Editing C-4 (explosive) (section)

== Characteristics and uses ==

=== Composition ===
The Composition C-4 used by the [[United States Armed Forces]] contains 91% [[RDX]] ("Research Department Explosive", an explosive [[nitroamine]]), bound by a mixture of 5.3% [[dioctyl sebacate]] (DOS) or [[dioctyl adipate]] (DOA) as the plasticizer (to increase the [[plasticity (physics)|plasticity]] of the explosive), thickened with 2.1% [[Polyisobutene|polyisobutylene]] (PIB, a [[synthetic rubber]]) as the [[binder (material)|binder]], and 1.6% of a [[mineral oil]] often called "process oil". Instead of "process oil", low-viscosity [[motor oil]] is used in the manufacture of C-4 for civilian use.<ref name="atf">{{cite journal|last1=Reardon|first1=Michelle R.|last2=Bender|first2=Edward C.|year=2005|title=Differentiation of Composition C4 Based on the Analysis of the Process Oil|journal=Journal of Forensic Sciences|volume=50|issue=3|pages=1–7|doi=10.1520/JFS2004307|url=http://www.astm.org/DIGITAL_LIBRARY/JOURNALS/FORENSIC/PAGES/JFS2004307.htm|publisher=Bureau of Alcohol, Tobacco, Firearms, and Explosives, Forensic Science Laboratory|location=Ammendale, MD|issn=0022-1198|url-access=subscription}}</ref>

The British PE4 consists of 88.0% RDX, 1.0% pentaerythrite dioleate and 11.0% DG-29 [[Lithium soap|lithium grease]] (corresp. to 2.2% [[lithium stearate]] and 8.8% mineral oil [[British Pharmacopoeia|BP]]) as the binder; a taggant (2,3-dimethyl-2,3-dinitrobutane, [[DMDNB]]) is added at a minimum of 0.10% weight of the plastic explosive, typically at 1.0% mass.  The newer PE7 consists of 88.0% RDX, 1.0% DMDNB taggant and 11.0% of a binder composed of low molecular mass [[hydroxyl-terminated polybutadiene]], along with an [[antioxidant]] and an agent preventing hardening of the binder upon prolonged storage. The PE8 consists of 86.5% RDX, 1.0% DMDNB taggant and 12.5% of a binder composed of di(2-ethylhexyl) sebacate thickened with high molecular mass polyisobutylene.

Technical data according to the [[United States Department of the Army|Department of the Army]] for the Composition C-4 follows.<ref name ="armymanual 8-111" />
{| class="wikitable"
 |-
 | Theoretical '''maximum density''' of the mixture, grams per cubic centimeter
 | style="text-align:right;" | 1.75
 |-
 | '''Nominal density''', grams per cubic centimeter
 | style="text-align:right;" | 1.72658
 |-
 | '''Heat of formation''', calories per gram
 | style="text-align:right;" | −32.9 to −33.33
 |-
 | Max heat of detonation with liquid water, kilocalories per gram
 | style="text-align:right;" | 1.59 (6.7 MJ/kg)
 |-
 | Max heat of detonation with gaseous water, kilocalories per gram
 | style="text-align:right;" | 1.40 (5.9 MJ/kg)
 |-
 | Remains plastic with no exudation, Celsius
 | style="text-align:right;" | −57 to +77
 |-
 | '''Detonation pressure''' with density of 1.58 grams per cubic centimeter, kilobars
 | style="text-align:right;" | 257
 |}

==== Manufacture ====
C-4 is manufactured by combining the above ingredients with binders dissolved in a [[solvent]]. Once the ingredients have been mixed, the solvent is extracted through drying and filtering. The final material is a solid with a dirty white to light brown color, a putty-like texture similar to modeling clay, and a distinct smell of motor oil.<ref name ="armymanual 8-111" /><ref name="fuelsource" /><ref name="homelandpresentation">{{cite web | url=https://info.publicintelligence.net/DHS-Explosives.pdf | title=Introduction to Explosives | publisher=U.S. Department of Homeland Security | work=C4: Characteristics, Properties, and Overview | access-date=18 July 2014 | pages=4–5}}</ref> Depending on its intended usage and on the manufacturer, there are differences in the composition of C-4.  For example, a 1990 U.S. Army technical manual stipulated that Class IV composition C-4 consists of 89.9±1% RDX, 10±1% polyisobutylene, and 0.2±0.02% dye that is itself made up of 90% [[Lead(II) chromate|lead chromate]] and 10% [[Carbon black|lamp black]].<ref name="armymanual 8-111">{{citation | url=http://www.lexpev.nl/downloads/tm91300214militaryexplosives.pdf | title=Department of the Army Technical Manual – Military Explosives| author=Headquarters, U.S. Department of the Army | date=25 Sep 1990 |postscript=.}}</ref> RDX classes A, B, E, and H are all suitable for use in C-4. Classes are measured by granulation.<ref>{{citation | url=http://www.lexpev.nl/downloads/tm91300214militaryexplosives.pdf | title=Department of the Army Technical Manual – Military Explosives| author=Headquarters, U.S. Department of the Army | date=25 Sep 1990 | pages=8–37–38 (124–125)|postscript=.}}</ref>

The manufacturing process for Composition C-4 specifies that wet RDX and plastic binder are added in a stainless steel mixing kettle. This is called the aqueous slurry-coating process.<ref name="bae">{{cite web |title=Recent Developments in Composition C-4: Towards an Alternate Binder and Reduced Sensitivity|last1=Owens|first1=Jim |last2=Vinh |first2=Paul |url=http://www.dtic.mil/ndia/2009insensitive/10Aowens.pdf|archive-url=https://web.archive.org/web/20130719235154/http://www.dtic.mil/ndia/2009insensitive/10Aowens.pdf|url-status=dead|archive-date=July 19, 2013|publisher=[[BAE Systems]] OSI|location=Holston Army Ammunition Plant}}</ref> The kettle is tumbled to obtain a homogeneous mixture. This mixture is wet and must be dried after transfer to drying trays. Drying with forced air for 16 hours at 50&nbsp;°C to 60&nbsp;°C is recommended to eliminate excess moisture.<ref name="armymanual 8-111" />{{rp|198}}

C-4 produced for use by the U.S. military, commercial C-4 (also produced in the United States), and PE-4 from the United Kingdom each have their own unique properties and are not identical. The analytical techniques of time-of-flight [[secondary ion mass spectrometry]] and [[X-ray photoelectron spectroscopy]] have been demonstrated to discriminate finite differences in different C-4 sources. Chemical, morphological structural differences, and variation in atomic concentrations are detectable and definable.<ref>{{cite journal|last1=Mahoney|first1=Christine M.|last2=Fahey|first2=Albert J.|last3=Steffens|first3=Kristen L.|last4=Benner|first4=Bruce A.|last5=Lareau|first5=Richard T.|year=2010|title=Characterization of Composition C4 Explosives using Time-of-Flight Secondary Ion Mass Spectrometry and X-ray Photoelectron Spectroscopy|journal=[[Analytical Chemistry (journal)|Analytical Chemistry]] |volume=82|issue=17|pages=7237–7248|doi=10.1021/ac101116r|pmid=20698494}}</ref>

=== Detonation ===
[[File:C4 explosion.jpg|thumb|A detonation within a blast-resistant trash receptacle using a large C-4 explosive charge]]

C-4 is very [[Explosive material#Stability|stable]] and [[Insensitive munition|insensitive]] to most physical shocks. C-4 cannot be [[Detonation|detonated]] by a gunshot or by dropping it onto a hard surface. It does not explode when set on fire or exposed to [[microwave]]s.<ref name="microwave">{{cite web|last1=Nagy|first1=Brian|title=Grosse Point Blank Microwave C4 Mercury Switch|url=https://www.cs.cmu.edu/~bnagy/GPB-MercurySwitch/|website=Carnegie Mellon University|access-date=14 July 2014}}</ref> Detonation can be initiated only by a [[Shock wave|shockwave]], such as when a detonator inserted into it is fired.<ref name="fuelsource" />
When detonated, C-4 rapidly [[Chemical decomposition|decomposes]] to release nitrogen, water and [[Oxocarbon|carbon oxides]] as well as other gases.<ref name="fuelsource" /> The detonation proceeds at an [[Detonation velocity|explosive velocity]] of {{convert|8092|m/s|ft/s|abbr=on}}.<ref name="Ribbands">{{cite web|url=http://www.ribbands.co.uk/prod-c4.php|work=Ribbands Explosives|title=C4 product page|access-date=2014-05-21|archive-url=https://web.archive.org/web/20170517101148/http://www.ribbands.co.uk/prod-c4.php|archive-date=2017-05-17|url-status=dead}}</ref>

A major advantage of C-4 is that it can easily be molded into any desired shape to change the direction of the resulting explosion.<ref name="fuelsource" /><ref name="shape">{{cite web|last1=Nordin|first1=John|title=Explosives and Terrorists|url=http://www.aristatek.com/Newsletter/05%2007%20July/The%20First%20Responder%20Explosives%20and%20Terrorists.htm|website=The First Responder|publisher=AristaTek|access-date=14 July 2014}}</ref> C-4 has high cutting ability. For example, the complete severing of a {{convert|36|cm|in|adj=on}} deep [[I-beam]] takes between {{cvt|680|and|910|g|lb}} of C-4 when properly applied in thin sheets.<ref>{{cite web |url=https://apps.dtic.mil/dtic/tr/fulltext/u2/479244.pdf |title=Steel cutting with high-explosive charges |id=Report 1839 |first=James A. |last=Dennis |date=December 1965 |publisher=U. S. Army Engineer Research And Development Laboratories |place=Fort Belvoir, Virginia |website=apps.dtic.mil|archive-url=https://web.archive.org/web/20190502002330/https://apps.dtic.mil/dtic/tr/fulltext/u2/479244.pdf |archive-date=2019-05-02 }}</ref>

=== Form ===
Military grade C-4 is commonly packaged as the M112 [[demolition]] block. The demolition charge M112 is a rectangular block of Composition C-4 about {{convert|2|x|1.5|in}} and {{convert|11|in}} long, weighing {{convert|1.25|lb|g|abbr=on}}.<ref name="global">{{Cite web |title=Explosives – Compositions |url=https://www.globalsecurity.org/military/systems/munitions/explosives-compositions.htm |archive-url=https://web.archive.org/web/20220819084947/https://www.globalsecurity.org/military/systems/munitions/explosives-compositions.htm |archive-date=19 August 2022 |access-date=14 July 2014 |publisher=[[GlobalSecurity.org]]}}</ref><ref name=M15>{{Cite book
 | publisher = Headquarters, Department of the Army
 | title = Use of Mine, Antitank: HE, Heavy, M15 as a Substitute for Charge Assembly Demolition, M37 Or M183
 | date = 1971
}}</ref> The M112 is wrapped in a sometimes olive color [[BoPET|Mylar]]-film container with a [[Pressure-sensitive tape|pressure-sensitive adhesive tape]] on one surface.<ref>{{cite web |title=M112 |url=http://www.aollc.biz/pdf/DemoBlockM112.pdf |publisher=American Ordnance |access-date=19 July 2014 |archive-url=https://web.archive.org/web/20150322080434/http://www.aollc.biz/pdf/DemoBlockM112.pdf |archive-date=22 March 2015 |url-status=dead }}</ref><ref>{{cite book |title=ATF Law Enforcement Guide to Explosives Incident Reporting |publisher=Bureau of Alcohol, Tobacco, Firearms, and Explosives |chapter-url=http://www.uaemt.org/uploads/explosives_plastics.pdf |access-date=15 July 2014 |chapter=Military Explosives |archive-date=19 July 2014 |archive-url=https://web.archive.org/web/20140719152211/http://www.uaemt.org/uploads/explosives_plastics.pdf |url-status=dead }}</ref>

The M112 demolition blocks of C-4 are commonly manufactured into the M183 "demolition charge assembly",<ref name=M15 /> which consists of 16 M112 block demolition charges and four priming assemblies packaged inside military Carrying Case M85. The M183 is used to breach obstacles or demolish large structures where larger [[satchel charge]]s are required. Each priming assembly includes a {{convert|5|or|20|ft|m|adj=on|spell=in}} length of detonating cord assembled with detonating cord clips and capped at each end with a booster. When the charge is detonated, the explosive is converted into compressed gas. The gas exerts pressure in the form of a shock wave, which demolishes the target by cutting, breaching, or cratering.<ref name="global" />

Other forms include the [[mine-clearing line charge]] and [[M18 Claymore mine|M18A1 Claymore mine]].<ref name=bae />

=== Safety ===
{{Further|Explosives safety|Safety testing of explosives}}

Composition C-4 exists in the U.S. Army Hazardous Components Safety Data Sheet on sheet number 00077.<ref name="TM-9-1300-214">{{citation | url=http://www.lexpev.nl/downloads/tm91300214militaryexplosives.pdf | title=Department of the Army Technical Manual – Military Explosives| author=Headquarters, U.S. Department of the Army | date=25 Sep 1990 | pages=A-13 (323)|postscript=.}}</ref>{{rp|323}} Impact tests done by the U.S. military indicate composition C-4 is less [[Sensitivity (explosives)|sensitive]] than composition C-3 and is fairly insensitive.  The insensitivity is attributed to using a large amount of binder in its composition.  A series of shots were fired at vials containing C-4 in a test referred to as "the rifle bullet test".  Only 20% of the vials burned, and none exploded.  While C-4 passed the Army's bullet impact and fragment impact tests at ambient temperature, it failed the shock stimulus, [[sympathetic detonation]] and [[shaped charge]] jet tests.<ref name="bae" /> Additional tests were done including the "pendulum friction test", which measured a five-second explosion temperature of 263&nbsp;°C to 290&nbsp;°C. The minimum initiating charge required is 0.2&nbsp;grams of [[Lead(II) azide|lead azide]] or 0.1&nbsp;grams of [[tetryl]]. The results of 100&nbsp;°C heat test are: 0.13% loss in the first 48 hours, no loss in the second 48 hours, and no explosions in 100 hours. The vacuum stability test at 100&nbsp;°C yields 0.2 cubic centimeters of gas in 40 hours. Composition C-4 is essentially [[Hygroscopy|nonhygroscopic]].<ref name="armymanual 8-111" />

The [[shock sensitivity]] of C-4 is related to the size of the nitramine particles. The finer they are the better they help to absorb and suppress shock. Using 3-nitrotriazol-5-one (NTO), or [[TATB|1,3,5-triamino-2,4,6-trinitrobenzene]] (TATB) (available in two particle sizes (5&nbsp;μm, 40&nbsp;μm)), as a substitute for RDX, is also able to improve stability to thermal, shock, and impact/friction stimulus; however, TATB is not cost-effective, and NTO is more difficult to use in the manufacturing process.<ref name="bae"/>

{| class="wikitable"
 |+ Sensitivity test values<br />{{nobold|reported by the U.S. Army.<ref name="TM-9-1300-214" />{{rp|311, 314}}}}
 |-
 | '''Impact''' test with 2 kilogram weight / PA APP (% TNT)
 | style="text-align:right;" |>100
 |-
 | '''Impact''' test with 2 kilogram weight / BM APP (% TNT)
 | {{NA}}
 |-
 | '''Pendulum friction''' test, percent explosions
 | style="text-align:right;" |0
 |-
 | '''Rifle bullet''' test, percent explosions
 | style="text-align:right;" |20
 |-
 | '''Explosion temperature''' test, Celsius
 | style="text-align:right;" |263 to 290
 |-
 | Minimum detonating charge, gram of [[lead azide]]
 | style="text-align:right;" |0.2
 |-
 | '''Brisance''' measured by Sand test (% TNT)
 | style="text-align:right;" |116
 |-
 | '''Brisance''' measured by plate dent test
 | style="text-align:right;" |115 to 130
 |-
 | Rate of '''detonation at density'''
 | style="text-align:right;" |1.59
 |-
 | Rate of '''detonation meters per second'''
 | style="text-align:right;" |8000
 |-
 | '''Ballistic pendulum''' test percent
 | style="text-align:right;" |130
 |}