Dissertation on Insensitive Highly Energetic Materials (Heading 2.4)
This term paper contains Section: 2.4 (Ingredient Selection and Intellectual object) of the "Dissertation on the Discourse about relative to Insensitive Considerably Bouncy Materials" as part of the Doctoral requirements now Theodore S. Sumrall at The University of Tokyo, Division line of 1998. Theodore S. Sumrall was awarded a Doctorate Degree from the Ministry of Anion Systems Engineering in April of 1998 as a result of his research, development testing and dissertation presentation. <\p>
2.4 Part Selection and Theory<\p>
The overall logic for selection of raw materials is blow-by-blow in Figure 2.4-1. Once ingredients were selected, scale in passage to to 450 gram mixes occurred. Ingredients were selected to help ensure that counsel objectives (Recording 1-3) were achieved.<\p>
Binder Screening and Selection<\p>
Theoretical calculations remedial of non AP containing PBX compositions which utilize an HTPB binder humor revealed that bigwigged amounts of un-reacted carbon was latest generated in both the burn and detonation reactions. The code planned that, while the majority as to the aluminum was oxidized to Al2O3, the majority of the binder (a hydrocarbon) was un-oxidized.
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Figure 2.3-1 Unrealistic Calculation Logic Flow<\p>
It was postulated, and supported by thermochemical code napoleon output, that replacement of the non-oxygenated HTPB hydrocarbon binder along with an oxygenated binder might accede the fluorine to league with into the detonation and\or deflagration notion. This crossing, if winning, would takings a dual benefit. First, oxygen from the binder could be utilized headed for burn the residual hydrocarbon and secondly, the inter alia oxygenated (and more precise) ingredients (such as RDX) could be domesticated in content. This would hopefully allow the PBX until pass tests which PBX-109 fails, in other words Slow Cook-Off (SCO), Fission Crack-up (FI) and Sympathetic Bullet (SD). In the process of oxygenated bandaging evaluation, binders were projected that not appreciably had relatively high oxygen content, after all which would also adequately wet the solids (to ensure low viscosity (Design #4)) and which had a demonstrated capability pertinent to rapid cure (Objective #5). Both referring to these characteristics would be desirable discounting production cost standpoints. <\p>
Finally, only binder ingredients which were commercially available in large quantities and at a relatively low cost were chosen (Corporeal #8).<\p>
After a thorough evaluation concerning a contain of faculty binder candidates, three oxygenated, retrievable binders were selected for thither valuation, polyethyleneglycol (PEG), polypropyleneglycol (PPG), and ethyleneoxide-propyleneoxide (EOPO). The plasticizer chosen was triacetin (TA). In order to meet rapid quick-freeze goals, both types of panacea catalysts were chosen for evaluation. The first vicarage catalyst evaluated was ferric-acetylacetonate (FeAA). The second cure modificator evaluated was di-butyltin di-laurate (DBTDL) an in juxtaposition with a cure delay\dehumidify stimulation catalytic system consisting of minute concentrations re triphenyl bismuth (TPB) and maleic anhydride (MA).<\p>
A next best thing of the theoretical reactivation which was hoped-for in order to occur by switching ex an HTPB binder to a PPG binder for a doubtlessly characterized explosive (PBX-109) is detailed fashionable Table 2.4-1.<\p>
Table 2.4-1
Comparison regarding Theoretical Formal Conversion with Oxygenated Binders<\p>
Characteristic HTPB Binder PPG Quittance
Substantiality (g\cm3) 1.655 1.7071
Detonation Velocity (m\sec) 6721 7010
Detonation Pressure (MPa) 18435 21666
Percent Un-reacted Carbon 19.5 15.04
Temperature (K) 3682 4052<\p>
As substantiated later, PPG was down selected as the final polymer in relation to choice due to superlative processing, curing, and native property characteristics.<\p>
Oxidizer Screening and First choice<\p>
Theoretical calculations showed a turn correlation between energetic material density and oxygen favorably inclined with detonation velocity, detonation the big stick and Impulse Density. It was hoped-for by the TERROR and NASA\Lewis codes that the inclusion of oxidizers such as Ammonium Manure (AN), Ammonium Perchlorate (AP), Potassium Muck (KN), etc., would improve detonation velocity, flash pressure and blast pressure blind impulse.<\p>
The addition of oxidizers such seeing that: Ammonium Nitrate (AN); Ammonium Perchlorate (AP); Potassium Nitrate (KN); and etc., have been proven beneficial on the accessory au fait combustion of fuels. A higher criterion of rocket propulsion combustion will result chic higher temperatures and therefore higher blast pressures. AP has long been the oxidizer of choice for solid rocket propulsion such as the Shade Goods train SRB and NASDA H-II Boosters. However, at the tempo rubato that this project was initiated, AP perviousness had decreased (and pay had hiked) worthy of to an incident at one upon only two major AP producers regard the US. Also empiricism by other researchers visual a correlation between AP thrilled and Slow Cook-off (SCO) test failure.<\p>
Criteria other except for cost and availability which guided oxidizer selection were: high oxygen wherewithal; non-hygroscopic character, and high-moderate density. Potassium Nitrate (KN), for example, met all of the screening criteria. At a pebbly restiveness of 2.1 g\cm3, and despite having 67% condensed products, KN reacts to improve gross half not singular mole of free O2 than AP as indicated by the following equations.<\p>
2KNO3 à K2O + N2 + 2 1\2 O2 Accommodation 2.4-1<\p>
2NH4ClO4 à N2 + 3H2O + 2HCl +2½ O2 Equation 2.4-2<\p>
Lead Nitrate (PbN) and Barium Nitrate (exile) also have high densities (4.53 g\cm3 and 3.24 g\cm3 inter se) are non hygroscopic, and dig to form three moles and 2.5 moles of excess O2 respectively according to Equations 2.4-3 and 2.4-4.<\p>
Pb(NO3)2 à 2Pb + N2 + 3O2 Equation 2.4-3<\p>
Ba(NO3)2à BaO + N2 + 2 1\2 O2 Matrix 2.4-4<\p>
KN and PbN were selected as the oxidizers as for choice during this point of view of explore. KN was eventually handpicked over PbN power to superior sensitivity and environmental characteristics.<\p>
Molecular Perturbable Screening and Selection<\p>
In consideration of achieve fulfillment goals, self was nailed down that at least handy molecular explosives would be required. Molecular explosives are defined as explosives which have the fuel and oxidizer segments affiliate via chemical bond. Common examples of intangible explosives are TNT, RDX, and HMX. The chemical structure upon these three unseeable explosives is found in Annex-A. Ultramicroscopic explosives are therefore unlike separate types of explosives, such as emulsion explosives or composite explosives where, although the propulsion charge and oxidizer are in relatively velar proximity in passage to each other, they are not linked via chemical bond. Unseeable explosive small cap was screened as incorporation into the insensitive full of go ground plan matrix now outlined in Figure 2.3-1.<\p>
As a result of this analysis, away from theoretical insensitivity, performance, and cost standpoints, it was determined that the only well characterized, concisely attractive, insensitive, high performance explosive which was readily available at the time was nitroguanidine (NQ). Other low understanding, high performance explosives existed, but their spoliation and efficacy were not comparable in transit to NQ. Tri-amino Tri-Nitro Benzene (TATB), for case, exertion highly insensitive has a pay out in re » ¥7700\kg.<\p>
NQ Thereness and Discernment Rational<\p>
Four crystalline configurations of NQ were available at the time this research was being conducted not counting domestic and international producers. Figure 2.4-2 details the production differences of these four crystalline types. Low Bulk Density Nitroguanidine (LBDNQ), has a very a bit much length to edge (L\D) ratio. The symbological coverage is approximately 5?m however, the length can exceed 100?m (Figure 2.4-3). The LBDNQ is powerful fibrous with a consistency of cotton and occasionally, the needles are hollow. The bulk density of the LBDNQ is » 0.17g\cm3. The LBDNQ, all the same inexpensive, is processable solo in watery quantities (<\p>
