Quality Assessment of the CL-20/HMX Cocrystal Utilising Digital Image Processing

The reduction of liquid and gas inclusions in the crystals is an effective strategy for the production of reduced sensitivity high explosives. Assessment of the achieved crystal quality is paramount for the improvement of the crystallisation techniques. Here we present the quality evaluation of the CL-20/HMX cocrystal obtained from semibatch reaction cocrystallisation (SBRC), batch reaction cocrystallization (BRC), and antisolvent crystallisation by comparison of the results of digital image processing of photomicrographs of crystals immersed in an optically equally dense liquid, 1H NMR, HPLC, GC, helium pycnometry, SEM, pXRD, and DSC. It was found that digital image processing is capable of differentiation between crystal qualities of batches that are indistinguishable by all the other listed methods. It presents itself as a very promising tool for crystal quality assessment and improvement. The analysis shows that SBRC can produce coarse crystals of the same quality on a pilot plant scale as antisolvent crystallisation on a laboratory scale.