User:ChemWorx/Composition C

Composition C is a plastic explosive consisting of the high explosive RDX mixed with a non-explosive plasticizer. Originally developed by the British during World War II for use in the No. 82 hand grenade, the composition was later standardized and improved by the U.S. Army. The variant most widely used today is Composition C-4.

History
During World War II, Captain R. C. Gammon of the British airborne forces invented the No. 82 hand grenade, which was popularly called the Gammon bomb. It was a replacement for the more dangerous No. 74 anti-tank hand grenade. The Gammon bomb could be loaded with various amounts of Composition C in the field depending on its intended use or target.

Unfortunately, Composition C had a limited range of useful temperatures, because the material became brittle at temperatures below 0°C, and at temperatures above 40°C the oily plasticizer separated from the explosive component, making it gummy. This led to further improvements in the formulation, all of which used RDX as the principal explosive component, but used different types of explosive and non-explosive plasticizers.

The only formulation remaining in production today is Composition C-4, which is used by all branches of the U.S. military in quantities of hundreds of thousands of pounds annually.

Characteristics and usage[edit]
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. While Composition C-3 had a much wider serviceable temperature range than Composition C, it could not be stored at elevated temperatures. Consequently, it was replaced around 1944 by Composition C-4. The velocity of detonation is about 7600 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 DNT and small amount of NT) and nitrocellulose or butyl phthalate and nitrocellulose.

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% NC, 5% NT, and 10% DNT. 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).

Formulations
Improvements to the original formulation of Composition C resulted in a plastic explosive with a wider range of useful temperatures, lower sensitivity and improved safety, and higher destructive power:

Composition C


 * 88.3% RDX
 * 11.7% oily plasticizer

Composition C-2


 * 80% RDX
 * 20% explosive plasticizer, including
 * 10% dinitrotoluene
 * 5% mononitrotoluene
 * 4% TNT,
 * 1% nitrocellulose, dimethylformamide)

Composition C-3


 * 77% RDX
 * 23% explosive plasticizer, including
 * 10% dinitrotoluene
 * 5% mononitrotoluene
 * 4% TNT
 * 3% tetryl
 * 1% nitrocellulose, dimethylformamide)

Composition C-4


 * 91% RDX
 * 9% polyisobutylene plasticizer