Cyclotols

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). 

Property Compositio nE Cyclotol 75/75 Octol 75/25 PentoHte 50/50 Earatol 67/23 Amatol 80/20... 

Use, RDX (60g) is stirred into 40g of molten N-methylpicramide at 120° to give a castable expl, deton rate 7750m/sec, vacuum stab better than Cyclotol (Ref 20)... 

The expl performance of Octol was generally an improvement over that of Cyclotol. Based on the physical and chemical properties of HMX and RDX the following improvements were observed (Ref 4) ... 

Octol shows a small increase in stability over that of Cyclotol at higher temps which may be sufficient to overcome the marginal stability of Cyclotol in specific cases... 

The 7—15% improvement in expl performance of Octol over that of Cyclotol is achieved at a 250—500% increase in cost (depending on purity), which has to be matched against the overall gain... 

Expls similar to Octol, viz, HMX/TNT/Al/Wax, 47/31/22/3-5, have been prepd and tested for air-blast and underwater effectiveness. The performance improvements that resulted (1—2%) over Cyclotol analogs were not considered worth the additional cost (Ref 4), and other expls are generally exploited for such applications... 

Another variable peculiar to composite, cast expls that must be controlled to achieve precision penetration and predictable destructiveness is the variation in density and compn of the expl within the warhead. In melt-loading operations with Octol, problems occur which do not arise in meltloading with TNT, Composition B, or Cyclotol. Specifically, there is a large amount of settling of HMX crystals while the charge is still molten. 

Thus it can be seen that continuous improvements in defensive armor require ever more sophisticated expl technology for its defeat, which in turn results in the escalation of military budgets for conventional warfare. The increased cost of HMX relative to other expls has caused continuing efforts to reduce manufg costs, to improve and more precisely evaluate its effectiveness. In a recent, very painstaking comparison of Cyclotol and Octol, the effects of changes in the compn, density, and diameter of the expl charge upon detonation velocity were determined. HMX was found more ef-... 

A linear relationship between Chapman-Jouguet pressure and density was confirmed for Cyclotol and Octol (Ref 28). Despite the near-equal performance of RDX and HMX at equal densities there appears to be no economical way of making the density of RDX equal to the cast density of HMX. Dinitrobenzene (DNB) has been evaluated as an economical or emergency substitute for TNT but charges prepared with DNB gave somewhat poorer performance than... 

Pentolites are castable expl mixts containing PETN and TNT. The most commonly used blend consists of 50/50 PETN/TNT, but other blends such as 75/25, 40/60, 30/70 and 10/90 have been occasionally employed. Molten TNT dissolves appreciable amounts of PETN as shown in Fig 1. The eutectic in the TNT-PETN system occurs at 76.7° for a 87/13 TNT/PETN mixt. Because correspondingly more PETN than RDX dissolves in TNT, the viscosity of Pentolites at casting temperatures is less than that of comparable Cyclotols (RDX/TNT blends)... 

Until the end of the First World War the main filling for mass ordnance was TNT and its mixtures with ammonium nitrate known as Amatols. During this period improved methods for the manufacture of RDX enabled its inclusion in munitions, usually in formulation with TNT in the form of the Cyclotols. RDX and its mixtures are still the most widely used explosives for military use. 

Composition B, and of 77/23 Cyclotol were measured by Deal (Ref 1) by determining initial free-surface vel as a function of thickness for 24ST-A1 plates in contact with the detonating expl. The pressures detd were as follows ... 

As acceptors used in underwater tests were 50/50-Pentolite, TNT, 60/40-Cyclotol, PBX 9404-03 and LX-04-1. The results gave thresholds for burning which are comparable in magnitude to Susan and Skid tests, but lower than those obtd by the modified gap test. This showed that burning can be produced at lower shock levels if the pressure were held longer and the wave front made flatter... 

PA were tested as 60-mm long receptor chges with 50/50 Cyclotol as donor in 20-mm diam cartridges) 27b) L. Deffet et al, CombustFlame 8(2), 105-11(1964)... 

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