Silk, nitrated

Silk, Nitrated. Vignon prepd a yel product by immersing ordinary silk in nitric acid (d 1.133 g/cc) at 45° for one min, followed by w washing. Although the dry product was not expl, it burned more rapidly than ordinary silk Refs 1) L. Vignon, BullFr 6, 898 (1891)... 

Picric Acid and Ammonium Picrate. Picric acid (PA) (2,4,6,-trinitrophenol) was the first modem high explosive to be used extensively as a burster ia gun projectiles. It was first obtained by nitration of iadigo, and used primarily as a fast dye for silk and wool. It offered many advantages when compressed, it was used as a booster for other explosives, and when cast (melting poiat 122.5°C) served as a burster ia shell it was stable, iasensitive, nonhygroscopic, relatively nontoxic, and of high density when cast, and could be made economically by simple nitration. 

Sir Joseph Swan, as a result of his quest for carbon fiber for lamp filaments (2), learned how to denitrate nitrocellulose using ammonium sulfide. In 1885 he exhibited the first textiles made from this new artificial sHk, but with carbon fiber being his main theme he failed to foUow up on the textile possibihties. Meanwhile Count Hilaire de Chardoimet (3) was researching the nitrocellulose route and had perfected his first fibers and textiles in time for the Paris Exhibition in 1889. There he got the necessary financial backing for the first Chardoimet silk factory in Besancon in 1890. His process involved treating mulberry leaves with nitric and sulfuric acids to form cellulose nitrate which could be dissolved in ether and alcohol. This collodion solution could be extmded through holes in a spinneret into warm air where solvent evaporation led to the formation of soHd cellulose nitrate filaments. 

The minerals on which the work was performed during the nineteenth century were indeed rare, and the materials isolated were of no interest outside the laboratory. By 1891, however, the Austrian chemist C. A. von Welsbach had perfected the thoria gas mantle to improve the low luminosity of the coal-gas flames then used for lighting. Woven cotton or artificial silk of the required shape was soaked in an aqueous solution of the nitrates of appropriate metals and the fibre then burned off and the nitrates converted to oxides. A mixture of 99% ThOz and 1% CeOz was used and has not since been bettered. CeOz catalyses the combustion of the gas and apparently, because of the poor thermal conductivity of the ThOz, particles of CeOz become hotter and so brighter than would otherwise be possible. The commercial success of the gas mantle was immense and produced a worldwide search for thorium. Its major ore is monazite, which rarely contains more than 12% ThOz but about 45% LnzOz. Not only did the search reveal that thorium, and hence the lanthanides, are more plentiful than had previously been thought, but the extraction of the thorium produced large amounts of lanthanides for which there was at first little use. 

Chardonnet A process for making artificial silk by nitrating cellulose and injecting the nitrate solution into water, thereupon regenerating the cellulose ... 

In the original process the cellulose nitrate itself was used as the fiber (hence its satirical description as mother-in-law silk ). The regenerating agent is ammonium hydrosulfide. The basic process was first demonstrated by J. W. Swan in London in 1885 but commercialized by Count L. M. H. B. de Chardonnet ( Father of the rayon industry ) in France in 1891 and operated there until 1934. The last working factory, that in Brazil, was burnt down in 1949. The other processes for making rayon fibers by regenerating cellulose ( viscose, cupram-monium) gave superior products. See also Rayon. 

J.W. Swan produced threads of cellulose nitrate in 1883 by forcing its solution through a spinning jet. This was called Swan Silk. Carbon filaments for early electric light bulbs were made from Swan Silk. Chardonnet manufactured artificial silk commercially in 1884 from cellulose nitrate. 

Natural fibers go back to prehistoric days. Probably one of the early applications was the conversion of a fiber (possibly wool or cellulose) into thread or rope strong enough to be used in a snare, net, or cage. Literature as far back as the 17th century notes that people attempted to make fibers out of something other than cotton, wool, or flax. The first man-made fiber, known as artificial silk, was made in the 19 th century, when wood pulp was treated with nitric acid. The result was known chemically as cellulose nitrate and (eventually) commercially as Rayon. The commercial name referred to the sheen that has the brilliance of the sun. ... 

Iron(lll) nitrate is used as a mordant for dyeing black and buff. Other applications are in tanning weighting silks and in preparation of analytical standards. 

Another method used in France was to add anti-flash pellets, consisting of four parts of potassium nitrate and one part of DNT, to propellant charges. The pellets weighed one gramme each and were about 2 mm thick and 15 mm dia. They were sewn in silk bags, in numbers depending on the calibre e.g. 200-300 were used for a 155 mm gun. Such pellets behaved as a propellant charge and did not reduce the muzzle velocity. 

Other early experimenters obtained picric acid by nitrating various organic substances such as silk, natural resins, etc. The correct empirical formula for picric acid was determined by Laurent in 1841 who prepared the acid by reacting phenol with nitric acid and isolated dinit-rophenol which was formed in an intermediate stage of the reaction. 

The basic substance is pure, non-nitrated cellulose in this are the silks obtained by the Langhans, Pauly, Despaissis, Dreaper and Tompkins, Fremery and Urban, and Bronnert processes. 

A little of the sample is dissolved in pure concentrated sulphuric acid and a crystal of diphenylamine sulphate added to the solution with artificial silks based on cellulose nitrate, a blue coloration is obtained. This test is applicable only to undyed fibres. 

Ha, S.W., Park, Y.H., and Hudson, S.M. "Dissolution of Bombyx mori silk fibroin in the calcium nitrate tetrahydrate-methanol system and aspects of wet spinning of fibroin solution". 

As a matter of fact, mankind knows polymers from ancient times, due to the existence of naturally occurring polymers such as latex, starches, cotton, wool, leather, silk, amber, proteins, enzymes, starches, cellulose, lignin, and others. The other type of polymers are synthetic polymers. Braconnot, in 1811, perhaps made the first significant contribution to polymer science by developing compounds derived from cellulose. Later, cellulose nitrate was obtained in 1846 by Schonbein, afterward in 1872, its industrial production was established. Besides, in 1839, Goodyear found out by accident that by heating latex with sulfur its properties were altered creating a flexible and temperature-stable rubber. This process is named vulcanization. 

Artificial silk was first produced from cotton waste in the early 1900s. Three Englishmen are credited with discovering how to produce viscose (rayon) from a cellulose solution using wood and woody materials. During World War I, this process was used to make guncotton (by nitrating the cellulose) and other explosives. The rayon was also used as artificial silk. Special dyes, now known as acid dyes, had to be developed to color this product. 

There were experiments prior to this working in the same area. In 1771 Woulfe treated indigo with nitric acid and discovered a yellow substance that dyed wool and silk. In 1779 Welter nitrated silk in another version of the same experiment. Both chemists had made picric acid, but without knowing it. In 1776 Scheele treated uric acid with nitric acid and evaporated the contents of the reaction. The reddish residue that appeared could dye skin. Scheele named it purpuric acid. In 1818 Proust prepared mureside from this. These experiments were not fully understood, but they were an unconscious groping towards the synthesizing of colour. 

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