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Fillers in PTFE

Because of its excellent properties, such as a very good temperature resistance, a very good chemical resistance, a low friction and/or a good insulation, virgin PTFE is the perfect solution for a wide range of applications that require a high performance material.

Though, in some applications the properties of virgin PTFE are not sufficient enough or suitable for the job. In that case adding a filler or combination of fillers to PTFE properties can enhance, emphasize or compensate PTFE base properties. Mostly used fillers are glass, carbon, graphite, bronze and Molybdenum disulfide (MoS2).


To improve specific properties of PTFE adding a filler can be an option.
PTFE with glass fibers ameliorates wear and creep resistance. It is used to make products like piston rings, bushings and threaded connections for high(er) surface pressure application in chemical environments.
When using PTFE + Glass one must take into account that the compound is more abrasive than virgin PTFE which could damage the counter part or material.

Commonly used glass filled PTFE compounds are PTFE + 15% glass, PTFE + 25% glass. The products have a yellowish colour.

Application: piston rings, bushings, threaded connections.
Most commonly used compounds:
PTFE + 25% glass fiber
PTFE + 15% + 5% MoS2 glass
PTFE + glass spheres
Often, these additional compounds are provided with a pigment, for example, red or blue.
Glass: Type E glass
Milled fibers having a nom. diameter = 13µm
Nominal length: 0.8 mm

CaF2 - Calcium Fluoride

Calcium fluoride is used when glass is not suitable due to the chemical resistance. Applications: gaskets, electrical applications.


Carbon, a versatile element, finds its utility in various forms such as powder or fibers. Its remarkable properties enhance the compressive strength, rendering it highly resistant to wear and tear. Moreover, carbon exhibits superior thermal conductivity and imparts electrical conductivity to materials. It surpasses glass in terms of abrasiveness, making it an excellent choice. When combined with graphite, carbon becomes an ideal candidate for applications involving smooth sliding movements.
Carbon: Amorphous carbon Petroleum
Purity: > 99%
Particle size: <75µm
Density: 1.8 g/m³


Graphite is a form of carbon. The flake-like crystals provide a perfect lubrication and reducing wear. Graphite is usually combined with other fillers such as glass and carbon.
Graphite: Synthetic
Purity: > 99%
irregular shape
Particle size: <75µm
Density: 2.26 g/m³

MoS2 (Molybdenum)

MoS2 has a lubricating effect and, therefore, gives better anti-friction properties to the material. MoS2 is added in small percentages in conjunction with other fillers such as glass and bronze.
MoS2: Mineral
Purity: > 98%
Particle size: <65µm
Density: 4.9 g/m³


A commonly used filler in PTFE is bronze. It enhances the wear resistance, provides a better heat conductivity, makes the material better pressure and creep resistant. Furthermore, compared to other filled PTFE compounds it has higher friction resistance. When choosing to add MoS2 (Molybdenum Disulfide) to the compound, friction resistance can even be reduced further. As bronze can oxidize, this should be considered when selecting the filler.

PTFE+Bronze compounds are an excellent choice for an application like ship bushings. Most commonly used compounds:
PTFE + 60% bronze
PTFE + 55% bronze + 5% MoS2
Bronze: Cu/Sn: 9/1
Irregular or spherical shape
Particle size: <60µm
Density: 8.95 g/m³


Stainless steel (SS) gives a higher resistance to wear and can be loaded much higher. Better chemical resistance than bronze filled material.
Application: parts in steam environments.


CaSiO3 wollastonite (calcium silicate) is a mineral and has similar properties as glass but can be applied in food applications, unlike fiberglass. Moreover, it is somewhat less abrasive.


Ekonol® is an aromatic polyester. Ekonol gives PTFE better properties at higher temperatures, makes it more wear-resistant and does not wear out in the steel counter material. Therefore, PTFE with Ekonol is very suitable for rotary applications. It is also suitablable for Food applications. Especially suitable for applications with soft counter materials such as aluminum.


Mica; a mineral which ensures that the material expands and shrinks less. However, it has limited mechanical properties. In particular, applications in compression techniques.

Polyimide (PI)

Polyimide is a high quality synthetic resin that makes the compound super abrasion resistant. This PI-PTFE compound has the lowest coefficient of friction of all PTFE compounds. This makes it extremely suitable for dry running applications. This material will not wear out in the counter surface, not even in soft materials such as copper and plastics. Cost price for this compound is higher than all other PTFE compounds.

More information?

Please contact our sales engineers if you require more information, an inquiry or to evaluate samples. Or download our technical data sheets.