EFFECT OF HMX CONTENT ON THERMAL SAFETY CHARACTERISTICS OF MODIFIED DOUBLE-BASE PROPELLANTS

Abstract

In order to explore the thermal safety characteristics of modified double-base propellants, differential scanning calorimetry (DSC) was used to study the thermal decomposition of modified double-base propellants with high melting explosive (HMX) content of 0%, 21%, and 40%, respectively. The thermal decomposition temperatures at the heating rates of 2, 5,10, and 20°C·min<sup>-1</sup> were obtained. The apparent activation energy, pre-exponential factor, reaction rate, Gibbs free energy, activation enthalpy, and activation entropy were calculated by thermal reaction kinetics analysis. The response characteristics of modified double-base propellants with different HMX contents were obtained through slow cook-off, 5 s explosion point, and methyl violet chemical stability tests to characterize the thermal safety of propellants. The insensitivity of modified double-base propellant containing HMX was further studied by flame sensitivity and mechanical sensitivity tests. The results showed that when HMX content was 21%, the apparent activation energy was the highest, the slow cook-off response was the lowest, the 5 s explosion point response temperature was the highest, the methyl violet test paper had the longest discoloration time, and the flame sensitivity and mechanical sensitivity were the lowest; With the increase of HMX content, the first decomposition peak temperature of DSC moves backward, and the apparent activation energy decreases. The slow cook-off response temperature of the double-base propellant moves to the high-temperature direction, and the response level increases accordingly. When the HMX content is 40% or more, the response level is explosive, which cannot pass the slow cook-off test. After HMX component is added into the sample, its 5 s explosion point temperature moves to high temperature, and the trend of rise is obvious. The discoloration time of methyl violet test paper is prolonged, and the thermal stability of modified double-base propellant is improved; The flame sensitivity and the mechanical sensitivity decreased, which was helpful to improve the low vulnerability of the formula.