Preparation and Characterization of Superfine CL‐20/EPDM Composite Microspheres

Abstract

AbstractTo improve the safety properties of 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20), the composite particle of CL‐20/EPDM energetic particles were prepared by an electrostatic spray method. The surface morphology of the composite was analyzed by scanning electron microscopy (SEM). The crystal structure of the composite was characterized by Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD). The thermal decomposition properties of the composite were also analyzed by differential scanning calorimetry (DSC). The safety properties were judged by mechanical sensitivity test. The SEM results revealed that the prepared composite was homogeneous with mean granularity of 1 μm and the morphology was distinct from raw CL‐20 and EPDM, which is nearly spherical. The FTIR and XRD analysis indicated that the new crystalline formation appeared in the composite. The crystal form of CL‐20 changed from ϵ to α. At 8 K⋅min−1, the peak temperature decreased 248.9 °C to 237.8 °C, and the apparent activation energy decreased from 255.1 kJ⋅mol−1 to 241.3 kJ⋅mol−1, which was only 13.8 kJ⋅mol−1 lower than CL‐20, indicating that the thermal stability of the composite microspheres was close to that of raw CL‐20. The decrease of critical temperature of thermal explosion from 228.4 °C to 223.4 °C indicates the improvement of thermal sensitivity. The impact sensitivity and friction sensitivity of CL‐20/EPDM composite were reduced compared to raw CL‐20. The value of H50 of the composite is 20 cm, which increased by 6.4 cm compared with raw CL‐20. And the explosion probability of the composite is reduced to 80%, compared with 100% of the raw CL‐20, indicating the better safety properties.