When you think of polytetrafluoroethylene, your pot and […]
When you think of polytetrafluoroethylene, your pot and pot on the non-stick coating may be the first thing to consider. Since the discovery in 1938, some of the same properties of food released from the cooking surface have made the attraction of PTFE to the engineers from insulation to sliding surfaces.
These same characteristics make PTFE and its extended derivatives (expanded PTFE) suitable for today's demanding highly flexible, low-shutdown applications in cables. The material can make the cable long bending life, additional strength, better signal transmission and clean room performance.
The molecular structure of PTFE and other fluoropolymers gives them the nature of placing them in their own class. The standard polyethylene molecule has repeating units of two carbon atoms, and each repeating unit is linked to its two adjacent carbon atoms into a single bond. Each carbon is also bonded to two hydrogen atoms to form C 2 H 4. In PTFE, the fluorine atom replaces the hydrogen atom to form C 2 F 4.
Let feldspar start, also known as fluorite CaF2. The mineral dissolved in sulfuric acid to form hydrofluoric acid, that is, the basic structural units of tetrafluoroethylene resin. Extruding the resin to form a block or sheet of PTFE, or synthesizing the powder for future use.
Controlling the expansion temperature, force, velocity, and direction allows the engineer to determine the many microstructural properties of the expanded PTFE, including the openness of the network, the density of the fibrils, and the distance between nodes. Each microstructure configuration, combined with the final product form - fiber, tube, tape or film - gives the expanded PTFE product unique features.
Expansion and additives can make expanded PTFE conductive and thermally conductive, or maintain the insulation properties of PTFE. Although the expanded polymer is chemically inert, the engineer may impregnate a substance that imparts a specific catalytic or chemical nature.
The open structure of the expanded PTFE can be designed to absorb moisture or chemicals or remain hydrophobic. Custom expansion can impart high or low dielectric constant, surface energy, abrasion resistance, hardness, stiffness and light transmittance to the polymer. The more open microstructure can be made to be absorptive or airtight. This last property is the key to breathable fabrics and ventilation products.