Unraveling the atypical co-crystal transformation process and mechanism of CL-20 and HMX in solid propellant formulations

The integration of CL-20 into solid propellants offers substantial potential for enhancing energy output, yet introduces critical challenges related to structural instability during multi-component blending, aging, and long-term storage. This work employs in-situ and off-line XRD, OM, and complement...

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Main Authors: Pangangjing Zou, Shiliang Huang, Haobin Zhang, Shichun Li, Jie Li, Yu Liu, Liangbin Li, Jinjiang Xu
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:Journal of Materials Research and Technology
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Online Access:http://www.sciencedirect.com/science/article/pii/S2238785425012050
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author Pangangjing Zou
Shiliang Huang
Haobin Zhang
Shichun Li
Jie Li
Yu Liu
Liangbin Li
Jinjiang Xu
author_facet Pangangjing Zou
Shiliang Huang
Haobin Zhang
Shichun Li
Jie Li
Yu Liu
Liangbin Li
Jinjiang Xu
author_sort Pangangjing Zou
collection DOAJ
description The integration of CL-20 into solid propellants offers substantial potential for enhancing energy output, yet introduces critical challenges related to structural instability during multi-component blending, aging, and long-term storage. This work employs in-situ and off-line XRD, OM, and complementary analytical techniques to probe the atypical co-crystallization pathways governing the interaction between CL-20 and HMX in propellant formulations. Key findings demonstrate that CL-20 and HMX spontaneously form a thermodynamically stable 2:1 co-crystal (2CL-20/HMX) not only in nitrate ester plasticizers (e.g., DOS) but also within polymeric binders such as GAP and HTPE, contrary to the inert behavior observed in HTPB, AP, or Al-containing systems. Kinetic analysis further established that the co-crystal structure transformation process is rate-limited by nucleation barriers, consistent with a kinetically controlled transformation mechanism. Moreover, the interaction between CL-20 and HMX proceeds through a solvent-mediated interface dissolution-reorganization pathway, thermodynamically favored by energy minimization. These results provide a fundamental understanding of co-crystal structure transformation in composite solid propellants containing HMX and CL-20. The resolution of co-crystallization mechanisms advances the practical implementation of CL-20-based propellants by reconciling energy enhancement with structural reliability.
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institution Kabale University
issn 2238-7854
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spelling doaj-art-dee0735057ae4ed79eb69844cf9c57c82025-08-20T03:53:12ZengElsevierJournal of Materials Research and Technology2238-78542025-05-01367859786910.1016/j.jmrt.2025.05.050Unraveling the atypical co-crystal transformation process and mechanism of CL-20 and HMX in solid propellant formulationsPangangjing Zou0Shiliang Huang1Haobin Zhang2Shichun Li3Jie Li4Yu Liu5Liangbin Li6Jinjiang Xu7CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Anhui, 230026, China; Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900, ChinaInstitute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900, ChinaInstitute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900, ChinaInstitute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900, ChinaInstitute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900, ChinaInstitute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900, China; Corresponding author. Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900, China.CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Anhui, 230026, ChinaInstitute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900, China; Corresponding author. Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900, China.The integration of CL-20 into solid propellants offers substantial potential for enhancing energy output, yet introduces critical challenges related to structural instability during multi-component blending, aging, and long-term storage. This work employs in-situ and off-line XRD, OM, and complementary analytical techniques to probe the atypical co-crystallization pathways governing the interaction between CL-20 and HMX in propellant formulations. Key findings demonstrate that CL-20 and HMX spontaneously form a thermodynamically stable 2:1 co-crystal (2CL-20/HMX) not only in nitrate ester plasticizers (e.g., DOS) but also within polymeric binders such as GAP and HTPE, contrary to the inert behavior observed in HTPB, AP, or Al-containing systems. Kinetic analysis further established that the co-crystal structure transformation process is rate-limited by nucleation barriers, consistent with a kinetically controlled transformation mechanism. Moreover, the interaction between CL-20 and HMX proceeds through a solvent-mediated interface dissolution-reorganization pathway, thermodynamically favored by energy minimization. These results provide a fundamental understanding of co-crystal structure transformation in composite solid propellants containing HMX and CL-20. The resolution of co-crystallization mechanisms advances the practical implementation of CL-20-based propellants by reconciling energy enhancement with structural reliability.http://www.sciencedirect.com/science/article/pii/S2238785425012050PropellantsCL-20HMXCo-crystalBinderFormulation
spellingShingle Pangangjing Zou
Shiliang Huang
Haobin Zhang
Shichun Li
Jie Li
Yu Liu
Liangbin Li
Jinjiang Xu
Unraveling the atypical co-crystal transformation process and mechanism of CL-20 and HMX in solid propellant formulations
Journal of Materials Research and Technology
Propellants
CL-20
HMX
Co-crystal
Binder
Formulation
title Unraveling the atypical co-crystal transformation process and mechanism of CL-20 and HMX in solid propellant formulations
title_full Unraveling the atypical co-crystal transformation process and mechanism of CL-20 and HMX in solid propellant formulations
title_fullStr Unraveling the atypical co-crystal transformation process and mechanism of CL-20 and HMX in solid propellant formulations
title_full_unstemmed Unraveling the atypical co-crystal transformation process and mechanism of CL-20 and HMX in solid propellant formulations
title_short Unraveling the atypical co-crystal transformation process and mechanism of CL-20 and HMX in solid propellant formulations
title_sort unraveling the atypical co crystal transformation process and mechanism of cl 20 and hmx in solid propellant formulations
topic Propellants
CL-20
HMX
Co-crystal
Binder
Formulation
url http://www.sciencedirect.com/science/article/pii/S2238785425012050
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