🧩 NBR – Nitrile Rubber
(Synthetic elastomeric material obtained by copolymerizing acrylonitrile (ACN) with butadiene. NBR offers excellent resistance to oils and fuels, combined with adaptable hardness. It is a thermoset rubber.)
🔹 What is NBR
NBR (Nitrile Butadiene Rubber) is the industry standard for oil-resistant automotive parts. At ReplastMD, we treat NBR as a high-performance chemical barrier. Its properties vary based on ACN content: higher ACN means better oil resistance but less cold flexibility. As a vulcanized (thermoset) material, it does not melt under heat. It is the core material for fuel lines, oil seals, and transmission gaskets.
🔧 Composition & Properties
- Polymer Base: Acrylonitrile + Butadiene copolymer (ACN 18–50%).
- Density: 1.00 – 1.20 g/cm³.
- Hardness (Shore A): 40 – 90.
- Operating Range: –30 °C to +110 °C.
- Chemical Resistance: Excellent for mineral oils, fuels, and greases.
- Weakness: Poor resistance to ozone and UV; will dry and crack if exposed to long-term sunlight.
🚗 Where NBR is used in the automotive industry
| Component | Example parts | Observations |
| Engine / Oil Seals | O-rings, oil pan seals, gaskets | Resists high oil pressure |
| Fuel Systems | Fuel lines, valves, diaphragms | Resists swelling in gasoline/diesel |
| Brake / Transmission | ATF seals, DOT gaskets | Compatible with technical fluids |
| Vibration Damping | Mounts, buffers | Good mechanical stability |
🔧 Welding Temperature and Methods
| Method | Compatibility | Observations |
| Hot Air | ❌ Cannot be welded | Vulcanized – burns rather than melts |
| Heat Plate (Mirror) | ❌ Impossible | Degrades and chars above 150 °C |
| Extrusion | ❌ N/A | Cannot be reshaped after curing |
| Chemical Bonding | ✅ Recommended | Cyanacrylate or nitrile rubber adhesives |
🔩 Compatibility (Bonding)
- ✅ Compatible: NBR, HNBR, ACM, AEM.
- ❌ Incompatible: PP, PE, PA, PC, PVC – poor adhesion without chemical treatment.
💡 ReplastMD Recommendation: NBR cannot be thermally welded. For small repairs or bonding O-rings, use rubber-specific cyanacrylates. For large-scale sealing, local chemical vulcanization with an activating primer is preferred.