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TEFLON®
PTFE
or TFE - polytetra-fluoroethylene is a very dense material having a density
of 2.13 - 2.19 grams/cc. TFE is well known for its chemical resistance.
It is insoluble in all organics with the exception of a few exotics. Electrical
properties are excellent. Impact strength is high but its resistance to
wear, tensile strength and creep resistance are low in comparison to other
engineering materials. Mechanical properties can be improved by adding
fillers such as glass fibers, bronze, carbon, and graphite. TFE has an
extremely low coefficient of friction. Very few materials will stick to
it. It has useful properties from cryogenic temperatures up to 260oC (550oF).
TFE is produced as Teflon.
Teflon is available in FDA compliant grades.
Product Applications
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Selecting the Right TFE Compound
Fillers
TFE fluorocarbon resin performs will in many applications without fillers. In fact, fillers can lessen its outstanding electrical and chemical properties. In mechanical applications, however compounds of Teflon and inorganic fillers offer improved wear resistance, reduce creep and initial deformation and increased stiffness and conductivity. Hardness is increased and the coefficient of thermal expansion is decreased. Compounds can therefore make it possible to gain the advantages of Teflon in applications where the unfilled resin cannot be used.
- Glass
Fiber
Glass in the form of short fibers is the most widely used filling material. The most popular compounds are 15% or 25% glass (by weight). It is sometimes combined with graphite of MoS2. Glass has little effect on most of the electrical properties of Teflon. It resists acids and oxidation, but it can be attacked by alkali. - Carbon
A typical carbon filler is high-purity coke powder. It is often used in combination with graphite in concentrations of 25% to 35% by weight. Compounds of Teflon and carbon have excellent wear resistance, both dry and in water. They are compatible with most chemicals and can carry heavy loads under rubbing contact. - Graphite
This crystalline form of carbon is used alone or in combination with glass or amorphous carbon. A typical compound is 15% graphite by weight. The addition of graphite helps reduce the wear of soft metal mating parts and improves frictional and wear properties when mixed with other fillers. Like other forms of carbon, it serves well in corrosive environments. - Bronze
Round or irregularly-shaped bronze particles are often used at 60% by weight, or 55% with 5% MoS2. Compounds of bronze and Teflon are creep-resistant and easily machined. They deliver good wear performance, low friction and relatively high thermal conductivity. - MoS2
Used in concentrations of approximately 5% by weight in compounds with glass or bronze. MoS2 can increase surface hardness and lower coefficient of friction and wear rate.
Typical Properties
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TFE
MATERIAL
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VIRGIN
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RE-
PROCESSED |
VIRGIN
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||||
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FILLER
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none
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none
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Glass
Fiber |
Bronze
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Graphite
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Carbon
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Glass,
MoS2 |
|
FILLER
CONTENT
BY WEIGHT |
0%
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0%
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25%
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40%
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10%
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10%
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23%,
2% |
| Physical Properties | |||||||
| Specific
Gravity Tensile Strength Break (psi) Elongation @ Break Shore Hardness Deformation Under Load (% @ 1200 psi) Limiting PV @ 100 FPM (psi x fpm) |
2.16
3,000 200% 54 6.2% 2,200 |
2.16
1,500 75% 56 60% 1,500 |
2.22
2,500 50% 63 4.9% 11,000 |
3.30
2,300 60% 65 3.6% 12,00 |
2.13
2,700 60% 57 4.0% 15,000 |
2.13
2,800 50% 62 3.7% 15,000 |
2.25
2,500 50% 64 2.7% 12,000 |
Properties Comparison
| PROPERTY TESTED |
TFE
|
FEP
|
PFA
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| Hardness,
Shore D Specific Gravity Tensile Strength, psi Elongation at Break, % Brittle Temperature Max. Oper. Temperature |
50-55
2.15 4000 250-450 <-275oF 500oF |
50-55
2.15 3500 300 <-275oF 400oF |
60 |