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S-HTPB (Mono-Hydroxyl Terminated Polybutadiene(S-HTPB) / Single Hydroxyl group HTPB )
Single Hydroxyl group HTPB/ Mono-OH HTPB
69102-90-5
GB/GJB(GJB1327A-2021)
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Carboxy-Terminated Nitrile Butadiene Rubber(CTBN) CAS No. 25265-19-4 CTBN
Carboxyl-terminated butadiene-acrylonitrile
CTBN
CAS No. 25265-19-4
Chemical name: Carboxyl-terminated butadiene-acrylonitrile
Code: CTBN
CAS No. 25265-19-4
Product Description
CTBN (Carboxyl-Terminated Butadiene-Acrylonitrile) is a low-molecular-weight butadiene-acrylonitrile copolymer with carboxyl groups (-COOH) at both ends of the molecular chain, classified as a reactive telechelic liquid rubber.
Appearance: Amber-colored viscous liquid (viscosity: ~8,000–12,000 cP at 25°C).
Structural Features:
Reactive carboxyl end groups
main chain with flexible butadiene segments and polar acrylonitrile units
acrylonitrile content: 18%–26%
number-average molecular weight: 3,000–4,000
Tg: approx. -40°C to -20°C
Key Advantages: Combines oil/solvent/aging resistance with low-temperature flexibility, high polarity, and strong adhesion; carboxyl groups chemically bond with epoxy, phenolic, polyurethane, and other resins, forming a stable “island-sea structure” that delivers toughening without significant loss of heat and medium resistance.
Product properties & Features
Enhances the toughness and flexibility of thermoset resins
lmproves adhesion to substrates that are difficult to bond to
Increases impact and crack resistance
Improves durability (fatique resistance)
Increases low-temperature mechanical properties
Key Property Comparison (CTBN vs. Conventional HTPB)
Polarity: CTBN (strong, with acrylonitrile) > HTPB
Adhesion: CTBN superior to metals/polar substrates
Oil Resistance: CTBN significantly better than HTPB
Reactive Sites: CTBN (dicarboxyl end groups); HTPB (dihydroxyl end groups)
Typical Uses: CTBN prioritizes epoxy toughening, oil-resistant adhesives/sealants; HTPB prioritizes polyurethanes, propellants, low-temperature flexible materials.
Applications
- 1. Epoxy Resin Toughening
- Addition of 10%–15% boosts epoxy impact strength by 300%+, significantly reducing brittleness and improving crack and fatigue resistance.
Used in aerospace structural adhesives, electronic potting compounds, advanced composite matrices, wind turbine blade adhesives.
- 2. Adhesives and Sealants
- Metal/composite bonding: Enhances peel strength, humidity/heat resistance, oil resistance, and low-temperature toughness.
Sealants: Oil-resistant seals, weld seals, wind power seals for automotive/construction machinery.
- 3. Solid Propellants
Serves as an energetic binder, improving propellant mechanical properties (elongation, low-temperature toughness) and processability.
- 4. Paints and Coatings
Epoxy/phenolic coating modification: Improves impact resistance, abrasion resistance, salt spray resistance, and adhesion for heavy-duty anticorrosion, marine, pipeline, and automotive undercarriage applications.
- 5. Other Resin Modifications
Toughening of phenolic, BMI, and cyanate ester resins for high-temperature structural components, electronic packaging, and high-performance laminates.
Packing & Storage
50kg/plastic drum or 170kg/metal drum packaging.
Storage should be cool, dry and ventilated.
The shelf life is 12 months, after the expiration of the re-inspection can still be used. Avoid rain and sun during transportation. Do not mix with strong oxidants.
Technical Index
| Item | CTBN-1 | CTBN-2 | CTBN-3 | CTBN-4 | CTBN-5 |
| Carboxyl value(mmol/g) | 0.45-0.55 | 0.45-0.65 | 0.45-0.65 | 0.65-0.75 | 0.45-0.70 |
| Appearance | Amber Viscous liquid, no visible impurities | ||||
| Viscosity (27℃,Pa.S) | ≤180 | ≤200 | ≤300 | ≤200 | ≤600 |
| Acrylonitrile content,% | 8.0-12.0 | 8.0-14.0 | 18.0-22.0 | 18.0-22.0 | 24.0-28.0 |
| Moisture,wt% ≤ | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 |
| Volatile Content,% ≤ | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| Molecular weight | 3600-4200 | 3000-4500 | 3000-4500 | 2500-3000 | 3000-4500 |
*NOTE: We can research and develop any new versions of CTBN according to the special demand of our customers.
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