The Effect of Aluminum and Ammonium Perchlorate Content on Temperature Sensitivity, Mechanical Properties and Performance of HTPB Propellants

Abstract

This paper describes the effect of aluminum content variation of HTPB (hydroxyl terminated polybutadiene) propellants on temperature sensitivity, mechanical properties and performance values. Aluminum (Al) content was applied as 16, 18 and 20 percent to the propellant compositions and those compositions were tested at small test motors with three different propellant area ratios (K=200, 250 and 300) by keeping the propellant grain at three different temperatures (231, 258 and 323 K). As a result of this, a relationship such as P=ae^sT was determined with different coefficients for each of the three compositions and propellant area ratios. The lowest temperature sensitivity value was obtained for the composition containing 20% Al and 65% AP. The second relation as P=bK^y was derived for three propellants and temperatures. The highest pressure was found with the K value of 300 for the propellant including 16% Al and 69% AP at 323 K. The third relationship such as r=cPⁿ was also determined for three propellant compositions and temperatures. It was observed that the propellant having 16% Al and 69% AP had the highest burning rate at 323 K. The highest maximum tensile stress and elongation values were obtained for the propellants including 20% Al and 16% Al respectively. Evaluation of performance values for those propellants exhibits that the maximum characteristic velocity value is attained for the propellant containing 16% Al and 69% AP.