Polyamides electrical

Polyamides. In 1988, 77% of U.S. demand for adipic acid was for nylon-6,6 fiber, while 11% was used in nyon-6,6 resins (195). In Western Europe only about 66% was for polyamide, because of the stronger competition from nylon-6. The fiber appHcations include carpets (67%), apparel (13%), tire cord (7%), and miscellaneous (13%). Nylon-6,6 resins were distributed between injection mol ding (85%) for such appHcations as automotive and electrical parts and for extmsion resins (15%) for strapping, film, and wire and cable. 

Commonly used materials for cable insulation are poly(vinyl chloride) (PVC) compounds, polyamides, polyethylenes, polypropylenes, polyurethanes, and fluoropolymers. PVC compounds possess high dielectric and mechanical strength, flexibiUty, and resistance to flame, water, and abrasion. Polyethylene and polypropylene are used for high speed appHcations that require a low dielectric constant and low loss tangent. At low temperatures, these materials are stiff but bendable without breaking. They are also resistant to moisture, chemical attack, heat, and abrasion. Table 14 gives the mechanical and electrical properties of materials used for cable insulation. 

An all aromatic polyetherimide is made by Du Pont from reaction of pyromelUtic dianhydride and 4,4 -oxydianiline and is sold as Kapton. It possesses excellent thermal stabiUty, mechanical characteristics, and electrical properties, as indicated in Table 3. The high heat-deflection temperature of the resin limits its processibiUty. Kapton is available as general-purpose film and used in appHcations such as washers and gaskets. Often the resin is not used directly rather, the more tractable polyamide acid intermediate is appHed in solution to a surface and then is thermally imidi2ed as the solvent evaporates. 

Eatty bisamides are used primarily to kicrease sHp, reduce blocking, and reduce static ki polymeric systems. Other specialty appHcations kiclude cosolvents or coupling agents for polyamide reskis, fillers for electrical kisulation coatings, additives for asphalt to reduce cold flow, and synthetic waxes for textile treatments (68). Bisamides have been used ki all the traditional primary amide appHcations to kicrease lubricity and have become the amide of choice because of thek better efficiency. Bisamides have the highest commercial value ki the amide market. 

The bisphenol A-derived epoxy resins are most frequendy cured with anhydrides, aUphatic amines, or polyamides, depending on desired end properties. Some of the outstanding properties are superior electrical properties, chemical resistance, heat resistance, and adhesion. Conventional epoxy resins range from low viscosity Hquids to soHd resins. 

Polyamide PPOs are manufactured by General Electric (Noryl GTX), BASF having now withdrawn from marketing their product (Ultranyl). Usage of the blends has so far been mainly in the automobile field for such applications as valance panels, wheel trims, grilles, rear quarter panels, front bumpers and tailgates. 

Where plastics are to be used for electrical applications, then electrical properties as well as mechanical and other properties need to be considered. Whilst properties such as resistivity, power factor and dielectric constant are important, they may not be all-important. For example, although polyamides and many thermosetting plastics may show only moderate values for the above properties, they have frequently been used successfully in low-frequency applications. Perhaps more important for many purposes are the tracking and arcing resistance, which are frequently poor with aromatic polymers. 

Nylon (Polyamide) PA is a crystalline plastic and the first and largest consumption of the engineering thermoplastic. This family of TPs are tough, slippery, with good electrical properties, but hygroscopic and with dimensional stability lower than most other engineering types. Also offered in reinforced and filled grades as a moderately priced metal replacement. 

Siloxane containing interpenetrating networks (IPN) have also been synthesized and some properties were reported 59,354 356>. However, they have not received much attention. Preparation and characterization of IPNs based on PDMS-polystyrene 354), PDMS-poly(methyl methacrylate) 354), polysiloxane-epoxy systems 355) and PDMS-polyurethane 356) were described. These materials all displayed two-phase morphologies, but only minor improvements were obtained over the physical and mechanical properties of the parent materials. This may be due to the difficulties encountered in controlling the structure and morphology of these IPN systems. Siloxane modified polyamide, polyester, polyolefin and various polyurethane based IPN materials are commercially available 59). Incorporation of siloxanes into these systems was reported to increase the hydrolytic stability, surface release, electrical properties of the base polymers and also to reduce the surface wear and friction due to the lubricating action of PDMS chains 59). 

This review is concerned with the engineering thermoplastic uses of polyamide materials in injection moulding and extrusion applications. Types of polyamides are described, and their key properties are considered. Commercial applications in the automotive, electrical/ electronic, engineering and construction, and packaging industries are discussed. Polyamide processing is... 

We can divide commodity plastics into two classes excellent and moderate insulators. Polymers that have negligible polar character, typically those containing only carbon-carbon and carbon-hydrogen bonds, fall into the first class. This group includes polyethylene, polypropylene, and polystyrene. Polymers made from polar monomers are typically modest insulators, due to the interaction of their dipoles with electrical fields. We can further divide moderate insulators into those that have dipoles that involve backbone atoms, such as polyvinyl chloride and polyamides, and those with polar bonds remote from the backbone, such as poly(methyl methacrylate) and poly(vinyl acetate). Dipoles involving backbone atoms are less susceptible to alignment with an electrical field than those remote from the backbone. 

Polyamide fibers, 19 739-772. See also Synthetic polyamides applications for, 19 765-766 chemical properties of, 19 745-747 cross-section shape of, 19 756 dyeability of, 19 758-760 early reactive dyes for, 9 468-470 electrical properties of, 19 745 manufacture of, 19 748-749 modified nylon-6 and nylon-6,6, 19 760-764... 

Meincke O, Kaempfer D, Weickmann H, Friedrich C, Vathauer M, Warth H (2004). Mechanical properties and electrical conductivity of carbon-nanotube filled polyamide-6 and its blends with acrylonitrile/butadiene/styrene. Polymer 45 739-748. 

For the same grade with the same thickness, the three indices can be identical (for example, a polyethylene grade with a 50° C UL index temperature) or different (for example, a polyamide grade with a temperature index varying from 75°C for the electrical and mechanical properties, impact included, up to 105°C for the electrical properties only). 

Figure 2.31 displays the market shares of the most commonly used commodity and engineering thermoplastics in the electrical electronics industry. Only polyamides are identified among the engineering thermoplastics. 

Polyamides are fair insulators in a dry environment and at ambient temperature, with fair dielectric resistivities and rigidities, and high loss factors. Special grades are marketed for electrical applications. 

Polyamide-imides are appreciated for good mechanical and electrical properties high service temperatures (up to 220°C with possible long service times at 260°C) rigidity good creep behaviour fatigue endurance low shrinkage and moisture uptake inherent flame retardancy chemical resistance usability down to -196°C. 

Nylons 6/6 and 6 comprise more than 90% of the polyamide market. The two have similar properties but nylon 6 has a lower Tm (223°C). Small amounts of nylons 6/9, 6/10, 6/12, 11, 12, 12/12, and 4/6 are produced as specialty materials. Those with more methylene groups than nylons 6/6 and 6 have better moisture resistance, dimensional stability, and electrical properties, but the degree of crystallinity, Tm, and mechanical properties are lower. Specialty nylons made from dimerized fatty acids find applications as hot-melt adhesives, crosslinking agents for epoxy resins, and thermographic inks. 

Aliphatic polyamides are used as fibers and as engineering thermoplasts in automotive, electrical, and consumer product applications. 

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