Properties of PTFE

PTFE has an unmatchable profile of unique properties which make it one of the most valuable and versatile engineering materials available.

Polytetrafluoroethylene

- the high performance fluoropolymer

See below for more information on:



more below

Properties of Pure PTFE

Total chemical resistance:

  • can be used in the most corrosive environments
  • will not contaminate the most sensitive medium
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Completely insoluble with high purity

  • No contamination in ultra-pure or corrosive applications
  • Very high intrinsic purity
...details

High thermal stability

  • Working temperatures from -200 to +300C
  • Thermal degradation does not start until 400+C
  • Does not melt to a liquid phase - an in-built safety feature
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Exceptional electrical properties

  • Extremely high electrical resistance
  • Low dielectric constant and dielectric loss factor
  • Does not support tracking
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Exceptional anti-adhesion properties

  • Lowest coefficient of friction of all solids
  • Other materials exhibit little or no adhesion to PTFE
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Good flexural properties

  • Outstanding resistance to fatigue
  • No embrittlement in liquid helium
...details



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Properties of Modified PTFE

Basic PTFE is a linear polymer of tetrafluoroethylene, CF2=CF2

Two co-polymers using perfluoropropylene-vinyl-ether (PPVE) as co-monomer are commercially important, these are:

  • TFM, a copolymer with about 0.1% PPVE
  • PFA, a copolymer with 3 - 15% PPVE

TFM is essentially similar to PTFE but with reduced porosity, improved tensile strength and a high degree of weldability.

PFA is a melt-processable thermoplastic with similar chemical resistance to PTFE. It has much lower porosity and is translucent.


FEP, Fluorinated Ethylene Propylene, a thermoplastic, is also a member of this family and shows the high chemical resistance characteristic of fluoropolymers along with excellent clarity.


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Properties of filled PTFE

A range of fillers, typically glass fibre, carbon, graphite, metal powders and molybdenum disulphide can be blended with PTFE resins, usually in the proportion of 2 - 40%, to improve certain characteristics.

The incorporation of fillers can:

  • Increase compressive strength
  • Improve thermal conductivity
  • Improve abrasion resistance
  • Reduce thermal expansion
  • Reduce cold flow
  • Impart electrical conductivity

It should be noted that the use of fillers may downgrade other properties of PTFE such as chemical and electrical resistance.


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Technical Data

Property PTFE TFM PFA FEP Polypropylene
Appearance


Density ( g.cm-3 )

Melting Point ( C )

Max. Service Temperature ( C )


Chemical Resistance


Water absorption

Hardness (Shore)

Tensile Strength at 23C (MPa)

Elongation at break (%)

Flammability


Electrical Resistance (Ohms.m-1)

Cost Index

Ivory-white, opaque

2.15

327

290


Excellent


Nil

60

20-40

250-500

Non-flammable

1018

1.0

Ivory-white, opaque

2.15

327

290


Excellent


Nil

60

40

250-500

Non-flammable

1018

1.5

Translucent


2.15

305

260


Excellent


Nil

63-65

15-25

100-250

Non-flammable

1016

3.0

Transparent


2.14

270

205


Excellent


Nil

63-65

20-30

250-300

Non-flammable

1018

2.5

Translucent


0.9

160

140 Short
110 Long

Good except for HC and oxidising agents

Nil

60-75

25-40

600

Ignites on flame contact & will burn

1016

0.25

Figures quoted are typical values

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