Polytetrafluoroethylene (PTFE) is a polymer belonging to the class of perfluorcarbons (PFC), coming from homo polymerization of tetrafluoroetene.,
It is worldwide known through trade names like (Teflon, Fluon and so on…).
Often other stabilizing or fluidifying components as well as fillers like bronze, graphite, carbon….. are added to this polymer to improve its performances in mechanical, pneumatic and chemical fields.
It is a plastic material, smooth to the touch, resistant to high temperatures, anti-adherent and proof to external agents. Its main characteristic is the friction coefficient: its value is the lowest among the plastic materials.
Virgin And Filled Ptfe
Filled PTFE
PTFE, because of the properties previously mentioned, is used in a very large number of applications. Some of its properties can be improved and/or modified by adding suitable fillers, allowing the use of PTFE in applications otherwise precluded to this polymer. The fillers most commonly used are: fibre glass, carbon, bronze and graphite. Other fillers can be: molybdenum disulfide, metal powders, ceramics, metal oxides, polymeric fillers and their blends.
The addition of fillers to PTFE impovers or modifies its properties depending upon the nature and the quantity of filler:
- Remarkable increase in wear resistance
- Decrease of deformation under load/permanent (creep)
- Reduction of linear thermal expansion coefficient
- Increase the thermal and electrical conductivity
Functions of the Loads
- Glass fibres: the glass fibre improves the wear properties and also the deformation under load. Glass itself, has a rather poor resistence. The coefficient of friction is slightly increased and for this reason, graphite or molybdenum disulfide are sometimes added to compensate this negative effect.
- Carbon: the carbon improves considerably, wear resistance and deformation under load while leaves pactically unchanged the chemical resistance.
- Bronze: bronze filled PTFE has excellent wear properties low deformation under load and good thermal and electrical conductivity. The chemical resistance is poor, especially in acidic environment.
- Graphite: graphite lowers the coefficient of fiction and, therefore is often added to other types of fillers.
- Other fillers: molybdenum disulfide, decreases the coefficient of fiction. Some metal powders (stainless steel), with good chemical resistence are use instead of bronze, evem though their wear resistence, is inferior. The metal oxides, in combination with other fillers, give better wear properties.
Virgin Ptfe: Main Characteristics
- High Heat Resistance
- High Resistance to External Chemical Agents and to Solvents
- Excellent Anti-Adhesion
- High Dielectric Characteristics
- Law Friction Coefficient
- Non Toxicity
Filled Ptfe: Main Characteristics
- Higher Resistance To The Compression
- Higher Wear Resistance
- Greater Hardness
- Lower Coefficient Of Thermal Expansion
Applications
- Electricity
- Food
- Medical
- Automotive
- Navigation
- Building
- Nuclear
- Oil & Gas
- Biotechnology
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