In order to study the effects of shape and size on the molecular tailoring process of single-base propellant,three gradi-ently denitrated single-base propellants(seven-holes,one-hole and non-hole single-base propellants)were prepared by using hy-drazine hydrate as denitration agent.Based on the Avrami model,the kinetics of the molecular tailoring process of different shapes of single-base propellants have been investigated.The results showed that the Avrami model could be used to describe the molecular tailoring process of the three single-base propellants.The Avrami index of seven-holes single-base propellant is n>1 in the range of 70-75℃,indicating that the molecular tailoring reaction process was controlled by the chemical reaction process.When the temperature was in the range of 75-80℃,n<1,it was controlled by a combination of internal diffusion and chemical reaction.The Avrami index n<1 for one-hole and non-hole single-base propellants,and the molecular tailoring process was controlled by a combination of internal diffusion and chemical reaction.According to the Fick's law,the diffusion coeffi-cient D of one-hole single-base propellants was 3.8×10-13-10.2×10-13 m2·s-1,and that of non-hole single-base propellants was 3.7×10-13-5.1×10-13 m2·s-1.Using the Arrhenius equation,the apparent activation energies of the seven-holes,one-hole and non-hole single-base propellants were calculated to be 45.84,52.88 and 38.26 kJ·mol-1,respectively.The study of the kinetics of molecular tailoring reaction for different shapes of single-base propellants can provide theoretical guidance for the controllable preparation of gradiently denitrated single-base propellants.
gradiently denitrated single-base propellantdifferent shapesmolecular tailoringreaction kineticsAvrami model
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