PTFE

The lowest coefficient of friction of any solid, and effectively inert to every common chemical, which is why it lines reaction vessels and coats pans. At 2170 kg/m³ it is the densest common plastic, roughly twice the density of the polyethylene and nylon it sits alongside. It has a real crystalline melting point at 327 °C but does not flow when melted — it is processed by sintering like a ceramic, not by injection moulding — and above about 260 °C it releases fumes that cause flu-like symptoms and are lethal to pet birds, which is the real reason not to leave a non-stick pan on a high empty flame.

Properties

Density

2,170 kg/m³ (2,140–2,200) — 2.17 g/cm³

Melting point

327 °C

Tensile strength

20–35 MPa

Young's modulus

0.5 GPa

Thermal conductivity

0.25 W/(m·K)

Thermal expansion

135 µm/(m·K)

Floats in water

No

Magnetic

No

What it is used for

• Non-stick pan coatings
• Plumbing thread seal tape
• Chemical-resistant gaskets and linings
• Low-friction slide bearings and cable liners

How it compares

Does it rust?

PTFE contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.

Is it magnetic?

PTFE is not a metal and has no ferromagnetic response.