🧩 PA12+EVOH – Polyamide 12 Ethanol Barrier
(A multi-layer technical material composed of Polyamide 12 (PA12) – a flexible and chemically resistant polymer – and EVOH (ethylene-vinyl alcohol), which acts as a barrier against the diffusion of fuel vapors and ethanol.)
🔹 What is PA12+EVOH
PA12+EVOH is a co-extruded combination of Polyamide 12 layers (inner and outer) and a central EVOH core. This structure ensures the flexibility and mechanical strength of PA12 while providing the chemical impermeability of EVOH. It is the ideal solution for modern fuel systems compliant with emission standards (EURO 6/7).
🔧 Composition
| Layer / Component | Role | Observations |
| PA12 (Polyamide 12) | Inner and Outer layer | Fuel resistance, flexibility, protection |
| EVOH (Ethylene-Vinyl Alcohol) | Intermediate layer | Total barrier to hydrocarbons and ethanol |
| Interlayer Adhesive | Tie layer | Compatibilizer between PA and EVOH phases |
🚗 Where PA12+EVOH is used in the automotive industry
| Component | Example parts | Observations |
| Fuel / Petrol Hoses | Renault, Peugeot, BMW | Internal EVOH barrier layer |
| EVAP / Return Lines | Bosch, Continental | Compliant with ISO 15500 / SAE J2260 |
| Tank Tubes / Canisters | Volkswagen, Opel | Prevents vapor leakage |
| Injection Systems | Ford, Mercedes | Anti-ethanol barrier (E10–E85) |
🔧 Welding Temperature and Methods
| Method | Optimal Temp | Observations |
| Hot Air | 250 – 270 °C | Recommended for PA12 layers |
| Plastic Extrusion | 240 – 260 °C | Ideal – focus on the outer layer |
| Heat Plate (Mirror) | 240 – 260 °C | Only for flat parts or tube terminals |
🔩 Material Compatibility
- ✅ Compatible: PA12, PA11, PE-HD, EVOH.
- ⚠️ Partially Compatible: PA6, PPA, PP, TPU (different melting points).
- ❌ Incompatible: PVC, PC, ABS (chemically and thermally incompatible).
💡 ReplastMD Recommendation: Direct the airflow only onto the PA12 layer; the EVOH layer should not be excessively melted — otherwise, the barrier function is lost. Use PA12 rods (VESTAMID® / Rilsan®) and a moderate temperature (260 °C).
🧠 How to Identify PA12+EVOH
- Engraved marking: >PA12-EVOH-PA12<, >PA12/EVOH<, >VESTAMID-EVOH<.
- Aspect: Layered (3 layers visible in cross-section), glossy exterior, translucent interior.
- ReplastMD practical test: Inner part softens at 180 °C, EVOH layer remains matte. Flame: burns uniformly with a faint starch scent (EVOH).
🛠️ PA12+EVOH Welding at ReplastMD:
At our ReplastMD service center (Chisinau, Ciocana sector), we perform professional PA12+EVOH welding for high-tech fuel lines, ensuring total vapor tightness and chemical stability.