Ageing behaviour of HTPB based rocket propellant formulations

The knowledge of the ageing behaviour of energetic materials is fundamental in order to estimate the in-service time period of the system. Solid rocket motor material has to withstand long periods of in-service across wide ranges of temperatures. The estimation of the in-service time period of a solid rocket motor has to consider the ageing of several items (electric circuits, igniter, fuse …) but the attention is focused here on the ageing behaviour of the solid rocket propellant. Several HTPB/AP/Al propellant formulations have been manufactured freshly and were investigated in unaged and aged conditions. The ballistic performances of the propellant formulations were calculated using the ICT-Thermodynamic code. EDX analyses of the unaged materials and SEM analyses of the unaged and aged materials were made using the scanning electron microscope. Uniaxial tensile tests have been conducted at room temperature using three different strain
rates. DMA analysis in torsion mode and DSC measurements were carried out with the purpose to investi-gate changes in the glass transition temperature of the materials and the presence or absence of secondary relaxation phenomena.