Polypropylene has properties almost identical to that of polyethylene and is used almost exclusively for thin wall primary insulations. Polypropylene can be rated for -30°C to 80°C. Polypropylene can be foamed for improved electrical properties.
Polyurethane in general has excellent low-temp flexibility, high tensile strength, and long flex-life. It exhibits excellent chemical, water, and abrasion resistance, as well as being extremely tough and cut-through resistant.
Plasticizers, which can migrate out to contaminate other compounds or cause embrittlement with aging, are not present in polyurethane.
Polyurethane is extremely flammable but can be offered in a flame-retardant version at the expense of tensile strength and surface finish.
One major disadvantage of polyurethane is its poor electrical qualities, which restrict its use to jackets. It does have excellent retractile cord characteristics, and is a good candidate for use in salt-spray and low-temperature military applications.
Hytrel* was developed by E. I. du Pont de Nemours and Company to be used for thin-wall applications. Hytrel* is similar to Nylon in its toughness, chemical resistance, flexibility, and resilience.
Some applications include primary insulation for retractile and telephone line cords, high flex-life cables, and cables requiring a tight bend radius.
Nylon* exhibits excellent jacket toughness, especially in thin-wall applications, and has excellent abrasion, cut-through, and chemical resistance. Its main application is to provide these qualities when extruded over softer insulation compounds. Nylon* has a very low coefficient of friction, making it a good choice for use in high flex applications.
Nylon* does absorb moisture, which somewhat degrades its electrical properties from their original state.
Surlyn*, an electrical grade ionomer from Dupont, has been used for application requiring excellent mechanical properties. Combining superb cut-through and stress cracking resistance with ultra low temperature flexibility and a brittleness temperature under -100°C, Surlyn* can be used to meet many of the stringent military requirements.
Thermoplastic Rubber was developed to act as a substitute in many applications for true thermoset rubber. Some advantages over thermoset material are: Colorability, higher processing speeds, and wide service temperature range. TPR has excellent heat, weathering, and aging resistance, and no curing is necessary.
Most commonly used in applications where cut-through resistance is not required, but other properties of rubber are still necessary.
KYNAR's advantages include: Exceptional chemical resistance, high tensile strength, abrasion resistance, cut through and UV resistance. Additionally, it is highly flame resistant and produces very little smoke in the presence of flame. For applications requiring increased flexibility and stress crack resistance, KYNAR FLEX® copolymers are recommended.
SOLEF® is a registered trademark of Soltex, which is a subsidiary of Solvay, a manufacturer of Vinylidene Fluoride-based resins. Solef has a number of grades which are widely being used in fiber and overall jacketing applications. It's properties are very similar to KYNAR's.
PFA possesses some of fluorocarbon's best properties. Its high temperature rating of 250°C, low temperature of -65°C and dissipation factor of .0002 equal or better most of the other fluorocarbons' properties. However, it does not possess the thermoset properties of TFE which limits it to a select group of applications. Although it can be processed in long lengths, PFA's high material cost has prevented it from gaining widespread use.
FEP is the most commonly used fluoropolymer currently because of its excellent processing characteristics and wide applications range. Although it is not a thermoset, this material does have high flame resistance. Hence, its usage in plenum cable and military applications has been steadily increased as pricing and processing improve. FEP can also be "foamed" for improved data transmission characteristics.
ETFE TEFZEL and ECTFE HALAR
Although lacking many of FEP's excellent electrical properties, ECTFE and ETFE posses better flexibility and mechanical strength than either PFA or FEP. Additionally, ECTFE & ETFE can become thermoset by the irradiation method. ECTFE can also be "foamed" for improved data transmission characteristics and is frequently used for the purpose of weight reduction.