CTBN (Carboxy-Terminated Butadiene-Acrylonitrile) Liquid Rubber
CTBN Liquid Rubber is a carboxy-terminated butadiene-acrylonitrile copolymer used as a reactive toughening agent for epoxy adhesives and structural composites. When reacted with epoxy resins, CTBN phase-separates to form rubber domains that arrest crack propagation, leading to dramatic improvements in fracture toughness (KIc), peel strength, and impact resistance with minimal sacrifice of stiffness or heat resistance. It is widely employed in aerospace structural adhesives, automotive body adhesives, and electronic underfills.
Technical Specifications
| viscosity | 50,000–200,000 mPa·s (27 °C) |
| acidNumber | 28–45 mg KOH/g |
| appearance | Amber viscous liquid |
| molecularWeight | 3,000–4,000 g/mol (Mn) |
| acrylonitrileContent | 10–26% (grade dependent) |
Applications
- Aerospace structural adhesives and film adhesives
- Automotive body-in-white adhesives
- Electronic underfill encapsulants
- Epoxy composite toughening
- Pipeline repair and maintenance adhesives
Key Features
- Reactive toughening—covalently bonds into epoxy network
- Dramatically increases fracture toughness and peel strength
- Minimal reduction in Tg or modulus
- Variable acrylonitrile content for tailored compatibility