Effect of Material Parameters on Pot Life of Composite Solid Propellant Based on Hydroxyl-Terminated Polybutadiene: A Short Review

Studying the material parameters in relation to the pot life of composite solid propellant (energetic composite) based on hydroxyl-terminated polybutadiene (HTPB) is important in production of large and medium scale grains. The present article is a review on extending the pot life of energetic composites based on HTPB using bicurative curing system of toluene diisocyanate (TDI) and isophorone diisocyanate (IPDI). Moreover, the effect of dibutyltin dilaurate (DBTDL) and ferric tris(acetyl acetonate) (FeAA), as curing catalysts, on curing reaction and pot life is studied. The studies showed that pot life extension of energetic composite is possible by tuning the material parameters such as type of curing agent, curing catalyst, plasticizer type and microstructure of HTPB. This can be obtained through primary and binary curatives, tuning the content of curing catalyst and plasticizer and by high cis- or high trans-HTPBs. Highest viscosity in energetic composite slurries has been obtained for TDI system and lowest one has been found for IPDI system. Bicurative curing system has shown a moderate viscosity range. Constant rates of k1 and k2 in both HTPB-IPDI and HTPB-TDI systems are increased by catalyst content. By increasing the vinyl content in HTPB, viscosity is increased. Also, the extension and pot life have been promoted by cis and trans contents or lowered vinyl content in HTPB microstructure.