TATB-based Formulations

A study has been conducted on PBXs based on TATB using various binders such as polyurethane (Estane 5703-Goodrich), Viton-A (copolymer of vinylidene fluoride and hexafluoropropylene Du Pont), silicone resin (Chemlok), Kel-F800 [copolymer (3 1) of chlorotrifluoroethylene and vinylidene fluoride 3M Company] and Teflon [poly (tetrafluoroethylene), PTFE Du Pont] etc. and it was concluded that 

TATB/Kel-F800 (90/10 wt.%) is best in terms of thermal stability coupled with a respectable performance [200]. Similarly, PBXs based on TATB, HMX and Kel-F800 are available, and sensitivity data on TATB/HMX-based PBXs clearly show that insensitivity rapidly decreases with increasing HMX content, even at relatively low levels of HMX. Evidently, some trade-off must be made between VOD and safety [201] (Table 2.5). Further, sensitivity and thermal test data (Table 2.6) also indicate that TATB-based formulations rank as the most insensitive explosive formulations [202]. 

These PBXs have relatively high thermal stability and sufficient power for certain applications where size of container is not severely restricted. For example, warheads of large rockets, large bombs etc. 

Formulation Property TATB/PU 95/5 TATB/Viton/ Chemlok95 /2.5 /2.5 TATB/Kel-F800 90/10 

Reprinted from S . Shokry, S.M. Shawki and A.K. Elmorsi, Proc.21st Ind. Ann. Conf. ICT, 1990, pl00/12 1990, ICT, Karlsruhe, Germany. 

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Some TNT-based formulations have been tailored, made and tested for sensitivity and ballistic performance. When TATB, DINGU and nitroguanidine (NQ) are incorporated in these formulations, they become IHEs. Further details of these formulations are available in the literature [176]. 

Some explosive formulations based on HMX, HMX and NTO, HMX and TATB (by wt.) and binder have been studied for density, VOD, IAD (number of cards), initiation sensitivity, ignition temperature and other explosive properties. The data given in Table 2.9 and Table 2.10 show a significant decrease in sensitivity, IAD (number of cards) and initiation sensitivity of explosive formulations with an increase in the proportion of NTO as well as TATB. However, performance of the NTO-based formulation is slightly better [222]. 

In supersonic missiles where warheads are subjected to aerodynamic heating, conventional explosives cannot be used and thermally stable explosives like TATB, TACOT, HNS and PYX, etc. are necessary for such systems. Some formulations based on these explosives are HNS/Kel-F800 95/5 (developed by Atomic Weapons Research Establishment, Aldermaston, UK) and AFX 521 (PYX/Kel-F800 95/5 — developed by Los Alamos National Laboratory, USA). Their shock sensitivities lie in the region required for boosters. HNS/Teflon explosive charges have also been used for the Apollo 17 seismic experiments [199]. 

The NTO/TNT formulation is characterized by a lower vulnerability than RDX/ TNT and Composition B. NTO is also used to produce pressed PBXs with thermoplastic binders and cast PBXs with thermosetting binders for IMs. NTO is an explosive with calculated performance near that of RDX but with insensitivity approaching that of TATB. Possible use of NTO is as an alternative to RDX in formulations where a lower sensitivity is desired or as an alternative to TATB where better performance is required without a large increase in sensitivity [123, 152, 153, 215]. The formulations based on NTO/binder (FPC-461, Viton-A, Kel-F800, Estane-5702 and Kraton G) in 95/5 (mass percent concentrations) have also been tested for compatibility and none of the NTO/binder formulations showed evidence of incompatibility. 

Some PBX formulations along with their density, VOD and compression strength are given in Table 3.4. Some important PBX formulations based on high explosives such as TATB, NTO and CL-20 which are used for specialized applications have already been described in Chapter 2. 

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