High-temperature cable insulation materials are used where cables need to operate above the temperature limits of common thermoplastic or thermosetting compounds. These materials are often selected for demanding industrial, process, transport, aerospace or specialist equipment applications.
The table below compares typical properties for common high-temperature fluoropolymer insulation materials. Values are indicative and should be checked against the cable manufacturer’s datasheet for the exact compound and cable construction being specified.
High-temperature insulation material comparison
| Property | PVDF Polyvinylidene fluoride | ETFE Ethylene-tetrafluoroethylene | FEP Fluorinated ethylene propylene | PFA Perfluoroalkoxy polymer | PTFE Polytetrafluoroethylene |
|---|---|---|---|---|---|
| Density, g/cm3 | 1.7-1.9 | 1.6-1.8 | 2.0-2.3 | 2.0-2.3 | 2.0-2.3 |
| Breakdown voltage, kV/mm at 20 °C | 25 | 36 | 25 | 25 | 20 |
| Specific volume resistivity, Ω cm at 20 °C | 1014 | 1016 | 1018 | 1018 | 1018 |
| Dielectric constant, 50 Hz at 20 °C | 9-7 | 2.6 | 2.1 | 2.1 | 2.1 |
| Dielectric loss factor, tan δ | 1.4 × 10-2 | 8 × 10-4 | 3 × 10-4 | 3 × 10-4 | 3 × 10-4 |
| Permanent working temperature, °C | -40 to +135 | -100 to +150 | -100 to +205 | -190 to +260 | -190 to +260 |
| Short-time temperature, °C | +160 | +180 | +230 | +280 | +300 |
| Melt temperature, °C | >170 | >265 | >225 | >290 | >325 |
| Flame resistance | Self-extinguishing | Self-extinguishing | Self-extinguishing | Self-extinguishing | Self-extinguishing |
| Oxygen index, LOI (% O2) | 40-45 | 30-35 | >95 | >95 | >95 |
| Heating value H0, MJ/kg | 15 | 14 | 5 | 5 | 5 |
| Thermal conductivity, W/(K·m) | 0.17 | 0.24 | 0.26 | 0.21 | 0.26 |
| Corrosive gases in case of fire | Hydrofluoric | Yes | Yes | Yes | Yes |
| Radiation resistance, max Mrad | 10 | 10 | 1 | 0.1 | 0.1 |
| Tensile strength, N/mm2 | 50-80 | 40-50 | 15-25 | 25-30 | 80 |
| Elongation at break, % | 150 | 150 | 250 | 250 | 50 |
| Shore hardness | 75-80 (D) | 70-75 (D) | 55-60 (D) | 55-60 (D) | 55-60 (D) |
| Abrasion resistance | Very good | Very good | Very good | Very good | Very good |
| Water absorption, % | 0.01 | 0.02 | 0.01 | 0.01 | 0.01 |
| Halogen free | No | No | No | No | No |
| Weather resistance | Very good | Very good | Very good | Very good | Very good |
| Cold resistance | Very good | Very good | Very good | Very good | Very good |
Design considerations
High-temperature insulation materials can offer excellent thermal, weathering and abrasion performance, but they are not automatically suitable for every installation. Fire behaviour, corrosive gas emission, radiation resistance, flexibility, termination method and cost should all be checked against project requirements.
For cable sizing and thermal design, use the manufacturer’s published operating temperature and material data for the actual cable construction.