Science in the Service of Man — Nylon

Nylon is a new conquest in the manufacture of fabrics. The threads this industry requires are either, like the threads of artificial silk, cotton, and linen, of vegetable origin, or, like the threads of wool and silk, of animal origin.

Nylon, however, is a purely synthetic substance, made from chemical compounds extracted by the distillation of coal by special processes. Neither plant nor animal, then, has any part in its composition — unless we carry our minds back tens of millions of years, when the earth was clothed in dense forests which the belly of the earth later swallowed up through earthquakes, and these trees, after long ages, under the effect of tremendous pressure and high heat, turned into coal and petroleum...

In this article I shall try to explain briefly what this nylon is, whose name is now on every lip and tongue, and which has been able to rival silk in many of its uses.

The raw materials for making nylon

Nylon was born — if it is right to call it an industrial newborn — on the twenty-eighth of February, 1935, the day the American chemist Carothers succeeded in obtaining the new substance after long experiments and researches. He was thereby the first to invent a purely synthetic material fit for use in the manufacture of fabrics.

This chemist obtained nylon as the result of a reaction between two organic compounds (Composés Organiques), one containing the elements carbon and oxygen, the other the elements carbon and nitrogen.

These two substances are made from phenic or carbolic acid (Acide phénique ou Acide carbolique), a compound much used in the manufacture of dyes and colors; it is also an antiseptic substance much used in dentistry and in certain kinds of soap, such as the Lifebuoy soap well known in Beirut.

This carbolic acid is extracted by the distillation of coal by special processes; it is then taken and subjected to several chemical reactions by which it is turned into a compound called adipic acid (Acide adipique), which is the compound containing the element oxygen. The second compound is made from this same adipic acid, by making the acid react with ammonia and hydrogen gas; from this results a substance called hexamethylene-diamine, which is the compound containing the element nitrogen.

How nylon is made

Suitable quantities of these two

compounds are taken and dissolved in an organic liquid somewhat resembling benzine, and the whole is placed in a polished steel boiler. The reason for dissolving the two compounds is that dissolving increases their readiness to react. When the dissolving is complete, the temperature is raised to 218 degrees centigrade and kept there for thirteen hours. During this time the desired reaction takes place; in brief, the molecules of these two compounds all unite to form an exceedingly long chain of carbon atoms, bound one to another by atoms of nitrogen and oxygen. From this results a new compound with properties utterly different from those of the raw materials used to make it: the new compound is sticky and elastic at the high temperature at which the reaction is carried out, while the two original substances from which it is made are two white powders which no observer would suppose to have the remotest connection with nylon.

And now that the chemical reaction is finished and the various molecules have united, the contents of the steel boiler are poured into a vessel consisting of a large quantity of alcohol (that is, ordinary spirits); and since nylon does not dissolve in alcohol, it settles to the bottom of the vessel as an ivory-white substance. The alcohol is then removed from it and it is thoroughly dried.

This is raw nylon, and from it are spun the threads used in making stockings and "nylon" fabrics. To this end the raw nylon is taken and subjected to high heat until it melts and turns into a liquid; this liquid is then forced through minute holes, from which it issues as long threads that are wound on spools prepared especially for the purpose. But these threads cannot yet be used for weaving fabrics, for they are still more elastic than they should be; add to this that they break easily. This comes of the fact that the molecules composing the thread are not drawn up in serried ranks but are arranged haphazard. Just as a man who tries, for example, to gather up his papers or his belongings in haste ends with an untidy bundle, so the molecules in the threads of raw nylon are still scattered and unordered, and they must all be ranged in serried ranks before we have a strong thread. To reach this end, the nylon thread is transferred from its old spools to new spools revolving at four times the speed of the old ones. The threads therefore do not merely pass from one spool to another: in the course of passing they are stretched, so that the thread's length increases fourfold, and it gains in luster and strength, because its molecules have all become ordered and regular. Here it has reached the stage at which it can be used industrially in the knitting of stockings or of the various textiles.

Nylon is still an infant in the world of industry — America began producing it industrially at the beginning of 1940 — so the time has not yet come to foretell the future of this new material. But there is no doubt that in the invention of nylon lies fresh evidence of man's productive genius, and one proof more of what science is doing in the service of man.