Functionalized Carbon Nanotube Guided Growth of HMX Crystals with Improved Thermal Stability and Reduced Sensitivity

This study focuses on the crystal growth of hybrid HMX crystals guided by functionalized carbon nanotubes (F-CNTs) acting as nucleation centers, leading to improved thermal stability and sensitivity. It has been shown that HMX would grow in a form of distinctive needle-like hybrid crystals due to strong interaction with one-dimensional F-CNTs. Notably, under the effect of 0.5 wt % of carbonyl functionalized CNTs, HMX crystals are formed with a length-diameter ratio of 23. Meantime, its decomposition E_a is 248.1 kJ·mol^-1, 43% higher than that of HMX. Due to high conductivity and strength of CNTs, the resulting hybrid HMX crystals have 131% higher impact initiation energy compared to the pure ones. Hybrid crystal doped with 0.5 wt % fluorinated carbon nanotube demonstrates the highest heat release values at 1267 J·g^-1, with an approximate 32% increase compared to pure HMX, and follows a random chain scission model (L2).