Preparation Method of Polyglycidyl Nitrate (PGN) Energetic Polymer and Properties of Its Based Composite Solid Propellant

Various energetic binder materials are being investigated in an attempt to increase the energy level of explosives and propellant formulations. The nitrate ester prepolymer poly(glycidyl nitrate) (PGN) is an energetic prepolymer that is used as a binder in propellant and explosives formulations. PGN is the most energetic polymer among the energetic polymers. Three steps in PGN synthesis from glycerol are nitration, cyclization and polymerization. Glycerol is a by-product of biodiesel industry that needs purification before any chemical reaction. In this paper various preparation methods of PGN have been investigated and optimum methods are introduced. The compatibility of PGN with energetic materials in propellants or explosives is the most important property of PGN in practical applications. PGN is compatible with energetic plasticizers. Therefore, the maximum decrease in glass transition temperature (Tg) has been seen by the addition of BuNENA energetic plasticizer and maximum increase in flow behavior (lowering of viscosity) has been observed by the addition of DEGDN energetic plasticizer. The cured PGN undergoes self-decomposition or de-curing (caused by chain scission) at room temperature due to the proximity of the terminal hydroxyl groups of the polymer to the nitrate ester groups. Research works showed that the most effective way of removing the de-curing of PGN after curing is to modify the end groups of PGN with potassium carbonate. In this paper, different formulations of PGN-based propellants are studied and their combustion, ballistic and mechanical properties have been compared with typical propellants. Finally, a PGN-based propellant formulation, mixing and preparation method is introduced.