Nitrocellulose

Nitrocellulose is a product obtained by nitration of pure cellulose , which is used, according to its characteristics, as a base for powders, dynamites, explosive jellies or paints.

Summary

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• 1 Discovery
• 2 Features
• 3 Uses
• 4 Problems of nitrocellulose.
• 5 Types of Nitrocellulose
• 6 External links

Discovery

Cellulose nitrate was discovered by Christian Schönbein in 1845 , like many things in science, it happened by chance, when drying with a cotton cloth (cellulose fiber) with the remains of a mixture between sulfuric and nitric acid , he observed that when he put it When drying on the stove, the rag became inflamed, as there was only nitric acid, sulfuric acid and the cotton rag, he deduced that the mixture of acids and cotton had reacted to form: nitrocellulose (cellulose nitrate).

Nitrocellulose, if left to air dry, was found to form a thin, hard, and highly resistant coating, indicating that it could be used to coat and care for surfaces.

Nitrocellulose was the first stable semi-synthetic resin, which was used for coating and finishing wood , due to its rigid and impact resistant texture. If we mix cellulose nitrate with solvents and plasticizers, we improve its flexibility and faster drying conditions, in addition to achieving a suitable viscosity for brush or spray application.

Characteristics

Nitrocellulose: Cellulose is a high molecular weight polysaccharide with a linear structure that has beta-glucose as its monomer, which has three free hydroxyls for each glucose unit. These will be responsible for nitration, which depending on the degree, we will obtain different nitrocellulose and viscosities.

The degree of polymerization of nitrocellulose is measured by the number of beta glycolysis bonds that exist in the molecule. This index indicates the viscosity.

Depending on the final degree of nitration, we will have different types of nitrocellulose, with the three hydroxyls of each molecule we will achieve a maximum of 14.40%.

We have the most important characteristics of nitrocellulose:

• Wide solubility in organic solvents.
• Compatibility with different resins and plasticizers.
• Transparent and odorless films.
• Ease of processing.
• Fast dry.
• Quick removal of solvents in the application.
• Low retention of residual solvents.
• Odorless and non-toxic.

Applications

Nitrocellulose due to its composition are easy to use and due to its characteristics, easy to apply in: car lacquers, surface coatings, inks, enamels, etc.

Nitrocellulose problems.

Nitrocellulose are very sensitive to humidity, for this reason drying is very important, so suitable solvents must be used, which have a slow evaporation, due to their high boiling point (100 – 140 ºC), which gives a perfect drying both in depth and superficiality, which eliminates the problems of veiling, caused by the retention or absorption of water.

Types of Nitrocellulose

There are three types of Nitrocellulose: NC-CP1; NC-CP2; NC-CP3 and NC-CP4.

• NC type CP1: mixed with NC type CP2 they constitute NC A1 [1], which is used in the manufacture of simple base powders.
• NC type CP2: in general, the low nitration NC is used mixed with NC type CP1 to obtain the NC A1 used in the production of monobasic powders, while the high nitration NC is used in the manufacture of double base powders and propellants.
• NC type CP3: used in the production of lacquers, varnishes, paints, enamels, etc.
• NC type CP4: intended for the manufacture of gelatine for explosives of this nature, due to its specific characteristics.