STUDIES ON LOW VULNERABILITY GUN PROPELLANTS BASED ON CONVENTIONAL BINDERS AND ENERGETIC PLASTICIZERS

To overcome the limitations of conventional single base, double base and triple base propellants, advanced low vulnerability ammunition (LOVA) propellants are being developed based on nitramines (RDX/HMX), energetic and non-energetic binders, and energetic plasticizers. LOVA propellants constitute an important branch of insensitive munitions (IM). In the present study, LOVA propellants, based on cellulose acetate (CA) and hydroxy terminated poly butadiene (HTPB) and their mixture as binders, with RDX and nitrocellulose (NC) as fillers and low molecular weight glycidyl azide polymer (GAP) (Mw 400−600) as energetic plasticizer were evaluated. The results obtained indicate that by using 70% RDX, 15% NC, 9% binders (CA/HTPB), and 6% GAP as plasticizer, the figure of insensitivity was increased to the 34−40 level. CA produced a figure of insensitivity (F of I) of 40 with a height of 50% explosion of 34 cm. These propellants can produce force constant in the range of 1100− 1150 J/g with linear burn rate coefficient of 0.3 cm/s/MPa. All the propellants studied are friction insensitive up to 36 kg weight. Their compressive strength is around 200 kg/cm2 with a compression of 5−8%. By including GAP as a plasticizer, a force constant on the order of 1200 J/g was obtained and the linear burn rate coefficient was reduced to a 0.13 cm/s/MPa level with a pressure index of 0.97. An increase in concentration of RDX to 75% at the cost of NC content (10%) led to a force constant increase to 1200 J/g. F of I was around 36 without any change in friction insensitivity. Likewise, 80% RDX, 5% NC with CA and HTPB as binders with 6% GAP as energetic plasticizer produced a force constant of 1340 J/g with a linear burning rate coefficient of 0.11 cm/s/MPa. A height of 50% explosion was in the range of 27−28 cm with an F of I at 33. Friction insensitivity was up to 36 kg.