Fluoropolymer insulated wires

Table 5.13 Marketing Durability of Flame- and Plasma-Treated Fluoropolymer Insulated Wires ...

Electrical Applications. Plastics are used for electrical insulation, conduit and enclosures, lighting fixtures, and mechanical devices. The most widely used plastic for wire and cable insulation is flexible, plasticized PVC, which constitutes well over half the market in insulating wires for buildings, automobiles, appHances, and power and control lines. Polyethylene is also a factor. Higher performance plastics such as nylon and fluoropolymers also play a smaller role in this area. 

Fluoropolymers are used to insulate wire for critical aerospace and industrial applications where chemical and thermal resistance is essential. They are also materials of construction for connectors for high-frequency cables and for thermocouple wiring that must resist high temperatures. 

Table 6.5. Drawdown Ratio of Fluoropolymers for Wire Insulation Extrusion ...

In electronic applications, wires are commonly stripped by heat and soldered for hookup of circuits. Fluoropolymer insulation is subjected to heat and decomposition occurs. It is important to remove the fumes by local ventilation to avoid exposure to gases. 

Military and aerospace applications often require the highest level of reliability for systems where failure can have catastrophic consequences. Fluoroplastics fill critical needs for insulation in terrestrial, aviation, and space applications. Many of these applications are defined by Military Specifications (MIL SPEC) with two of the most important being MIL-C-17 for critical coaxial cable applications and MIL-W-22759 for fluoropolymer-insulated single conductor electrical wires primarily used as aircraft wire. 

Some atmospheric plasma treatments allow in-line surface modification of almost any wire insulation material. Examples include polyamides, polyesters, and the fluoropolymers most difficult to treat. A treated surface can then accept inkjet printing for marking purposes. Table 5.13 shows a comparison of the marking durability on ethylene tetrafluoro-ethylene copolymer (ETFE) and fluorinated ethylene propylene copolymer (FEP) for untreated (U), flame treated (FI), and plasma treated (PI) conditions. Some wires have been cross-linked by irradiation (IR) to enhance cut-through resistance of the insulation. Wire suppliers have been identified in each case and all ink was UV curable. 

Cross-linkable polymers used for wire and cable insulations are polyolefins, certain fluoropolymers, and elastomers. Among these, radiation cross-linked polyethylene is the most widely used. The radiation cross-linking process of PE has also been the most widely studied. ... 

PVC, another widely used polymer for wire and cable insulation, crosslinks under irradiation in an inert atmosphere. When irradiated in air, scission predominates.To make cross-linking dominant, multifunctional monomers, such as trifunctional acrylates and methacrylates, must be added. Fluoropolymers, such as copol5miers of ethylene and tetrafluoroethylene (ETFE), or polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF), are widely used in wire and cable insulations. They are relatively easy to process and have excellent chemical and thermal resistance, but tend to creep, crack, and possess low mechanical stress at temperatures near their melting points. Radiation has been found to improve their mechanical properties and crack resistance. Ethylene propylene rubber (EPR) has also been used for wire and cable insulation. When blended with thermoplastic polyefins, such as low density polyethylene (LDPE), its processibility improves significantly. The typical addition of LDPE is 10%. Ethylene propylene copolymers and terpolymers with high PE content can be cross-linked by irradiation. ... 

Fluoropolymers, such as copolymer of ethylene and tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF), are widely used in wire and cable insulations. They are relatively easy to process and have excellent chemical and thermal resistance, but tend to creep, crack and possess low mechanical stress at temperatures near their melting points. Radiation has been found to improve their mechanical properties and crack resistance.36... 

In telecommunications similar requirements are placed on insulation materials in addition to low dielectric losses. Thus, even here fluoropolymers are capable of meeting them. Typical applications are insulations and jackets for wires and cables, tubing, piping, and films. 

Fluoropolymers. Melt processable fluoropolymers such as Teflon FEP, Tefzel ETFE, poly(vinylidene fluoride) (Kynar), and ethylene-chlorotrifluoroethylene copolymer (Halar) are suitable for wire insulation in special applications because they combine good physical properties with low flammability. They are used for instrumentation cable in process-control rooms, as well as for computer and aircraft wiring and in military applications. The... 

Miscellaneous Extrusion-Applied Polymers. As mentioned earlier, there is a tendency to develop solventless magnet wire enamel formulations, and extrudable polymer systems would fulfill that requirement. There have been reports about extrusion of thin coatings of polyesters over copper wire. At this point, the state of the art allows extrusion of thin insulating films only with thermoplastic materials. The reliable extrusion of uniform and concentric insulating films of approximately 0.001-0.002 in. wall thickness is already an improvement over the more traditional extrusions of polyethylene, poly(vinyl chloride), and several fluoropolymers in much greater wall thicknesses. Because cross-linked insulation is ultimately required for most magnet wire applications, further materials development needs to be done to provide polymer compositions that are both extrudable as thin films and can be cross-linked in an economical process suitable for large-scale industrial application. 

In houseware, fluoropolymers are applied as nonstick coatings for cookware and appliance surfaces. These applications depend on thermal and chemical resistance as well as anti-stick performance. PTFE and ETFE are chosen to insulate appliance wiring that must withstand high temperatures. 

Extrusion is one of the most popular processes for fabricating parts from fluoropolymers. Fiber and filament account for a relatively small share of all fluoropolymers extrusion. The principal end products are wire insulation, tubing, film, and sheet. Fluo-ropolymer films are widely used in release, surface protection, and packaging. Sheet and profile extrusions account for a small share of fluoropol5uners consumption. 

Applications of fluoropolymers are still growing, even decades after the discovery of the first plastic (polytetrafluoroethylene) in this family. The increasing use of fluoropolymers in such dynamic industries as wire and cable insulation, automotive, aerospace, oil and gas recovery, and semiconductor manufacture has led to significant material developments and trends in the last few years. New fluoropolymers have been introduced to the market (amorphous fluoroplastics, modified PTFE, low-temperature fluoroelastomers, and amine-resistant fluo-... 

Fluoropolymers are polytetrafluoroethylene (PTFE) and ethylene tetrafluoroethylene (ETFE). They can assist as redundant insulation and are primarily used as a coating to defend conductor wires from corrosion. The advantages of those materials are their inert and biocompatible behavior and high tensile strength. Otherwise, their stiffness, creep. 

D4565 Test Method for Determining the Physical/Environ-mental Performance Properties of Insulation and Jackets for Telecommunications Wire and Cable D4591 Test Method for Determining Temperatures and Heats of Transitions of Fluoropolymers by DSC D3012 Test Method for Thermal Oxidative Stability of... 

Partially fluorinated fluoroplastics can be cross-linked to improve the mechanical properties of shaped articles such as wire insulation. For example, the aerospace industry requires wire and cable that can withstand abrasion and cutting in addition to flammability. Cross-linking a fluoropolymer like ETFE, ECTFE, or PVDF enhances its mechanical properties. For example, actual cross-linking is accomplished by incorporating a cross-linking agent in ETFE after the extrusion of the insulation, followed by irradiation.fi l... 

Fluoropolymers are widely used for wire and cable insulation (Figs. 16.9 and 16.10), but not always for the same reasons. It is true that all applications make use of a polymer s dielectric properties, but not to the same degree. Some uses exploit the ability of fluoropolymers to serve over a wide temperature range, and particularly at high temperatures. Others rely on their resistance to chemicals or their resistance to changes in properties over time. 

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