Introduction to Nitrocellulose
Nitrocellulose, also known as cellulose nitrate, is a highly flammable compound made up of nitric esters of cellulose that is used as the main ingredient in modern gunpowder and in some lacquers and paints. It was the foundation of the first man-made fibres and plastic materials in the late 19th and early 20th centuries.
In this article, we will study the uses of nitrocellulose group including dow nitrocellulose, synthesia nitrocellulose, Dupont nitrocellulose, and nitrocellulose price in detail.
Nitrocellulose Industry
Cellulose is a polymer derived from wood pulp or the small fibres that cling to cotton seeds. It is made up of alternating glucose units with the molecular structure C6H7O2(OH)3
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The X in the molecular formula of unaltered cellulose stands for hydrogen (H), suggesting the existence of three hydroxyls (OH) groups on the cellulose molecule. As a result of the strong hydrogen bonds formed by the OH groups between cellulose molecules, cellulose cannot be softened by heat or dissolved by solvents without causing chemical decomposition. OH, groups are substituted by nitro (NO2) groups after treatment with nitric acid in the presence of a sulfuric acid catalyst and water.
Preparation of Nitrocellulose:
To transform cellulose to nitrocellulose, a mixture of nitric acid and sulfuric acid is used. The cellulose's consistency is critical. Nitrocellulose made from hemicellulose, lignin, pentosans, and mineral salts is inferior. Nitrocellulose is a nitrate ester, not a nitro compound, in chemical terms. The cellulose chain's glucose repeat unit (anhydroglucose) has three OH groups, each of which can form a nitrate ester. As a result, nitrocellulose may refer to mono-nitrocellulose, di-nitrocellulose, tri nitrocellulose, or a combination of these materials.
Nitrocellulose do not aggregate by hydrogen bonding because they have fewer OH groups than parent cellulose. The nitrocellulose is soluble in organic solvents as a result of this. The dinitrate is used to make most lacquers, while the trinitrate is used to make explosives.
The following is the chemical equation for the formation of trinitrate:
3 HNO3 + C6H7(OH)3O2 + H2SO4 → C6H7(ONO2)3O2 + 3 H2O
Properties and Characteristics of Nitrocellulose
The grades of Walsroder Nitrocellulose and Walsroder NC-Chips are distinguished by their
Viscosity (molar mass), Nitrogen content (degree of substitution), and Phlegmatiser / stabilizer (wetting/damping agent or plasticizer).
In comparison to other cellulose-based products, the degree of substitution in nitrocellulose is indicated indirectly through the nitrogen content (in relation to dry substance). Nitrogen content of 14.14 per cent is theoretically probable (all three positions in an anhydroglucose unit are converted, i.e. substituted).
The viscosity of Walsroder Nitrocellulose or Walsroder NC-Chips is determined by the nitrocellulose's molar mass (molecular weight). Since determining the molar mass is much more difficult than determining the viscosity, and since the viscosity of the solution is important in practical terms, a viscosity index is used to specify the viscosity of the nitrocellulose in a given solvent mixture.
The content and type of damping agent in Walsroder Nitrocellulose and Walsroder NC-Chips is another grading feature. Industrial nitrocellulose must contain at least 25% damping agent (e.g. alcohol, water) or 18% plasticizer, according to the rule.
To deactivate the harmful properties of dry nitrocellulose, damping agents or plasticizers are used to phlegmatizer or stabilize the nitrocellulose (high flammability, high burning rates). Wolff Cellulosics' nitrocellulose grades are dampened with at least 30% alcohol or water, or, in the case of NC-Chips, phlegmatized with 20% plasticizer.
Other Uses of Nitrocellulose
Membrane filters made of a mesh of nitrocellulose threads with varying porosities are used in laboratory procedures for particle retention and cell capture in liquid or gaseous solutions, as well as obtaining particle-free filtrates in the reverse direction.
A sticky membrane used for immobilizing nucleic acids in southern and northern blots is a nitrocellulose slip, nitrocellulose membrane, or nitrocellulose document. Because of its nonspecific preference for amino acids, it is often used to immobilize proteins in western blots and atomic force microscopy. Nitrocellulose is commonly used as a help in antigen-antibody binding diagnostic tests, such as pregnancy tests, U-albumin tests, and CRP tests.
Nitrated cellulose was discovered to be soluble in ether and alcohol in 1846. The solution was given the name collodion and was soon used as a wound dressing. It's also used in topical skin applications including liquid skin and the application of salicylic acid, which is the active ingredient in Compound W wart remover.
On some flights, Copenhagen Suborbitals used nitrocellulose to jettison components of the rocket/space capsule and deploy recovery systems. However, after several missions and flights, it was discovered that in a near-vacuum environment, it lacked the necessary explosive properties. Since the Philae comet lander's 0.3 grams of nitrocellulose propulsion charges failed to fire during the landing in 2014, the harpoons were not deployed.
For much of the twentieth century, nitrocellulose lacquer was used as a finish on guitars and saxophones, and it is still used in some modern applications. The paint was also used on cars with the same colour codes as many guitars, including Fender and Gibson brands, but it fell out of favour for a variety of reasons, including pollution and the way the lacquer yellows and cracks over time.
Alternative cellulosic and other materials have increasingly replaced nitrocellulose lacquer as an aircraft dope, which was painted onto fabric-covered aircraft to tighten and secure the content.
It is used to cover playing cards and keep staples in office staplers together.
Nitrocellulose lacquer is used to make nail polish because it is cheap, dries easily, and is not harmful to the skin.
To make one-off phonograph albums, nitrocellulose lacquer is spin-coated onto aluminium or glass discs, then a groove is carved with a lathe to make masters for pressing or for play in dance clubs. Acetate discs are what they're called.
Nitrocellulose is esterified to various degrees depending on the production process. Table tennis balls, guitar sticks, and certain photographic films have low levels of esterification and burn slowly, leaving a charred residue.
Did You Know?
Collodion is a flammable liquid made up of nitrocellulose in ether and ethanol. Nitrocellulose is explosive when dry, and it can be ignited by fire, sparks, or friction. The explosions in Tianjin in 2015 are thought to have started with an overheated container of dry nitrocellulose.
FAQs on Nitrocellulose
1. What is nitrocellulose and how is it chemically prepared?
Nitrocellulose, also known as cellulose nitrate, is a highly flammable compound created by the nitration of cellulose. It is prepared by treating cellulose (often from cotton linters or wood pulp) with a mixture of nitric acid (HNO₃) and sulfuric acid (H₂SO₄). The sulfuric acid acts as a catalyst and a dehydrating agent. During this reaction, the hydroxyl (-OH) groups on the glucose units of cellulose are replaced by nitrate ester (-ONO₂) groups.
2. What are the major applications and uses of nitrocellulose?
The uses of nitrocellulose vary depending on its degree of nitration. Key applications include:
- Explosives and Propellants: Highly nitrated nitrocellulose (guncotton) is a primary component in modern smokeless gunpowder and solid rocket propellants.
- Lacquers and Finishes: Less nitrated forms are used in fast-drying nitrocellulose lacquers for finishing wood, cars, and musical instruments like guitars.
- Consumer Products: It is the film-forming polymer in most nail polishes and is used to make table tennis balls.
- Scientific Applications: Nitrocellulose membranes are crucial in laboratories for protein immobilization in Western blots and nucleic acid immobilization in Southern and Northern blots.
3. Why is nitrocellulose considered a nitrate ester and not a nitro compound?
This is a crucial distinction based on chemical structure. A nitrate ester has a C-O-NO₂ bond, which forms when an alcohol's hydroxyl (-OH) group reacts with nitric acid. A nitro compound has a C-NO₂ bond, where the nitro group is directly attached to a carbon atom. Since cellulose is a polymer rich in hydroxyl groups, the reaction results in the formation of C-O-NO₂ linkages, making nitrocellulose an ester, not a true nitro compound.
4. How does the degree of nitration affect the properties of nitrocellulose?
The degree of nitration, or the percentage of nitrogen, fundamentally changes the properties of nitrocellulose:
- High Nitration (~13% N): Known as guncotton, this form is highly explosive and insoluble in ether-alcohol mixtures. It is primarily used for propellants.
- Low Nitration (~11-12% N): Known as pyroxylin or collodion cotton, this form is less flammable and soluble in a mixture of ether and alcohol. It is used to make lacquers, plastics (celluloid), membranes, and nail polish.
5. What is the difference between guncotton and collodion?
Guncotton and collodion are both forms of nitrocellulose, but they differ in their nitrogen content and primary use. Guncotton is trinitrocellulose with a high nitrogen content (over 12.5%), making it a powerful explosive and propellant. Collodion has a lower nitrogen content and is a solution of pyroxylin (dinitrocellulose) in ether and alcohol. It is not used as an explosive but as a film-forming agent for wound dressings, lacquers, and photographic films.
6. Why is nitrocellulose so flammable and explosive?
The explosive nature of nitrocellulose comes from its chemical structure. It contains both a fuel source (the carbon and hydrogen backbone of cellulose) and an oxidiser (the nitrate groups) within the same molecule. When ignited, it undergoes extremely rapid, self-contained decomposition without needing external oxygen. This reaction produces a large volume of hot gases (like N₂, CO₂, CO, and H₂O), causing a rapid expansion and creating the explosive force.
7. Why must industrial nitrocellulose be stored wet with water or alcohol?
Dry nitrocellulose is extremely dangerous because it is sensitive to heat, friction, static discharge, and shock, which can cause it to ignite or explode. Storing it dampened with at least 25-30% water or alcohol is a process called phlegmatization. The wetting agent absorbs energy and separates the nitrocellulose fibres, dramatically reducing its sensitivity and making it much safer to transport, store, and handle in industrial settings.
