CTBN Rubber-Modified Epoxy Resin (Toughened)
CTBN Rubber-Modified Epoxy Resin is a pre-reacted adduct of standard bisphenol A epoxy resin with CTBN (carboxyl-terminated butadiene-nitrile rubber), producing a single-component toughened epoxy that significantly improves fracture toughness, peel strength, and impact resistance versus unmodified epoxy without requiring a separate rubber addition at point of use. The reactive adduct format ensures the rubber phase is chemically bonded into the cured network, forming a phase-separated microstructure that absorbs crack propagation energy. It is the standard toughening approach in aerospace structural adhesives, automotive body panel bonding, and high-performance composite matrices.
Technical Specifications
| EEW | 200–400 g/eq |
| viscosity | 5000–80000 mPa·s at 25 °C |
| appearance | Amber to dark amber viscous liquid |
| CTBNContent | 10–40% by weight |
| acrylonitrileContent | 18–26% in CTBN segment |
Applications
- Aerospace and defense structural adhesives
- Automotive body panel bonding and hem flange adhesives
- High-performance epoxy composite matrix resins
- Industrial pipe and flange repair compounds
- Impact-resistant epoxy tooling and casting compounds
Key Features
- CTBN Rubber-Modified Epoxy Resin delivers pre-reacted toughening — rubber is covalently bonded, ensuring consistent performance without phase separation on storage
- Dramatically improves peel strength (T-peel up to 5–10× vs. neat epoxy) and Mode I fracture toughness (KIc)
- Maintains high glass transition temperature because rubber is dispersed as discrete micro-domains, not a continuous phase
- Drop-in replacement approach — compatible with standard amine and anhydride hardeners without reformulation