Hydroxyl-terminated polybutadiene

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Hydroxyl-terminated polybutadiene (HTPB) is a polymer of butadiene terminated at each end with a hydroxyl functional group. It belongs to a class of polymers known as polyols. It is used to react with a diisocyanate to form a polyurethane, a stable and easily stored synthetic material.

[edit] Physical properties

HTPB is a clear, viscous liquid. 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.

[edit] Uses

HTPB is used to bind the fuel and oxidizer into a solid mass for solid rocket motors. It is also used as a hybrid rocket fuel. Together with N₂O (nitrous oxide, or "laughing gas") as the oxidizer, it is used to power the SpaceShipOne hybrid rocket motor, developed by SpaceDev. It also powers all 3/4 stages of the Japanese M-5 rocket satellite launchers. JAXA describe the fuel as "HTPB/AP/Al=12/68/20" which means, proportioned by mass, HTPB 12% (binder and fuel), Ammonium perchlorate 68% (oxidizer), and Aluminium powder, 20% (fuel).