The Role of Acrylonitrile Content in NBR: Balancing Low-Temp Flex vs. Oil Swelling.
The Role of Acrylonitrile Content in NBR: Balancing Low-Temp Flex vs. Oil Swelling.
RubberQ Engineering
The Role of Acrylonitrile Content in NBR: Balancing Low-Temp Flex vs. Oil Swelling
Problem Statement
Nitrile rubber (NBR) seals in hydraulic systems face competing demands: low-temperature flexibility (-40°C) and resistance to oil swelling (ASTM Oil #3). Standard NBR grades fail when acrylonitrile (ACN) content is mismatched to the operating environment.
Material Science Analysis
ACN content determines NBR's polarity. Higher ACN (34-51%) improves oil resistance but reduces low-temperature flexibility by increasing glass transition temperature (Tg). Low-ACN NBR (18-25%) maintains flexibility below -30°C but swells over 25% in oil.
Technical Specs
- Optimal ACN Range: 28-34% for balanced performance
- Shore A Hardness: 50-90 (customizable via plasticizer content)
- Tensile Strength: 10-25 MPa (ASTM D412)
- Elongation at Break: 300-600%
- Temperature Range: -40°C to +120°C (short-term 150°C)
- Compression Set (ASTM D395): 25-40% after 22h at 100°C
| Parameter | High-ACN NBR (45%) | Medium-ACN NBR (30%) | Low-ACN NBR (20%) |
|---|---|---|---|
| Oil Swell (ASTM D471, 70h @100°C) | +5% | +12% | +28% |
| TR-10 Low Temp (°C) | -15 | -30 | -45 |
| Tensile Strength (MPa) | 22 | 18 | 14 |
| ISO 3601 Fluid Resistance Rating | Class A | Class B | Class D |
Standard Compliance
RubberQ's IATF 16949-certified compounding ensures ±2% ACN content consistency via FTIR verification. All batches meet ASTM D2000 BF, BK, and CH callouts with full traceability.
For custom material compound development or IATF 16949 documentation, consult RubberQ's engineering department.
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