Molecular dynamics study of the structures and properties of RDX/GAP propellant

Molecular dynamics simulations have been performed to investigate well-known energetic material cyclotrimethylene trinitramine (RDX) crystal, glycidyl azide polymer (GAP) and RDX/GAP propellant. The results show that the binding energies on different crystalline surface of RDX change in the order of (0 1 0) > (1 0 0) > (0 0 1). The interactions between RDX and GAP have been analyzed by means of pair correlation functions. The mechanical properties of RDX/GAP propellant, i.e., elastic coefficients, modulus, Cauchy pressure, and Poisson's ratio, etc., have been obtained. It is found that mechanical properties are effectively improved by adding some amounts of GAP polymer, and the overall effect of GAP on three crystalline surfaces of RDX changes in the order of (1 0 0) > (0 1 0) > (0 0 1). The energetic properties of RDX/GAP propellant have also been calculated and the results show that compared with the pure RDX crystal, the standard theoretical specific impulse (I(sp)) of RDX/GAP propellant decrease, but they are still superior to those of double base propellant.