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Investigation Of Crystallisation Conditions to Produce CL‐20/HMX Cocrystal for Polymer‐bonded Explosives
Author(s) -
Herrmannsdörfer Dirk,
Gerber Peter,
Heintz Thomas,
Herrmann Michael J.,
Klapötke Thomas M.
Publication year - 2019
Publication title -
propellants, explosives, pyrotechnics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.56
H-Index - 65
eISSN - 1521-4087
pISSN - 0721-3115
DOI - 10.1002/prep.201800332
Subject(s) - cocrystal , crystallization , materials science , explosive material , solvent , polymer , acetonitrile , chemical engineering , process engineering , chemistry , chromatography , molecule , organic chemistry , composite material , hydrogen bond , engineering
Since its discovery in 2012, multiple techniques to generate the CL‐20/HMX cocrystal have been published. However, as yet no assessment or trial has been reported of crystallisation methods capable of producing the cocrystal in a size region and production scale suitable for its use in polymer bonded explosives (PBX). This paper provides insight into the selection of suitable crystallisation methods, solvent selection and process optimisation with a focus on the efficient production of high‐quality cocrystals for use in PBX. Through extensive solvent screening, acetonitrile was identified as the best solvent for solution‐based crystallisation, due to its capability to produce compact parallelepipedic crystals and its comparably wide cocrystal phase region. Crystallisation conducted at 60 °C was found to increase the conversion rate and the material efficiency compared to room temperature. By application of an advanced seeding procedure, high‐quality cocrystals in the size region of 180–250 μm were produced in laboratory‐scale antisolvent and cooling crystallisations. By pilot‐plant‐scale batch reaction cocrystallization, cocrystals with a volume‐weighted mean diameter of 33 μm were produced in quantities of 250 g per day.