|UN number||0072, 0391, 0483|
|Molar mass||222.12 g mol−1|
205.5 °C, 479 K, 402 °F
234 °C, 507 K, 453 °F
|Explosive velocity||8750 m/s|
(what is this?) |
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
RDX, also known less commonly as cyclonite, hexogen (particularly in German and German-influenced languages), and T4, and chemically as Cyclotrimethylenetrinitramine, is an explosive nitroamine widely used in military and industrial applications. Nomenclature variants include cyclotrimethylene-trinitramine and cyclotrimethylene trinitramine.
In its pure, synthesized state RDX is a white, crystalline solid. As an explosive, it is usually used in mixtures with other explosives and plasticizers, phlegmatizers or desensitizers. It is stable in storage and is considered one of the most powerful and brisant of the military high explosives.
RDX forms the base for a number of common military explosives:
RDX is also used as a major component of many plastic bonded explosives used in nuclear weapons.
The velocity of detonation of RDX at a density of 1.76 g/cm³ is 8750 m/s.
It is a heterocycle and has the molecular shape of a ring. It starts to decompose at about 170 °C and melts at 204 °C. Its structural formula is: hexahydro-1,3,5-trinitro-1,3,5-triazine or (CH2-N-NO2)3.
At room temperature, it is very stable. It burns rather than explodes and detonates only with a detonator, being unaffected even by small arms fire. It is less sensitive than pentaerythritol tetranitrate (PETN). However, it is very sensitive when crystallized, below −4 °C. Under normal conditions, RDX has a figure of insensitivity of exactly 80 (as this is the reference point).
The discovery of RDX dates from 1898 when Georg Friedrich Henning obtained a German patent (patent No. 104280) for its manufacture, by nitrating hexamethylenetetramine. In this patent, its properties as an explosive were at length described, as well as its possible use as a medical compound mentioned. Research and development were not published further until G. C. V. Herz obtained a British patent in 1921 and a U.S. patent in 1922, for its manufacture by nitrating hexamethylenetetramine. Later in the 1920s RDX was produced by the direct nitration of hexamine.
RDX was used by both sides in World War II.
In the United Kingdom RDX was manufactured from 1933 in a pilot plant at the Royal Arsenal in Woolwich, London, a larger pilot plant being built at the RGPF Waltham Abbey just outside London in 1939. In 1939 a twin-unit industrial-scale plant was designed to be installed at a new 700 acres (280 ha) site, ROF Bridgwater, away from London; and production of RDX started at Bridgwater in 1941. The United Kingdom and British Empire were fighting without allies against Nazi Germany until the end of 1941 and had to be self-sufficient; Canada, a self-governing dominion of the British Empire, was looked upon to supply ammunition and explosives, including RDX.
A slightly different method of production, but still using hexamine, was found and used in Canada, possibly at the McGill University Department of Chemistry. Urbanski provides details of five methods of production.
Near the beginning of World War II the US Government turned to Tennessee Eastman Company (TEC), Kingsport, Tennessee, US, a leading manufacturer of acetic anhydride, to develop a continuous-flow manufacturing process for RDX. RDX was crucial to the war effort and the current batch-production process could not keep up. The US began research to safely make large quantities of RDX. Werner Emmanuel Bachmann of the University of Michigan developed the “combination process” which required large quantities of acetic anhydride instead of nitric acid in the old British “Woolwich process”. In February 1942, TEC built the Wexler Bend pilot plant and began producing small amounts of RDX. This led to the US Government authorizing TEC to design and build Holston Ordnance Works (H.O.W.) in June 1942. By April 1943, RDX was being manufactured there. The US Bachmann process for RDX was found to be richer in HMX than the United Kingdom's RDX. This later led to a RDX plant using the Bachmann process being set up at ROF Bridgwater in 1955, to produce both RDX and HMX.
RDX was widely used during World War II, often in explosive mixtures with TNT such as Torpex, Composition B, Cyclotols, and H6. RDX was used in one of the first plastic explosives. RDX is believed to have been used in many bomb plots including terrorist plots. The bombs used in the "Dambusters Raid" contained 6,600 pounds of Torpex .
Outside of military applications, RDX is also used in controlled demolition to raze structures. The demolition of the Jamestown Bridge in the U.S. state of Rhode Island is one example where RDX shaped charges were used to remove the span.
Ahmed Ressam, the al-Qaeda Millenium Bomber, used a small quantity of RDX as one of the components in the explosives that he prepared to bomb Los Angeles International Airport on New Year's Eve 1999/2000; the combined explosives could have produced a blast 40x greater than that of a devastating car bomb.
There are many explanations for the name RDX, including (but not limited to) Royal Demolition eXplosive, Research Department (composition) X, Research Developed eXplosive, and Research Department eXplosive. Research Department composition X is most likely correct. In the United Kingdom, new military explosives were given an identification number preceded by the letters 'RD' indicating 'Research Department No.'. For some reason, this explosive was unable to be given a number. Instead, the letter 'X' was appended to indicate 'unknown' with the intention of adding the number later.
The first public reference in the United Kingdom to the name RDX, or R.D.X to use the official title, appears in 1948; its authors were the Managing Chemist, ROF Bridgwater, the Chemical Research and Development Department, Woolwich, and the Director of Royal Ordnance Factories, Explosives; it is referred to as simply RDX.
Davis, writing in the USA in 1943, stated it was generally known in the USA as cyclonite; the Germans called it Hexogen, the Italians T4.