Explosives
An explosive is defined as a material (chemical or nuclear) that can be initiated to undergo very rapid, self-propagating decomposition that results in the formation of more stable material, the liberation of heat, or the development of a sudden pressure effect through the action of heat on produced or adjacent gases. All of these outcomes produce energy; a weapon's effectiveness is measured by the quantity of energy - or damage potential - it delivers to the target.
Modern weapons use both kinetic and potential energy to achieve maximum lethality. Kinetic energy systems rely on the conversion of kinetic energy to work, while potential energy systems use explosive energy directly in the form of heat and blast, or by accelerating metal as a shaped charge, EFP or case fragments to increase their kinetic energy and damage volume.
Energy may be broadly classified as potential or kinetic. Potential energy is energy of configuration or position, or the capacity to perform work. For example, the relatively unstable chemical bonds among the atoms that comprise trinitrotoluene (TNT) possess chemical potential energy. Potential energy can, under suitable conditions, be transformed into kinetic energy, which is energy of motion. When a conventional explosive such as TNT is detonated, the relatively unstable chemical bonds are converted into bonds that are more stable, producing kinetic energy in the form of blast and thermal energies. This process of transforming a chemical system's bonds from lesser to greater stability is exothermic (there is a net production of energy).
A chemical explosive is a compound or a mixture of compounds which, when subjected to heat, impact, friction, or shock, undergoes very rapid, self-propagating, heat- producing decomposition. This decomposition produces gases that exert tremendous pressures as they expand at the high temperature of the reaction. The work done by an explosive depends primarily on the amount of heat given off during the explosion. The term detonation indicates that the reaction is moving through the explosive faster than the speed of sound in the unreacted explosive; whereas, deflagration indicates a slower reaction (rapid burning). A high explosive will detonate; a low explosive will deflagrate. All commercial explosives except black powder are high explosives.
Low-order explosives (LE) create a subsonic explosion [below 3,300 feet per second] and lack HE's over-pressurization wave. Examples of LE include pipe bombs, gunpowder, and most pure petroleum-based bombs such as Molotov cocktails or aircraft improvised as guided missiles.
A High Explosive (HE) is a compound or mixture which, when initiated, is capable of sustaining a detonation shockwave to produce a powerful blast effect. A detonation is the powerful explosive effect caused by the propagation of a high-speed shockwave through a high explosive compound or mixture. During the process of detonation, the high explosive is largely decomposed into hot, rapidly expanding gas.
The most important single property in rating an explosive is detonation velocity, which may be expressed for either confined or un-confined conditions. It is the speed at which the detonation wave travels through the explosive. Since explosives in boreholes are confined to some degree, the confined value is the more significant. Most manufacturers, however, measure the detonation velocity in an unconfined column of explosive 1- i/4 in. in diameter. The detonation velocity of an explosive is dependent on the density, ingredients, particle size, charge diameter, and degree of confinement. Decreased particle size, increased charge diameter, and increased confinement all tend to increase the detonation velocity. Unconfined velocities are generally 70 to 80 percent of confined velocities.
The confined detonation velocity of commercial explosives varies from 4,000 to 25,000 fps. With cartridge explosives the confined velocity is seldom attained. Some explosives and blasting agents are sensitive to diameter changes. As diameter is reduced, the velocity is reduced until at some critical diameter, propagation is no longer assured and misfires are likely.
Relative effectiveness factor (R.E. factor) is a measurement of an explosive's power for military demolitions purposes. It measures the detonating velocity relative to that of TNT, which has an R.E. factor of 1.00. TNT equivalent is a measure of the energy released from the detonation of a nuclear weapon, or from the explosion of a given quantity of fissionable material, in terms of the amount of TNT (trinitrotoluene) which could release the same amount of energy when exploded. The twelve-kiloton Hiroshima atomic bomb had had a blast effect alone equivalent to some twenty-five million pounds of TNT-that's million.
Denser explosives usually give higher detonation velocities and pressures. A dense explosive may be desirable for difficult blasting conditions or where fine fragmentation is required. Low-density ex-plosives will suffice in easily fragmented or closely jointed rocks and are preferred for quarrying coarse material.
Energetic materials are made in two ways. The first is by physically mixing solid oxidizers and fuels, a process that, in its basics, has remained virtually unchanged for centuries. Such a process results in a composite energetic material such as black powder. The second process involves creating a monomolecular energetic material, such as TNT, in which each molecule contains an oxidizing component and a fuel component. For the composites, the total energy can be much greater than that of monomolecular materials. However, the rate at which this energy is released is relatively slow when compared to the release rate of monomolecular materials. Monomolecular materials such as TNT work fast and thus have greater power than composites, but they have only moderate energy densities-commonly half those of composites. Greater energy densities versus greater power-that's been the traditional trade-off.
Ingredients of high explosives are classified as explosive bases, combustibles, oxygen carriers, antacids, and absorbents. Some ingredients perform more than one function. An explosive base is a solid or liquid which, upon the application of sufficient heat or shock, decomposes to gases with an accompanying release of considerable heat. A combustible combines with excess oxygen to prevent the formation of nitrogen oxides. An oxygen carrier assures complete oxidation of the carbon to prevent the formation of carbon monoxide. The formation of nitrogen oxides or carbon monoxide, in addition to being undesirable from the standpoint of fumes, results in lower heat of explosion and efficiency than when carbon dioxide and nitrogen are formed. Antacids increase stability in storage, and absorb-ents absorb liquid explosive bases.
Explosives are classified as primary or secondary based on their susceptibility to initiation. Primary explosives, which include lead azide and lead styphnate, are highly susceptible to initiation. Primary explosives often are referred to as initiating explosives because they can be used to ignite secondary explosives. Secondary explosives, which include nitroaromatics and nitramines are much more prevalent at military sites than are primary explosives. Because they are formulated to detonate only under specific circumstances, secondary explosives often are used as main charge or bolstering explosives.
Secondary explosives can be loosely categorized into melt-pour explosives, which are based on nitroaromatics such as TNT, and plastic-bonded explosives which are based on a binder and crystalline explosive such as RDX.
Propellants include both rocket and gun propellants. Most rocket propellants are composites based on a rubber binder, ammonium perchlorate oxidizer, and a powdered aluminum fuel; or composites based on a nitrate esters, usually nitroglycerine or nitrocellulose and nitramines. If a binder is used, it usually is an isocyanate-cured polyester or polyether. Some propellants also contain combustion modifiers, such as lead oxide. One group of gun propellants are called "single base" (principally nitrocellulose), "double base" (nitrocellulose and nitroglycerine), or "triple base" (nitrocellulose, nitroglycerine, and nitroguanidine). Some of the newer, lower vulnerability gun propellants contain polymer binders and crystalline nitramines.
Pyrotechnics include illuminating flares, signaling flares, colored and white smoke generators, tracers, incendiary delays, fuses, and photo-flash compounds. Pyrotechnics usually are composed of an inorganic oxidizer and metal powder in a binder. Illuminating flares contain sodium nitrate, magnesium, and a binder. Signaling flares contain barium, strontium, or other metal nitrates.
Explosive and incendiary (fire) bombs are further characterized based on their source. "Manufactured" implies standard military-issued, mass produced, and quality-tested weapons. "Improvised" describes weapons produced in small quantities, or use of a device outside its intended purpose, such as converting a commercial aircraft into a guided missile. Manufactured (military) explosive weapons are exclusively HE-based. Terrorists will use whatever is available - illegally obtained manufactured weapons or improvised explosive devices (also known as "IEDs") that may be composed of HE, LE, or both. Manufactured and improvised bombs cause markedly different injuries.
Plastic explosive means an explosive material in flexible or elastic sheet form formulated with one or more high explosives which in their pure form has a vapor pressure less than 10-4 Pa at a temperature of 25 deg. C., is formulated with a binder material, and is as a mixture malleable or flexible at normal room temperature.
The energetic materials used by the military as propellants and explosives are mostly organic compounds containing nitro (NO2) groups. The three major classes of these energetic materials are nitroaromatics (e.g., tri-nitrotoluene or TNT), nitramines (e.g., hexahydro-1,3,5 trinitroazine or RDX), and nitrate esters (e.g., nitrocellulose and nitroglycerine).
Since the invention of the cannon, the explosive fills used to drive lethal mechanisms have been the subject of ever increasing interest and study. Traditionally, munitions designers have used such ex-plosives as Comp-B, TNT, or LX-14, depending upon the particular application.
During the 1920s and into the 1940s, the Army's Picatinny Arsenal was instrumental in designing, modeling and evaluating such high explosive material as TNT, RDX, and Haleite. This work greatly influenced battlefield lethality during WWII where explosives exhibiting a higher brisance, or shattering effect, than TNT were in great demand.
The 1960s brought new explosives such as HMX that was chemically analogous to RDX, but even more powerful to give soldiers greater lethality capability. Picatinny laboratories also developed precision warheads for several missile systems, including the DRAGON-MAW, a Medium Antiarmor Weapon.
The Army uses Research Department Explosive (RDX) and High Melt Explosive (HMX) as basic explosives for munitions and tactical missiles as well as propellants for strategic missiles rather than TNT because of their superior energy.
Most modern explosives are reasonably stable and require percussive shock or other triggering devices for detonation. Energetic materials are especially vulnerable to elevated temperature, with possible consequences ranging from mild decomposition to vigorous deflagration or detonation. Energetic materials can also be initiated by mechanical work through friction, impact, or electricity (e.g., current flow, spark, electrostatic discharge, or electromagnetic radiation). Other stimuli (e.g., focused laser light or chemical incompatibility) can have consequences ranging from mild decomposition to detonation.
Explosives may be toxic, with exposure pathways being inhalation of dust or vapor, ingestion, or skin contact. Most explosives are not highly toxic, but improper handling can result in systemic poisoning, usually affecting the bone marrow (i.e., the blood cell-producing system) and the liver. Some explosives are vasodilators, which cause headaches, low blood pressure, chest pains, and possible heart attacks. Some explosives may irritate the skin.
Some detonation or combustion products from explosives are toxic. Such products can be respiratory and skin irritants and lead to systemic effects following short-term exposure to high levels. Soot from detonated explosives is not mutagenic; however, soot from burned gun propellants may be mutagenic and is therefore treated as a mutagen.
Fortunately, contamination usually occurs in dilute, aqueous solutions or in relatively low concentrations in the soil and present no explosion hazard. Masses of pure crystalline explosive material have, however, been encountered in soils associated with wastewater lagoons, leach pits, burn pits, and firing ranges. These materials remain hazardous for long periods of time and great care must be used during the investigation and remediation process.
Molecular weights are moderate, of the order of a few hundreds of grams per mole. The molecular structure, particularly the types and positions of subsidiary functional groups, controls environmental behavior.
All of the common explosives are solid at normal environmental temperatures and pressures. Melting point temperatures for explosives solids are moderate (50-205 0C). Melting points are of little direct value in predicting environmental fate and transport, but several parameter estimation relations for solids incorporate the influence of molecular crystal bonding by including a term dependent on the melting point. Melting points are not available for many of the breakdown products. Most of the explosives and associated contaminants have very low volatility, with vapor pressures estimated to be less than 6 x 10-4 torr. Henry's law constants (KH) range from 10-4 to 10-11 atm·m-2·mole-1. Only those with KH greater than 10-5 volatilize significantly from aqueous solution 12. Though explosives compounds may not be volatile, some of the transformation products, other key reactants, or products may be volatile to semivolatile.
Showing posts with label history of modern explosives. Show all posts
Showing posts with label history of modern explosives. Show all posts
Sunday, December 27, 2009
Short History of Modern Explosives ....
Explosives
Nitrate esters
http://www.globalsecurity.org/military/systems/munitions/explosives-nitrate.htm-
On December 25, 2009, Umar Farouk Abdulmutallab, a Nigerian national, was accused of trying to ignite an incendiary device aboard a Northwest Airlines Flight headed to Detroit, MI; an act the White House declared "an attempted act of terrorism". The incendiary device was later identified by authorities of being a PETN-based device.
Nitrate (NO3-) (CAS No. 014797-55-8) is an inorganic anion resulting from the oxidation of elemental nitrogen. It is an essential nutrient for plant protein synthesis and plays a critical role in the nitrogen cycle of soil and water. Nitrates are produced by natural biological and physical oxidations and therefore are ubiquitous in the environment (Ridder and Oehme 1974). Most nitrate compounds are strong oxidizing agents and some can react violently with oxidizable substances and may explode if exposed to heat or shock.
Nitrates are produced by natural biological and physical oxidations and therefore are ubiquitous in the environment. Most of the excess nitrates in the environment originate from inorganic chemicals manufactured for agriculture. Organic molecules containing nitrate groups are manufactured primarily for explosives or for their pharmacological effects
NC [Nitrocellulose]
for many centuries gunpowder was the world's only explosive, and was not superseded until the discovery of guncotton. So long ago as 1832 Bracon discovered that woody fiber could be turned into an explosive by the action of concentrated nitric acid; and a few years later a French inventor, Dumas, tried to make cartridges of paper treated in similar fashion. If he had succeeded these would have been the first smokeless cartridges, but he failed; and it was not until 1845 that Schönbein, a German chemist, hit upon the proper method of treating cotton wool with nitric and sulphuric acids, so as to turn it into guncotton.
In 1847 an English firm, Messrs. Hall and Son of Faversham, began to manufacture guncotton, and military experts hailed it as the new explosive which would take the place of gunpowder. But this explosive was so terribly powerful that, when used in a gun or rifle, it blew the barrel to pieces. Worse than that, it was most dangerous to manufacture.
Two main problems had to be solved before it could be used as a gun propellant. First, the velocity of the explosion had to be reduced so that the charge weight required to propel the projectile would not shatter the gun tube. second, the density had to be increased so that a given charge weight would pack into a reasonable space. The first problem was solved in part by igniting NC instead of firing it with a detonator. The solution to the second problem actually solved both. In 1886, Vielle first colloided or gelatinized NC with alcohol and ether and, thus reduced the burning rate to acceptable levels. The procedure significantly increased the loading density of NC, establishing it as the foundational element in gun propellants used through the present day. Further developments resulted in materials that could be added to improve stowage qualities, reduce or eliminate flash, reduce hygroscopicity, reduce flame temperature, and even increase the propellant force or impetus.
Munitions manufacturing processes may generate nitrocellulose (NC) fines. Disposal of these fines is difficult because of their reactive nature. Composting has potential to be a safe and cost effective means of disposal. Open burning is no longer permitted in several states and is expected to banned nationally in the future. Open detonation is also the least acceptable form of disposal because of uncontrolled pollution by-products. In its role as the Department of Defense Manager for conventional munitions, Army must be able to dispose of Propellants/Explosives/Pyrotechnics production wastes. In composting, a controlled biological process, microorganisms convert biodegradable hazardous material to innocuous, stabilized by-products, typically at elevated temperatures between 50 - 55 °C. The increased temperatures result from heat produced by the microorganisms as they degrade the organic material in the waste. The NC fines are mixed with bulking agents and organic amendments, such as wood chips and animal and vegetable wastes, to enhance the porosity of the mixture. Maintaining moisture content, pH, oxygenation, temperature, and the carbon-to-nitrogen ratio achieves maximum degradation efficiency.
NG [Nitroglycerin ]
Nitroglycerin (NG) [Synonyms: 1,2,3-Propanetriol trinitrate; glycerol trinitrate; nitroglycerol; NG; trinitroglycerol; NTG; trinitrin] is an oily liquid at room temperature; colorless in pure form and pale yellow or brown in commercial form. It is used in manufacture of dynamite, gunpowder, and rocket propellants, and as a therapeutic agent primarily to alleviate angina pectoris. NG is used to make smokeless gun powder and rocket propellants. Single-base powders contain only nitrocellulose, double-base powders contain nitrocellulose and NG, and triple-base powders contain nitrocellulose, NG, and other combustible materials.
In 1847 a new explosive came into being. This was nitroglycerine, made by treating glycerine with nitric and sulphuric acids. But at first it was even more dangerous to handle than guncotton, for the least shock exploded it, and its violence was terrific.
The great chemist Alfred Nobel tried to improve it by mixing it with gunpowder, but the powder did not absorb all the nitroglycerine, and accidents of the most terrible kind became more and more frequent. Yet the new explosive, being liquid, could be poured into crevices in rocks, and was so useful as a blasting agent that its manufacture went on until a large vessel carrying cases of the explosive from Hamburg to Chili blew up at sea. The ship was blown to bits and her crew killed, and the disaster caused so great a sensation that the manufacture of nitroglycerine was prohibited in Sweden, Belgium, and in England. But Nobel still continued his experiments, and at last, after trying sawdust and all other sorts of absorbents in vain, found the perfect absorbent in the shape of keiselguhr-a sort of earth made of fossil shells. The mixture is what we know to-day as dynamite; and in spite of the fact that modern chemistry has produced very many new explosives, some of terrific power, dynamite remains the safest and most widely used of all explosives.
Nitroglycerin (NG) is a vasodilator and has been associated with acute episodes of angina pectoris, myocardial infraction, and sudden death. Workers engaged in the production or use of dynamite are potentially exposed to mixed vapors of nitroglycerin (NG) and ethylene glycol dinitrate (EGDN). Initial exposure to NG (or NG:EGDN mixtures) characteristically results in an intense throbbing headache that begins in the forehead and moves to the occipital region. Volunteers developed mild headaches when exposed to NG:EGDN vapor at concentrations of 0.5mg/m^3 for 25 minutes. It has been suggested that at least some workers may develop headaches at concentrations in excess of 0.1 mg/m^3. Other signs and symptoms associated with initial exposure include dizziness, nausea, palpitations, and decreases in systolic, diastolic, and pulse pressures. These initial signs and symptoms, including headache, are indicative of a shift in blood volume form the central to the peripheral circulatory system, initiated by dilation of the blood vessels.
After 2 to 4 days of repeated NG exposure, tolerance to the vasodilatory activity occurs, probably as a result of compensatory vasoconstriction. Tolerance may be lost during periods without NG exposure, such as weekends and holidays. Chronic repeated exposures to NG and NG mixtures also have been associated with more serious cardiovascular effects, including angina pectoris and sudden death.
Signs and symptoms of ischemic heart disease were observed in nine munitions workers involved in handling a nitroglycerin-cellulose mixture. Within 1 to 4 years of initial exposure, these workers developed nonexertional chest pain, which was relieved either by therapeutic nitroglycerin or by returning to work after the weekend. Coronary angiography performed in five of the patients showed no obstructive lesions. In one patient, observed while in a withdrawal state, coronary artery spasm was demonstrated and readily reversed by sublingual nitroglycerin.
Sudden deaths in previously healthy workers have been reported among those exposed to NG or to NG: EGDN mixtures. Like the attacks of angina pectoris, sudden deaths occurred most frequently during brief periods away from work, in particular on Sunday nights or Monday mornings. In most cases, there were no premonitory signs or symptoms although some subjects had anginal episodes during brief periods away from work. Atherosclerotic plaques, with or without thrombosis, have been found in the coronary arteries of workers at autopsy, but their coronary arteries generally were not occluded to the same extent as those of unexposed workers who had died suddenly.
The pathogenesis of the sudden death syndrome has been postulated to be due to withdrawal of coronary vasodilators (e.g. NG), resulting in vasoconstriction with acute hypertension, or with myocardial ischemia in workers adapted to and dependent on NG to maintain a minimum level of coronary flow. A second contributing mechanism for coronary artery toxicity due to NG may relate to so-called aging of the vessels due to repeated dilation. Other theories suggest that sudden deaths may be related to peripheral vasodilation consequent to reexposure of NG.
Estimates of exposure levels associated with sudden death have not been made because workers typically absorb considerable amounts of NG through the skin in addition to inhalation.
Employees handling NG should be given personal protective equipment to prevent the absorption of NG through the skin. However, neither natural rubber nor synthetic rubber gloves, including neoprene gloves, are impervious to NG. The wearing of such gloves tends to hold the chemical in contact with the skin, thus promoting its absorption. Preferably, cotton-lining gloves should be worn underneath nitrile gloves and both gloves changed ever 2-1/2 hours (USAEHA Technical Guide 24).
More recent studies have suggested that the effects of long-term workplace exposure to NG may not be completely reversed after exposure is terminated. Former workers may be at increased risk for cardiovascular mortality for months to years after exposure has ceased.
Individuals with preexisting ischemic heart disease should not be assigned to work where significant exposure to NG may occur. Early identification of cardiovascular disease is the primary goal of medical surveillance of nitroglycerin workers. A preplacement examination must be administered to all new employees occupational histories, a physical examination, and indicated laboratory tests, record of their pulse rates. Periodic examinations should be conducted semiannually, with the same focus as the preplacement examination. During the periodic examination, the physician should be aware that headaches that occur during work shifts could indicate skin absorption of nitroglycerin, even if air concentrations of nitroglycerin are below the PEL. Examinations with similar content are necessary when exposure to nitroglycerin has been terminated, although surveillance should perhaps extend beyond employment, due to the latency of the withdrawal effects. Monitoring should include pulse, blood pressure, CBC, urinalysis, resting EKG and lipid profile.
PETN [Pentaerythritol tetranitrate]
Pentaerythritol tetranitrate, C5H8N4012 (PETN), has a specific gravity of solids of 1.76 and a confined detonation velocity of over 25,000 fps. PETN is used as a priming composition in detonators, a base charge in blasting caps, and a core load for detonating fuse. PETN is very much used in Detonating Cord of which it is the explosive core (Primacord), where it develops a velocity rate of 21,000 feet per second. Detonating cord is insensitive to friction and ordinary shock, but may be exploded by rifle fire. It also detonates sympathetically with the detonation of an adjacent high explosive.
PETN is one of the strongest known high explosives with a relative effectiveness factor (R.E. factor) of 1.66. It is more sensitive to shock or friction than TNT or tetryl, and it is never used alone as a booster. It is primarily used in booster and bursting charges of small caliber ammunition, in upper charges of detonators in some land mines and shells, and as the explosive core of primacord.
During World War II the M9A1 2.36" Rocket Launcher (Bazooka) charge, with 8 oz of pentolite, could penetrate up to 5 inches of armor.
Demolition charge, M118, commonly called Flex-X or sheet explosive, consists of 4 half-pound sheets of flexible explosive packed in a plastic envelope. Each sheet is approximately 3 inches wide, 12 inches long, and 1/4 inch thick. Note: The exact explosive contained in an M118 charge varies with the manufacturer. At present, some manufacturers use PETN as the basic explosive. Others use RDX. Charges manufactured in the future may include other explosives.
PETN does not occur naturally, so the production and use of this kind of compound can lead to contamination of the environment. PETN is subject to biodegradation in untreated or unpreserved urine and feces. There also have been some reports of its degradation by bacteria, whose PETN reductase sequentially denitrates PETN into tri- and dinitrates (French et al., 1996). The last compound shown in the pathway, pentaerythritol dinitrate, is degraded further to unknown products.
In 1995 Haustein KO, Winkler U, Loffler A, Huller G. of the Abteilung Klinische Pharmakologie, Medizinische Hochschule Erfurt, Germany reported on a study of PETN's cardiovascular effects. The effects of 80 mg pentaerithrityl-tetranitrate (PETN) as suspension or formulated as tablets were compared to placebo in a single blind, randomized, crossover study in 18 healthy subjects (study A), and the bioequivalence of two tablet formulations (marketed Dilcoran 80 vs a new formulation) was studied in 24 healthy subjects after administration of single oral doses of 80 mg PETN according to a placebo controlled, randomized, double blind, two-way crossover study design (study B). The perfusion of the right middle finger was measured by rheography (altitude A of the changes of resistance and of the incisure D) before and 24 h post-dose, and blood pressure and heart rate were measured in supine position at the same time. The values of area under curve (AUC) of the ratio A/D were calculated by the trapezoidal rule. In study A the mean A/D-values were reduced from about 2.0 to about 1.3 after intake of PETN (solution or tablet) with a minimum 60 to 90 min postdose (solution) and 2 h postdose (tablet). A significant reduction in this ratio was seen up to 8 (solution) or 12 h (tablet) post dose. Changes in blood pressure were not observed while the heart rate decreased in the subjects of all three groups 1 to 2 h postdose followed by an increase by 6 to 10 beats per min. After subtraction of the AUC values of placebo from the PETN-derived AUC values, mean values of 6.61 (SD 1.52, solution) and 7.25 (SD 1.48, A/D*h, tablet) were calculated (p > 0.1, study A).
EGDN [ethylene glycol dinitrate]
Ethylene Glycol Dinitrate [SYNONYM(s): Glycol dinitrate; Nitroglycol; Dinitroglycol; EGDN; Glycerin trinitrate] is a colorless to yellow, oily, odorless liquid. It is an explosive ingredient (60-80%) in dynamite along with nitroglycerine (40-20%).
EGDN and NG are used with a mixture of sodium nitrate and an absorbent, often wood pulp, to produce dynamite. EGDN is added to lower the freezing point of the EGDN/NG mixture and is currently the major component. The EGDN/NG ratio is about 8/2 or 9/1. This is the only commercial use for EGDN. Because EGDN is more volatile than NG, there is usually more airborne EGDN than NG from the dynamite mixture. In 1976, about 250 million pounds of dynamite, containing 5 to 50% EGDN/NG, were produced by U.S. manufacturers.
Headaches have developed in workers exposed to 0.4 to 0.67 mg/m3 for 25 minutes; all workers had decreases in blood pressure [Trainor and Jones 1966]. Ethylene glycol dinitrate and nitroglycerine are vasodilators and initial exposures result in headache, dizziness, nausea, or decreases in blood pressure; however, workers became tolerant of the vasodilatory activity after 2 to 4 days of exposure.
Angina pectoris has been reported among workers who were exposed to EGDN and/or NG. In those affected, the angina usually occurred in periods away from work. Sudden deaths without any apparent cause have also been reported among these workers. The deaths, like the angina, occurred more frequently during periods away from work. In most cases, the workers who died suddenly had no symptoms other than angina during periods away from work. The deaths are thought to be related to compensatory vasoconstriction (tolerance) induced by repeated exposure to the substances. Vasoconstriction is thought to lead to spasms of the coronary arteries and then the related angina pectoris and sudden deaths.
No data on acute inhalation toxicity are available on which to base the IDLH for ethylene glycol dinitrate (EGDN) and/or nitroglycerin. The chosen IDLH, therefore, is based on chronic toxicity data concerning the physiological response of animals to EGDN. According to Patty [1963], rats and guinea pigs survived 6 months of exposure to 500 mg/m3 (80 ppm) EGDN with the only effect being slight drowsiness and some Heinz body formation [Stein 1956]. Although Patty [1963] stated that EGDN is more toxic for cats and rabbits, the chosen IDLH is still probably conservative because cats given 2hour daily exposures to 21 ppm EGDN for 1,000 days exhibited only marked blood changes [von Oettingen 1946]. However, because of the assigned protection factor afforded by each device, 2,000 × the OSHA PEL of 0.1 mg/m3 (i.e., 200 mg/m3) is the concentration above which only the "most protective" respirators are permitted.
Nitrate esters
http://www.globalsecurity.org/military/systems/munitions/explosives-nitrate.htm-
On December 25, 2009, Umar Farouk Abdulmutallab, a Nigerian national, was accused of trying to ignite an incendiary device aboard a Northwest Airlines Flight headed to Detroit, MI; an act the White House declared "an attempted act of terrorism". The incendiary device was later identified by authorities of being a PETN-based device.
Nitrate (NO3-) (CAS No. 014797-55-8) is an inorganic anion resulting from the oxidation of elemental nitrogen. It is an essential nutrient for plant protein synthesis and plays a critical role in the nitrogen cycle of soil and water. Nitrates are produced by natural biological and physical oxidations and therefore are ubiquitous in the environment (Ridder and Oehme 1974). Most nitrate compounds are strong oxidizing agents and some can react violently with oxidizable substances and may explode if exposed to heat or shock.
Nitrates are produced by natural biological and physical oxidations and therefore are ubiquitous in the environment. Most of the excess nitrates in the environment originate from inorganic chemicals manufactured for agriculture. Organic molecules containing nitrate groups are manufactured primarily for explosives or for their pharmacological effects
NC [Nitrocellulose]
for many centuries gunpowder was the world's only explosive, and was not superseded until the discovery of guncotton. So long ago as 1832 Bracon discovered that woody fiber could be turned into an explosive by the action of concentrated nitric acid; and a few years later a French inventor, Dumas, tried to make cartridges of paper treated in similar fashion. If he had succeeded these would have been the first smokeless cartridges, but he failed; and it was not until 1845 that Schönbein, a German chemist, hit upon the proper method of treating cotton wool with nitric and sulphuric acids, so as to turn it into guncotton.
In 1847 an English firm, Messrs. Hall and Son of Faversham, began to manufacture guncotton, and military experts hailed it as the new explosive which would take the place of gunpowder. But this explosive was so terribly powerful that, when used in a gun or rifle, it blew the barrel to pieces. Worse than that, it was most dangerous to manufacture.
Two main problems had to be solved before it could be used as a gun propellant. First, the velocity of the explosion had to be reduced so that the charge weight required to propel the projectile would not shatter the gun tube. second, the density had to be increased so that a given charge weight would pack into a reasonable space. The first problem was solved in part by igniting NC instead of firing it with a detonator. The solution to the second problem actually solved both. In 1886, Vielle first colloided or gelatinized NC with alcohol and ether and, thus reduced the burning rate to acceptable levels. The procedure significantly increased the loading density of NC, establishing it as the foundational element in gun propellants used through the present day. Further developments resulted in materials that could be added to improve stowage qualities, reduce or eliminate flash, reduce hygroscopicity, reduce flame temperature, and even increase the propellant force or impetus.
Munitions manufacturing processes may generate nitrocellulose (NC) fines. Disposal of these fines is difficult because of their reactive nature. Composting has potential to be a safe and cost effective means of disposal. Open burning is no longer permitted in several states and is expected to banned nationally in the future. Open detonation is also the least acceptable form of disposal because of uncontrolled pollution by-products. In its role as the Department of Defense Manager for conventional munitions, Army must be able to dispose of Propellants/Explosives/Pyrotechnics production wastes. In composting, a controlled biological process, microorganisms convert biodegradable hazardous material to innocuous, stabilized by-products, typically at elevated temperatures between 50 - 55 °C. The increased temperatures result from heat produced by the microorganisms as they degrade the organic material in the waste. The NC fines are mixed with bulking agents and organic amendments, such as wood chips and animal and vegetable wastes, to enhance the porosity of the mixture. Maintaining moisture content, pH, oxygenation, temperature, and the carbon-to-nitrogen ratio achieves maximum degradation efficiency.
NG [Nitroglycerin ]
Nitroglycerin (NG) [Synonyms: 1,2,3-Propanetriol trinitrate; glycerol trinitrate; nitroglycerol; NG; trinitroglycerol; NTG; trinitrin] is an oily liquid at room temperature; colorless in pure form and pale yellow or brown in commercial form. It is used in manufacture of dynamite, gunpowder, and rocket propellants, and as a therapeutic agent primarily to alleviate angina pectoris. NG is used to make smokeless gun powder and rocket propellants. Single-base powders contain only nitrocellulose, double-base powders contain nitrocellulose and NG, and triple-base powders contain nitrocellulose, NG, and other combustible materials.
In 1847 a new explosive came into being. This was nitroglycerine, made by treating glycerine with nitric and sulphuric acids. But at first it was even more dangerous to handle than guncotton, for the least shock exploded it, and its violence was terrific.
The great chemist Alfred Nobel tried to improve it by mixing it with gunpowder, but the powder did not absorb all the nitroglycerine, and accidents of the most terrible kind became more and more frequent. Yet the new explosive, being liquid, could be poured into crevices in rocks, and was so useful as a blasting agent that its manufacture went on until a large vessel carrying cases of the explosive from Hamburg to Chili blew up at sea. The ship was blown to bits and her crew killed, and the disaster caused so great a sensation that the manufacture of nitroglycerine was prohibited in Sweden, Belgium, and in England. But Nobel still continued his experiments, and at last, after trying sawdust and all other sorts of absorbents in vain, found the perfect absorbent in the shape of keiselguhr-a sort of earth made of fossil shells. The mixture is what we know to-day as dynamite; and in spite of the fact that modern chemistry has produced very many new explosives, some of terrific power, dynamite remains the safest and most widely used of all explosives.
Nitroglycerin (NG) is a vasodilator and has been associated with acute episodes of angina pectoris, myocardial infraction, and sudden death. Workers engaged in the production or use of dynamite are potentially exposed to mixed vapors of nitroglycerin (NG) and ethylene glycol dinitrate (EGDN). Initial exposure to NG (or NG:EGDN mixtures) characteristically results in an intense throbbing headache that begins in the forehead and moves to the occipital region. Volunteers developed mild headaches when exposed to NG:EGDN vapor at concentrations of 0.5mg/m^3 for 25 minutes. It has been suggested that at least some workers may develop headaches at concentrations in excess of 0.1 mg/m^3. Other signs and symptoms associated with initial exposure include dizziness, nausea, palpitations, and decreases in systolic, diastolic, and pulse pressures. These initial signs and symptoms, including headache, are indicative of a shift in blood volume form the central to the peripheral circulatory system, initiated by dilation of the blood vessels.
After 2 to 4 days of repeated NG exposure, tolerance to the vasodilatory activity occurs, probably as a result of compensatory vasoconstriction. Tolerance may be lost during periods without NG exposure, such as weekends and holidays. Chronic repeated exposures to NG and NG mixtures also have been associated with more serious cardiovascular effects, including angina pectoris and sudden death.
Signs and symptoms of ischemic heart disease were observed in nine munitions workers involved in handling a nitroglycerin-cellulose mixture. Within 1 to 4 years of initial exposure, these workers developed nonexertional chest pain, which was relieved either by therapeutic nitroglycerin or by returning to work after the weekend. Coronary angiography performed in five of the patients showed no obstructive lesions. In one patient, observed while in a withdrawal state, coronary artery spasm was demonstrated and readily reversed by sublingual nitroglycerin.
Sudden deaths in previously healthy workers have been reported among those exposed to NG or to NG: EGDN mixtures. Like the attacks of angina pectoris, sudden deaths occurred most frequently during brief periods away from work, in particular on Sunday nights or Monday mornings. In most cases, there were no premonitory signs or symptoms although some subjects had anginal episodes during brief periods away from work. Atherosclerotic plaques, with or without thrombosis, have been found in the coronary arteries of workers at autopsy, but their coronary arteries generally were not occluded to the same extent as those of unexposed workers who had died suddenly.
The pathogenesis of the sudden death syndrome has been postulated to be due to withdrawal of coronary vasodilators (e.g. NG), resulting in vasoconstriction with acute hypertension, or with myocardial ischemia in workers adapted to and dependent on NG to maintain a minimum level of coronary flow. A second contributing mechanism for coronary artery toxicity due to NG may relate to so-called aging of the vessels due to repeated dilation. Other theories suggest that sudden deaths may be related to peripheral vasodilation consequent to reexposure of NG.
Estimates of exposure levels associated with sudden death have not been made because workers typically absorb considerable amounts of NG through the skin in addition to inhalation.
Employees handling NG should be given personal protective equipment to prevent the absorption of NG through the skin. However, neither natural rubber nor synthetic rubber gloves, including neoprene gloves, are impervious to NG. The wearing of such gloves tends to hold the chemical in contact with the skin, thus promoting its absorption. Preferably, cotton-lining gloves should be worn underneath nitrile gloves and both gloves changed ever 2-1/2 hours (USAEHA Technical Guide 24).
More recent studies have suggested that the effects of long-term workplace exposure to NG may not be completely reversed after exposure is terminated. Former workers may be at increased risk for cardiovascular mortality for months to years after exposure has ceased.
Individuals with preexisting ischemic heart disease should not be assigned to work where significant exposure to NG may occur. Early identification of cardiovascular disease is the primary goal of medical surveillance of nitroglycerin workers. A preplacement examination must be administered to all new employees occupational histories, a physical examination, and indicated laboratory tests, record of their pulse rates. Periodic examinations should be conducted semiannually, with the same focus as the preplacement examination. During the periodic examination, the physician should be aware that headaches that occur during work shifts could indicate skin absorption of nitroglycerin, even if air concentrations of nitroglycerin are below the PEL. Examinations with similar content are necessary when exposure to nitroglycerin has been terminated, although surveillance should perhaps extend beyond employment, due to the latency of the withdrawal effects. Monitoring should include pulse, blood pressure, CBC, urinalysis, resting EKG and lipid profile.
PETN [Pentaerythritol tetranitrate]
Pentaerythritol tetranitrate, C5H8N4012 (PETN), has a specific gravity of solids of 1.76 and a confined detonation velocity of over 25,000 fps. PETN is used as a priming composition in detonators, a base charge in blasting caps, and a core load for detonating fuse. PETN is very much used in Detonating Cord of which it is the explosive core (Primacord), where it develops a velocity rate of 21,000 feet per second. Detonating cord is insensitive to friction and ordinary shock, but may be exploded by rifle fire. It also detonates sympathetically with the detonation of an adjacent high explosive.
PETN is one of the strongest known high explosives with a relative effectiveness factor (R.E. factor) of 1.66. It is more sensitive to shock or friction than TNT or tetryl, and it is never used alone as a booster. It is primarily used in booster and bursting charges of small caliber ammunition, in upper charges of detonators in some land mines and shells, and as the explosive core of primacord.
During World War II the M9A1 2.36" Rocket Launcher (Bazooka) charge, with 8 oz of pentolite, could penetrate up to 5 inches of armor.
Demolition charge, M118, commonly called Flex-X or sheet explosive, consists of 4 half-pound sheets of flexible explosive packed in a plastic envelope. Each sheet is approximately 3 inches wide, 12 inches long, and 1/4 inch thick. Note: The exact explosive contained in an M118 charge varies with the manufacturer. At present, some manufacturers use PETN as the basic explosive. Others use RDX. Charges manufactured in the future may include other explosives.
PETN does not occur naturally, so the production and use of this kind of compound can lead to contamination of the environment. PETN is subject to biodegradation in untreated or unpreserved urine and feces. There also have been some reports of its degradation by bacteria, whose PETN reductase sequentially denitrates PETN into tri- and dinitrates (French et al., 1996). The last compound shown in the pathway, pentaerythritol dinitrate, is degraded further to unknown products.
In 1995 Haustein KO, Winkler U, Loffler A, Huller G. of the Abteilung Klinische Pharmakologie, Medizinische Hochschule Erfurt, Germany reported on a study of PETN's cardiovascular effects. The effects of 80 mg pentaerithrityl-tetranitrate (PETN) as suspension or formulated as tablets were compared to placebo in a single blind, randomized, crossover study in 18 healthy subjects (study A), and the bioequivalence of two tablet formulations (marketed Dilcoran 80 vs a new formulation) was studied in 24 healthy subjects after administration of single oral doses of 80 mg PETN according to a placebo controlled, randomized, double blind, two-way crossover study design (study B). The perfusion of the right middle finger was measured by rheography (altitude A of the changes of resistance and of the incisure D) before and 24 h post-dose, and blood pressure and heart rate were measured in supine position at the same time. The values of area under curve (AUC) of the ratio A/D were calculated by the trapezoidal rule. In study A the mean A/D-values were reduced from about 2.0 to about 1.3 after intake of PETN (solution or tablet) with a minimum 60 to 90 min postdose (solution) and 2 h postdose (tablet). A significant reduction in this ratio was seen up to 8 (solution) or 12 h (tablet) post dose. Changes in blood pressure were not observed while the heart rate decreased in the subjects of all three groups 1 to 2 h postdose followed by an increase by 6 to 10 beats per min. After subtraction of the AUC values of placebo from the PETN-derived AUC values, mean values of 6.61 (SD 1.52, solution) and 7.25 (SD 1.48, A/D*h, tablet) were calculated (p > 0.1, study A).
EGDN [ethylene glycol dinitrate]
Ethylene Glycol Dinitrate [SYNONYM(s): Glycol dinitrate; Nitroglycol; Dinitroglycol; EGDN; Glycerin trinitrate] is a colorless to yellow, oily, odorless liquid. It is an explosive ingredient (60-80%) in dynamite along with nitroglycerine (40-20%).
EGDN and NG are used with a mixture of sodium nitrate and an absorbent, often wood pulp, to produce dynamite. EGDN is added to lower the freezing point of the EGDN/NG mixture and is currently the major component. The EGDN/NG ratio is about 8/2 or 9/1. This is the only commercial use for EGDN. Because EGDN is more volatile than NG, there is usually more airborne EGDN than NG from the dynamite mixture. In 1976, about 250 million pounds of dynamite, containing 5 to 50% EGDN/NG, were produced by U.S. manufacturers.
Headaches have developed in workers exposed to 0.4 to 0.67 mg/m3 for 25 minutes; all workers had decreases in blood pressure [Trainor and Jones 1966]. Ethylene glycol dinitrate and nitroglycerine are vasodilators and initial exposures result in headache, dizziness, nausea, or decreases in blood pressure; however, workers became tolerant of the vasodilatory activity after 2 to 4 days of exposure.
Angina pectoris has been reported among workers who were exposed to EGDN and/or NG. In those affected, the angina usually occurred in periods away from work. Sudden deaths without any apparent cause have also been reported among these workers. The deaths, like the angina, occurred more frequently during periods away from work. In most cases, the workers who died suddenly had no symptoms other than angina during periods away from work. The deaths are thought to be related to compensatory vasoconstriction (tolerance) induced by repeated exposure to the substances. Vasoconstriction is thought to lead to spasms of the coronary arteries and then the related angina pectoris and sudden deaths.
No data on acute inhalation toxicity are available on which to base the IDLH for ethylene glycol dinitrate (EGDN) and/or nitroglycerin. The chosen IDLH, therefore, is based on chronic toxicity data concerning the physiological response of animals to EGDN. According to Patty [1963], rats and guinea pigs survived 6 months of exposure to 500 mg/m3 (80 ppm) EGDN with the only effect being slight drowsiness and some Heinz body formation [Stein 1956]. Although Patty [1963] stated that EGDN is more toxic for cats and rabbits, the chosen IDLH is still probably conservative because cats given 2hour daily exposures to 21 ppm EGDN for 1,000 days exhibited only marked blood changes [von Oettingen 1946]. However, because of the assigned protection factor afforded by each device, 2,000 × the OSHA PEL of 0.1 mg/m3 (i.e., 200 mg/m3) is the concentration above which only the "most protective" respirators are permitted.
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