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During World War I, an enormous amount of chemical and conventional munitions was fired. Many of these munitions did not explode and are still recovered in the soil of the regions where the war raged for several years. After the war, many of the remaining munitions were dumped in the sea as an easy way of removal. These unexploded and dumped munitions are still present so many years after the end of the war. The explosive material inside the munitions is more than 100 years old now. Samples were collected from some of these old munitions. These samples have been analyzed to determine their composition. The explosives typically used in World War I (TNT, DNT, DNB and picric acid) have been identified. It has been shown that the aged samples still contain their energy. They have not become more sensitive to friction or impact. For one the samples, it has been shown that it is still cap-sensitive and detonates normally. These results are important for any risk assessment involving old munitions. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Explosives & Propellants is the property of Chinese Journal of Explosives & Propellants Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In response to the problem of the high friction sensitivity of 3,4-bis(3-nitrofurazan-4-yl) furoxan (DNTF) in solid propellants, the inherent component of solid propellants, nitrocellulose (NC), was used to coat DNTF explosives via the water suspension method. The coated samples were characterized by scanning electron microscopy (SEM) and friction sensitivity tests at a fixed 66° swing angle, and molecular dynamics calculations were performed to study the friction sensitivity and desensitization mechanism of NC-based DNTF coatings. The results show that NC, when used as a coating layer, can form a white gel on the surface of DNTF crystals, which can effectively reduce the friction sensitivity of DNTF. The coating effect becomes more obvious as the NC content increases. When the NC content is 5%, the friction sensitivity decreases by 72%, and a prediction formula for the exponential decay of DNTF friction sensitivity is obtained. MD calculation data show that NC can weaken the stiffness, enhance the elastic-plastic properties, increase the ductility and toughness of DNTF materials, and effectively improve the mechanical properties of DNTF. By combining experiments and simulation calculations, while considering the compatibility of new components and changes in propellant energy and other unpredictable new issues, NC can be referred to as a better coating layer for DNTF, as it has a certain feasibility for improving the friction sensitivity of DNTF. [ABSTRACT FROM AUTHOR]

In this paper, we report a quantitative structure-property relationship (QSPR) model development for friction sensitivity prediction of nitramine energetic materials. The model is obtained by means of a sophisticated method, namely, genetic function approximation and consists of 10 descriptors. As a training set, we have applied 80 nitramine energetic materials of a few families, both molecular and salt-like. The corresponding test set included 30 compounds. As a result, we have obtained a good correlation with R2 = 0.90. Only two descriptors, the heat of formation and quadrupole components, need semi-empirical quantum-chemical calculations, while the rest ones are so-called “fast descriptors” meaning the relatively short time of the prediction. Using the obtained QSPR model along with our recent method for fast crude estimation of the detonation properties based on empirical formulas we have modified a few energetic salts in order to obtain materials with better friction sensitivity and detonation performance. This was mainly done by changing the constituting ions: thus, 10 nitramine energetic materials with improved characteristics were proposed.

In order to study the ignition process and response characteristics of cast polymer-bonded explosives (PBX) under the action of friction, HMX-based cast PBX explosives were used to carry out friction ignition experiments at a 90° swing angle and obtain the critical ignition loading pressure was 3.7 MPa. Combined with the morphology characterization results of HMX-based cast PBX, the friction temperature rise process was numerically simulated at the macro and micro scale, and the ignition characteristics were judged. The accuracy of the numerical simulation results was ensured based on the experiment. Based on the thermal–mechanical coupling algorithm, the mechanical–thermal response of HMX-based cast PBX tablet under friction was analyzed from the macro scale. The results show that the maximum temperature rise is 55 °C, and the temperature rise of the whole tablet is not enough to ignite the explosive. Based on the random circle and morphology characterization results of tablet, the mesoscopic model of HMX-based cast PBX was constructed, and the microcrack friction formed after interface debonding was introduced into the model. The temperature rise process at the micro scale shows that HMX crystal particles can be ignited at a temperature of 619 K under 4 MPa hydraulic pressure loaded by friction sensitivity instrument. The main reason for friction ignition of HMX-based cast PBX is the friction hot spot generated by microcracks formed after interface damage of the tablet mesoscopic model, and the external friction heat between cast PBX tablet and sliding column has little effect on ignition. External friction affects the ignition of HMX-based cast PBX by influencing the formation of internal cracks and the stress at microcracks. [ABSTRACT FROM AUTHOR]

In this second part of our work on the sensitivity of pentaerythritol tetranitrate (PETN) the investigations focus on the manufacturing process. Literature about the explosive during production is very rare and optimization or changes in the process demand more in‐depth knowledge of the safety parameters. Therefore, the industrial process is imitated in a small‐scale laboratory reactor. Then impact and friction sensitivities of emergency drowned, spent acid wet and acid washed PETN are investigated. In advance, PETN samples were taken from the filter of the SSE production and measured in the same manner. It becomes clear at which point a sensitive material is expected in the process. The data will improve handling safety and plant design. [ABSTRACT FROM AUTHOR]

Reducing the sensitivity of high-energy simple explosives is the key technology in improving the practical application of high-energy insensitive powder. As the most widely used high-energy explosive, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is limited in application due to its high sensitivity. In this work, polyvinylidene fluoride (PVDF) was used as an energetic binder. Core-shell-structured RDX@PVDF microspheres are produced using electrospray assembly technology and fully characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, and mechanical sensitivity. Their thermal stability and mechanical sensitivity are directly related to the weight fraction of the added PVDF. Moreover, core-shell-structured RDX@PVDF microspheres with RDX and PVDF in the proportion three to one possess a spherical-like morphology, the lowest impact sensitivity, the lowest friction sensitivity, and the highest thermal stability. This work provides a facile method for the positive design energetic materials and the prediction of their environmental adaptability. [ABSTRACT FROM AUTHOR]

Each pyrotechnic composition has specific sensitivity such as electrostatic discharge (ESD) sensitivity and friction sensitivity (FS), and it also has specific ignition performance, including luminous intensity (LI) and burning rate (BR). These parameters depend on the concentration of pyrotechnic composition ingredients. In this study, Mg/Ba(NO3)2/novolac resin compositions were prepared using different weight ratios (wt.%) of Mg, Ba(NO3)2, and novolac resin. Then, they were investigated by their FS, LI, and BR. The results showed that by increasing Ba(NO3)2 concentration from 33.76 to 84.54 wt.% Ba(NO3)2, the FS increases from 343 N to 65.5 N. However, the LI and BR of this composition increased by increasing Ba(NO3)2 concentration until a 3/1 stoichiometric ratio of Mg/Ba(NO3)2 (from 13086 to 20588 cd (candela) and 11.25 to 13.71 cm/s, respectively for 33.76 to 64.92 wt.% Ba(NO3)2) and decreased afterward (from 20488 to 53.24 cd and 13.71 to 6.45 cm/s, respectively). For Mg/Ba(NO3)2/novolac resin containing 3 to 12 wt.% novolac resin FS increased from 56 to above 360 N. LI and BR decreased from 20057 to 1203 cd and 17.3 to 1.2 cm/s, respectively. The stoichiometric ratio of Mg/Ba(NO3)2 has the highest enthalpy of reaction. Therefore, it can be concluded that it has the highest LI and BR. [ABSTRACT FROM AUTHOR]

Pentaerythritol tetranitrate (PETN) is a sensitive and brisant explosive. PETN is transported wetted (25 %) with water to limit its impact and friction sensitivities. Literature on its sensitivities in function of its water content is controversial as the measurements were performed by several operators and laboratories rendering difficult to compare the values. Literature studies of mechanical sensitivity methods show the weaknesses and problems of mechanical measurements. Indeed, it is important to analyze a sample with standardized machines and by a single operator. During this work, pure PETN samples with water contents of 0 to 35 % were prepared and the water content was measured by Karl‐Fischer titration. The sensitivities were analyzed by the "BAM Fallhammer" and the "BAM Friction Apparatus". The resulting trends were analyzed and discussed with regard to their meaning for handling safety. The study should help to better assess dangers when working with wet PETN (10–25 %) in order to avoid accidents. [ABSTRACT FROM AUTHOR]

In order to study the ignition process and response characteristics of cast polymer-bonded explosives (PBX) under the action of friction, HMX-based cast PBX explosives were used to carry out friction ignition experiments at a 90° swing angle and obtain the critical ignition loading pressure was 3.7 MPa. Combined with the morphology characterization results of HMX-based cast PBX, the friction temperature rise process was numerically simulated at the macro and micro scale, and the ignition characteristics were judged. The accuracy of the numerical simulation results was ensured based on the experiment. Based on the thermal–mechanical coupling algorithm, the mechanical–thermal response of HMX-based cast PBX tablet under friction was analyzed from the macro scale. The results show that the maximum temperature rise is 55 °C, and the temperature rise of the whole tablet is not enough to ignite the explosive. Based on the random circle and morphology characterization results of tablet, the mesoscopic model of HMX-based cast PBX was constructed, and the microcrack friction formed after interface debonding was introduced into the model. The temperature rise process at the micro scale shows that HMX crystal particles can be ignited at a temperature of 619 K under 4 MPa hydraulic pressure loaded by friction sensitivity instrument. The main reason for friction ignition of HMX-based cast PBX is the friction hot spot generated by microcracks formed after interface damage of the tablet mesoscopic model, and the external friction heat between cast PBX tablet and sliding column has little effect on ignition. External friction affects the ignition of HMX-based cast PBX by influencing the formation of internal cracks and the stress at microcracks.

Relations between crystal type, particle size and mechanical sensitivities of dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate (HATO) made by different production methods were analysized. Results showed that impact sensitivities of HATO flake-like is higher, but friction sensitivity of HATO with different morphology and particle size is similar on statistics.HATO by milling process possesses higher impact sensitivity and lower friction sensitivity than before. HATO mixture with ETPE has higher impact sensitivity and higher friction sensitivity than pure HATO. Graphite lowers HATO’s impact sensitivity and friction sensitivity significantly.Loading density, gap between impact columns, and explosive’s friction factor influence production of “hot spot”,thus influence explosive’s impact sensitivity. Evaluating mechanical sensitivities with current equipments is limited, and novel equipment should be designed to evaluate explosive’s real mechanical sensitivities. [ABSTRACT FROM AUTHOR]

Reducing the sensitivity of high-energy simple explosives is the key technology in improving the practical application of high-energy insensitive powder. As the most widely used high-energy explosive, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is limited in application due to its high sensitivity. In this work, polyvinylidene fluoride (PVDF) was used as an energetic binder. Core-shell-structured RDX@PVDF microspheres are produced using electrospray assembly technology and fully characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, and mechanical sensitivity. Their thermal stability and mechanical sensitivity are directly related to the weight fraction of the added PVDF. Moreover, core-shell-structured RDX@PVDF microspheres with RDX and PVDF in the proportion three to one possess a spherical-like morphology, the lowest impact sensitivity, the lowest friction sensitivity, and the highest thermal stability. This work provides a facile method for the positive design energetic materials and the prediction of their environmental adaptability.

Copyright of Chinese Journal of Explosives & Propellants is the property of Chinese Journal of Explosives & Propellants Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Measurement Science & Instrumentation is the property of Journal of Measurement Science & Instrumentation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A recent near miss involving ignition of a small amount of red phosphorus was investigated. The near miss is discussed in detail along with the root cause investigation. Six possible root causes were examined. Three were deemed unlikely, and three were either probable or likely root causes. In the end, electrostatic discharge appears to be the most likely root cause. The Case Study serves to remind scientists about the importance of keeping a clutter-free work area and about hazards associated with common reagents. [ABSTRACT FROM AUTHOR]

Friction sensitivity of composite propellants and their ingredients is of significant interest to mitigate the risk associated with the accidental initiation while processing, handling, and transportation. In this work, attempts were made to examine the friction sensitivity of passive binder: Hydroxy Terminated Polybutadiene/Aluminium/ Ammonium Perchlorate and active binder: (Polymer + Nitrate Esters)/Ammonium Perchlorate/Aluminium/Nitramine based composite propellants by using BAM Friction Apparatus. As per the recommendation of NATO standard STANAG-4487, the friction sensitivity was assessed by two methods: Limiting Frictional load and Frictional load for 50% probability of initiation (F50). The test results showed that the active binder based formulations were more vulnerable to frictional load as compared to the formulations with passive binders. Examination of a comprehensive set of propellant compositions revealed that the particle size distribution of Ammonium Perchlorate and burn rate catalysts were the most influential factors in dictating the friction sensitivity for HTPB/Al/AP composite propellants. For active binder/AP/Al/Nitramine composite propellants, the formulation with RDX was found more friction sensitive with a sensitivity value of 44 N as compared to its HMX analog (61 N). The correlation studies of friction sensitivity, burning rate, and thermal decomposition characteristics of HTPB/Al/AP composite propellants is described. [ABSTRACT FROM AUTHOR]

Abstract: Friction sensitivity is an important safety parameter for assessment when working with new energetic ionic liquids (EILs) during mixing, pouring, sieving, priming and consolidation operations in working places. This work introduces a reliable method to predict friction sensitivity of quaternary ammonium‐based EILs, which are based on elemental composition of cation and anion of a desired ionic liquid as well as the contribution of specific cations and anions. For 47 EILs, the values of coefficient of determination (R2) and Root Mean Squared Error (RMSE) of the new model are 0.9057 and 33 N, respectively. High accuracy of the novel method confirms that prediction of friction sensitivity of quaternary ammonium‐based EILs is not necessarily enhanced by greater complexity. [ABSTRACT FROM AUTHOR]

Microencapsuled red phosphorus (MRP), with a phenolic resin coating layer, was successfully prepared. It was characterized by Fourier-transform infrared spectroscopy (FTIR) and Scanning electron microscope (SEM). Meanwhile its water absorption, thermostability, thermodynamic properties and critical ignition temperature ( Tb) have been studied. The results show that the MRP which is coated with phenolic resin can decrease the water absorption, increase thermostability and critical ignition temperature ( Tb) significantly, compared with red phosphorus (RP). The thermodynamic properties which include apparent activation energy ( E), pre-exponential factor ( A), activation entropy (Δ S#), activation enthalpy (Δ H#) and Gibbs free energy (Δ G#) of RP and MRP are obtained. Moreover, the MRP can reduce the water absorption and friction sensitivity of red phosphorus smoke agent significantly with the best content of phenolic resin is 0.5 % or 1 %. [ABSTRACT FROM AUTHOR]

Writing was an important factor in human society since long time ago. And previous studies indicatemany consumers evaluate pens in handwriting feeling above all other factors when they select recently pens. The fact they work always grabbed in hands considered, the emotional design of writing tools is essential. However, the feeling such as handwriting feelings is gradually disappearing due to the development of mobile devices. So we thought that the need for an engineering approach. The technology of the sense of touch belongs to the technology of the sensibility field, but it is positively necessary to objectify the sense of touch in order to develop new technologies or products by expressing this numerically and applying it to engineering. In order to objectify the sense of touch, the variables (the pressure, temperature, texture of material, etc.) of the friction when the stylus pen first touches the surface of the object should be digitized. And static and dynamic friction models should be established and the variables that affect the friction behavior should be organized. This study investigated the handwriting feeling of various writing tools and attempted to use it for the development of new mobile devices in the future through physical friction test. This study investigated the handwriting feeling of various writing tools and attempted to use it for the development of future mobile devices through physical friction test. Using developed model which can explain how the experimental parameters and emotional user experience, developer can design their product which can give user expected emotional sensibility. [ABSTRACT FROM AUTHOR]

Solid spherical octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine/fluororubber2602 (HMX/F2602) was prepared by the suspension spray-drying method as follows: firstly, thinning octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) was obtained by a solvent–anti-solvent method. Secondly, thinning HMX suspended in ethyl acetate solvent in a solution of a binder—F2602—was made into a suspension. Finally, the samples were prepared by spray drying. The samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), and Fourier transform infrared (FTIR), and its thermal stability as well as mechanical and spark sensitivities were measured. The results of SEM showed that the grain of HMX/F2602was solid spherical and the particle distribution was homogeneous. The results of XPS indicated that F2602can be successfully coated on the surface of HMX crystals. Compared to raw HMX, th characteristic drop height was increased from 19.60 to 40.37 cm, an increase of 79.10%. The friction sensitivities of HMX reduced from 100 to 28% and the spark sensitivity of HMX/F2602increased. The critical explosion temperatures of raw HMX and HMX/F2602were 275.43 and 274.30°C, respectively. The amount of gas evolution of raw HMX and HMX/F2602was 0.15 and 0.12 ml·(5 g)−1, respectively. The results of DSC and vacuum stability tests (VSTs) indicate that the thermal stability of HMX/F2602was equal to that of raw HMX and HMX and F2602had good compatibility. [ABSTRACT FROM AUTHOR]

The knowledge of sensitiveness of an energetic compound to friction stimuli is important to ensure the safety of people and protection of property during shipment. The information on sensitivity to friction is considered very valuable for nitramines, which show relatively higher sensitivity with respect to the other classes of secondary explosives. This study presents a novel general simple model for prediction of the relationship between friction sensitivity and activation energy of thermolysis of cyclic and acyclic nitramines on the basis of their molecular structures. This methodology assumes that friction sensitivity of an energetic compound with general formula CaHbNcOd can be expressed as a function of activation energy of thermolysis and the contribution of specific molecular structural parameters. For 21 nitramines with different molecular structures, the new correlation has the root mean square and the average standard deviations of 14.2 and 17.8 N, respectively, as compared to experimental values. The proposed new method is also tested for further 8 nitramines containing complex molecular structures, which gives good predictions. [ABSTRACT FROM AUTHOR]

Desensitisation of explosive materials using polymers is an important area in safe utilisation of explosives in various applications. The RDX/viton composition has been developed using co-precipitation method with varying content of viton, ranging from 5 to 35 wt per cent. RDX and viton were dissolved in acetone which is a common solvent for RDX and viton, and then the acetone was extracted from the solution by distillation resulting in homogeneous RDX/viton composition. Infrared spectroscopy studies indicated presence of RDX and viton in the resulting compositions. Thermogravimetric and differential thermal analysis studies made on yielded compositions conirmed that RDX is present in the composition in desired content. The shift in exotherm of RDX/viton composition as compared to RDX showed that polymer-bonded RDX compositions are more stable. The impact sensitivity studies showed that sensitivity of RDX/viton composition decreased with increasing content of viton. The similar trend was observed for friction sensitivity. The co-precipitation method has been found to be advantages to obtain homogeneous composition of RDX and viton (with viton content up to 25 wt per cent) as revealed by linear trend in sensitivity data measurements. It has been demonstrated that the sensitivity of RDX can be tailored within a wide range using viton so as to suit in desired applications. [ABSTRACT FROM AUTHOR]

The mechanism of initiation is essential to enumerate the sensitivity and evaluate the risks associated with energetic mixtures. To understand the mechanism of initiation under frictional loading, the initiation events such as initiating time and critical load have to be evaluated. This study aims to assess experimentally the initiation mechanism under frictional load by measuring the event of initiation and the critical load using a modified version of the BAM friction tester augmented with a press force sensor, an accelerometer and a photodiode arrangement. Differences in the range of diagnostics were identified for various material interactions. The data generated have the implications for assessing the safety of energetic mixtures. [ABSTRACT FROM AUTHOR]

The flash powder composition is used in the fireworks industry to manufacture the firecrackers which consist of potassium nitrate, aluminium and sulphur in 75 μm range. This study focuses on the synthesis of nano and micro flash powders with different trials of composition. The particle sizes of the nanochemicals are 142.8, 93.10 and 91.28 nm for KNO, Al and S, respectively. The nano flash powder is mixed with micron flash powder in different ratios to manufacture the crackers and thus the noise level for the crackers are found. Thermal analysis was conducted in differential thermal and thermo gravimetric analyser. Also, impact sensitivity and friction sensitivity of the nano flash powder are analysed. The nano flash powder shows low ignition temperature compared to micron and also has high mechanical sensitivity. Fire crackers which contains one gram of 100 % nano flash powder emits the threshold noise level of 125 dB(AI) in spite of 4 g of 10 % nano flash powder for the same composition. [ABSTRACT FROM AUTHOR]

Fire and explosions in the processing of matchhead compositions are reported due to the friction sensitivity of materials used. This investigation is aimed at investigating the influence of different types of contact materials and their surface roughness on the friction sensitivity of a matchhead composition. The friction sensitivity of the matchhead composition was found to be dependent on the contact materials and their roughness. The results demonstrated that the contact materials and their surface roughness imparted variations to the sensitivity, ranging from 108 to 360 N. The sensitivity response of the energetic mixture was quicker in case of aluminum plate-aluminum pin combinations than those when steel plate-steel pin and brass plate-brass pin combinations were used. For the first time, the experimental investigation identified a new value based on the material's surface roughnesses called critical surface roughness, at which the matchhead composition ignited at a minimum frictional load. The matchhead composition was found to be highly hazardous at the critical surface roughness values of 1.09, 1.01, and 1.05 μm for aluminum, brass, and steel surfaces, respectively. Based on the experimental results this paper also discusses mechanism of ignition caused by the frictional load. [ABSTRACT FROM AUTHOR]

The article presents a study on the affect of scale in flood inundation modelling in urban environments in Great Britain. It notes that a two-dimensional (2D) flood inundation model is applied to resolve flows on the high-resolution grids necessary to double urban features. Moreover, a 2D cell-type model storage is used to evaluate the effectiveness of coarse grids that represent flood flows through urban environments. It also emphasizes that internal prediction of water depth is essential to understand flood dynamics and evolution. Furthermore, the combination of global performance measures and internal forecasts of water depth highlights an initial estimate of the minimum grid cell size for urban applications.

[Display omitted] • Impact, friction, and thermal sensitivity data for 150 CHNOFCl species is reported. • Impact testing of high-melting and low-sensitive compounds is most challenging. • Mechanical sensitivity generally increases with the energy content of compound. • Increasing of detonation performance without compromising sensitivity is possible. Mechanical and thermal hazards are critical for chemical compounds. Foremost, the design of novel energetic materials that are stable, insensitive, but have a detonation performance superior to in-service materials is of great interest. However, a single source of safety data for hazardous materials with explosophoric functionalities is still missing. Herein, an experimental database on thermal stability, impact, and friction sensitivity for 150 CHNOFCl compounds is presented. Mechanical sensitivity is discussed in detail: particle size and shape effects, instrument design, and experimental protocol are considered. The entire dataset was analyzed using the simple descriptors of molecular structure. Mechanical sensitivity was found to be linearly correlated with the maximal heat of explosion for certain classes of compounds (nitrobenzenes, furazans, pyrazoles, etc.). Consideration of all species shows that previously proposed sensitivity increase with an energy content rise is relevant, although it is not strict line, as was assumed, but rather a widened "strip". A new parameter, safety factor, is proposed to combine two types of sensitivity data. With this factor, the limiting values of mechanical sensitivity at a given energy content are provided that represent the state-of-art development of energetic materials and may be used for screening and design of novel compounds. [ABSTRACT FROM AUTHOR]