Migration and leakage of some mobile components in rocket propellant produces an inhomogeneous composition region at which migration takes place, which can lead to premature detonation, changes in ballistic characteristics, and so on. It is, therefore, important to be able to predict the behavior of low-molecular-weight mobile additives and to control the leakage of them from the propellant. At this point, our chief interest was to study the magnitude of the migration and to understand the factors that influence the migration process. In this study, the migration of a ferrocene-based burning-rate catalyst [acetyl ferrocene (AcF)] a from hydroxyl-terminated polybutadiene (HTPB) based elastomer in the presence of a plasticizer (dioctyl adipate) was examined in accelerated aging conditions at 60 degrees C for various time intervals. We also tried to minimize the migration of AcF from the loaded to the unloaded part by using an extra barrier layer consisting of polyfunctional aziridine (AST D45+) in addition to the HTPB-toluene diisocyanate composition. The migration enhanced with aging of the AcF and the barrier effects of the layer with intensified crosslink density to this migration were studied extensively. The migration was monitored by both ultraviolet-visible and atomic absorption spectroscopy (AAS) methods. A comparison of the data obtained from both of these methods was also done. The two techniques were found to be in agreement, and the Fe determinations from both methods were highly correlated, suggesting that the data were reliable, although the AAS data were found to be symmetrically somewhat higher. (c) 2005 Wiley Periodicals, Inc.