Corrosion Resistance Comparison of Common Plastics
The corrosion resistance of plastics depends on their molecular structure and chemical stability. Fluoroplastics such as PTFE have the highest corrosion resistance, followed by polyolefins like PE and PP. Engineering plastics such as ABS, PC, and PA have limited resistance in certain corrosive environments.
Key Factors Affecting Corrosion Resistance
Non‑polar plastics (PE, PP, PTFE) are generally more resistant to acids and alkalis because their molecular chains have no reactive groups. Polar plastics (PA, PC, ABS) contain ester, amide, or other active groups, making them more susceptible to strong oxidizers, acids, and alkalis. Higher crystallinity usually improves corrosion resistance, as seen in HDPE compared to LDPE.
Performance in Acid and Alkaline Environments
In acidic and alkaline environments, PTFE resists almost all chemicals, including concentrated sulfuric acid and sodium hydroxide. PE and PP also perform well with most acids and alkalis but may fail in strong oxidizing conditions. ABS, PC, and PA are less resistant and may crack, swell, or degrade when exposed to strong acids or alkalis.
| Plastic Type | Acid & Alkali Resistance | Organic Solvent Resistance | Typical Applications | Limitations |
|---|---|---|---|---|
| PTFE | Excellent (resists all acids & alkalis) | Excellent (resists all solvents) | Chemical anti-corrosion parts, seals | Difficult to process, high cost |
| PE | Excellent (resists weak acids/alkalis, not strong oxidants) | Medium (resists alcohols, not aromatics/halohydrocarbons) | Acid-alkali storage tanks, conveying pipes | Softens at high temperatures |
| PP | Excellent (slightly better than PE) | Medium (resists alcohols, not aromatics/halohydrocarbons) | Chemical containers, valve fittings | High brittleness at low temperatures |
| PVC | Medium (resists acids/alkalis, not strong oxidants) | Medium (resists alcohols, not ketones/aromatics) | Water supply/drainage pipes, anti-corrosion coatings | Releases harmful substances at high temperatures |
| ABS | Poor (only resists weak acids/alkalis) | Poor (soluble in ketones/esters) | Home appliance casings, general structural parts | Suitable only for dry environments |
| PC | Medium (resists weak acids, not strong alkalis) | Poor (not resistant to ketones/halohydrocarbons) | Transparent structural parts, protective masks | Prone to hydrolysis, not resistant to long-term corrosion |
| PA | Medium (resists alkalis, not strong acids) | Medium (resists oil, not aromatics) | Wear-resistant gears, oil pipe fittings | High hygroscopicity, poor dimensional stability |
| POM | Medium (resists weak acids/alkalis) | Medium (resists alcohols, not aromatics) | Precision gears, pump components | Not resistant to strong acids/alkalis, prone to embrittlement |
Performance in Organic Solvent Environments
With organic solvents, PTFE remains stable in almost all solvents. PE and PP are resistant to alcohols but may swell in aromatic or halogenated hydrocarbons. PVC resists alcohols and esters but is not suitable for ketones or aromatics. Engineering plastics generally have poor solvent resistance; ABS dissolves in ketones and esters, PC cracks in ketones and halogenated hydrocarbons, and POM may become brittle in certain solvents.
Key Material Selection Principles
When selecting materials, PTFE is preferred for highly corrosive conditions. For less severe environments, PE and PP offer a good balance of performance and cost. Engineering plastics should be avoided in strong acid, strong alkali, or harsh solvent applications.
