RDX—

RDX and HMX are rather more recalcitrant, especially under aerobic conditions, but there are promising indications that biodegradation can occur under some conditions, especially composting (67). Several strains of bacteria able to use RDX (and Triazine) as a sole source of nitrogen for growth have recentiy been isolated, and this is an area where rapid progress is being made. 

Acid—Base Chemistry. Acetic acid dissociates in water, pK = 4.76 at 25°C. It is a mild acid which can be used for analysis of bases too weak to detect in water (26). It readily neutralizes the ordinary hydroxides of the alkaU metals and the alkaline earths to form the corresponding acetates. When the cmde material pyroligneous acid is neutralized with limestone or magnesia the commercial acetate of lime or acetate of magnesia is obtained (7). Acetic acid accepts protons only from the strongest acids such as nitric acid and sulfuric acid. Other acids exhibit very powerful, superacid properties in acetic acid solutions and are thus useful catalysts for esterifications of olefins and alcohols (27). Nitrations conducted in acetic acid solvent are effected because of the formation of the nitronium ion, NO Hexamethylenetetramine [100-97-0] may be nitrated in acetic acid solvent to yield the explosive cycl o trim ethyl en etrin itram in e [121 -82-4] also known as cyclonit or RDX. 

Both RDX and HMX are stable, crystalline soHds, somewhat less sensitive to impact than PETN. Both may be handled with no physiological effect if appropriate precautions are taken to assure cleanliness of operations. Both RDX and HMX detonate to form mostiy gaseous, low molecular weight products and some intermediate formation of soHd carbons. The calculated molar detonation products of RDX are 3.00 H2O, 3.00 N2, 1.49 CO2, and 0.02 CO. RDX has been stored for as long as 10 months at 85°C without perceptible deterioration. 

Both RDX and HMX are substantially desensitized by mixing with TNT to form cyclotols (RDX) and octols (HMX) or by coating with waxes, synthetic polymers, and elastomeric biaders. Most of the RDX made ia the United States is converted to Composition B (60% RDX, 40% TNT, 1 part wax added). Composition A5 (RDX 98.5/stearic acid 1.5) and composition C4 (RDX91/nonexplosive plasticizer) account for the next largest uses. HMX is used as a propellant and ia maximum-performance plastic bonded explosives such as PBX 9401 and PBX N5 and the octols (147—150). 

Ma.nufa.cture. The two most common processes for making RDX and HMX use hexamethylenetetramine (hexamine) as starting material. The Woolwich or direct nitrolysis process used ia the United Kingdom proceeds according to ... 

The RDX particle size distribution must be carefully controlled to produce castable slurries of RDX and TNT having acceptable viscosity. Several classes of RDX are produced to satisfy requirements for the various pressed and cast RDX-based compositions. A continuous process for medium-scale production of RDX has been developed by Biazzi based on the Woolwich process (79,151—154). 

Tetiyl. 2,4,6-Trinitrophenylmethylm tramine (tetryl) was used ia pressed form, mostly as a booster explosive and as a base charge ia detonators and blasting caps because of its sensitivity to initiation by primary explosives and its relatively high energy content. Properties are presented ia Table 11 (173). Batch and continuous processes for the production of tetryl have been developed. Tetryl is no longer used ia the United States and has been replaced by RDX (174-178). 

Military. The single-component explosives most commonly used for military compositions are TNT, RDX or HMX, nitrocellulose, and nitroglycerin. The last two are used almost exclusively to make propellants. The production volume of TNT far exceeds that of any other explosive. It is used as manufactured, as a base of biaary slurries with other high melting explosives, or ia ternary systems generally containing a biaary mix and aluminum. 

The incorporation of aluminum increases the blast effect of explosives but decreases the rates of detonation, fragmentation effectiveness, and shaped charge performance. Mixes with aluminum are made by first screening finely divided aluminum, adding it to a melted RDX—TNT slurry, and stirring until the mix is uniform. A desensitizer and calcium chloride may be incorporated, and the mixture cooled to ca 85°C then poured. Typical TNT-based aluminized explosives are the tritonals (TNT + Al), ammonals (TNT, AN, Al), minols (TNT, AN, Al) torpexes and HBXs (TNT, RDX, Al) (Table 14) (223-226). 

J. A. Hathaway and C. R. Buck, "Report of Absence of Health Ha2ards Associated with RDX Manufacture and Use in Shell Loading Plants," in Minutes of 17th Explosives Safety Seminar, Dept, of Defense Explosives Safety Board, Washington, D.C., 1976, p. 683. 

Polymer-based rocket propellants are generally referred to as composite propellants, and often identified by the elastomer used, eg, urethane propellants or carboxy- (CTPB) or hydroxy- (HTPB) terrninated polybutadiene propellants. The cross-linked polymers act as a viscoelastic matrix to provide mechanical strength, and as a fuel to react with the oxidizers present. Ammonium perchlorate and ammonium nitrate are the most common oxidizers used nitramines such as HMX or RDX may be added to react with the fuels and increase the impulse produced. Many other substances may be added including metallic fuels, plasticizers, stabilizers, catalysts, ballistic modifiers, and bonding agents. Typical components are Hsted in Table 1. 

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