IMPROVEMENT OF THE STABILITY TEST PROCEDURE FOR NITROCELLULOSE-BASED PROPELLANTS USING STABILIZER DEPLETION

LJILJANA JELISAVAC

Military Technical Institute, Belgrade, jelisavach@yahoo.com

Abstract:  This work was carried out comparison of the procedures of chemical stability assessment of different type’s of aged and no-aged nitrocellulose-based propellants according to actual standards: SORS 8069/91, STANAG 4117 and AOP-48, Ed.2.

It was shown that the basic concept of the SORS 8069/91 procedur , was essentially different from the procedures provided in the NATO trials, such as STANAG 4117 and AOP-48 Ed.2, which are based on isothermal single-temperature ageing of propellants and have the ability to predict and guarantee that propellant will remain chemically stable if stored at ambient temperatures (25  C) for minimum of 10 years.

In this article, temperature dependence (60 to 90  C) of depletion of diphenylamine and ethylcentralite stabilizers in different types of propellants was investigated, to compared the stability assessment according STANAG 4117 test (different sentencing criteria and different test ageing conditions with fixed ageing temperatures and periods for different propellant types) and the AOP-48, Ed.2 test (identical sentencing criteria and identical but no-fixed ageing conditions adopted from STANAG 4582 for all propellant types). It was found that the values of stabilizer consumption according AOP-48, Ed.2 were comparable at all freely chosen test temperature within the range

60  C and 80  C. The results of examination are explained by comparing of experimental values of energies activation for different types of propellants (calculated by kinetic modeling of the nth order) and the value of energy activation (Ea=120 KJ/mol) adopted from STANAG 4582 in the expression for calculating the period of the test at different temperatures, which leads to the same degree of decomposition as and 10-year storage at 25  C.  Experiments have confirmed that the results of assessment of chemical stability of single-base powder according to the procedure Ed.2 AOP-48 in relation to the highly reactive stabilizer diphenylamine, too conservative and in relation to the effective diphenylamine calculated by SORS 8069/91, are too optimistic. Realistic assessment of chemical stability of single-base powder was obtained by calculating the effective diphenylamine content in accordance with STANAG 4117 tests and AOP-48 Ed.2.