PTFE Components

Teflon Components is mainly used in wear-resistance & corrosion prevention applications. Teflon components possess many merits. They can provide effective protection against atmospheric acids. Therefore Teflon moulded and machined components guarantee maximum durability. Besides they possess the characteristic of easy application and low maintenance cost. Higher electrical performance is another merit of Teflon components. The Teflon resists attacks from aggressive chemicals. Lastly Teflon also reduces the risk of media contamination.

Product Description

Virgin PTFE – Detailed Technical Information

Thermal properties of PTFE – Rod, Sheet & Tube

Thermal stability of Teflon Component

Teflon Components is one of the most thermally stable plastic materials. There are no appreciable decompositions at 260°C, so that PTFE, at this temperature, still possesses most part of its properties. Appreciable decomposition begins at over 400°C.

Transition Points of Teflon Components

The geometry of the Teflon Components molecules (crystalline structure) varies with the temperature. There are different transition points, with the most important ones being the following: that at 19°C corresponding to a modification of some physical properties and that at 327°C which corresponds to the disappearance of the crystalline structure: the Teflon Components assumes an amorphous aspect conserving its own geometric form.

Expansion of Teflon Components

The linear thermal expansion coefficient varies with the temperature. In addition, because of the orientation caused by the working process, the Teflon Components pieces are generally anisotropic; in other words, the coefficient of expansion varies also in relation to direction.

Thermal conductivity of Teflon Components

The coefficient of the thermal conductivity of Teflon Components does not vary with the temperature. It is relatively high, so that Teflon Components can be considered to be a good insulating material. The mixing of suitable fillers improves the thermal conductivity 

Specific Heat of Teflon Components

The specific heat, as well as the heat content (enthalpy) increases with the temperature.

Behaviour of Teflon Components in presence of foreign agents

Resistance of Teflon Components to chemical agents

Teflon Components is practically inert against known elements and compounds. It is attacked only by the alkaline metals in the elementary state, by Chlorine trifluoride and by elementary Fluorine at high temperatures and pressures.

Solvent resistance of Teflon Components

Teflon Components is insoluble in almost all solvents at temperatures up to about 300°C. Fluorinated hydrocarbons cause a certain swelling which is however reversible; some highly fluorinated oils, at temperatures over 300°C, exercise a certain dissolving effect upon PTFE.

Resistance of Teflon Components to atmospheric agents and light

Test pieces of Teflon Components, exposed for over twenty years to the most disparate climatic conditions, have not shown any alteration of their characteristic properties.

Resistance of Teflon Components to radiations

High energy radiations tend to cause the breaking of the PTFE molecule, so that the resistance of the product to radiations is rather poor.

Gas permeability of Teflon Components

The permeability of Teflon Components is similar to other plastic materials. The permeability does not depend, obviously, only on the thickness and pressure, but also on the working techniques.

Physical – mechanical properties of Teflon Components

Tensile and compressive properties of Teflon Components

These properties are to a large degree influenced by the working processes and the employed powder. Teflon Components , however, can be used continuously at temperatures up to 260°C, while possessing still a certain compressive plasticity at temperatures near to the absolute Zero.

Flexibility of Teflon Components

PTFE is quite flexible and does not break when subjected to stresses of 0,7 N/mm2 according to ASTM D 790. Flexural modulus is about 350 to 650 N/mm2 at room temperature, about 2000 N/mm2 at -80°C, about 200 N/mm2 at 100°C and about 45 N/mm2 at 260°C.

Impact properties of Teflon Components

PTFE possesses very high resilience characteristics also at low temperatures.

Plastic memory

If a piece of Teflon Components is subjected to tensile or compression stresses below the yield point, part of the resulting deformations remain (as permanent deformations) after the discontinuance of the stresses, with the result that certain strains are induced in the piece. If the piece is reheated, these strains tend to release themselves within the piece which resumes its original form. This property of the Teflon Components is commonly indicated as “plastic memory” and is made use of in different applications.

Also most of the semi-finished products, because of the transformation processes, possesses similar strains, to a certain degree. When it is desired to obtain semi-finished parts dimensionally stable at high temperatures, it is possible to subject the parts to a temperature of 280°C for one hour every 6 mm of thickness and then cool them slowly. The parts obtained in this manner are almost completely free from internal strains and are in general known as “conditioned” or “thermostabilised” material.

Hardness of Teflon Components

The hardness Shore D, measured according to the method ASTM D 2240, has values comprised between D50 and D60. According to DIN 53456 (load 13,5 Kg for 30 sec) the hardness sways between 27 and 32 N/mm2.

Teflon Components – Coefficient of Friction

Teflon Components possesses the lowest friction coefficients of all solid materials; between 0.05 and 0.09:

• the static and dynamic friction coefficients are almost equal, so that there is no seizure or stick-slip action
• when increasing the load, the friction coefficient decreases until reaching a stable value
• the friction coefficient increases with the speed
• the friction coefficient remains constant at temperature variations.

Wear properties of Teflon Components

The wear depends upon the condition of the other sliding surface and obviously depends upon the speed and loads. The wear is considerably reduced when adding suitable fillers to the Teflon Components

Electrical properties of Teflon Components

Teflon Components is an excellent insulator and precious dielectric as shown by the relative data reported in datasheet and maintains these characteristics throughout a large range of environmental conditions, temperatures and frequencies.

Dielectric strength of Teflon Components

The dielectric strength of Teflon Components varies with the thickness and decreases with increasing frequency. It remains practically constant up to 300°C and does not vary even after a prolonged treatment at high temperatures (6 months at 300°C). It depends also upon the transformation processes.

Dielectric constant and dissipation factor of Teflon Components

Teflon Components have very low dielectric constant and dissipation factors values; these remain unvaried until 300°C, in a frequency field of up to 109 Hz even after a prolonged thermal treatment (6 months at 300°C). The dielectric constant, dissipation factor as well as the volume resistivity and surface resistivity, considered as being independent from the transformation processes.

Arc-resistance of Teflon Components

Teflon Components has a good resistance to the arc. The arc resistance time according to ASTM D 495 is 700 sec.. After a prolonged action there are no signs of surface charring.

Corona effect resistance

The discharges caused by the corona effect may result in erosions of the Teflon Components surface which, nevertheless, is indicated as a suitable insulator in case of high potential differences.