Is the electrical insulation of engineering plastic polyamide good?

The electrical insulation performance of engineering plastic polyamide (nylon) has significant characteristics, but it needs to be comprehensively evaluated in combination with environmental conditions. The specific manifestations are as follows:

1. Advantages of normal insulation
In a dry state, the polar groups of the molecular chain (- CONH -) bind charge migration, and the volume resistivity can reach the forefront of polymer materials. It can withstand conventional low-voltage electric fields (<1000V) and is widely used in electrical components such as circuit breaker casings and wiring terminals.

2. Deadly humidity defect
Polyamide has strong hygroscopicity (saturated water absorption rate>8%), and after water infiltration:
Forming ion conductive channels, reducing volume resistivity by 3 orders of magnitude
The dielectric loss tangent (tan δ) skyrockets, and self ignition occurs due to heating in a high-frequency electric field
Typical failure: Relay nylon gear carbonized due to leakage in humid environment

3. Temperature related characteristics
Low temperature stability: maintaining excellent insulation at -40 ℃, superior to brittle plastics such as PS
High temperature collapse: When the temperature exceeds 120 ℃, the number of thermally excited charge carriers increases dramatically, and the insulation strength drops sharply

4. Direction of Modification Technology
Nanocomposites: Montmorillonite/Silicon Dioxide Build Maze Barrier to Block Moisture Penetration Paths
Blending optimization: Adding polyolefin (PP/PE) to reduce moisture absorption and sacrifice some mechanical strength
Surface metallization: permanent moisture isolation achieved by electroplating zinc nickel layer or coating with fluororesin

5. High frequency application forbidden zone
In a high-frequency electric field at the MHz level:
The relaxation effect of polar molecules triggers a dielectric loss peak, converting energy into thermal energy
Prohibited for high-frequency scenarios such as RF equipment and 5G base station antennas, PTFE or PPO must be used instead