High-temperature performance testing of PEEK insulated wires is crucial for ensuring their reliable operation under extreme conditions. Testing must adhere to international/industry standards and employ a multi-dimensional, multi-stress coupling verification system to comprehensively evaluate the material’s electrical, mechanical, and chemical stability at high temperatures. The following is a systematic testing methodology guide summarized by TST CABLE Nico:
I. TST CABLE Peek Cable Core Testing Standard System
| Standards Organization | Key Standards | Test content |
| IEC | IEC 60216 | Evaluation of the heat resistance of electrical insulation materials (temperature index TI) |
| UL | UL 746B | Long-term aging assessment of polymer materials |
| ASTM | ASTM D3032 | Winding wire thermal life test method |
| IEEE | IEEE 323/383 | Nuclear-grade equipment thermal aging + environmental assessment |
| ISO | ISO 188 | Rubber/Plastic Hot Air Aging Test |
| National Standard | GB/T 11026 | Guidelines for heat resistance of electrical insulation materials |
✅ Recommended combination: IEC 60216 (Temperature Index) + ASTM D3032 (Thermal Life) + IEEE 323 (Nuclear-grade Validation)
II. Key Test Items and Methods
1. Temperature Index (TI) Measurement
Objective: To determine the long-term permissible operating temperature (e.g., 250°C) for PEEK insulation.
method:
Multiple groups of samples were prepared and placed at 5–7 temperature gradients (e.g., 230℃, 240℃, 250℃, 260℃, 270℃).
Periodically remove and test tensile strength, insulation resistance, and dielectric strength;
When the performance drops to 50% of the initial value, the failure time at that temperature is recorded.
Extrapolate the Arrhenius equation to the temperature corresponding to a lifespan of 20,000 hours (approximately 20 years).
Judgment: The temperature resistance (TI) of PEEK is usually ≥240℃ (180℃ for Class H insulation, which PEEK far exceeds).
2. Thermal aging test
condition:
Temperature: 250℃±2℃ (or as required by application);
Time: 168h, 500h, 1000h, 2000h (equivalent to different service years);
Atmosphere: Air or nitrogen (simulating different environments).
Test metrics:
| index | Test methods | Qualification Standard |
| Tensile strength retention | ASTM D638 | ≥70% (after 1000h) |
| Elongation at break | ASTM D638 | ≥50% (after 1000h) |
| Insulation resistance | IEC 60243 | ≥10⁹ Ω·km |
| Dielectric strength | IEC 60243 | ≥15 kV/mm |
| Appearance | Visual inspection + microscope | No cracking, bulging, or carbonization |
3. Thermal shock test
Objective: To verify the crack resistance under sudden temperature changes (such as equipment start-up and shutdown, and accident conditions).
Method (ASTM D3032):
The sample was bent 180° around the mandrel (mandrel, diameter = 4 × wire diameter);
Immediately place in a 250℃ oven and keep for 30 minutes;
Remove and cool to room temperature, then check for cracks in the insulation layer;
Repeat the cycle 3–5 times.
Judgment: No visible cracks in the insulation layer, and no breakdown during high-voltage testing.
4. High Temperature and High Pressure Test (LOCA Simulation)
Suitable for: high temperature, high pressure and high humidity coupled environments such as nuclear power and deep sea.
condition:
Temperature: 170℃–200℃;
Pressure: 0.4–1.0 MPa saturated steam;
Time: 30 days (simulating water loss accident conditions).
Testing: After the test, insulation resistance, dielectric strength, and water absorption rate are measured.
Judgment: Insulation resistance ≥ 10⁸ Ω, no delamination/bulging.
5. High-temperature bending life test
Suitable for: dynamic applications (such as robots and cable chains).
method:
Temperature: 200℃ constant temperature environment;
Bending radius: 6–8 × D;
Frequency: 0.5–2 Hz;
Number of times: 500,000–5,000,000.
Judgment: Continuous conduction, no insulation damage.
III. Testing Equipment Requirements
| equipment | Technical Requirements |
| High temperature oven | Temperature control accuracy ±1℃, maximum 300℃, forced convection |
| autoclave | Pressure resistance 2 MPa, temperature 200℃, steam compliant |
| Dielectric tester | Adjustable from 0 to 50 kV, frequency from 50 Hz to 1 MHz |
| micro-Eurometer | Accuracy 0.1 μΩ, measuring conductor resistance change |
| Thermogravimetric analyzer (TGA) | Measure the decomposition temperature of PEEK (should be >550℃). |
| Differential Scanning Calorimeter (DSC) | Measure the glass transition temperature Tg (PEEK≈143℃) and melting point Tm (≈343℃). |
IV. Judgment Criteria Reference
| Test Project | Typical PEEK symptoms | Pass line |
| Temperature Index (TI) | 240–250℃ | ≥220℃ |
| Thermal aging (250℃×1000h) tensile retention rate | ≥75% | ≥70% |
| Thermal shock (250℃ × 5 times) | No cracks | No cracks |
| LOCA insulation resistance | ≥10⁹ Ω | ≥10⁸ Ω |
| High-temperature bending (200℃ × 1 million cycles) | Normal conduction | No circuit break |
| Decomposition temperature (TGA) | >580℃ | >550℃ |
V. Recommendations for Practical Application Verification
While laboratory testing is rigorous, real-world operating conditions are far more complex. We suggest adding:
On-site sample loading test: Install samples in the target equipment and take samples for testing periodically;
Accelerated aging + actual measurement comparison: extrapolation using the Arrhenius model, but correction with actual measurement data is required;
Failure analysis: SEM (scanning electron microscopy) and FTIR (fiber spectroscopy) were performed on the aged samples to analyze the degradation mechanism;
Third-party verification: Reports were commissioned from independent organizations such as UL, TÜV, and Shanghai Cable Research Institute.
VI. Warnings on Common Testing Mistakes
❌ Short-term high temperature testing only: No problem at 250℃×24h ≠ Reliable at 250℃×1000h;
❌ Ignore temperature fluctuations: Constant temperature testing ≠ actual thermal cycling conditions;
❌ Measuring only electrical properties: Mechanical properties (tensile and bending) are equally important;
❌ Coupling stress not considered: The combined effects of high temperature, radiation, and chemical media are even more severe;
❌ Do not use material data instead of finished product testing: Extrusion processes can affect crystallinity, which in turn affects temperature resistance.
The test wasn’t about “passing the test,” but rather about “getting a feel for the situation.”
The high-temperature resistance test for PEEK insulated wire
is not for obtaining a certificate,
but to understand the true performance of the material at the limits.
True reliability is not about “passing the test”,
but about “having a safety margin even when exceeding the test conditions”.
We recommend
customizing your testing plan
based on your specific operating conditions (temperature profile, environmental medium, lifespan requirements) –
because behind every PEEK cable
lies a system that cannot afford to fail.
Also available in:
English
