PTFE

What is PTFE?

PTFE or Polytetrafluoroethylene has a molecular structure which is based on a chain of carbon atoms. However, unlike some other fluoropolymers each carbon atom in PTFE is linked to two fluorine atoms that form a helical spiral which surrounds the carbon chain and protects it.

The carbon-fluorine bond is one of the strongest in any polymer and it is this structure which accounts for the unique properties of PTFE including excellent chemical resistance.

Key properties

  • Wide temperature range of -70° C to +260° C.
  • Excellent insulation, dielectric properties.
  • Extremely low coefficient of friction; non-stick!
  • Chemically inert, with the exception of a small number of unusual substances and conditions, including: liquid boiling sodium metal and fluorine gas at high pressure and temperature.
  • PTFE is hydrophobic (will not absorb moisture).
  • Excellent UV resistance.
  • Unlimited shelf life.
  • Excellent flex fatigue qualities. Exceeds all other hose rivals.
  • PTFE conforms to FDA 21 CFR 177.1550.
  • Antistatic PTFE conforms to FDA 21 CFR 178.3297 and is non-leaching.

 

The table below lists a generally accepted summary of properties that we believe to be reliable. Please note that many of these resins are produced in several varieties and property characteristics may vary. Therefore, determination of resin is dependent on the application and this table is only meant to serve as a general guideline.

Properties ASTM or unit PTFE
MECHANICAL PROPERTIES
Specific Gravity D792 2.18
Elongation % D638 200 ~ 450
Tensile Strength (psi) D638 2,000~7,000
Flexural Strength (psi) D790 no break
Compressive Strength D695 3.500
Tensile Elastic Modulus (Young’s Modulus) (psi) D638 57.000
(psi) Flexural Modulus 103MPa (103kgf/cm2) D790
D790
71,000 ~ 85,000
0.5-0.6 (5.0-6.0)
FlexLife (MIT cycles) D2176 >1,000,000
Hardness Durometer Shore D D636 D50 ~ 65
Coefficient of Friction On steel 0.02
Abrasion Resistance 1000 revs. Taber 12
Impact Strength IZOD 73°F/23°C, notched ft/lbs/in D256 3
Properties ASTM or unit PTFE
THERMAL PROPERTIES
Melting Point °C (°F) 327 (621)
Upper Service Temperature(20,000h) °C (°F) 260 (500)
Flame Rating** UL 94 V-0
Thermal Conductivity BTU/hr/ft2/deg F in
cal/sec/cm2,ºC/cm
1.7
6 x 10-4
Linear Coefficient of Thermal Expansion 10-5 °C D696 >11.6
Heat of Fusion BTU/LB 29-37
Heat of Combustion BTU/LB 2200
Low Temperature Embrittlement °C (°F) -268 (-450)
Properties ASTM or unit PTFE
ELECTRICAL PROPERTIES
Dielectric Constant D150/103Hz
D150/106Hz
2.1
2.1
Dielectric Strength 10 mil film D149 >1400
Volume Resistivity ohm-cm D257 >1018
Surface Resistivity ohm/sq. D257 >1017
Properties ASTM or unit PTFE
GENERAL PROPERTIES
Chemical/Solvent Resistance D543 Excellent
Water Absorption, 24h % >0.01
Deformation Under Load *D621/100°C
**D621/25°C
5.0
7.0
Refractive Index 1.35
Limiting Oxygen Index >95 >95
Properties ASTM or Unit PTFE
*6.8 MPa (986 psi),24h
**13.7 MPa (1987 psi),24h