If you ask which plastic is "the most resistant" in three categories at once — heat, chemicals, and friction — engineers worldwide give the same answer: PTFE, best known by the trade name Teflon. This guide covers what it excels at, where it's used, and the limits you must know before ordering.
What is PTFE?
PTFE (Polytetrafluoroethylene) is a fluoropolymer whose molecular backbone is built from carbon–fluorine bonds — among the strongest in organic chemistry. Almost no chemical can attack it, which is the source of every one of its legendary properties.
Why do chemical and high-heat jobs need PTFE? Three unmatched strengths
1. Resists nearly every aggressive chemical
Concentrated acids, strong alkalis, solvents — PTFE shrugs them all off. It is the standard material for plating lines, chemical tanks, flange gaskets in chemical plants, and any part in direct contact with corrosive media.
2. Continuous service at 260°C
Rated for continuous use up to about 260°C and stays functional deep into cryogenic temperatures — the widest service range of any common engineering plastic.
3. The lowest friction
PTFE has the lowest coefficient of friction of any engineering solid. Almost nothing sticks to it, so it's used for slide surfaces, bearing pads, and seals in constant rotating or sliding motion.
What are PTFE's key numbers?
Typical values for virgin PTFE:
| Property | Typical Value | What it means in practice |
|---|---|---|
| Service temperature range | −200 to +260°C | Widest of the common engineering plastics |
| Friction coefficient | ~0.05–0.10 | Lowest of any engineering solid — slides without lubrication |
| Density | ~2.13–2.20 g/cm³ | Roughly double most plastics |
| Tensile strength | ~20–35 MPa | Not high — sustained compressive load is its weak point |
| Moisture absorption | ~0% | Dimensions never change with humidity |
| Dielectric strength | Very high, ~60–80 kV/mm (thin film) | Excellent insulator even at high frequency |
What is PTFE used for?
- Seals and gaskets — survives heat and chemistry without swelling or rotting
- Slide plates / bearing pads — slippery with zero lubrication
- Electrical insulation — superb dielectric properties, used in high-frequency work
- Chemical line components — valves, fittings, bushes in corrosive environments
- Food industry — food-contact grades, non-stick, easy to clean
How do filled PTFE grades differ from virgin PTFE?
Virgin PTFE's weakness — creep under sustained load — is solved by compounding with reinforcing fillers. These are the grades real-world seals actually use:
- Glass-filled (15–25% glass fibre) — several times better creep and wear resistance; the standard for seals and piston rings
- Carbon-filled — good wear resistance, better thermal conduction, dissipates static; suited to dry-running seals at speed
- Bronze-filled (40–60% bronze powder) — strongest and best heat conduction of the group, common in hydraulics; trades away some chemical resistance and food-contact approval
If your part is a gasket or seal under continuous compression, ask for a filled grade first — the price difference from virgin is small, the service-life difference is not.
What are PTFE's limits?
- Soft, and creeps — sustained high compressive loads slowly deform it; use filled grades or step up to PEEK
- Abrasion resistance loses to Nylon — for pure heavy sliding wear with no heat or chemicals, Nylon or POM is better value
- Costs more than general plastics — you pay for the chemical/heat immunity; don't pay for spec the job doesn't need
Summary
PTFE is the answer for aggressive chemicals, high heat, or ultra-low friction. We stock PTFE sheet and rod, cut to size, and can machine it into seals, gaskets and bushes to your drawing. For the overall selection method, read How to Choose the Right Engineering Plastic.