemical is prepared and brought to temperature.
- 3Samples are immersed for a defined period of time.
- 4Samples are removed, cleaned and conditioned.
- 5Mass, size and appearance change are measured.
- 6Mechanical properties are measured again and compared to the control.
Chemical Resistance Acceptance Criteria
Acceptance criteria are given in the specification: mass/size change and loss of mechanical properties remain below the limit.
Evaluation of Results
Increasing the temperature may change the mechanism; The accelerated test result cannot be directly translated into service life. Circumferential stress cracking in material under tension develops much more rapidly than in stress-free immersion; If there is this risk, ISO 22088 type testing is required.
Chemical Resistance Report
- Standard applied
- Chemical, concentration and temperature
- Exposure duration
- Before/after measurements and control comparison
- Appearance findings
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
- Product and facility specifications
Plastics Testing — What Does This Testing Field Cover?
The section below describes the field that the Chemical Resistance 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 Chemical Resistance
According to which standard is Chemical Resistance made?
Chemical Resistance is executed in scope ISO 175, ASTM D543, ISO 4599 (under tension) and ISO 22088 (environmental stress cracking). 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 Chemical Resistance apply to?
Mainly applied to Chemical plant pipe and tank materials, Automotive engine compartment parts, Gaskets and sealing elements and Coatings and primers. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Chemical Resistance done?
The determining parameters are: Kimyasal — Liquid representing the service medium; defined in specification, Temperature — Service temperature or accelerated temperature defined in the standard and Time — Defined in the standard; typically days to weeks. 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 Chemical Resistance?
Sample dimensions and surface condition must comply with the standard, All measurements should be recorded before exposure and Control samples (unexposed) should be kept together. The number of samples is determined according to the product standard and the scope to be reported.
How long does Chemical Resistance take?
1–6 weeks depending on duration. 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 Chemical Resistance result called "appropriate"?
Acceptance criteria are given in the specification: mass/size change and loss of mechanical properties remain below the limit.