Effect of addictives on polymorphic transition of ε-CL-20 in castable systems

Zhang, Pu; Xu, Jinjiang; Guo, Xueyong; Jiao, Qingze; Zhang, Jingyuan

doi:10.1007/s10973-014-3798-z

Cited by 25 publications

(15 citation statements)

References 21 publications

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“…Therefore, to satisfy the requirement of high energy density, energetic materials with high density and a stable structure have to be prepared. The polymorphic transformation kinetics of an explosive could be affected by many factors, such as temperature, solvent, pressure, and additives, and have been of serious concern to the energetic materials industry [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Thermally Induced Polymorphic Transformation of Hexanitrohexaazaisowurtzitane (HNIW) Investigated by in-situ X-ray Powder Diffraction

Liu¹,

Li²,

Ze-shan³

et al. 2016

Cent. Eur. J. Energ. Mater.

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Abstract:The ε→γ phase transition of HNIW induced by heat was investigated with in situ X-ray powder diffraction (PXRD). The effects of purity, particle size, insensitive additives and the time of isothermal heat treatment on the phase transition were evaluated. It was found that the phase transition is irreversible with changes in temperature, and the two phases can coexist in a certain temperature range. Moreover, the initial phase transition temperature increases with increasing purity and decreasing particle size of HNIW, and thus with the approximate crystal density. The addition of graphite and paraffin wax to HNIW as insensitive additives leads to a decrease in the initial phase transition temperature, but the addition of TATB does not affect the initial phase transition temperature. Thus, TATB is a suitable insensitive additive. Moreover, at the critical temperature, the isothermal time determined the efficiency of the ε-to γ-phase transition. This work lays the foundations for the choice of molding technologies, performance test methods, ammunition storage options, as well as the manufacture of HNIWbased explosive formulations.

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Section: Introductionmentioning

confidence: 99%

Thermally Induced Polymorphic Transformation of Hexanitrohexaazaisowurtzitane (HNIW) Investigated by in-situ X-ray Powder Diffraction

Liu¹,

Li²,

Ze-shan³

et al. 2016

Cent. Eur. J. Energ. Mater.

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“…The The apparent activation energy a Ea/kJ mol Thermal decomposition properties and compatibility 1937 described in the literature [2,3,6,[16][17][18]. It is connected with other conditions of performed experiments as well as with the fact that in the part of papers the minimum of decomposition peak was the analysed parameter.…”

Section: Resultsmentioning

confidence: 99%

Thermal decomposition properties and compatibility of CL-20 with binders HTPB, PBAN, GAP and polyNIMMO

Gołofit

Zyśk

2015

J Therm Anal Calorim

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The compatibility of filler 2, 4,6,8,10,4,6,8,10, with rocket propellant binders: hydroxyl-terminated polybutadiene (HTPB), butadiene-acrylonitrile-acrylic acid terpolymer (PBAN), glycidyl azide polymer (GAP) and poly(3-nitratomethyl-3-methyloxetane) (polyNIMMO), has been examined. The compatibility of the compounds has been tested in accordance with the STANAG 4147 standard and its modification consisting in the change of the heating rate. As it arises from STANAG 4147 standard criterion, CL-20 is not compatible with polyNIMMO, PBAN and GAP and possibly incompatible with HTPB. Changes of relative position of peaks between measurements performed in hermetical pans and pans with a pinhole and with different heating rate were observed. In case of polyNIMMO and HTPB, changes of measurement parameters lead to estimated compatibility change. The analysis of the thermal decomposition of CL-20 revealed that it is a two-phase process. The first phase is associated with decomposition in solid phase; the second phase is associated with decomposition of volatile intermediate products of CL-20 decomposition. Due to the complex process of decomposition of tested samples, the apparent activation energy was used for the assessment of the compatibility. The apparent activation energy of the initial phase of decomposition CL-20 and its mixtures with binders are compatible with one another within the limits of measurement error. Results of measurement of apparent activation energy do not indicate a destabilizing effect of binders on the initial phase of decomposition of CL-20.

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“…All the surfaces were imprinted numerous boundaries and cracks with different lengths (Figure 5c and 5 f). Previous reports illustrate that e!g transition of CL-20 undergoes two stages: rearrangement of the molecular structure and arrangement of lattice atoms [25]. Under heating, the molecular structures and locations are rearranged to form new lattice atoms (crystal nuclei).…”

Section: Crystal Morphology In Transformationmentioning

confidence: 97%

“…There is no doubt that the solid-solid phase transition mechanism of the CL-20 polymorphs is very complex. It is generally believed that a solid-solid phase transition will consist of two stages: rearrangement of the molecular structure and arrangement of lattice atoms [25], which involves both kinetics and thermodynamics. The solid-solid phase transition has to overcome a relatively high activation energy barrier as a result of nucleation and growth in the solid matrix, thereby such phase transitions require either high temperatures or high pressures.…”

Section: Solid-solid Phase Transition Mechanism Under the Multiplex Smentioning

confidence: 99%

Sensitivity and Phase Transition of Heated ϵ‐CL‐20 in Drop‐Weight Impact Test

Wen

et al. 2018

Propellants Explo Pyrotec

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In order to understand the effect of polymorphic transformation on the impact sensitivity of heated hexanitrohexaazaisowurtzitane (CL-20) and its composite, the polymorphic transition of CL-20 crystal under heat stimulation was investigated using powder X-ray diffraction (PXRD) and microscopic methods. The effects of particle size and PDA coating on polymorphic transition of CL-20 were explored. The experiments showed that the polymorphic transition at 160 8C was related to the particle size and surroundings of CL-20 crystals. As the temperature increases, changes in the molecule conformation of larger crystals were more facili-tated than in smaller ones, the e!g solid-solid phase transitions went along thoroughly in larger crystals. Poly (dopamine) (PDA) coating played a key role in the significant inhibition of phase transition owing to the restriction effect via its compact and rigid shell. The lower pressure caused by drop-weight impact can facilitate the e!g phase transition of heated CL-20. This investigation contributes to comprehend the polymorphic transformation mechanism of CL-20 and provides guidance for effective control on the CL-20 polymorphs in CL-20-based composites.

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Effect of addictives on polymorphic transition of ε-CL-20 in castable systems

Cited by 25 publications

References 21 publications

Thermally Induced Polymorphic Transformation of Hexanitrohexaazaisowurtzitane (HNIW) Investigated by in-situ X-ray Powder Diffraction

Thermally Induced Polymorphic Transformation of Hexanitrohexaazaisowurtzitane (HNIW) Investigated by in-situ X-ray Powder Diffraction

Thermal decomposition properties and compatibility of CL-20 with binders HTPB, PBAN, GAP and polyNIMMO

Sensitivity and Phase Transition of Heated ϵ‐CL‐20 in Drop‐Weight Impact Test

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