Medium Wall PTFE Sleeving for Cables in Harsh Environments.

Description

Thermal Properties
PTFE is one of the most thermally stable plastic materials; there is no appreciable decomposition below 400°C. The arrangement of the PTFE molecules varies with temperature. There are different transition points, with the most important ones being 19°C corresponding to a modification of some physical properties, and then at 327°C which corresponds to the disappearance of the crystalline structure; the PTFE assumes an amorphous aspect, conserving its own geometric form.
The linear thermal expansion coefficient varies with temperature. In addition, because of the orientation caused by the working process, the PTFE pieces are in general anisotropic; the coefficient of expansion varies also in relation to direction. The coefficient of thermal conductivity of the PTFE does not vary with temperature; it is relatively high so that PTFE can be considered to be a good insulation material.
The specific heat, as well as the heat content (enthalpy) increases with the temperature.

Chemical Resistance
PTFE 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. PTFE is insoluble in almost all solvents at temperatures ip 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.
Test pieces of PTFE exposed for over twenty years to the most disparate climate conditions have not shown any alteration of their characteristic properties. High energy radiation tends to cause the breaking of the PTFE molecule, so the resistance to radiation is rather poor. The permeability of PTFE is similar to other plastic materials.

Physical Properties
PTFE can be used continuously at 260°C while still possessing a certain compressive plasticity at temperatures approaching absolute zero. 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 350-650 N/mm² at room temperature. PTFE possesses very high resilience characteristics at low temperatures. The hardness is Shore D measured according to the method ASTM D 2240; values between D50 and D60.
PTFE possesses the lowest friction coefficients of all solid materials, between 0.05 and 0.09. Additional information can be found in the PTFE material sheets available from our sales office.