Comparative study of two methods used for the characterization of the degradation of the polymer binder in gap-based propellants

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Abstract
Reliability assessment for composite propellants calls for effective shelf-life predicting tools, implying the existence of appropriate accelerated-aging procedures and of quantitative methods for the characterization of the degradation process. Ideally, one would like to investigate stabilizer depletion as well as the mechanical integrity of the polymer network used as the binder. There are many available methods that can be combined to achieve this goal. In the present work, a comparative study of two of these methods has been performed. The first procedure makes use of FTIR spectroscopy to characterize the binder's degradation and of HPLC to follow stabilizer depletion. The other method, based on 1H NMR spectroscopy allows the measurement of the polymer network degradation, the depletion of the stabilizer and the loss of plasticizer in a single step. Finally, the pros and cons of both procedures have been evaluated from the analysis of experimental data related to accelerated aging at 40, 60 and 80°C of GAP-based composite propellant formulations.