Effect of Temperature on Mechanical Properties of Solid Rocket Propellants

Mechanical properties of solid rocket propellants are dependent on temperature. Any change in temperature brings significant change in the tensile strength, percentage elongation, and elastic modulus of the propellant. Different classes of operational solid rocket propellants namely extruded double-base propellants, composite, extruded composite and nitrarte ester polyester propellants were evaluated at different temperatures in the operating range of the rockets and missiles preferably in the range of –50 oC to +55 oC. It was observed that for each class of propellant, as temperature reduces, propellant becomes hard. This is depicted by increase in elastic modulus and tensile strength of the material. However, trend of percentage elongation is not very uniform. Extruded double-base propellants show less percentage elongation (around 1 per cent) at reduced temperature (–50 oC) probably due to brittleness. So is the trend with case-bonded composite propellants. However, reverse trend is exhibited by cartridge-loaded composite propellants and nitrate ester polyester propellants. Such propellants show higher percentage elongation (6 per cent for CLCP and 35 per cent for NEPE) at reduced temperature (–50 oC). This makes such propellants tough and more area under stress-strain curve at reduced temperature is observed.Defence Science Journal, 2011, 61(6), pp.529-533, DOI:http://dx.doi.org/10.14429/dsj.61.77