Editorial Feature

Polytetrafluoroethylene - PTFE

Polytetrafluoroethylene (PTFE) is a totally fluorinated polymer which is white, semi-opaque, and semi-crystalline. It has excellent chemical resistance, is unaffected by nearly all chemicals, and has a very high oxygen index (i.e. is inherently non-flammable). It is stable to high temperatures and has a very low coefficient of friction.

It is soft, easily deformed, low in strength, and has very low creep resistance with poor radiation resistance. PTFE is relatively expensive and cannot be melt-processed (albeit theoretically, it melts at 327 °C, the melt viscosity of normal grades is almost infinite) and so is formed by powder sintering methods.

Polymer Type

Thermoplastic

Advantages

Outstanding chemical resistance.  Low coefficient of friction.  High continuous use temperature (c 180 °C/360 °F).  Very high oxygen index.

Disadvantages

High cost.  Low strength and stiffness.  Cannot be melt processed.  Poor radiation resistance.

Applications

Bearings, chemical vessel linings, pipe and valve linings, gaskets, diaphragms, piston rings, high temperature electrical insulation.  As a coating for non-stick applications.

Industrial applications include O-rings, seals, and non-stick coatings and linings for vessels. PTFE’s unique properties make it perfect for a wide range of laboratory applications.

Typical Properties

Property Value
Density (g/cm3) 2.15
Surface Hardness SD63
Tensile Strength (MPa) 25
Flexural Modulus (GPa) 0.70
Notched Izod (kJ/m) 0.16
Linear Expansion (/°C x 10-5) 15
Elongation at Break (%) 400
Strain at Yield (%) 70
Max. Operating Temp. (°C) 180
Water Absorption (%) 0.01
Oxygen Index (%) 95
Flammability UL94 V0
Volume Resistivity (log ohm.cm) 18
Dielectric Strength (MV/m) 45
Dissipation Factor 1 kHz 0.0001
Dielectric Constant 1 kHz 2.1
HDT @ 0.45 MPa (°C) 121
HDT @ 1.80 MPa (°C) 54
Material. Drying hrs @ (°C) NA
Melting Temp. Range (°C) NA
Mould Shrinkage (%) NA
Mould Temp. Range (°C) NA

Comments

  1. Sanket Gaikwad Sanket Gaikwad India says:

    Can I know, what is the good range of hardness of PTFE produce from paste extrusion method?

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