Studies on the Effect of Nitrate Esters on the Properties of Advanced Energetic Propellants

Propulsion designers all over the world are exploring the possibility of achieving higher performance by enhancing the energy of solid propellants. This can be achieved by replacing non-energetic ingredients with energetic ones or by replacing low density ingredients, particularly binders, with higher density ones, without affecting the processibility and ageing characteristics. The same has been attempted by using nitroglycerine (NG) and butanetriol trinitrate (BTTN) as plasticizers in propellant compositions. In the present study, NG and BTTN have been used in different plasticizer to polymer ratios (Pl/Po) and various parameters of each composition have been theoretically predicted. Three propellant compositions plasticized with NG, BTTN and a 1:1 combination of NG and BTTN, have been processed and analyzed for targeted properties. From the theoretical data, it was observed that there is a negligible increase in density impulse beyond a Pl/Po ratio of 2, apart from the higher density and calorimetric values of the NG-plasticized propellant; these plasticizers have a significant effect on the ballistic and mechanical properties. Another observation was that the elongation of BTTN and NG/BTTN (1:1) plasticized propellants is significantly higher at a low crosshead rate than NG-plasticized propellant, implying that the two former propellants have higher strain capabilities at low temperatures and can be used for missiles having long term low temperature storage requirements. Thermal decomposition studies have been carried out by DSC, and for each composition 5 distinct peaks were observed.