Investigating the Effect of Dual Curing Agent TDI: DDI on Mechanical Properties and Burning Rate of HTPB Based Solid Propellant

In this research, the effect of dual curing agent TDI:DDI with different ratios on properties such as mechanical strength, elongation percentage, elastic modulus, hardness, burning rate and pressure exponent (n) has been investigated. Dimeryl diisocyanate (DDI) is a diisocyanate with long carbon chain, high molecular weight, low toxicity and low reactivity. In order to investigate the effect of the TDI: DDI double curing agent on propellant properties, five propellant formulations with the same loading rate and R value were produced and the prepared samples were tested for mechanical properties and burning rate. The results of the tensile test on the seventh day of the propellant curing process showed that with the increase in the ratio of DDI to TDI in the propellant formulation, the amount of elongation increases, the tensile strength decreases and the modulus decreases with the passage of time. The results of the burning rate test showed that with the increase in the ratio of DDI to TDI in the propellant formulation, the burning rate decreases. Comparing the propellants with different ratios of dual TDI:DDI curing agents with the propellant that is the only TDI curing agent, shows that as the amount of DDI in the formula increases, the pressure exponent (n) will decrease.