Hydroxyl-terminated Polybutadiene

Hydroxyl-terminated Polybutadiene

Hydroxyl-terminated polybutadiene (HTPB) is a polymer of butadiene terminated at each end with a hydroxyl functional group. It reacts with diisocyanate to form polyurethane, a stable and easily stored synthetic material.

HTPB is a translucent liquid with a very similar color to wax paper; it is highly viscous. The properties cannot be precisely stated, because HTPB is manufactured in various grades to meet specific requirements. HTPB is thus a generic name for a class of compounds. It consists of many butadiene molecules linked together into a polymer forming polybutadiene. Both ends of the chain are terminated with a hydroxide ion, thus giving it the name Hydroxyl-Terminated Polybutadiene. It is used in model rocketry as a high power fuel known commonly as RBS. It has also found its way into the pyrotechnics industry with a use as mortar tubes for aerial-shell fireworks. It is insoluble in water making it a good sealant. Although it is used in rocket fuel it does not ignite easily – it requires temperatures in excess of 773K to combust. The curing agent for it is usually a polyisocyanate compound.