Showing papers on "Ammonium perchlorate published in 2005"

The origin of naturally occurring perchlorate: the role of atmospheric processes.

Abstract: Perchlorate, an iodide uptake inhibitor, is increasingly being detected in new places and new matrices. Perchlorate contamination has been attributed largely to the manufacture and use of ammonium perchlorate (the oxidizer in solid fuel rockets) and/or the earlier use of Chilean nitrate as fertilizer (∼0.1% perchlorate). However, there are regions such as the southern high plains (Texas Panhandle) where there is no clear historical or current evidence of the extensive presence of rocket fuel or Chilean fertilizer sources. The occurrence of easily measurable concentrations of perchlorate in such places is difficult to understand. In the southern high plains groundwater, perchlorate is better correlated with iodate, known to be of atmospheric origin, compared to any other species. We show that perchlorate is readily formed by a variety of simulated atmospheric processes. For example, it is formed from chloride aerosol by electrical discharge and by exposing aqueous chloride to high concentrations of ozone. ...

Burning of Nano-Aluminized Composite Rocket Propellants

Abstract: Several aluminum nanopowders were examined and compared with the final goal to evaluate their application in solid rocket propulsion. A detailed investigation of pre-burning properties by the Brunauer-Emmet-Teller method, electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy was carried out. Ballistic properties and the combustion mechanism of several aluminized propellant formulations were investigated. In particular, aggregation and agglomeration of metal particles at and near the burning surface were analyzed by high-speed high-resolution color digital video recordings. All tested nano-powders are of Russian production; their physical characterization was carried out at the Istituto Donegani (Novara, Italy); ballistic studies were performed at the Solid Propulsion Laboratory (Milano, Italy) using laboratory and, for comparison, industrial composite propellants based on ammonium perchlorate as an oxidizer. Results obtained under a fair variety of operating conditions typical of rocket propulsion indicate, for increasing nano-Al mass fraction or decreasing nano-Al size, larger steady burning rates with essentially the same pressure sensitivity. While aggregation and agglomeration phenomena still occur, their significance may be reduced by using nano-Al instead of micro-Al.

Effects of Ammonium Perchlorate on Thyroid Function in Developing Fathead Minnows, Pimephales promelas

Abstract: Perchlorate is a known environmental contaminant, largely due to widespread military use as a propellant. Perchlorate acts pharmacologically as a competitive inhibitor of thyroidal iodide uptake in mammals, but the impacts of perchlorate contamination in aquatic ecosystems and, in particular, the effects on fish are unclear. Our studies aimed to investigate the effects of concentrations of ammonium perchlorate that can occur in the environment (1, 10, and 100 mg/L) on the development of fathead minnows, Pimephales promelas. For these studies, exposures started with embryos of < 24-hr postfertilization and were terminated after 28 days. Serial sectioning of thyroid follicles showed thyroid hyperplasia with increased follicular epithelial cell height and reduced colloid in all groups of fish that had been exposed to perchlorate for 28 days, compared with control fish. Whole-body thyroxine (T4) content (a measure of total circulating T4 in fish exposed to 100 mg/L perchlorate was elevated compared with the T4 content of control fish, but 3,5,3-triiodothyronine (T3) content was not significantly affected in any exposure group. Despite the apparent regulation of T3, after 28 days of exposure to ammonium perchlorate, fish exposed to the two higher levels (10 and 100 mg/L) were developmentally retarded, with a lack of scales and poor pigmentation, and significantly lower wet weight and standard length than were control fish. Our study indicates that environmental levels of ammonium perchlorate affect thyroid function in fish and that in the early life stages these effects may be associated with developmental retardation.

High Pressure Testing Of Composite Solid Rocket Propellant Mixtures: Burner Facility Characterization

Abstract: Much Research on composite solid propellants has been performed over the past few decades and much progress has been made, yet many of the fundamental processes are still unknown, and the development of new propellants remains highly empirical. Ways to enhance the performance of solid propellants for rocket and other applications continue to be explored experimentally, including the effects of various additives and the impact of fuel and oxidizer particle sizes on burning behavior. One established method to measure the burn rate of composite propellant mixtures in a controlled laboratory setting is to use a constant-volume bomb, or strand burner. To provide high-pressure burn rate data at pressures up to 360 atm, the authors have installed and characterized a new strand burner facility at the University of Central Florida. Details on the new facility and the measurement procedures are summarized. Repeatability between different batches of the same mixture has been demonstrated to be very good, and two common HTPB/Ammonium Perchlorate (AP) propellant mixtures containing 7/3 and 5/5 bimodal AP distributions were tested in the burner. The resulting burn rates are compared to data from the literature with good agreement in burn rate exponent and the impact of changing from a 7/3 to a 5/5 AP split.

Experimental and Model Study of Agglomeration of Burning Aluminized Propellants

Abstract: Agglomerate sizes of ammonium perchlorate/cyclotrimethylene trinitramine/aluminum/hydroxyl-terminated polybutadiene propellants with virgin aluminum sizes of 7, 17, and 30 μm were measured by a cinephotomicrography experimental technique under 300- (2.07-) and 1000-psi(6.89-MPa) pressures. The measured sizes followed a log-normal distribution. A decrease in the virgin aluminum size leads to an increase in the mean agglomerate size. The effect diminishes when the aluminum size increases or the pressure decreases. Gany and Caveny's theory indicates that the virgin aluminum size/mobile molten layer thickness controls the degree of agglomeration. Their theory was tested and validated using data obtained from three different propellant systems. Agglomerate size data from 14 different sources in the literature were carefully reviewed. These data were obtained from aluminized composite propellants containing two different types of oxidizer: ammonium perchlorate and ammonium perchlorate and cyclic nitramines. A new agglomeration parameter A that is a function of burning rate and propellant formulation is proposed to correlate the selected 126 agglomerate size data including 6 experimental data generated in the study. It was found that the proposed new agglomerate size model can better explain the literature data for both ammonium perchlorate/aluminum/rubber and ammonium perchlorate/nitramine/aluminuni/rubber propellants rather than the Hermsen model over a wide range of experimental conditions. Validity of the new model was tested with data from a recent publication.

Perchloric Acid and Perchlorates

Abstract: Perchlorates are chlorine oxyanions in which the chlorine is present in its highest oxidation state (+7). The most outstanding property of the perchlorates, which are more stable than other chlorine oxyanions, is their oxidizing ability. Most cations form perchlorate compounds. Commercially, one of the most important compounds of this class is ammonium perchlorate, used as an oxidizer in propellant formulations for solid rocket fuel. Perchlorates are also used in explosives and pyrotechnics, in dry batteries, and in oxygen-generation systems. Commercial perchlorates are prepared by electrochemical oxidation. Perchloric acid, commercially available as a 72% aqueous solution, is one of the strongest of the mineral acids. Properties, manufacturing, and uses of these compounds are described. Keywords: chlorine heptoxide; perchloric acid; ammonium perchlorate; alkali metal perchlorates; trace metal analysis; perchlorates

Novel biomarkers of perchlorate exposure in zebrafish.

Abstract: Perchlorate inhibits iodide uptake by thyroid follicles and lowers thyroid hormone production. Although several effects of perchlorate on the thyroid system have been reported, the utility of these pathologies as markers of environmental perchlorate exposures has not been adequately assessed. The present study examined time-course and concentration-dependent effects of perchlorate on thyroid follicle hypertrophy, colloid depletion, and angiogenesis; alterations in whole-body thyroxine (T4) levels; and somatic growth and condition factor of subadult and adult zebrafish. Changes in the intensity of the colloidal T4 ring previously observed in zebrafish also were examined immunohistochemically. Three-month-old zebrafish were exposed to ammonium perchlorate at measured perchlorate concentrations of 0, 11, 90, 1,131, and 11,480 ppb for 12 weeks and allowed to recover in clean water for 12 weeks. At two weeks of exposure, the lowest-observed-effective concentrations (LOECs) of perchlorate that induced angiogenesis and depressed the intensity of colloidal T4 ring were 90 and 1,131 ppb, respectively; other parameters were not affected (whole-body T4 was not determined at this time). At 12 weeks of exposure, LOECs for colloid depletion, hypertrophy, angiogenesis, and colloidal T4 ring were 11,480, 1,131, 90, and 11 ppb, respectively. All changes were reversible, but residual effects on angiogenesis and colloidal T4 ring intensity were still present after 12 weeks of recovery (LOEC, 11,480 ppb). Whole-body T4 concentration, body growth (length and weight), and condition factor were not affected by perchlorate. The sensitivity and longevity of changes in colloidal T4 ring intensity and angiogenesis suggest their usefulness as novel markers of perchlorate exposure. The 12-week LOEC for colloidal T4 ring is the lowest reported for any perchlorate biomarker in aquatic vertebrates.

Perchlorate occurrence mapping

Abstract: The national occurrence of perchlorate in drinking water was analyzed and geographically mapped by compiling data from existing perchlorate occurrence surveys. The existing surveys included studies by USEPA and by the States of Arizona, California, Massachusetts, and Texas. Perchlorate occurrence was found to be national in scope, with detections in 26 states and Puerto Rico. Perchlorate was detected in at least one entry point to the distribution system of approximately 5% of the nation’s large (>10,000 population) Community Water Systems. Geographically, the highest density of perchlorate detection was found to be in Southern California, west central Texas, along the east coast between New Jersey and Long Island and in Massachusetts. At the present time no perchlorate has been detected in drinking water in the northern Great Plains, the central and northern Rocky Mountains, Alaska or Hawaii. If detected, perchlorate was typically present at concentrations of less than 12 ug/L. The frequency of perchlorate detection increased with lower detection limits, indicating that perchlorate will be more frequently detected if analytical methods of greater sensitivity are used. Perchlorate was often detected in drinking water in areas for which there was no documented environmental release of perchlorate. This implies that the environmental release of perchlorate is more wide spread than anticipated or that undocumented mechanisms of perchlorate formation exist. Since two of the occurrence surveys summarized by this study are still in progress, it is likely that the estimates of perchlorate occurrence made by this report represent a lower bound of the actual number of drinking water systems impacted by perchlorate contamination. 1.0 INTRODUCTION In 1998 perchlorate was added to the USEPA contaminant candidate list (CCL), indicating the agency’s potential interest in regulating this contaminant in drinking water. Inclusion of perchlorate on the CCL was primarily based upon the discovery of perchlorate in California drinking water supplies. Of key concern was the environmental release of ammonium perchlorate by two manufacturers located in Nevada. These releases were associated with low levels of perchlorate contamination in found in Lake Mead and the Colorado River. This water is used for drinking water, irrigation and recreation by millions of people in Nevada, California, and Arizona. Subsequent investigations have identified perchlorate releases to the environment in as many as 26 states. Salts of perchlorate (ClO4) are used in a number of applications including as an oxidizer in solid rocket fuel, and as a component of fireworks, pyrotechnics, flares and explosives. It has also been used medicinally as a treatment for hyperthyroidism as well as a analytical chemical reagent. Perchlorate has also been identified in fertilizers. On a volume basis, more perchlorate is used in the production of solid rocket fuel than for all other uses combined. While the vast majority of perchlorate occurrence in the environment is anthropogenic in nature, there may be instances of natural perchlorate occurrence.

The Effect of Ammonium Nitrate, Coarse/Fine Ammonium Nitrate Ratio, Plasticizer, Bonding Agent, and Fe 2 O 3 Content on Ballistic and Mechanical Properties of Hydroxyl Terminated Polybutadiene Based Composite Propellants Containing 20 % AP

Abstract: It was aimed to develop the HTPB (hydroxyl terminated polybutadiene) based composite solid propellant with reduced smoke in acceptable mechanical and ballistic properties by using AN (ammonium nitrate) and AP (ammonium perchlorate) as oxidizing agents. For this reason, five different combinations, employed by increasing the AN content as 33, 43, 53, 63, and 73 % and decreasing the AP content as 40, 30, 20, 10, and 0 % were used. The propellant containing 20 % AP and 53 % AN was selected to have good processability and lower smoke content among five compositions. The content of DOA (dioctyl adipate) used as a plasticizer was varied between 35 % and 25 % of HTPB binder to improve the mechanical properties with taking the above composition as a reference. In decreasing the DOA content, mechanical properties could not be improved to the desired level, and the amount of the bonding agent TEPANOL (tetraethylene pentamineacrylonitrileglycidol) was increased from 0.2 % to 0.35 mass percent with keeping DOA content at the level of 25 % of HTPB binder. 0.495 N/mm2 maximum tensile stress and 25.5 % elongation at maximum tensile stress and 3.635 N/mm2 elastic modulus values were then obtained with 0.35 % TEPANOL value. The effect of coarse/fine AN ratio on buring rate of the propellant was also tested for three different ratios, i.e., 80/20, 70/30, and 60/40. The 70/30 ratio gave the highest burning rate. Then, the content of burning rate catalyst Fe2O3 (iron oxide) was varied between 2 % and 1.0 % with keeping the coarse/fine AN ratio at 70/30, and it was found that 2 % Fe2O3 gave the highest burning rate. Values of densities and heat of explosion were also determined for all compositions tested.

Laminate Propellant Combustion (Review) 1. Experimental Investigations

Abstract: A review of experimental research of the combustion of laminate propellants of solid oxidizer (primarily ammonium perchlorate) and hydrocarbon binder is given. The purpose and description of the simplification of heterogeneous propellants through the use of constituent layers is detailed. This first of a two-part review describes the development of knowledge of the deflagration of laminates through a number of experimental methods used to quantitatively and qualitatively observe the condensed phase, surface structure, gas phase flame structure, burning rate, species concentrations, and temperature fields. These observations have generated a wealth of two-dimensional experimental data that can be used for validating computational and theoretical models.

Propellant formulation and projectiles and munitions employing same

Abstract: A solid, heterogeneous, high performance rocket propellant, operable at high pressure with a burn rate relatively insensitive to changes in pressure and temperature. The propellant includes a binder, ammonium perchlorate particles, metal particles, and iron oxide. The ammonium perchlorate particles comprise a multimodal mixture of rounded particles having a weight mean diameter of from about 70 μm to about 110 μm and of nonrounded particles having a weight mean diameter of from about 7.5 μm to about 15 μm. In one embodiment, the propellant includes a binder formed from the reaction of a hydroxy terminated polybutadiene with a diisocyanate, ammonium perchlorate as an oxidizer, aluminum as a fuel, and iron oxide as a burn rate modifier. The propellant may also include bonding agents, curing catalysts, a plasticizer, antioxidant/peroxide scavengers, and pot life extenders.

Perchlorate Leaching from Solid Rocket Motor Propellant in Water

Abstract: Several launch vehicle solid rocket motor propellants contain ammonium perchlorate as a major ingredient, and so the potential exists for perchlorate release to the environment during launch operations and propellant manufacture. Solid composite base propellants containing four types of binder were studied: hydroxyl-terminated polybutadiene, carboxyl-terminated polybutadiene, polybutadiene-acrylic acid-acrylonitrile terpolymer, and polyurethane. The rate of perchlorate release from solid propellant during immersion in deionized and simulated seawater has been measured at 5, 20, and 29°C. The rate-limiting step is most probably diffusion, and the diffusion coefficient is given. Arrhenius terms are presented to facilitate calculation of diffusion coefficients at intermediate temperatures. The diffusion coefficients for all propellant types and conditions tested fall in the range from 3.6 X 10 - 1 2 to 1.1 × 10 - 1 3 m 2 s - 1 . The diffusion coefficients for each propellant type are proportional to temperature and inversely related to salinity.

Catalysis of Nanometer Transition Metals on the Thermal Decomposition of Ammonium Perchlorate

Abstract: To study the influence of na no meter transition metals on the thermal decomposition of ammonium perchlorate (AP ),three kinds of nanometer transition metals (Ni,Cu and Co) were prepared from a n aqueous solution by reducing their corresponding metal salts DTA was employed to test the thermal decomposition of AP in the nanometer transition metal/AP co mposite Results indicate that the catalysis of nanometer Ni and Cu increases wi th the content of nanometer metals and the high and low temperature decompositio n peaks have a tendency of overlapping together The suitable content of nanomet er metal Co powder in the composite presentes at about 5%,while the catalysis of nanometer metal Co results in the lowest thermal decomposition temperature of A P in the composite at about 288 ℃ The catalytic capability of nanometer transi tion metals accordes with the stabilization energy order of their complexes formed with NH_3 as a decomposed intermediate of AP: CoCuNi

Synthesis of chiral crown ethers and complexation with chiral protonated amine compounds: X-ray crystal and nuclear magnetic resonance studies of perchlorate salt of chiral benzo-monoaza-15-crown-5 and chiral monoaza-15-crown-5

Abstract: The X-ray crystal structure of IX, perchlorate salt of R-(−-2-ethyl-N-benzyl-4,7,19,13-tetraoxa-8,9-benzo-1-azacyclopentadec-8-ene has been determined. In the molecule, the protonated nitrogen atom participates in two N-H⋯O hydrogen bonds. The unusually high proton affinity of aza crown ether leads to the formation of diastreomer instead of complex formation with chiral R-(+)-1-phenyl ethyl ammonium perchlorate and S-(−)-1-phenyl ethyl ammonium perchlorate. The complex ability of host ethers was evaluated in terms of structural modification.

Effect of Nanometer Cu Powder on Thermal Decomposition of Ammonium Perchlorate

Abstract: The decomposition behaviour of ammonium perchlorate (AP) has been investigated in the presence of Cu nanopowder by DTA. The results show that nanometer Cu powder decreased the first and second thermal decomposition temperature of AP by 35.1 ℃ and 130.2 ℃, respectively, and the DTA heat release of AP in the presence of Cu nanopowders increased to 1.20 kJ·g-1, showing good catalytic effect on the thermal decomposition of AP. The catalytic effect of Cu micron-size powder on the thermal decomposition of AP was less than that of Cu nanopowder. With the increase in content, Cu nanopowder enhanced its catalytic effect on the high temperature decomposition of AP, however, it weakened its catalytic effect on the low temperature decomposition of AP. The mechanism of catalysis for the thermal decomposition of AP is as follows: (1) metal oxider acts as the intermedium in the process of election tranfer, (2) Cu nanopowder reacts with the decomposed product of AP, (3) Cu nanopowder has special surface effect.

Antistatically finished polymer compositions the production thereof and their use

Abstract: The invention relates to a polymer composition, which contains at least one ammonium perchlorate and at least one organic solvent and which is provided for preferably halogen-containing polymers.

Preparation of Nanometer Cu Powder and Study on Its Catalytic Characteristic of Thermal Decomposition of Ammonium Perchlorate

Abstract: Crystal nanometer Cu powder, the average particle size of which is 20nm, is prepared in solution. The composite particle of the nanometer Cu and of micrometer ammonium perchlorate has been obtained by grinding. DTA was used to investigate the catalytic characteristics of the nanometer Cu. The findings show that the nanometer Cu makes both the low and the high temperature exothermic peak decrease 35.1℃ and 130.2℃ respectively, while the apparent decomposition heat of ammonium perchlorate increases by 172.7%, indicating that the nanometer Cu can produce very good catalytic effect on ammonium perchlorate. The catalytic mechanism of the nanometer Cu on the thermal decomposition of ammonium perchlorate is explored as well.

Pyrotechnic gas generating composition for car safety systems having a combustion temperature below 2200 degree K

Abstract: Pyrotechnic gas-generating composition comprises ammonium perchlorate (15-30 wt.%), copper oxide and/or manganese oxide, and nitroguanidine, guanidinium nitrate, oxamide, dicyandiamine or a metal cyanamide. The weight ratio of ammonium perchlorate to copper oxide and/or manganese oxide is less than 1.

Preparation and Thermal Decomposition Behavior of Nano-Nd_2O_3/Ammonium Perchlorate Composite Particles

Abstract: Nano neodymium oxide has been synthesized by solid reaction at room temperature.The nano-Nd_2O_3/ammonium perchlorate (AP) composite particles have been prepared by a novel solvent-nonsolvent method. XRD and TEM are used to characterize this microstructure. The catalytic effect of nanosized Nd_2O_3 on thermal decomposition reaction of AP in the composite particle has been investigated by DTA method. It is shown that the decomposition temperature of nano-Nd_2O_3 /AP composite at high temperature side decreases (88°C).

Preparation of nano-structured copper-chromium oxide and its catalytic effect on RDX/AP/Al/HTPB propellant

Abstract: A novel nano-structured Copper-Chromium oxide(ns-CC),which consisted of Copper-Chromium oxide(CC) nano particles and an inert component,was prepared to solve the aggregation problem of nano particles.It was studied that the effect of pyrolytic conditions of copper ammonium chromate precursor on the particle size of CC in ns-CC.Upon XRD analysis and TEM observation.The results show that particle size of CC decreases as heating rate increases and holding time at maximum pyrolytic temperature has no obvious influence on particle size of CC.The catalytic thermal decomposition of ammonium perchlorate(AP) with ns-CC showes that the apparent exothermic heat of AP is enhanced greatly and the decomposition temperature at high-temperature decomposition zone of AP is lowered from 446℃(pure AP) to 351℃ with addition of small amount of ns-CC.When 0.5% ns-CC and common CC(by weight) were added into RDX/AP/Al/HTPB composite propellant,the burning rates at 6MPa increased from 6.31 mm/s(without catalyst) to 8.82 and 8.69 mm/s respectively;and the pressure exponent in the range of 4~10 MPa increased from 0.35(without catalyst) to 0.38 and 0.49 respectively,implying the prosperous potential of using ns-CC as propellant catalyst.

Pyrotechnic charge comprising deuterated compounds

Abstract: A pyrotechnic charge for producing IR radiation comprises a deuterated compound as either a fuel and/or oxidising agent and/or binder. A minimum of 50% of hydrogen atoms in the deuterated compound are deuterium atoms and the fuel compound may be selected from deuterated hydrocarbons, boranes, polysilanes, alkali metal borodeuterides, alkali metal deuterides, deuterated anthracene or phenanthrene. The mass of the fuel is between 10-55%. The oxidising agent may be a deuterated ammonium compound such as an ammonium perchlorate, nitrate, dinitramide or hydrazinium nitroformate. The mass of the oxidising agent is between 40-85%. The binding agent may be a deuterated polymer, such as a PVC, HTPB or polystyrene. The mass of the binding agent is between 1.5-5%. The use of the desired pyrotechnic charge, which preferably provides the signature of a decoy aircraft, leads to a greater selective radiant emission in the b -band whilst also reducing the selective radiant emission in the a -band.

Effects of Fullerene on Thermal Decomposition Characteristics of Ammonium Perchlorate

Abstract: The thermogravimetric analysis (TG-DTG), differential thermal analysis (DTA) and oxygen bomb combustion calorimetry experiments are used to evaluate the effects of carbon black (CB), fullerene soot (FS), extracted fullerene soot (EFS) and pure C60 on the thermal decomposition characteristics of Ammonium Perchlorate (AP). The investigations show that FS can evidently improve the low temperature decomposition of AP and i ncrease the exothermic amount and detonation heat of AP.