Kinetic modelling of the concentrations of the stabilizer DPA and some of its consecutive products as function of time and temperature

By kinetic modelling of the possible reactions of diphenylamine (DPA) and its nitrated consecutive products used to stabilize cellulose nitrate (CN), one can get reactivities for the nitrated DPA compounds for the situation inside a real CN formulation and therewith determine their stabilizing contribution. Concentration data of DPA and seven of its consecutive products have been determined by HPLC from isothermal ageing of a CN formulation at temperatures between 65 and 90 degreesC for up to 344 days. A comparison between the modelling presented and modellings published in the literature using the steady-state approximation is made. The steady-state approximation oversimplifies the stabilizer reaction behaviour in a CN formulation. From the applied modelling the question about N-NO-DPA as a key intermediate can be answered.