Effect of Bonding Agent on the Mechanical Properties of GAP High-Energy Propellant

Three kinds of bonding agent were chosen to improve the mechanical properties of GAP high-energy composite propellant based on GAP, BuNENA, HMX, AP, and Al. These bonding agents are N,N′-bis(2-hydroxyethyl) dimethylhydantoin and 1,3,5-trisubstituted isocyanurates (BA1), cyano-hydroxylated amines (BA2), and hyperbranched polyether with terminal groups substituted by hydroxyl, cyano and ester functional groups (BA3). To study the interaction between bonding agents and oxidizers, the effect of coating by bonding agents on the characteristic absorption peaks of AP and HMX were first studied by infrared spectroscopy. Then the effect of bonding agents on the adhesion work between oxidizers and binder system were determined. The results showed that BA2 has the strongest interaction with AP, whereas BA1 and BA3 have relatively strong interaction with HMX. The AP grain coated by BA2 has the strongest adhesion work to the binder system, and there is not much difference in the values of adhesion work towards binder system of three coated HMX grains. At last the three bonding agents were added to GAP propellant, which has a theoretical specific impulse of 276.03 s. When the three kinds of bonding agent was used alone, the sense of “dewetting” in propellant was relieved but still existed. The combination of BA2 to BA1 or BA3 improved the adhesions between oxidizers and binder system effectively, and the mechanical properties of GAP propellant reached to δ_m=0.69 MPa, ϵ_b=32.7 %.