Cellulose nitrate

Structural formula
General
Surname	Cellulose nitrate
other names	Nitrocellulose Gun cotton Lightning floss NITROCELLULOSE ( INCI )
CAS number	9004-70-0
Monomers / partial structures	β - D - glucose (partially nitrated)
Type of polymer	Biopolymer
properties
Physical state	firmly
density	1.67 g cm −3
Melting point	160-180 ° C
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 201 P: 250-372
Toxicological data	> 5,000 mg kg −1 ( LD 50 ,  rat ,  oral )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Cellulose nitrate (also cellulose nitrate ) is a white, fibrous, odorless and tasteless mass. It is also known colloquially as gun cotton or nitrocellulose (or nitrocellulose ). The latter designation is problematic according to the IUPAC nomenclature, because it is not about an RC – NO ₂ bond, as the prefix “Nitro-” requires, but rather a nitric acid ester of cellulose .

Cellulose nitrate can be present in various degrees of nitric acid esterified form, typically as di- or tri-nitrate.

history

The “gun cotton” was discovered in 1846 by Christian Friedrich Schönbein and independently of that in the same year by the chemist Rudolf Christian Böttger . The first communication from Schönbein took place on May 27, 1846 before the Basler Naturforschenden Gesellschaft and can thus be found in the published minutes of the meeting. The Braunschweig professor Friedrich Julius Otto (1809–1870) also produced gun cotton independently of both in the same year and published the method in October of the same year.

Extraction and presentation

Cellulose nitrate is produced in the chemical industry by converting cellulose with nitrating acid. From a formal point of view, it is the reaction of an alcohol with an acid to form an ester . The nitrogen content of the cellulose nitrate to be produced is regulated by the composition of the nitrating acid and the duration of the reaction. Then at a nitrogen content> 12.75% is predominantly cellulose tri nitrate (gun cotton), at a level <12.75% to cellulose di nitrate ( collodion cotton ).

Conversion of cellulose to cellulose trinitrate

After the reaction, the remaining nitrating acid is washed out with water until the cellulose nitrate has a pH value of  7, otherwise traces of remaining nitric acid can cause spontaneous combustion. In the past, there were frequent explosions in factories because impurities in the fibers, such as the sulfuric acid esters formed as a by-product, caused spontaneous decomposition of the cellulose nitrate. It was not until 1864 that the Englishman Frederick Augustus Abel discovered that it can be completely stabilized by moist shredding in a paper dutchman .

The nitrocellulose is usually sold in a phlegmatized, moistened form in cardboard drums. Water, butanol , ethanol or isopropanol are used as humidifying agents . In addition, goods plasticized and pelletized with plasticizers are also offered.

properties

Physical Properties

• Explosion temperature: approx. 3100 ° C
• Lead block bulge : 37 cm ³ / g
• Impact sensitivity : 3 N · m
• Nitrogen content: 14.14% max. (theoretical), practically 13.5% max.
• Detonation speed : 6300 m / s
• Heat of explosion : 5475.75 kJ kg ⁻¹
• Explosive strength (TNT equivalent) : 147% of TNT
• Oxygen balance: −28.7% (13.4% nitrogen content)

Chemical properties

Cellulose nitrate burns immediately after it is ignited - even in the absence of atmospheric oxygen - with a yellowish flame to form carbon dioxide , carbon monoxide , water vapor and nitrogen . In contrast to black powder  , combustion does not produce any smoke that is visible to the human eye , which is why cellulose nitrate is also known as smokeless powder .

and display information about the image

Burning off nitrocellulose

use

Sign in the projection room of a cinema

Celluloid table tennis balls, 40 mm diameter (2012)

Cellulose nitrate based adhesive (CN, plasticizer, solvent)

• Cellulose nitrate earlier one was rayon , called Chardonnet silk produced. Due to their fire hazard, however, production was quickly stopped again.
• Adding camphor as a plasticizer turns cellulose dinitrate into celluloid ( abbreviation CN ). This material was the first thermoplastic and, despite its high degree of fire hazard, was used as a material for a large number of products. Celluloid was also used as a carrier for photographic films until the early 1950s, before it was consistently replaced by security film after it was banned in 1951 . This use is still a big problem today: film archives from this time are extremely endangered by the tendency of the material to self-ignite and explode and must be secured accordingly. Some products are still made from celluloid today. Table tennis balls were made from celluloid until, from July 1, 2014, for example, the DTTB required balls made of less flammable plastic.
• Dissolved in acetone , ethyl acetate and other solvents , cellulose dinitrate is used as the eponymous binder in nitro lacquer . Since different viscosities of the nitro lacquers are required for the various areas of application (e.g. flexographic or gravure printing , leather or wood lacquer), the viscosity of cellulose dinitrate is reduced by overpressure boiling in an autoclave .
• Cellulose nitrate is also a component of zapon varnish and nail polish .
• In some adhesives and mastics is collodion cotton used as a binder.
• Due to its low smoke content, cellulose trinitrate is used as the main component of low-smoke gunpowder , propellant powder and mining explosives and as a component in rocket fuels . In pyrotechnics , it is estimated that there is little smoke for fireworks effects in closed rooms. It is marketed in many forms, such as pyro wadding, paper, cord, flakes or chips, which differ in their burning behavior.
• In molecular biology and biochemistry are membranes of cellulose nitrate at different blotting used. See: Southern Blot , Northern Blot , Western Blot .
• Part of spray plasters

Fires caused by celluloid film

Celluloid film played an initiating or promoting role in the following fires:

• Bazar de la Charité , Paris, May 4, 1897: The fire started from the film projector ( Drummond's light with ether flame ), 129 dead.
• Cinémathèque Française , burning down of the film store, in rue de Courcelles , in June 1959, spontaneous combustion on a hot afternoon.
• Cinémathèque Française, fire in a makeshift film warehouse in Le Pontel, on the outskirts of Paris, on the night of August 3, 1980 - thousands of films were destroyed.

safety instructions

Highly nitrated guncotton can at impact, static discharge and rapid heating explode . Due to the high oxygen content, it burns independently of the supply of oxygen from the air and can therefore only be extinguished with suitable means, especially large amounts of water.

Accordingly, collodion wool and products, which largely consist of it, are mainly transported and stored in paper or cardboard containers.

When classifying hazardous substances in accordance with RL 67/548 / EEC, a distinction was made in Appendix 1 between the two nitration levels "contains up to 12.6% nitrogen" (highly flammable) and "contains" until the 31st amendment was published (January 16, 2009) more than 12.6% nitrogen "(explosive). This distinction has been omitted since then; both entries in the material register have been combined. This new version was heavily criticized in specialist circles, especially since there is no compelling need to do so.

Trivia

• In Jules Verne's 1865 science fiction novel From Earth to the Moon , the projectile (not a rocket) flying to the moon is accelerated by 400,000 pounds of gun cotton.
• Johann Strauss dedicated the Explosions-Polka (1847) to the subject.

Individual evidence

1. ↑ Entry on NITROCELLULOSE in the CosIng database of the EU Commission, accessed on February 25, 2020.
2. ^ Frank Douglas Miles: Cellulose nitrate: The physical chemistry of nitrocellulose, its formation and use , Oliver and Boyd, 1955.
3. ↑ ^{a b c} Entry on nitrocellulose in the GESTIS substance database of the IFA , accessed on July 30, 2017(JavaScript required) .
4. ↑ MACHEREY-NAGEL: Porablot NCL (200x200 mm) sample, RS PM , accessed on December 9, 2015.
5. ↑ Jochen Gartz: From Greek fire to dynamite - a cultural history of explosives. ES Mittler & Sohn, Hamburg-Berlin-Bonn 2007, ISBN 978-3-8132-0867-2 .
6. ↑ Itzehoer Wochenblatt of October 29, 1846, columns 1626–1627.
7. ↑ after explosives. 9th edition.
8. ↑ ^{a b c} Rudolf Meyer: Explosivstoffe. VCH Verlagsgesellschaft, 1985, 6th edition, pp. 207-210, ISBN 3-527-26297-0 .
9. ↑ ^{a b} Regula Fuchs: Back to the Future , tagesanzeiger.ch, March 31, 2015, accessed December 5, 2016.
10. ↑ Matze: Table tennis balls - approval and details tischtennis-weblog.de, October 1, 2014, accessed December 5, 2016.
11. ^ State versus private - on the history and present of the Cinémathèque française: Kino und Kris nzz.ch, June 30, 2003, accessed December 5, 2016.
12. ↑ Patrick Olmeta: La Cinémathèque française: De 1936 à nos jours books.google.at, p. 138 f., June 26, 2013, accessed December 5, 2016.
13. ↑ Jérémie Couston: Exposition Henri Langlois: dix questions sur un monstre cinéphile www.telerama.fr, April 8, 2014, accessed December 5, 2016.

literature

• Jochen Gartz: From Greek Fire to Dynamite - A Cultural History of Explosives. ES Mittler & Sohn, Hamburg-Berlin-Bonn 2007, ISBN 978-3-8132-0867-2 .

Web links

Wiktionary: Gun cotton  - explanations of meanings, word origins, synonyms, translations

• Safety data sheet for the storage and handling of nitrocellulose (PDF; 1600 kB)