DECOMPOSITION OF DIPHENYLAMINE IN NITROCELLULOSE BASED PROPELLANTS .1. OPTIMIZATION OF A NUMERICAL-MODEL TO CONCENTRATION-TIME DATA FOR DIPHENYLAMINE AND ITS PRIMARY DEGRADATION PRODUCTS DETERMINED BY LIQUID-CHROMATOGRAPHY WITH DUAL-AMPEROMETRIC DETECTION

The consumption of diphenylamine (DPA) in two nitrocellulose (NC) base d propellants subjected to a heat storage test at 85 degrees has been studied. A previously developed method based on reversed-phase liquid chromatography with dual-amperometric detection was used to monitor th e concentrations of DPA, 2-nitro-DPA and 4-nitro-DPA during the test. A numerical model based on first order rate equations was fitted to th e obtained analytical data with the use of a specially-written curve f itting program. The model implemented in the program describes the ini tial nitrosation and nitration steps of DPA in aging NC propellants. T he use of matrices in the calculation of concentration-time (CT) curve s enables the introduction of a general algorithm which can be readily changed in order to simulate any system of first order reactions. The program can therefore be used in other applications such as mechanist ic studies in organic synthesis. The general simulation algorithm allo ws inclusion of unknown (not analysed) components in the reaction mech anism. In this application, it was possible to simulate the course of N-nitroso-DPA which is not detectable by the amperometric principle.