Editing Composition C

{{Short description|Family of related US-specified plastic explosives consisting primarily of RDX}}
{{Multiple issues|
{{Cleanup reorganize|date=October 2016}}
{{More citations needed|date=December 2009}}
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The '''Composition C''' family is a family of related US-specified [[plastic explosive]]s consisting primarily of [[RDX]]. All can be moulded by hand for use in demolition work and packed by hand into [[shaped-charge]] devices. Variants have different proportions and plasticisers and include Composition C-1, Composition C-2, Composition C-3, and [[C-4 (explosive)|Composition C-4]].<ref>{{cite book|title=Explosives|year=2002|url=https://archive.org/details/explosives00meye_710|url-access=limited|author1=Rudolf Meyer |author2=Josef Köhler |author3=Axel Homburg |publisher=Wiley-VCH|page=[https://archive.org/details/explosives00meye_710/page/n113 63]|isbn=9783527302673 }}</ref>

==History==
The term ''Composition'' is used for any explosive material compounded from several ingredients. In particular, in the 1940s the format "Composition <letter>" was used for various compositions of the (relatively) novel explosive RDX, such as [[Composition B]] and other variants.

==Development==
The original material was developed by the British during [[World War II]], and was used in the [[Gammon bomb]]. It was standardised as Composition C when introduced to US service. This material consisted of 88.3% RDX and a mineral oil-based plasticiser and [[phlegmatized|phlegmatiser]]. It suffered from a relatively limited range of serviceable temperatures, and was replaced by Composition C-2 around 1943, which would later be redeveloped around 1944 as Composition C-3. Research on a replacement for C-3 was begun prior to 1950, but the new generation of Composition C ([[C-4 (explosive)|C-4]]) did not begin pilot production until 1956.

===Composition===
Composition C-1 contained a slightly smaller proportion of RDX, but used an explosive plasticiser, which contained [[tetryl]], [[nitrocellulose]] and a mixture of nitroaromatics produced during the manufacture of TNT (containing [[trinitrotoluene]], [[dinitrotoluene]], and [[mononitrotoluene]]), and a trace of solvent.

==Characteristics and usage==
Composition C-3 was very similar to Composition C-1, but removed the solvent and varied the exact proportions of plasticisers to improve high temperature storage. It is a yellow, putty-like material. It remained a service item through the [[Korean War]], but had marginal plasticity at the very low temperatures encountered in Korean winters, and was significantly toxic, including by vapour and skin absorption.<ref name=Arb1MemoIsn841>{{cite web
| url=http://www.dod.mil/pubs/foi/detainees/csrt_arb/ARB_Round_1_Factors_000694-000793.pdf#7
| title=Unclassified Summary of Evidence for Administrative Review Board in the case of Nashir, Sa id Salih Sa id
| pages=7–9
| publisher=[[United States Department of Defense]]
| author=OARDEC
| author-link=OARDEC
| date=2005-11-23
| access-date=2008-12-07
| quote=The detainee was trained to use the [[Kalashnikov rifle]], [[rocket propelled grenade]]s, [[hand grenade]]s, [[land mine]]s, Composition-3 (C-3) and Composition-4 (C-4) explosives.
| archive-date=2008-12-01
| archive-url=https://web.archive.org/web/20081201020040/http://www.dod.mil/pubs/foi/detainees/csrt_arb/ARB_Round_1_Factors_000694-000793.pdf#7
| url-status=dead
}}</ref> While Composition C-3 had a much wider serviceable temperature range than Composition C-1, it could not be stored at elevated temperatures. Consequently, it would eventually be replaced by Composition C-4. The [[velocity of detonation]] is about 7600&nbsp;m/s (25,000 feet per second).

Composition C-3 consists of 77%–85% cyclonite ([[RDX]]) and 15%–23% gel made out of liquid nitro compounds (e.g. liquid [[dinitrotoluene|DNT]] and small amount of [[mononitrotoluene|NT]]) and nitrocellulose or butyl phthalate and nitrocellulose.<ref>{{cite book|title= Chemistry and Technology of Explosives
|author=Urbanski Tadeusz
|publisher= Pergamon
|location= Oxford
|year=1985
|edition= second
|orig-year= 1984
|others= Volumes I–IV
}}</ref>

One of the first reported and tested compositions of C-3 was very similar to earlier Composition C-2 and contained 77% [[RDX]], 3% [[tetryl]], 4% [[TNT]], 1% [[Nitrocellulose|NC]], 5% [[mononitrotoluene|NT]], and 10% [[dinitrotoluene|DNT]].<ref>
{{cite web
| url=http://www.globalsecurity.org/military/systems/munitions/explosives-compositions.htm
| title= Explosives - Compositions
| author=GlobalSecurity.org
| quote= Composition-3 (C-3) and Composition-4 (C-4) explosives, Semtex.
}}
</ref> The last two compounds (they are very poor explosives) are oily liquids and plasticise the mixture. The most important later innovation of C-3 introduced the non-explosive [[plasticiser]] butyl phthalate instead of this mixture of nitro compounds. This reduced the toxicity while increasing the concentration of [[RDX]] and improving safety of use and storage. It also opened the way to begin study of new non-explosive low-toxicity plasticisers (esters of dicarboxylic acid) and binder (branched [[polymers]]).

==Properties==
Since 1960 the mixture of [[C-4 (explosive)|C-4]] has contained:
* 90.0–91.0% of cyclonite ([[RDX]] explosives)
* ~2.1% of polyisobutylene (short chain)
* ~1.6% of motor oil
* ~5.3% of di-(2-ethylhexyl)sebacate (dioctyl sebacate), sometimes it was replaced partly by similar compounds such as dioctyl adipate
* less than 0.6% of water
* (small amount of marker or odorising taggant)

It is less volatile than C-3 and has less tendency to harden at low temperature. It has a density 1.48–1.60&nbsp;g/ml, does not become hard even at −55&nbsp;°C (−67&nbsp;°F), and does not exude at +77&nbsp;°C (171&nbsp;°F). C-4 has a detonation velocity of 8092&nbsp;m/s (26550&nbsp;ft/s) at high density and velocity of 7550&nbsp;m/s (24770&nbsp;ft/s) at low density 1.48&nbsp;g/ml. It is so successful that it remains in [[army]] service up to the current time without any significant changes.

==See also==
* [[C-4 (explosive)|Composition C4]]
* [[Composition B]]
* [[Composition H6]]
* {{slink|Plasticizer#Energetic materials}}
* [[Polymer-bonded explosive]]
* [[RE factor]]
* [[Semtex]]

==References==
{{Reflist}}

[[Category:Explosives]]