• PTFE
  • PTFE
  • PTFE

PTFE is a unique material in that it is very versatile and covers a wide range of applications, this is due to it being virtually chemically inert, with only a few strong acids and alkali being able to effect its performance.
Also it as a very low coefficient of friction, one of the lowest of all man made materials.
And lastly it as a very wide operating temperature range, it remains effective in liquid nitrogen at -196 deg C and does not become brittle even in liquid helium at -269 deg C.
At the other end of the scale it as a continuous working temperature of 260 deg C with a short term usage of up to 300 deg C.

PTFE in its unfilled state is quite a soft material, but the mechanical properties of PTFE can be improved with the addition of fillers.
For instance the addition of glass fibre gives the material a much better wear resistance, allowing a longer life span, in such applications as ball valve seats.
Whilst the addition of Carbon fibre greatly improves its creep resistance especially at raised temperature, also giving a better expansion resistance making it a good bearing material.

Below is a chart showing some generic mechanical properties of PTFE and a few compounds.

Material

Spec. gravity

Tensile strength

Elongation at break

Deformation under load

Coefficient or friction

Hardness shore D

Virgin PTFE

2.15

30 – 40 N/mm2

300 / 450 %

17% under 15N/mm2 load

0.05 / 0.2

50 / 60

25% Glass filled PTFE

2.24

15 – 20 N/mm2

200 / 350 %

14% under 15N/mm2 load

0.09 / 0.2

60 / 70

25% Carbon/Graphite filled PTFE

2.10

10 – 18 N/mm2

100 / 150 %

9% under 15N/mm2 load

0.1 / 0.2

65 / 75

Bronze filled PTFE

3.9

15 – 16 N/mm2

150 / 250 %

9% under 15N/mm2 load

0.07 /0.2

65 / 75

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