Types of PTFE and PTFE Fillers

Types of PTFE

PTFE Granular
PTFE Dispersions
PTFE Fine Powders
(TexLoc uses Fine Powders)

PTFE General Filler Properties

• Mechanical Properties
• Thermal Properties
• Electrical Properties
• Chemical Properties
• Tribological Properties

Types of Fillers (How They Affect PTFE)

• Alumina Filler
• Calcium Fluoride
• Carbon Black
• Carbon Filler
• Carbon Fiber
• Ceramic Fillers
• Glass Beads
• Glass Fiber
• Graphite Filler 
• Metallic Fillers
• Molybdenum disulfide
• Silica Filler

Granular PTFE Back to Top

Specified by ASTM Method D 4894

• Homopolymer
• Modified Resins

• Fine cut - Low Flow
• Pelletized - Free Flow

PTFE Dispersions Back to Top

Specified by ASTM  Method D 4441

Produced by dispersion (emulsion) polymerization, followed by a surfactant stabilization and usually a form of concentration.

Fine Powder PTFE Back to Top

Specified by ASTM Method D 4895

Produced by dispersion (emulsion) followed by coagulation, isolation and drying. 

Filler Properties

Mechancial Properties 

Fillers increase the hardness of PTFE and reduce creep. 

Thermal Properties Back to Top

Fillers reduce the linear coefficient of thermal expansion and contraction of compounds.  

Electrical Properties Back to Top

Generally, they significantly increase the porosity of PTFE, drop the dielectric strength and raise the dielectric constant and dissipation factor.  

Chemical Properties Back to Top

Fillers increase the permeability of PTFE.  In general, chemical properties of filled PTFE compounds are not as good as those of unfilled resin.   For specific characteristics of  PTFE chemical properties with fillers, please refer to the specific filler.  

Tribological Properties  Back to Top

Wear rate is reduced.

Types of Fillers

Glass Fiber - The most common filler.   Back to Top

• Reduces creep
• Chemically inert (except its reactivity with hydrofluoric acid and strong bases)
• Perform well in oxidizing environments
• Improves the wear characteristics of PTFE

Carbon Black Back to Top

• Reduces creep
• Increases Hardness
• Elevates thermal conductivity of PTFE
• Improves the wear characteristics of PTFE
• Electrical conductivity
• Increases resistances to UV light
• Also called Colladial Carbon

Carbon Filler Back to Top

• Reduces creep
• Increases Hardness
• Elevates thermal conductivity of PTFE
• Improves the wear characteristics of PTFE
• Electrical conductivity
• Improves lubricity
• Also called Powdered Carbon, Carbon Powder

Carbon Fiber Back to Top

• Lowers creep
• Increases flex and compressive modulus
• Raises hardness
• Inert to hydrofluoric acid and strong bases
• Less carbon fiber needed than glass to achieve the same effects of glass fiber
• Elevates thermal conductivity of PTFE
• Increased wear resistance
• Also called Graphite Fiber

Graphite Filler Back to Top

• Extremely low coefficient of friction
• Chemically inert
• Can be incorporated with other fillers such as glass or carbon
• Increased wear resistance, especially against soft metals
• Also called Powdered Graphite, Plumbago, Graphite Powder, Carbon Graphite, Black Lead.

Metallic Fillers Back to Top

• Most popular metallic filler
• Reduce deformation under load
• Raises the  thermal and electrical conductivity of PTFE

Molybdenum disulfide Back to Top

• Increases surface hardness
• Decreases friction
• Normally combined with other fillers such as glass
• Reacts with oxidizing acids and is inert toward most other chemicals

Calcium Fluoride Back to Top

• Can replace glass in end uses where glass is attacked by chemicals

Alumina (Ceramics) Back to Top

• Excellent electrical insulator
• Improves the mechanical properties of PTFE

Silica Fillers (Glass Beads) Back to Top

• Increased dimensional stability
• Increased chemical resistance
• Increased moisture resistance
• Increased thermal stability
• Also called Glass Beads, Glass Filler