Thermal characterization of glycidyl azide polymer (GAP) and GAP-based binders for composite propellants

Abstract

Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to investigate the thermal behavior of glycidyl azide polymer (GAP) and GAP-based binders, which are of potential interest for the development of highperformance energetic propellants. The glass transition temperature (T g ) and decomposition temperature (T d ) of pure GAP were found to be Ϫ45 and 242°C, respectively. The energy released during decomposition (⌬H d ) was measured as 485 cal/g. The effect of the heating rate on these properties was also investigated. Then, to decrease its T g , GAP was mixed with the plasticizers dioctiladipate (DOA) and bis-2,2-dinitropropyl acetal formal (BDNPA/F). The thermal characterization results showed that BDNPA/F is a suitable plasticiser for GAP-based propellants. Later, GAP was crosslinked by using the curing agent triisocyanate N-100 and a curing catalyst dibuthyltin dilaurate (DBTDL). The thermal characterization showed that crosslinking increases the T g and decreases the T d of GAP. The T g of cured GAP was decreased to sufficiently low temperatures (Ϫ45°C) by using BDNPA/F. The decomposition reaction-rate constants were calculated. It can be concluded that the binder developed by using GAP/N-100/ BDNPA/F/DBTDL may meet the requirements of the properties that makes it useful for future propellant formulations.

Research on the Mechanical Properties and Curing Networks of Energetic GAP/TDI Binders

“…Initially the physical entanglement in the GAP/TDI binders was studied, and the phenomenological theory of rubber in large elastic deformation. This gives the stored energy function expressed in terms of the strain invariables [25]: (6) Because the stored energy function (W) in the phenomenological theory of rubber in large elastic deformation is equal to the elastic free energy of deformation (ΔF), on the basis of this equivalent relation W can be substituted by the second-order approximation of the elastic free energy of deformation (ΔF) in the general deformation range, thus: (7) where W is the stored energy function, I 1 , ln(I 1 /3) and ln(I 3 ) denote the principal deformation variables, respectively, α is the elongation ratio corresponding to τ, and C 100 , C 020 , and C 200 represent the contributions of chemical cross-linking, entanglement, and non-Gaussian chains to the elastic modulus, respectively. According to the relations between W and the deformation derived from the statistical theories of rubber elasticity [26], the expression of the stress-strain relationship during uniaxial tension can be expressed as: (8) (9) where τ denotes tensile stress.…”

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

“…In addition, GAP has many other desirable properties including good thermally stability, insensitivity, high burning rate (∼1 cm s −1 at 40 atmospheres) and relatively pressure exponent (∼0.5) [3]. Thus, it offers an unique energetic binder and plasticizer system for advanced propellants and plastic bonded explosives (PBX) for achieving higher performance, superior structural integrity and low vulnerability and has become the focus and heat point in the field of energy materials [1][2][3][4][5][6][7][8][9].…”

Synthesis and Kinetic Study of PCL-GAP-PCL Tri-block Copolymer

“…The second mass loss corresponds to the slow decomposition of the rest of the polymer after the initial N 3 elimination. The latter stage mass loss occurs without any considerable heat release as there is no exothermic peak observed after the decomposition of the energetic groups [12,13,24,25]. Consequently, the tri-block copolymer has more thermal stability than GAP.…”