Aziridine type bonding agents for composite solid rocket propellant

Bonding agents, as a paramount component in the composite solid rocket propellant, effectively enhance the interactions between polybutadiene matrix and oxidizer. It mainly affects the processing ability, mechanical behavior, and aging. Bonding agent plays the role of an anonymous soldier to defeat stresses produced by loading conditions, changes in the environmental condition, and transportation of composite propellant. The role and the mechanism of aziridine type bonding agents are discussed focusing on a novel MST aziridine bonding agent (Tris-(2-methyl-1-aziridinyl) phosphine oxide (MAPO) plus Stearic acid plus Tartaric acid) (poly (isopropylamine N(2-methyl-1-aziridinyl) phosphine oxide octadecanoic)-co-(isopropylamine tartrate)). Preparation of composite solid propellant samples containing the same weight percentage of different bonding agents is conducted. Mechanical properties and aging behavior for the prepared samples were monitored to extract the impact of bonding agent type. Mechanical properties of the bonding agents were recorded at three different temperatures in order to simulate various environmental conditions. Results of stress-strain responses during uniaxial tensile tests showed that MST bonding agent has the strongest interaction with solid particles reaches a value of 50.4 % strain and 8.052 Kg/cm² stress at normal conditions. Compared to MT-4 (produced from the reaction of 2 moles MAPO plus 0.7-mole Adipic acid and 0.3-mole Tartaric acid) and MAPO, MST improved the aging behavior.