Sources and scope for this page: ISO 175:2010, covering the immersion-test basis behind the ratings; and ASTM D543-21, covering the standard practice for the resistance ratings (one more source is tabulated below). No independent source check is recorded for this page: the content rests on the sources listed and on the working shown on the page. Full sources, values and limits on this page.
Page last changed 2026-11-08 · based on ISO 175:2010
Quick Answer
Chemical Resistance of Engineering Plastics
| Material[1] | Dilute acids[1] | Concentrated acids[1] | Bases (alkalis)[1] | Ketones[1] | Aromatic hydrocarbons[1] | Chlorinated solvents[1] | Oils & fuels[1] | Hot water > 60 °C[1] |
|---|---|---|---|---|---|---|---|---|
| PTFE # | A | A | A | A | A | A | A | A |
| PEEK # | B | C | A | A | A | B | A | A |
| PPS # | A | B | A | A | B | B | A | A |
| UHMW-PE # | A | B | A | B | C | C | A | A |
| Rigid PVC # | A | B | A | D | C | D | A | A |
| POM-C (Acetal copolymer) # | C | D | B | A | A | A | A | C |
| POM-H (Delrin) # | C | D | C | B | B | B | A | D |
| PET-P (Ertalyte) # | B | C | C | B | B | C | A | C |
| Nylon 6/6 # | D | D | B | A | B | B | A | C |
| Polycarbonate # | C | D | C | D | D | D | B | C |
| PEI (Ultem) # | C | D | C | D | C | D | B | C |
| Acrylic (PMMA) # | B | C | C | D | D | D | B | B |
A = no significant effect at ambient temperature · B = minor effect, suitable for most service · C = limited use, swelling, softening or property loss expected · D = not recommended, rapid attack or dissolution. Ratings assume ambient temperature unless the column says otherwise, and assume no mechanical stress. Stress and temperature both accelerate chemical attack: a material rated C unstressed can crack in days when stressed, and a rating that holds at 20 °C may not hold at 60 °C.
How Each Chemical Family Attacks Plastics
Dilute acids attack nylons and acetals by hydrolysing the polymer chain — nylon is dissolved outright by formic acid and degraded by mineral acids. Polyolefins, PVC, PTFE and PPS are essentially unaffected.
Concentrated acids are a much smaller set of survivors: PTFE, and to a lesser degree PPS and UHMW-PE. PEEK resists most acids but is dissolved by concentrated sulphuric acid. Everything else in the table is degraded.
Bases are the mirror image. Most plastics tolerate alkalis well, but polyester-based materials hydrolyse, and acetal homopolymer is attacked by strong bases and hot water.
Ketones (acetone, MEK) and chlorinated solvents (dichloromethane, chloroform) are the two families that destroy amorphous plastics. Polycarbonate, PEI and acrylic dissolve or stress-crack in ketones and chlorinated solvents; PVC is attacked by both. Semi-crystalline plastics — PEEK, PPS, acetal, nylon, PTFE, polyolefins — are generally resistant to both, which is one of the practical advantages of a crystalline structure.
Aromatic hydrocarbons (benzene, toluene, xylene) swell polycarbonate, acrylic and PEI badly, and affect polyolefins moderately. PEEK, PPS, acetal and PTFE are resistant.
Hot water is the most underrated item in the table. Hydrolysis is temperature-driven, so water that is harmless at 20 °C can destroy a part at 80 °C. Acetal homopolymer is the classic example: fine in cold water, fails in hot. Use copolymer if hot water is unavoidable, and PPS, PSU or PEEK if it is continuous.
Stress Cracking, and Why a Rating Can Be Wrong
The letter in this table describes an unstressed specimen in the chemical at ambient temperature. Real parts are stressed, and that changes the answer.
Environmental stress cracking is the failure mode to design against. A chemical that merely swells an unstressed part can crack a stressed one in hours — the chemical lowers the energy needed for a crack to grow, and the stress provides the driving force. Polycarbonate, acrylic and PEI are the most susceptible of the materials here; the classic case is a polycarbonate part assembled with a press fit and then cleaned with an alcohol or ketone, which cracks at the press fit days later.
Temperature accelerates everything. Reaction rates roughly double for every 10 °C, so a rating that holds at 20 °C may fail at 50 °C. Whenever a part sees both a chemical and an elevated temperature, treat the table rating as one grade worse.
Mixtures are not averages. A blend of two chemicals can attack a plastic that neither attacks alone. This is common with cleaning solutions, where surfactants and solvents act together.
For any part in continuous contact with a chemical — a pump housing, a tank liner, a seal — the compatibility table is a shortlisting tool, not a qualification. Immersion-test the actual material in the actual medium at the actual temperature, under the actual stress, before committing to production.
Frequently Asked Questions
- What is the most chemical-resistant plastic?
- PTFE. It is resistant to essentially every chemical family in this table and to nearly all industrial chemicals, with the exceptions of molten alkali metals, elemental fluorine at elevated temperature, and some fluorinated compounds under pressure. PEEK and PPS are the next most resistant among the melt-processable plastics, but PEEK is dissolved by concentrated sulphuric acid.
- Which plastics are attacked by solvents?
- Amorphous plastics are the vulnerable group: polycarbonate, acrylic (PMMA), PEI and rigid PVC are all attacked by ketones and chlorinated solvents, and polycarbonate, acrylic and PEI are also swollen or dissolved by aromatic hydrocarbons. Semi-crystalline plastics — PTFE, PEEK, PPS, acetal, nylon and the polyolefins — resist these solvent families.
- Why did my polycarbonate part crack after cleaning?
- Environmental stress cracking, most likely. Polycarbonate is highly susceptible: a cleaning solvent — alcohol, ketone or an aggressive surfactant — lowers the energy needed for a crack to propagate, and any residual assembly stress provides the driving force. The crack typically appears at a press fit, a thread or a sharp corner, hours or days after cleaning. Anneal the part, reduce the assembly stress, or switch to a cleaning chemistry the table rates A for polycarbonate.
- Is a compatibility rating valid at high temperature?
- No. Ratings assume ambient temperature, and chemical attack roughly doubles in rate for every 10 °C rise. A material rated B at 20 °C should be treated as C or D at 60 °C, and hot water in particular hydrolyses materials that cold water does not touch — acetal homopolymer being the standard example. Always check the temperature column of the supplier's compatibility table, not just the chemical.
Related
Value Sources
References and calculation methods used for this page are listed below. Numbered markers connect table columns where present. A reference listing does not itself establish that every value has been independently checked.
| # | Source | Type | Revision / method |
|---|---|---|---|
| [1] | Published polymer chemical-compatibility tables (supplier and resin-producer compilations) | reference | compilations as published 2024–2026 |
Data Sources
| Standard | Revision | What it covers on this page |
|---|---|---|
| ISO 175 — Plastics — Determination of the effects of immersion in liquid chemicals | ISO 175:2010 | the immersion-test basis behind the ratings |
| ASTM D543 — Resistance of Plastics to Chemical Reagents | ASTM D543-21 | the standard practice for the resistance ratings |
| Supplier chemical-compatibility tables (resin producers and stock-shape distributors) | compilations as published 2024–2026 | the individual rating letters |
Verification scope
No page-specific independent source review is recorded here. The listed references and formulas explain the basis of the compilation; automated consistency checks do not verify the original sources or establish product conformity.
Ratings describe unstressed specimens at ambient temperature in the pure chemical. Stress, elevated temperature, chemical mixtures and long exposure all make attack more likely, so treat the rating as an optimistic bound rather than a guarantee. For continuous contact with a chemical, immersion-test the actual material in the actual medium at the actual temperature under the actual stress before production. Ratings for filled and modified grades can differ from the base polymer.
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