B. Min, Sung June Kim, Hong Min Shim, Heung Bae Jeon
We have innovatively formulated solid propellants by employing a catalyst‐free azide‐alkyne cycloaddition approach, steering away from the conventional urethane curing system reliant on moisture‐sensitive isocyanate compounds. These conventional systems exhibits poor compatibility with the eco‐friendly ionic oxidizers. Azide polymers, including polycaprolactone ether (PCE), polycaprolactone (PCL), and polyethylene glycol (PEG) were incorporated, with their terminal hydroxyl groups strategically modified with azides. Additionally, glycidyl azide polymer (GAP), characterized by an abundance of azides in its side chains, was introduced. For polybutadiene‐based solid propellants, a departure from the norm was pursued. We employed polybutadiene (PB) terminated with electron‐deficient alkynes(propiolate), synthesized through a urethane reaction involving an unsymmetric divalent chain‐linker containing both isocyanate and propiolate functionalities with hydroxyl‐terminated polybutadiene (HTPB). This approach diverged from the common practice of modifying other polymers with azides at the terminal. To ensure the attainment of optical mechanical properties in azide‐terminated polymer‐based solid propellants, trivalent propiolate curatives were judiciously combined with divalent propiolate curatives in an appropriate blend ratio. A meticulously synthesized series of polymeric bonding agents, designed to establish chemical links between solid oxidizers and polymer binder, revealed the idenfication of exceptional bonding agents. These agents played a pivotal role in delivering outstanding mechanical properties in solid propellants based on ammonium perchlorate (AP) and nitramine‐typed oxidizers. GAP‐based solid propellants were meticulously prepared, incorporating both urethane moieties at the terminal and triazole moieties at the side chains. Trivalent azide‐terminal curatives were introduced for crosslinking PB terminated with propiolates. Generally, triazole‐curing system resulted in solid propellants exhibiting notably higher burning rates compared to those crosslinked through urethanes. In summary, this research presents a sophisticated approach to the formulation of solid propellants, emphasizing a departure from conventional systems, strategic polymer modifications, and the meticulous synthesis of bonding agents to achieve superior mechanical properties and burning rates.
我们采用无催化剂叠氮-炔烃环加成法创新配制了固体推进剂，摒弃了依赖对湿气敏感的异氰酸酯化合物的传统聚氨酯固化体系。这些传统体系与环保型离子氧化剂的兼容性很差。我们加入了叠氮聚合物，包括聚己内酯醚（PCE）、聚己内酯（PCL）和聚乙二醇（PEG），并用叠氮化物对它们的末端羟基进行了战略改性。此外，还引入了缩水甘油叠氮聚合物（GAP），其特点是侧链中含有大量叠氮化物。对于以聚丁二烯为基础的固体推进剂，我们采用了不同于常规的方法。我们采用了以缺电子炔（丙炔酸盐）为末端的聚丁二烯（PB），这种聚丁二烯是通过不对称二价链连接剂与羟基末端聚丁二烯（HTPB）的氨基甲酸酯反应合成的，该连接剂同时含有异氰酸酯和丙炔酸盐官能团。这种方法有别于在末端使用叠氮化物改性其他聚合物的常见做法。为确保叠氮封端的聚合物基固体推进剂具有光学机械性能，三价丙炔酸酯固化剂与二价丙炔酸酯固化剂以适当的混合比例进行了明智的组合。为了在固体氧化剂和聚合物粘合剂之间建立化学联系，我们精心合成了一系列聚合物粘合剂，发现了一些特殊的粘合剂。这些粘接剂在基于高氯酸铵（AP）和硝胺类氧化剂的固体推进剂中提供出色的机械性能方面发挥了关键作用。我们精心制备了基于 GAP 的固体推进剂，在末端加入了聚氨酯分子，在侧链上加入了三唑分子。引入了三价叠氮末端固化剂，用于交联以丙二醇酯为末端的 PB。一般来说，三唑固化体系产生的固体推进剂与通过聚氨酯交联的推进剂相比，燃烧速率明显更高。总之，这项研究提出了一种复杂的固体推进剂配方方法，强调偏离传统体系，对聚合物进行战略性改性，并精心合成粘合剂，以获得优异的机械性能和燃烧率。
{"title":"Eco‐friendly chemically crosslinked solid composite propellants via catalyst‐free azide‐alkyne cycloaddition","authors":"B. Min, Sung June Kim, Hong Min Shim, Heung Bae Jeon","doi":"10.1002/prep.202400016","DOIUrl":"https://doi.org/10.1002/prep.202400016","url":null,"abstract":"We have innovatively formulated solid propellants by employing a catalyst‐free azide‐alkyne cycloaddition approach, steering away from the conventional urethane curing system reliant on moisture‐sensitive isocyanate compounds. These conventional systems exhibits poor compatibility with the eco‐friendly ionic oxidizers. Azide polymers, including polycaprolactone ether (PCE), polycaprolactone (PCL), and polyethylene glycol (PEG) were incorporated, with their terminal hydroxyl groups strategically modified with azides. Additionally, glycidyl azide polymer (GAP), characterized by an abundance of azides in its side chains, was introduced. For polybutadiene‐based solid propellants, a departure from the norm was pursued. We employed polybutadiene (PB) terminated with electron‐deficient alkynes(propiolate), synthesized through a urethane reaction involving an unsymmetric divalent chain‐linker containing both isocyanate and propiolate functionalities with hydroxyl‐terminated polybutadiene (HTPB). This approach diverged from the common practice of modifying other polymers with azides at the terminal. To ensure the attainment of optical mechanical properties in azide‐terminated polymer‐based solid propellants, trivalent propiolate curatives were judiciously combined with divalent propiolate curatives in an appropriate blend ratio. A meticulously synthesized series of polymeric bonding agents, designed to establish chemical links between solid oxidizers and polymer binder, revealed the idenfication of exceptional bonding agents. These agents played a pivotal role in delivering outstanding mechanical properties in solid propellants based on ammonium perchlorate (AP) and nitramine‐typed oxidizers. GAP‐based solid propellants were meticulously prepared, incorporating both urethane moieties at the terminal and triazole moieties at the side chains. Trivalent azide‐terminal curatives were introduced for crosslinking PB terminated with propiolates. Generally, triazole‐curing system resulted in solid propellants exhibiting notably higher burning rates compared to those crosslinked through urethanes. In summary, this research presents a sophisticated approach to the formulation of solid propellants, emphasizing a departure from conventional systems, strategic polymer modifications, and the meticulous synthesis of bonding agents to achieve superior mechanical properties and burning rates.","PeriodicalId":508060,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"1 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141267272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Meriem Amina Fertassi, S. Belkhiri, Sabri Touidjine, M. K. Boulkadid, Akbi Hamdane, K. Khimeche
This study aims to compare the catalytic effects of three nano‐metal oxides (nMOs); Litharge (α‐PbO), Tenorite (CuO), and Hematite (α‐Fe2O3) on the thermal decomposition of an ammonium perchlorate based cross‐linked composite modified double base propellant (AP‐XLCMDBP). The three nMOs are synthesized via a chemical precipitation method and then characterized using XRD, FTIR, and SEM. Their effect on the thermal decomposition of AP‐XLCMDBP is studied using thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The results indicate that Litharge has no significant effect on the thermal decomposition of AP‐XLCMDBP. However, both Tenorite and Hematite nanocatalysts accelerate the thermolysis process and enhance the total heat released from AP‐XLCMDBP. Moreover, compared to Tenorite, Hematite nanoparticles are found to be a more efficient catalyst, where their presence in AP‐XLCMDBP leads to a significant decrease in activation energies of the first and the second decomposition stages by 13.67 kJ/mol and 17.57 kJ/mol, respectively. An increase of the total decomposition heat by 153.73 J/g is also attained in the presence of Hematite, displaying its high catalytic action on the thermal decomposition of AP‐XLCMDBP.
{"title":"Examining the impact of nano‐sized Litharge, Tenorite, and Hematite on the thermal decomposition of ammonium perchlorate‐based cross‐linked composite modified double base propellant","authors":"Meriem Amina Fertassi, S. Belkhiri, Sabri Touidjine, M. K. Boulkadid, Akbi Hamdane, K. Khimeche","doi":"10.1002/prep.202300308","DOIUrl":"https://doi.org/10.1002/prep.202300308","url":null,"abstract":"This study aims to compare the catalytic effects of three nano‐metal oxides (nMOs); Litharge (α‐PbO), Tenorite (CuO), and Hematite (α‐Fe2O3) on the thermal decomposition of an ammonium perchlorate based cross‐linked composite modified double base propellant (AP‐XLCMDBP). The three nMOs are synthesized via a chemical precipitation method and then characterized using XRD, FTIR, and SEM. Their effect on the thermal decomposition of AP‐XLCMDBP is studied using thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The results indicate that Litharge has no significant effect on the thermal decomposition of AP‐XLCMDBP. However, both Tenorite and Hematite nanocatalysts accelerate the thermolysis process and enhance the total heat released from AP‐XLCMDBP. Moreover, compared to Tenorite, Hematite nanoparticles are found to be a more efficient catalyst, where their presence in AP‐XLCMDBP leads to a significant decrease in activation energies of the first and the second decomposition stages by 13.67 kJ/mol and 17.57 kJ/mol, respectively. An increase of the total decomposition heat by 153.73 J/g is also attained in the presence of Hematite, displaying its high catalytic action on the thermal decomposition of AP‐XLCMDBP.","PeriodicalId":508060,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"27 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141266523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sean Whalen, Emily Sellards, Bradley Gobin, Gregory Young
The influence of additives on the decomposition and combustion characteristics of electrically controlled solid propellants was investigated through small scale experiments. Carbon black and aluminum additives were explored in a polyethylene oxide, lithium perchlorate propellant. Additives were used to improve the voltage response and their impact on ignition and combustion was characterized. The data showed that conductive additives can mitigate the loss of solid phase conductivity through solvent evaporation and that ignition delay decreases with higher voltage and solid phase conductivity. Steady‐state combustion experiments showed that electrical decomposition of the propellants proceeded more rapidly than a purely thermal stimulus illustrating the importance of electrochemistry in ECSP combustion. The combined effects of pressure and voltage on combustion rates were summarized in Saint‐Robert's burn relations. The regression rates increased with both applied voltage and pressure. The pressure deflagration limit of propellants with the carbon black additive was significantly reduced compared to a neat PEO/LP propellant, whereas the addition of 10 % aluminum did not affect the pressure deflagration limit.
{"title":"Exploring the influence of additives on the ignition, combustion and quenching of electrically controlled solid propellants","authors":"Sean Whalen, Emily Sellards, Bradley Gobin, Gregory Young","doi":"10.1002/prep.202300299","DOIUrl":"https://doi.org/10.1002/prep.202300299","url":null,"abstract":"The influence of additives on the decomposition and combustion characteristics of electrically controlled solid propellants was investigated through small scale experiments. Carbon black and aluminum additives were explored in a polyethylene oxide, lithium perchlorate propellant. Additives were used to improve the voltage response and their impact on ignition and combustion was characterized. The data showed that conductive additives can mitigate the loss of solid phase conductivity through solvent evaporation and that ignition delay decreases with higher voltage and solid phase conductivity. Steady‐state combustion experiments showed that electrical decomposition of the propellants proceeded more rapidly than a purely thermal stimulus illustrating the importance of electrochemistry in ECSP combustion. The combined effects of pressure and voltage on combustion rates were summarized in Saint‐Robert's burn relations. The regression rates increased with both applied voltage and pressure. The pressure deflagration limit of propellants with the carbon black additive was significantly reduced compared to a neat PEO/LP propellant, whereas the addition of 10 % aluminum did not affect the pressure deflagration limit.","PeriodicalId":508060,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"60 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140975027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Benjamin P Wilkins, Hope T. Sartain, Sheana Schneidereit, Benjamin Ostrow, Joaquin Aparicio, Andrew Horan, Kevin Pedersen, Jeffrey Barber, Johnny Perez, Marc Richard, Elizabeth Pollock, John J Brady
1,3,5‐trinitroso‐1,3,5‐triazine (R‐Salt) is an insensitive energetic that has previously been used as an improvised explosive. The work presented here is a comprehensive study on the thermal properties and chemical characterization of R‐Salt. Thermal analysis was performed via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) which found both crude and recrystallized R‐Salt have similar thermal properties but the selected lid impacted both the thermal profile and onset temperature. Chemical characterization performed via Raman, Fourier‐transform Infrared (FT‐IR), nuclear magnetic resonance (NMR) spectroscopy and high‐resolution mass spectrometry indicate that recrystallization does not quantitatively improve the purity of crude R‐Salt., The reported NMR 2D‐HSQC, FT‐IR, and Raman spectra are the first to be reported within the published literature, as to the authors’ knowledge.
1,3,5-三亚硝基-1,3,5-三嗪（R-盐）是一种不敏感的高能物质，曾被用作简易爆炸物。本文介绍的工作是对 R 盐的热特性和化学特征进行全面研究。通过差示扫描量热法（DSC）和热重分析法（TGA）进行的热分析发现，粗制和重结晶的 R 盐具有相似的热特性，但所选的盖子会影响热曲线和起始温度。通过拉曼、傅立叶变换红外（FT-IR）、核磁共振（NMR）光谱和高分辨率质谱进行的化学特性分析表明，重结晶并不能定量地提高粗制 R 盐的纯度。
{"title":"A comprehensive study on the thermal properties and chemical characterization of 1,3,5‐trinitroso‐1,3,5‐triazine (R‐Salt)","authors":"Benjamin P Wilkins, Hope T. Sartain, Sheana Schneidereit, Benjamin Ostrow, Joaquin Aparicio, Andrew Horan, Kevin Pedersen, Jeffrey Barber, Johnny Perez, Marc Richard, Elizabeth Pollock, John J Brady","doi":"10.1002/prep.202400028","DOIUrl":"https://doi.org/10.1002/prep.202400028","url":null,"abstract":"1,3,5‐trinitroso‐1,3,5‐triazine (R‐Salt) is an insensitive energetic that has previously been used as an improvised explosive. The work presented here is a comprehensive study on the thermal properties and chemical characterization of R‐Salt. Thermal analysis was performed via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) which found both crude and recrystallized R‐Salt have similar thermal properties but the selected lid impacted both the thermal profile and onset temperature. Chemical characterization performed via Raman, Fourier‐transform Infrared (FT‐IR), nuclear magnetic resonance (NMR) spectroscopy and high‐resolution mass spectrometry indicate that recrystallization does not quantitatively improve the purity of crude R‐Salt., The reported NMR 2D‐HSQC, FT‐IR, and Raman spectra are the first to be reported within the published literature, as to the authors’ knowledge.","PeriodicalId":508060,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"7 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140973435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yi Zeng, Wei Huang, Jia‐Xing Chen, Jin-sheng Xu, Xiong Chen, Rui Wu, Qi‐Xuan Song
This study employed macroscopic uniaxial compression tests at low and medium strain rates, coupled with microscopic electron microscopy, to extensively analyse the impact of thermomechanical coupled aging on the accelerated aging of Hydroxyl‐terminated Polybutadiene (HTPB) propellants, contrasting it with the effects of isolated factors such as heat and dynamic reciprocating force. Results indicate that at various environmental temperatures (323 K, 343 K, and 363 K), thermomechanical coupled aging more significantly affects HTPB propellants than isolated factors. This effect is macroscopically evident in increased ease of deformation, permanent deformation during aging, continual increase in dissipated energy, and a decrease in average stress and ultimate strain post‐aging. Microscopically, the effect predominantly arises from the interplay between matrix thermal degradation and particle fragmentation, which rapidly accumulate and substantially impact the material's macroscopic mechanical properties. Furthermore, as the aging temperature rises, the alterations in both macroscopic mechanical properties and microscopic morphology of HTPB propellants become more pronounced. However, overly high temperatures may swiftly result in substantial material performance deterioration. Consequently, while elevating temperature effectively accelerates thermomechanical aging, the potential adverse effects on material performance must be judiciously considered. This underscores the necessity of balancing temperature regulation with aging efficiency enhancement in HTPB propellants to ensure effective control and quantitative assessment of the aging process, while minimizing material degradation.
{"title":"Analysis of thermomechanical coupled accelerated aging of HTPB propellants","authors":"Yi Zeng, Wei Huang, Jia‐Xing Chen, Jin-sheng Xu, Xiong Chen, Rui Wu, Qi‐Xuan Song","doi":"10.1002/prep.202300311","DOIUrl":"https://doi.org/10.1002/prep.202300311","url":null,"abstract":"This study employed macroscopic uniaxial compression tests at low and medium strain rates, coupled with microscopic electron microscopy, to extensively analyse the impact of thermomechanical coupled aging on the accelerated aging of Hydroxyl‐terminated Polybutadiene (HTPB) propellants, contrasting it with the effects of isolated factors such as heat and dynamic reciprocating force. Results indicate that at various environmental temperatures (323 K, 343 K, and 363 K), thermomechanical coupled aging more significantly affects HTPB propellants than isolated factors. This effect is macroscopically evident in increased ease of deformation, permanent deformation during aging, continual increase in dissipated energy, and a decrease in average stress and ultimate strain post‐aging. Microscopically, the effect predominantly arises from the interplay between matrix thermal degradation and particle fragmentation, which rapidly accumulate and substantially impact the material's macroscopic mechanical properties. Furthermore, as the aging temperature rises, the alterations in both macroscopic mechanical properties and microscopic morphology of HTPB propellants become more pronounced. However, overly high temperatures may swiftly result in substantial material performance deterioration. Consequently, while elevating temperature effectively accelerates thermomechanical aging, the potential adverse effects on material performance must be judiciously considered. This underscores the necessity of balancing temperature regulation with aging efficiency enhancement in HTPB propellants to ensure effective control and quantitative assessment of the aging process, while minimizing material degradation.","PeriodicalId":508060,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"62 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140975389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Solid propellant, as the energy source for solid rocket engines, it is of great significance to achieve accurate quantitative detection of aging damage of solid propellant. In this paper, a novel approach based on frequency impedance spectroscopy impedance combined with CARS‐SVM algorithm was proposed. First, the temperature, humidity, and pressure of environmental information around the solid rocket motor were sampled, and then the impedance at corresponding frequencies of the propellant was obtained by AD5933 chip. Second, the processed experimental data were subjected to abnormal sample detection before further variables selection using uninformative variables elimination (UVE) competitive adaptive reweighted sampling (CARS), respectively. Finally, support vector machine (SVM), UVE‐SVM and CARS‐SVM quantitative calibration methods were established. The results showed that the determination coefficient (R2), root mean square error (RMSE), and mean absolute percentage error (MAPE) of CARS‐SVM model were 0.9919, 0.7540, and 0.0480, respectively. Therefore, the results prove that impedance of solid propellant combined with CARS‐SVM model can effectively achieve high precision quantitative detection of aging damage of solid propellant, which lays a new method for the application of solid propellants aging damage in the online quantitative detection.
{"title":"Quantitative detection of aging damage of solid propellant based on frequency impedance spectroscopy combined with CARS‐SVM algorithm","authors":"Leiguang Duan, Xueren Wang, Binbin Zhang, Hongfu Qiang","doi":"10.1002/prep.202300227","DOIUrl":"https://doi.org/10.1002/prep.202300227","url":null,"abstract":"Solid propellant, as the energy source for solid rocket engines, it is of great significance to achieve accurate quantitative detection of aging damage of solid propellant. In this paper, a novel approach based on frequency impedance spectroscopy impedance combined with CARS‐SVM algorithm was proposed. First, the temperature, humidity, and pressure of environmental information around the solid rocket motor were sampled, and then the impedance at corresponding frequencies of the propellant was obtained by AD5933 chip. Second, the processed experimental data were subjected to abnormal sample detection before further variables selection using uninformative variables elimination (UVE) competitive adaptive reweighted sampling (CARS), respectively. Finally, support vector machine (SVM), UVE‐SVM and CARS‐SVM quantitative calibration methods were established. The results showed that the determination coefficient (R2), root mean square error (RMSE), and mean absolute percentage error (MAPE) of CARS‐SVM model were 0.9919, 0.7540, and 0.0480, respectively. Therefore, the results prove that impedance of solid propellant combined with CARS‐SVM model can effectively achieve high precision quantitative detection of aging damage of solid propellant, which lays a new method for the application of solid propellants aging damage in the online quantitative detection.","PeriodicalId":508060,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"15 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140976695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joseph R. Lawrence, Gabriel A. Montoya, Austin D. Koeblitz, Steven F. Son
Inhomogeneities within explosives affect the sensitivity and detonation waveshape of energetic materials. The influence of voids on explosive initiation has been well documented; however, the effects that voids between 0.1 mm and 10 mm have on a propagating detonation wave remains largely unexplored. The effect of single cylindrical voids on detonation waveshape and re‐initiation was examined here using manufactured voids in a rubberized 1,3,5‐trinitro‐1,3,5‐triazinane (RDX) explosive. Two streak imaging techniques were fielded to investigate void influence. For the first, back‐surface streak imaging, the location of the void on the samples was changed and the resulting change in detonation waveshape at the downstream breakout was captured using a streak camera in cut‐back experiments. The results from this experiment showed the effects of an initial jet form for short cut‐back distances and as shock propagation progressed, the jet formation was absorbed by the unaffected portions of the wave front. The second method, top‐surface streak imaging, was used to investigate the re‐initiation/downstream propagation of the detonation front and the detonation velocity of the rubberized explosive. These experiments were compared to similar experimental results from machined voids in PBX 9501, an 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane (HMX)‐based explosive, to investigate the interaction of a detonation wave with a 0.5 mm void for different explosives. The experiments were also compared to simulations using a multi‐dimensional and multi‐material hydrodynamic code. These results showed the influence that small features can have on detonation waveshaping and how explosive properties play a key role in that interaction.
{"title":"Influence and comparison of cylindrical engineered defects on detonation waveshape in a rubberized RDX explosive","authors":"Joseph R. Lawrence, Gabriel A. Montoya, Austin D. Koeblitz, Steven F. Son","doi":"10.1002/prep.202300292","DOIUrl":"https://doi.org/10.1002/prep.202300292","url":null,"abstract":"Inhomogeneities within explosives affect the sensitivity and detonation waveshape of energetic materials. The influence of voids on explosive initiation has been well documented; however, the effects that voids between 0.1 mm and 10 mm have on a propagating detonation wave remains largely unexplored. The effect of single cylindrical voids on detonation waveshape and re‐initiation was examined here using manufactured voids in a rubberized 1,3,5‐trinitro‐1,3,5‐triazinane (RDX) explosive. Two streak imaging techniques were fielded to investigate void influence. For the first, back‐surface streak imaging, the location of the void on the samples was changed and the resulting change in detonation waveshape at the downstream breakout was captured using a streak camera in cut‐back experiments. The results from this experiment showed the effects of an initial jet form for short cut‐back distances and as shock propagation progressed, the jet formation was absorbed by the unaffected portions of the wave front. The second method, top‐surface streak imaging, was used to investigate the re‐initiation/downstream propagation of the detonation front and the detonation velocity of the rubberized explosive. These experiments were compared to similar experimental results from machined voids in PBX 9501, an 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane (HMX)‐based explosive, to investigate the interaction of a detonation wave with a 0.5 mm void for different explosives. The experiments were also compared to simulations using a multi‐dimensional and multi‐material hydrodynamic code. These results showed the influence that small features can have on detonation waveshaping and how explosive properties play a key role in that interaction.","PeriodicalId":508060,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"14 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140976563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We conducted an analysis of the natural aging characteristics of an electric pyrotechnic initiator stored for 11 years, using 10‐cm3 Closed Bomb Tests (CBTs). For the comparative analysis, we utilized the closed bomb test data from other three batches that were tested 11 years ago when they were produced. Notably, two aged samples exhibited peculiar phenomena in terms of maximum pressure and the time taken to reach it, both of which are the performance indicators of Closed Bomb Tests. The time taken to reach maximum pressure increased in both aged samples compared to the pristine samples. Additionally, while one aged sample demonstrated a higher maximum pressure, the other displayed a significantly lower value compared to the pristine ones. Through statistical analysis of test results from three batches of the reference samples and one batch of aged samples led us to propose the existence of a natural aging effect on the initiator. The increase in time taken to reach maximum pressure compared to the reference samples can be attributed to the phenomenon of an increasing particle size distribution of spherical combustion particles in the present combustion model. Furthermore, the aging of the binder of the initiator charge likely contribute to a relative increase in the size of the combustion particles due to the binder hardening over time. To explain the phenomenon of the pressure initially reaches its maximum value on the CBT pressure‐time curve and subsequently decrease, we introduce the concept of condensation, where the gas phase transitions into liquid and solid phases.
{"title":"Understanding aging characteristics of a pyrotechnic initiator through performance modeling in Closed Bomb Tests","authors":"Seung‐gyo Jang, Dong‐seong Kim, Doo‐Hee Han","doi":"10.1002/prep.202300284","DOIUrl":"https://doi.org/10.1002/prep.202300284","url":null,"abstract":"We conducted an analysis of the natural aging characteristics of an electric pyrotechnic initiator stored for 11 years, using 10‐cm3 Closed Bomb Tests (CBTs). For the comparative analysis, we utilized the closed bomb test data from other three batches that were tested 11 years ago when they were produced. Notably, two aged samples exhibited peculiar phenomena in terms of maximum pressure and the time taken to reach it, both of which are the performance indicators of Closed Bomb Tests. The time taken to reach maximum pressure increased in both aged samples compared to the pristine samples. Additionally, while one aged sample demonstrated a higher maximum pressure, the other displayed a significantly lower value compared to the pristine ones. Through statistical analysis of test results from three batches of the reference samples and one batch of aged samples led us to propose the existence of a natural aging effect on the initiator. The increase in time taken to reach maximum pressure compared to the reference samples can be attributed to the phenomenon of an increasing particle size distribution of spherical combustion particles in the present combustion model. Furthermore, the aging of the binder of the initiator charge likely contribute to a relative increase in the size of the combustion particles due to the binder hardening over time. To explain the phenomenon of the pressure initially reaches its maximum value on the CBT pressure‐time curve and subsequently decrease, we introduce the concept of condensation, where the gas phase transitions into liquid and solid phases.","PeriodicalId":508060,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"24 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140975433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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