ROHM AND HAAS CO HUNTSVILLE AL REDSTONE RESEARCH LABS
Strand burning rates of ammonium perchlorate-containing composite propellants having plastisol-nitrocellulose, carboxyl-terminated-polybutadiene, and NF binders have been measured to 20,000 psig. For the first two types and probably the NF type the major influences on burning-rate transition are those resulting from variations in binder type and in oxidizer concentration and particle size the presence of aluminum or burning-rate promoters has little effect on the pressure-dependence of the burning rate at high pressure. The pressure exponents of plastisol-nitrocellulose formulations reach constant values of 1.0 to 1.3 at about 6000 psi, with little dependence on AP particle size. Carboxyl-terminated-polybutadiene formulations examined give indexes from 0.3 at 2000 psi to 2 up to 10,000 psi, with appreciable AP-particle-size dependence above 10,000 psi the index decreases to 0.9 and appears to be insensitive to oxidizer size. A proposed model suggests an alteration in the volatilization processes which ensue from differences in pressure-dependence of the respective binder and oxidizer release rates.