Experimental study on the liquid migration during the co-curing of IPDI-HTPB propellant and liner

To investigate the migration behavior of small-molecule liquid components during the co-curing of IPDI-HTPB propellant and liner, gas chromatography and attenuated total reflection infrared spectroscopy were utilized. These analytical techniques quantified the mass percentage variations of the plasticizer DOS and curing agent IPDI at multiple locations across the propellant-liner interface over an 8-day curing period. The findings indicate that the primary driving force for small-molecule migration within the propellant-liner bonding system arises from differences in mass fractions of the small molecules within the continuous phases of the propellant and liner. At the initial stage, concentration gradients for both DOS and IPDI were oriented from the propellant toward the liner. The complete co-curing process required approximately 8 days, during which component migration resulted in the formation of transition zones within both materials. These zones exhibited DOS concentrations that deviated from those in the respective bulk regions. Specifically, the DOS content in the propellant transition zone was lower than in the bulk propellant. Furthermore, compared to molecular migration, the curing reactions occurring within the liner body and at the interfacial region between the liner and propellant exerted a more significant influence on the distribution of NCO near the interface.