Polymeric fuel grain

The polymeric hydrocarbon also acts as a binder of the particles, holding them together so as to formulate a propellant grain. Ammonium perchlorate (AP) is a typical crystalline oxidizer and hydroxy-terminated polybutadiene (HTPB) is a typical polymeric fuel. When AP and HTPB are decomposed thermally on the propellant surface, oxidizer and fuel gases are produced, which diffuse into each other and react to produce high-temperature combustion gases. 

From the earliest times man depended upon nature for polymeric materials like wood as fuel, furs and fibres as clothing, grain and flesh as food. Many polymeric materials behave as plastics, i.e., in some stage of their fabrication they are soft and putty like and can be moulded into any desired shape and then set to retain that shape. 

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