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Facile Recrystallization Process for Tuning the Crystal Morphology and Thermal Safety of Industrial Grade PYX

In this study, the crystal appearance of industrial grade 2,6-diamino-3,5-dinitropyridine (PYX) was mostly needle-shaped or rod-shaped with an average aspect ratio of 3.47 and roundness of 0.47. According to national military standards, the explosion percentage of impact sensitivity s about 40% and...

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Autores principales: Zhang, Mi, Fu, Jianbo, Ren, Hui, Li, Shengfu, Sun, Xiaole, Jiao, Qingjie
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10302596/
https://www.ncbi.nlm.nih.gov/pubmed/37375289
http://dx.doi.org/10.3390/molecules28124735
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author Zhang, Mi
Fu, Jianbo
Ren, Hui
Li, Shengfu
Sun, Xiaole
Jiao, Qingjie
author_facet Zhang, Mi
Fu, Jianbo
Ren, Hui
Li, Shengfu
Sun, Xiaole
Jiao, Qingjie
author_sort Zhang, Mi
collection PubMed
description In this study, the crystal appearance of industrial grade 2,6-diamino-3,5-dinitropyridine (PYX) was mostly needle-shaped or rod-shaped with an average aspect ratio of 3.47 and roundness of 0.47. According to national military standards, the explosion percentage of impact sensitivity s about 40% and friction sensitivity is about 60%. To improve loading density and pressing safety, the solvent–antisolvent method was used to optimize the crystal morphology, i.e., to reduce the aspect ratio and increase the roundness value. Firstly, the solubility of PYX in DMSO, DMF, and NMP was measured by the static differential weight method, and the solubility model was established. The results showed that the Apelblat equation and Van’t Hoff equation could be used to clarify the temperature dependence of PYX solubility in a single solvent. Scanning electron microscopy (SEM) was used to characterize the morphology of the recrystallized samples. After recrystallization, the aspect ratio of the samples decreased from 3.47 to 1.19, and roundness increased from 0.47 to 0.86. The morphology was greatly improved, and the particle size decreased. The structures before and after recrystallization were characterized by infrared spectroscopy (IR). The results showed that no chemical structure changes occurred during recrystallization, and the chemical purity was improved by 0.7%. According to the GJB-772A-97 explosion probability method, the mechanical sensitivity of explosives was characterized. After recrystallization, the impact sensitivity of explosives was significantly reduced from 40% to 12%. A differential scanning calorimeter (DSC) was used to study the thermal decomposition. The thermal decomposition temperature peak of the sample after recrystallization was 5 °C higher than that of the raw PYX. The thermal decomposition kinetic parameters of the samples were calculated by AKTS software, and the thermal decomposition process under isothermal conditions was predicted. The results showed that the activation energy (E) of the samples after recrystallization was higher by 37.9~527.6 kJ/mol than raw PYX, so the thermal stability and safety of the recrystallized samples were improved.
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spelling pubmed-103025962023-06-29 Facile Recrystallization Process for Tuning the Crystal Morphology and Thermal Safety of Industrial Grade PYX Zhang, Mi Fu, Jianbo Ren, Hui Li, Shengfu Sun, Xiaole Jiao, Qingjie Molecules Article In this study, the crystal appearance of industrial grade 2,6-diamino-3,5-dinitropyridine (PYX) was mostly needle-shaped or rod-shaped with an average aspect ratio of 3.47 and roundness of 0.47. According to national military standards, the explosion percentage of impact sensitivity s about 40% and friction sensitivity is about 60%. To improve loading density and pressing safety, the solvent–antisolvent method was used to optimize the crystal morphology, i.e., to reduce the aspect ratio and increase the roundness value. Firstly, the solubility of PYX in DMSO, DMF, and NMP was measured by the static differential weight method, and the solubility model was established. The results showed that the Apelblat equation and Van’t Hoff equation could be used to clarify the temperature dependence of PYX solubility in a single solvent. Scanning electron microscopy (SEM) was used to characterize the morphology of the recrystallized samples. After recrystallization, the aspect ratio of the samples decreased from 3.47 to 1.19, and roundness increased from 0.47 to 0.86. The morphology was greatly improved, and the particle size decreased. The structures before and after recrystallization were characterized by infrared spectroscopy (IR). The results showed that no chemical structure changes occurred during recrystallization, and the chemical purity was improved by 0.7%. According to the GJB-772A-97 explosion probability method, the mechanical sensitivity of explosives was characterized. After recrystallization, the impact sensitivity of explosives was significantly reduced from 40% to 12%. A differential scanning calorimeter (DSC) was used to study the thermal decomposition. The thermal decomposition temperature peak of the sample after recrystallization was 5 °C higher than that of the raw PYX. The thermal decomposition kinetic parameters of the samples were calculated by AKTS software, and the thermal decomposition process under isothermal conditions was predicted. The results showed that the activation energy (E) of the samples after recrystallization was higher by 37.9~527.6 kJ/mol than raw PYX, so the thermal stability and safety of the recrystallized samples were improved. MDPI 2023-06-13 /pmc/articles/PMC10302596/ /pubmed/37375289 http://dx.doi.org/10.3390/molecules28124735 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Zhang, Mi
Fu, Jianbo
Ren, Hui
Li, Shengfu
Sun, Xiaole
Jiao, Qingjie
Facile Recrystallization Process for Tuning the Crystal Morphology and Thermal Safety of Industrial Grade PYX
title Facile Recrystallization Process for Tuning the Crystal Morphology and Thermal Safety of Industrial Grade PYX
title_full Facile Recrystallization Process for Tuning the Crystal Morphology and Thermal Safety of Industrial Grade PYX
title_fullStr Facile Recrystallization Process for Tuning the Crystal Morphology and Thermal Safety of Industrial Grade PYX
title_full_unstemmed Facile Recrystallization Process for Tuning the Crystal Morphology and Thermal Safety of Industrial Grade PYX
title_short Facile Recrystallization Process for Tuning the Crystal Morphology and Thermal Safety of Industrial Grade PYX
title_sort facile recrystallization process for tuning the crystal morphology and thermal safety of industrial grade pyx
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10302596/
https://www.ncbi.nlm.nih.gov/pubmed/37375289
http://dx.doi.org/10.3390/molecules28124735
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