Published Online: 4 April 2005
Page Count: 15
Nihal Tüzün, F
Gazi University, Corum,
(Received 23 June 2004; accepted 21 December 2004)
In this study, three different HTPB (hydroxyl terminated polybutadiene) based composite propellants were developed by varying the aluminium (Al) content 16, 18, and 20 %; and the effect of aluminium content variation on burning rate, P-K relationship, viscosity, heat of explosion, density, and hardness of the propellants developed were investigated. Propellants were cured at 65°C for 7 days, and then applied to the small test motors and kept at three different temperatures (−42, −15, and 50°C) for a night (8 h) before testing. Tests on the small motors were performed with three different K values (200, 250, and 300) statically. As a result of this, two relationships were determined, and the coefficients of those relationships are also given in Table 1.
First relationship: P = d Ky (1), where P = pressure; y = K index; d = P-K relationship constant; and K = Propellant-area ratio. This relationship shows that pressure is highly affected by K values at 50°C in each of three compositions.
Second relationship: r = a Pn (2), where P = pressure; r = burning rate; a = burning rate constant; and n = combustion index.
This relationship also shows that burning rate has the lowest value in the propellant containing 20 % Al. Therefore; it was observed that the burning rate exponent (n) was below the safety limit value of 0.4 in three compositions, which shows that Al content should not exceed 18 %. These results also indicate that viscosity and hardness remain constant, density increases, and heat of explosion decreases with increasing Al content in the three compositions.
Paper ID: JAI12936