Hydroxyl-terminated polybutadiene

The properties vary because HTPB is a mixture rather than a pure compound, and it is manufactured to meet customers' specific requirements.

[1] This product consists of oligomeric units typically containing 40–50 butadiene molecules bonded together, with each end of the chain terminated with a hydroxyl [OH] group: R-45HTLO has a functionality of 2.4-2.6, which means that there is (approximately) one additional hydroxyl group located along the chain for every two oligomeric units.

Some products include: rigid foam insulation panels; durable elastomeric wheels and tires (used for roller coasters, escalators, skateboards, etc.

It binds the oxidizing agent, fuel and other ingredients into a solid but elastic mass in most composite propellant systems.

[3] The land speed record attempt Bloodhound SSC was to have used HTPB with a high-test peroxide oxidizer, but that plan was altered in 2017.