Investigation of the Effect of Curing Agent Ratio on Tensile Strength and Bonding Strength of Liner Based on HTPB

Nowadays solid rocket motors (SRMs) are widely used because of simple structure and reliability. One of the requirements in SRMs is high tensile and bonding strength of liner for integrity of grain structure and neutralizes stresses applying to motor. In this research, effect of curing agent ratio (NCO/OH) in the range of (R=0.9-1.4) on tensile strength of liner and bonding strength of liner-propellant was investigated. Results showed, increase in isocyanate which grows crosslinking, increase the tensile strength and decrease elongation at break. In addition, with increase of NCO content, the ability urethane linkage formation in liner - propellant interface grows, therefore bonding strength increases. Finally, with considering of design requirements, processability, costs and safety the optimized NCO/OH ratio was selected.