Teflon (PTFE) and Polyacrylonitrile (PAN)

Two substitutes of asbestos are Teflon (PTFE) and Polyacrylonitrile (PAN)

Teflon (PTFE) fibres

Teflon is the trade name for PTFE (polytetrafluoroethylene) fibres. They are used in seals and gaskets to prevent sticking. They are also used in packings at low shaft speeds where the temperature limit of 2600C can be accommodated. The high thermal expansion of Teflon can be a problem in various applications.

When compared against chrysotile asbestos their chemical resistance is superior, but their cost is much higher, their strength is lower and their heat resistance is lower. The cost of Teflon fibre varies from 10.00 to 25.00 $/kg.

The following properties are assigned to Teflon fibres
Specific gravity 2.1-2.3
Tensile strength 170-320 Mpa
Elongation; dry 13-140%
Temperature limit 2000 C

Polyacrylonitrile (PAN)

Polyacrjlortitrile (PAN) fibres have been used to replace asbestos in fibre-cement sheet products with a limited degree of success. The cost of PAN fibre ranges from 2.00 to 3.00$/kg.

The properties of PAN fibres are presented hereunder
Specific gravity 1.17-1.4
Tensile strength 200-320 MPa
Elongation at break; dry 10-50%
Elongation at break wet 26-60%
Temperature limits 150-3000 C
Substitutes for asbestos – Marcel Cossette