Nitroglycerin - Use As An Explosive and A Propellant

Use As An Explosive and A Propellant

The main use of nitroglycerin, by tonnage, is in explosives such as dynamite and in propellants.

Nitroglycerin is an oily liquid that may explode when subjected to heat, shock or flame. It is dangerously sensitive and dropping or bumping a container may cause it to explode.

Alfred Nobel developed the use of nitroglycerin as a blasting explosive by mixing the nitroglycerin with inert absorbents, particularly "kieselguhr," or diatomaceous earth. He named this explosive dynamite and patented it in 1867. It was supplied ready for use in the form of sticks, individually wrapped in greased water-proof paper. Dynamite and similar explosives were widely adopted for civil engineering tasks, such as in drilling highway and railroad tunnels, for mining, for clearing farmland of stumps, in quarrying, and in demolition work. Likewise, military engineers have used dynamite for construction and demolition work.

Nitroglycerin was also used as an ingredient in military propellants for use in firearms.

Nitroglycerin is a high explosive which is so sensitive that a slight jolt, friction, or impact may cause it to detonate. The molecule contains oxygen, nitrogen, and carbon with stressed chemical bonds. Hence when it explodes, great energy is released as the atoms rearrange to form new molecules with strong, stable bonds such as N₂, H₂O, and CO₂. It is the speed of the decomposition reaction which makes it such a violent explosive. A supersonic wave passing through the material causes it to decompose almost instantly. This instantaneous destruction of all molecules is called a detonation, and the destructive blast results from the rapid expansion of hot gases. Nitroglycerin has an advantage over some other high explosives, that practically no visible smoke is produced, therefore it acts as a "smokeless powder".

Because of its extreme sensitivity, nitroglycerin was rendered obsolete as a military explosive, and was replaced by less sensitive explosives such as TNT, RDX, and HMX. Combat engineers still use dynamite.

Alfred Nobel then developed ballistite, by combining nitroglycerin and guncotton. He patented it in 1887. Ballistite was adopted by a number of European governments, as a military propellant. Italy was the first to adopt it. However, it was not adopted by the British Government. This government and the Commonwealth governments, adopted cordite, which had been developed by Sir Frederick Abel and Sir James Dewar of the United Kingdom in 1889. The original Cordite Mk I consisted of 58% nitroglycerin, 37% guncotton, and 5.0% petroleum jelly. Ballistite and cordite were both manufactured in the forms of cords.

Smokeless powders were originally developed using nitrocellulose as the sole explosive ingredient. Therefore they were known as single base propellants. A range of smokeless powders that contain both nitrocellulose and nitroglycerin, known as double base propellants, were also developed. Smokeless powders were originally supplied only for military use, but they were also soon developed for civilian use and were quickly adopted for sports. Some are known as sporting powders. Triple base propellants contain nitrocellulose, nitroglycerin, and nitroguanidine, but are reserved mainly for extremely high caliber ammunition rounds such as those used in tank cannons and naval artillery.

Blasting gelatin, also known as gelignite, was invented by Nobel in 1875, using nitroglycerin, wood pulp, and sodium or potassium nitrates. This was an early low-cost, flexible explosive.