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Semtex
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Semtex is a general-purpose plastic explosive containing RDX and PETN. It is used in commercial blasting, demolition, and in certain military applications. Semtex became notoriously popular with terrorists because it was, until recently, extremely difficult to detect, as in the case of Pan Am Flight 103.
Composition, manufacture and use
There is more than one explosive composition called "Semtex." There are two common varieties, A for blasting and H (or SE) for hardening:
A variant called Semtex 10SE is sold in the form of a thin sheet usually 2 mm thick which is sandwiched between two plastic sheets and rolled onto a spool, 10SE is bright white with an almost translucent appearance.
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Encyclopedia
Semtex is a general-purpose plastic explosive containing RDX and PETN. It is used in commercial blasting, demolition, and in certain military applications. Semtex became notoriously popular with terrorists because it was, until recently, extremely difficult to detect, as in the case of Pan Am Flight 103.
Composition, manufacture and use
There is more than one explosive composition called "Semtex." There are two common varieties, A for blasting and H (or SE) for hardening:
A variant called Semtex 10SE is sold in the form of a thin sheet usually 2 mm thick which is sandwiched between two plastic sheets and rolled onto a spool, 10SE is bright white with an almost translucent appearance. Its intended use is for hardening of manganese steel. In fact as at December 2008, Explosia's product guide lists a current total of five explosives sold under the name "Semtex."
History
Semtex was invented in the late 1950s by Stanislav Brebera, a chemist at VCHZ Synthesia. The explosive is named after Semtín, a suburb of Pardubice in the Czech Republic where the mixture was first manufactured starting in 1964. The plant was later renamed to become Explosia s.a., a subsidiary of Synthesia.
Semtex was similar to other plastic explosives, especially C-4, in that it was easily malleable; but it was usable over a greater temperature range than other plastic explosives. There are also visual differences: whereas C-4 is off-white in colour, Semtex is brick-orange.
The new explosive was widely exported, notably to the government of North Vietnam, which received 14 tonnes during the Vietnam War. However, the main consumer was Libya; about 700 tonnes of Semtex were exported to Libya between 1975 and 1981 by Omnipol. It has also been used by Islamic militants in the Middle East and by republican paramilitaries such as the Provisional Irish Republican Army (IRA) and Irish National Liberation Army in Northern Ireland.
Exports fell after the name became closely associated with terrorist blasts. Export of Semtex was progressively tightened and since 2002 all of Explosia's sales were controlled by a government ministry. , approximately only 10 tonnes of Semtex were produced annually, almost all for domestic use.
Also in response to international agreements, Semtex has a detection taggant added to produce a distinctive vapor signature to aid detection. First, ethylene glycole dinitrate was used, later switched to 2,3-dinitro-2,3-dimethylbutane (3,4-dinitrohexane, DMDNB), which is used nowadays. According to the manufacturer, the taggant agent was voluntarily being added since 1991, years before the protocol signed became compulsory. Batches of Semtex made before 1990, however, are untagged, though it is not known whether there are still major stocks of such old batches of Semtex. The shelf life of Semtex was reduced from 10 years guarantee prior to 1990s to 5 years now. Explosia states that there is no compulsory tagging allowing reliable post-detonation detection of a certain plastic explosive (such as incorporating a unique metallic code into the mass of the explosive), so Semtex isn't tagged in this way.
On May 25, 1997 Bohumil Šole, a scientist often said to have been involved with inventing Semtex, strapped the explosive to his body and committed suicide in the Priessnitz spa of Jeseník. Sole, 63, was being treated there for depression. Twenty other people were hurt in the explosion, while six were seriously injured. It should be noted, however, that the manufacturer, Explosia, states that he was not a member of the team that developed the explosive.
Note
Various sources state that production started in 1964 or 1966. Explosia's brief historical document states it was 1964, but most other credible sources state it was in 1966. Most of these also state that development was started at the same time, in response to a request from Vietnam for a counterpart to the US's introduction of C-4.
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