PTFE/TECAPOWDER PI compounds

The reinforcement of PTFE (chemically Polytetrafluoroethylene and colloquially referred to as Teflon®) with high performance polymers has many advantages compared to inorganic fillers. The most important properties are the excellent wear behavior without abrasion of the sliding partner. TECAPOWDER PI (based on P84® by Evonik) is an active filler in PTFE. This is shown by a highly increased creep resistance and a good mechanical bonding of the powder into the matrix.

The development of extremely fine powders lead to excellent surfaces of machined parts and skived films of these compounds.

PTFE/TECAPOWDER PI-compounds replace other materials

TECAPOWDER PI filled PTFE (Teflon®) compounds outperform inorganic fillers in many ways. Many inorganic fillers have poor wear resistance, low elongations at high loadings and some fillers can be abrasive to the mating surface.

Application

Replacement (type of compounds)

Replaced material

Compressor parts piston and rider rings in bone dry applications  85/15 and 80/20
 PEEK composites, PTFE/bronze and PTFE/carbon/graphite compounds
Hydraulic seals, spring reinforced and others 93/7 and 90/10
PTFE/carbon,PTFE/bronze and PTFE/EKONOL 
Dynamic seals in air components 80/20 and 85/15 P1 PE/carbon compounds, rubber and PUR seals
Sealing bands for turbo charger 80/20
PTFE/bronze and PTFE/bronze/MoS2 compounds
Sealing bans for shock absorbers 75/20/5
Most other PTFE compounds tested
Sliding liner for multilayer bearings in automotive applications 75/25 and 75/20/5, standard and paste types   PTFE/MoS2 and PTFE/lead compounds 
Inner liner for push-pull cables Proprietary paste compounds PTFE/glass types, PTFE/PPS compounds
Guidance films for pistons and gliding components, esp. in weaving equipment   85/15 with 1200 mesh, also with NPA additive RULON

 

TECAPOWDER PI compositions tailormade for different applications

 

Lip-seals, packings, and spring-reinforced dynamic seals 93 % PTFE / 7 % PI Powder
Rod packings, rider and piston rings in compressor applications, proved in "bone-dry" gas compressors as a piston and rider ring, skived films as gliding surfaces on several machinery elements, especially in textile equipment 85 % PTFE / 15 % PI Powder
Bearings and gliding elements in highly stressed applications, sealing bands for rotating equipment in compressors and pumps 80 % PTFE / 20 % PI Powder 
Piston rings in pumps and compressors for dry gases, gliding elements in weaving machines 75 % PTFE / 20 % PI Powder / 5 % Graphite
This composition for hot moulding is used in high load bearings and sealants in machining equipment and as guidance material in mechanical end uses 60 % PTFE / 40 % PI Powder 
Push-pull cable inner-liners to maintain long service life without any additional lubrication 90 % PTFE / 10-15 % PI Powder 

TECAPOWDER PI in PTFE compounds improves the properties

The most important properties of TECAPOWDER PI filled PTFE (Teflon®)  are excellent wear resistance at elevated temperatures, high elongation, and no abrasion of the sliding partner — all without the need for lubrication.

TECAPOWDER PI as an active filler in PTFE improves the mechanical properties of the PTFE. Blending 5-20 % loadings of TECAPOWDER PI VPD in PTFE creates wear resistant PTFE compounds that extend the performance envelope of standard PTFE materials especially at high pressures, velocities and temperatures. TECAPOWDER PI polyimide filled PTFE compounds are especially good running against soft mating surfaces.

Teflon® is a registered trademark of E.I. du Pont de Nemours and Company.

  • Good chemical resistance
  • Very good slide & wear properties
  • High toughness
  • Lower friction and wear 
  • High electrical insulation

Tribological properties of PTFE compounds against steel in comparison to PPS or Ekonol as fillers

Creep under load

Creep under load at room temperature
Creep under load at 100 °C (212 °F)

K factors

K factors on different sliding surfaces
K factors on steel at different temperatures

Abrasion of sliding counterparts

Processing Guidelines

To mould these compounds standard PTFE free sintering process conditions are can be used.

  • To offer extremely low porosity and smooth machined surfaces, TECAPOWDER PI is available in different grain sizes. For technical parts i.e. bearings, gliding elements and piston rings, 325 mesh is used. For skived films and dynamic seals 425 mesh and 1200 mesh is offered. The discolouration of the outside section will be reduced with finer particles.

  • The mechanical properties are strongly affected by the base PTFE resin. Fine PTFE particles offer a maximum on elongation and strength.

  • PTFE / PI Powder compounds require slightly higher moulding pressures than virgin PTFE. With TECAPOWDER PI loadings of more than 20 % the moulding pressure is twice the pressure of standard PTFE. This high compaction is required to obtain a maximum on density and hardness. Also, the porosity is influenced. The compaction speed should be slower than standard compounds because of the micro-porous structure of PI Powder. The moulded billets should be stored in air overnight to enable the release of compressed air.

  • The sintering of high loaded compounds requires modified sintering temperatures over virgin PTFE. High temperatures up to 370 °C (700 °F) lead to a maximum in hardness and better tribological results. But this temperature must not be exceeded. More than 20 % TECAPOWDER PI powder needs to be sintered at lower temperatures (see table for conditions). Loadings of more than 30 % by wt. of P84 requires hot moulding conditions at a maximum temperature of 345 °C (650 °F).

  • Skiving should be done with preheated blocks up to 150 °C (300 °F). This guarantees best surface qualities.
  • For more information please contact [obfemailstart]dGVjYXBvd2RlckBlbnNpbmdlcnBsYXN0aWNzLmNvbQ==[obfemailend].

     

Product datasheets, safety documents and certificates

For further information please contact [obfemailstart]dGVjYXBvd2RlckBlbnNpbmdlcnBsYXN0aWNzLmNvbQ==[obfemailend].