Jun 25 2003
Polytetrafluoroethylene coated glass fabric (PTFE 75/ Glass 25) are fabrics woven from continuous filament glass yarns and coated with polytetrafluoroethylene (PTFE) to give a stiff, flexible, fairly smooth surfaced material that is chemically inert with excellent release properties.
Polytetrafluoroethylene (PTFE) is a fully fluorinated polymer which is semi-crystalline, semi-opaque, and white. It has exceptional chemical resistance being unaffected by nearly all chemicals and also has a very high oxygen index (i.e. is fundamentally non-flam).
It has a very low coefficient of friction and is stable in high temperatures. It is soft, easily deformed, highly susceptible to creep, and low in strength with poor radiation resistance.
It is relatively expensive and cannot be melt-processed (even though in theory it melts at 327 °C, the melt viscosity of normal grades is virtually infinite) and so is formed by powder sintering metods.
Applications
Industrial applications of Polytetrafluoroethylene coated glass fabric (PTFE 75/ Glass 25) include release material, protective curtains and conveyor belts e.g. in food processing machines, seals, high temperature electrical insulation, O-rings, bearings, non-stick coatings and linings for vessels etc. Its rare properties make it valuable for numerous laboratory applications.
Key Properties
The key properties of Polytetrafluoroethylene Coated Glass Fibre ( PTFE 75 / Glass 25 ) are tabulated below.
Table 1. Key properties
Chemical Resistance |
Acids - concentrated |
Good |
Acids - dilute |
Good |
Alcohols |
Good |
Alkalis |
Good |
Aromatic hydrocarbons |
Good |
Greases and Oils |
Good |
Halogens |
Fair |
Ketones |
Good |
Electrical Properties |
Surface resistivity ( Ohm/sq ) |
>1013 |
Volume resistivity ( Ohm.cm ) |
>1015 |
Physical Properties |
Density ( g.cm-3 ) |
2.08 |
Thermal Properties |
Lower working temperature ( °C ) |
-190 to -60 |
Upper working temperature ( °C ) |
260 |
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