RESEARCH ON WOOL.

New Zealand Herald, Volume LXVIII, Issue 20982, 19 September 1931, Page 20

RESEARCH ON WOOL.

INVESTIGATION AT LEEDS. STRUCTURE OF T&E FIBRE. NEW ZEALANDER'S WORK. [from our own correspondent.] ' LONDON, July 10. Miss Thora 0. Warwick, who has been awarded a travelling scholarship by the University of Leeds to investigate woolgrowing and sheep-breeding in New Zealand, will leave by the Bemuora on July 31. Miss Marwick is a New Zealander, having graduated at the Otago University, obtaining there here M.Sc. degree. For some years, she was assistant to the professor of physics at Victoria University College. She came to England at the end of 1927, and spent nearly three years in research work under Sir William Bragg, at the Davy Faraday Laboratory of the Boyal Institution, London, gaining the degree of Ph.D. In 1930 she was awarded a Clothmakers' Fellowship, and for the past year slio has been cni gaged iri wool research at the lextile | i'Jiysics Laboratory oi the University of j Leeds. I Speaking of her work at Leeds, Miss j Marwick said that all investigations ' hitherto niude on wool have shown it j to be an extremely complex substance .with properties so unusual that its bei haviour under any new conditions could | rarely be foretold with certainty. The aim 'of the textile research worker is to determine'exactly what wool is, so that it may be used in any desired process, and the results foreseen. Further, there is no fundamental reason why, the structure once being known, it should not be capable of modification, as cotton is adapted to special purposes by the process of mercerisation. Use of X-Ray. "Until recently," continued Miss Marwick, "the determination of structure was based on microscopic investigation and on the observation of the more familiar physical and chemical properties. Within the last 20 years, however, science has acquired a new and powerful weapon in X-rays. These are, essentially, rays of light of such a very short wave-length that they can penetrate all substances and produce on a photographic plato a pattern dependent on the structure of the substance under examination. '•This is not the ordinary shadow photography of radio-therany, but a phenomenon similar to the production of a pattern of lights when a street lamp is viewed through a mushn curtain. With liquids, a single broad ring is produced similar to the rings of light which appear when a lamp is seen through a misty* window-pane, and just as theso latter rings are produced by the passage of light through a multitude of fine drops of water, so the X-ray rings are caused by the 'diffraction' of the rays by the extremely small units, the molecules, of which all matter is composed. For the so-called 'amorphous' substances, such as liquids and certain solids, such as glass, the inoleculsr arrangement is quito irregular, but X-ray analysis has shown that most substances hitherto regarded as amorphous possess in reality a crystalline' structure, that is, are built of definite units of pattern which are repeated in a regular manner in all directions. Problem for Solution. "Thus, it has been shown by X-rays that wool, silk, and cellulose (cotton, artificial silk, etc.), are all composed of minute crystals ('crystallites'), very much elongated in the direction of the fibre length-—though, to be sure, the whole length of such a crystallite amounts to no more than four-nhllionths of an inch! The crystallites are themselves built up of groups of molecules, and it is on the nature and arrangement of these molecules that the properties of the substance depend. The difference between natural and mercerised cellulose is due merely to a small change in the relative positions of the molecular groups, and it is not too much to hope that the utility of wool may be similarly increased by some analogous process. "More fundamental than differences in structure are differences in the nature of the individual units which go to make up the pattern. In wool, this unit is a molecule of an insoluble protein, keratin, composed of atoms of carbon, hydrogen, oxygen, nitrogen, and sulphur. It is this molecule, varying slightly in form, according to the proportion of these elements present, which forms the basis of the protective epidermal proteins. Wool, horn, finger nails, hair, porcupine quill and whalebone are found to give substantially the same X-ray photograph, indicating beyond doubt that these are merely variations, to suit different applications, of one primitive substance. Stretched Wool. " The most astonishing result achieved in this field by means of X-rays," said Miss Marwick, " is the demonstration of the fact that the crystalline structure of stretched wool is different from that of unstretched wool. The only other fibrous substance known to exhibit this feature is rubber, which shows no apparent crystallisation until it has been stretched very considerably. It is highly significant that these two fibres also possess extraordinary powers of extension and complete subsequent recovery. This fact, coupled with the X-ray evidence, has led to the theory that in both cases the" atoms are arranged in long zig-zag chains which are coiled up in the normal state, but which, on extension, become drawn out to their full length. " That unstretched wool also gives a photograph points to a regular arrangement of the coils of the chain, but what is most striking is that the dimensions of the photograph are in keeping with that coiled structure which is most in agreement with the chemical -behaviour of unsi retched wool. "An interesting feature of this stretched ('beta') form—in contra-distinction to the unstretched ('alpha') form—is that it may bo permanently 'set' by the action of steam. This ie, in essence, the fundamental principle of most systems of permanent waving.' Further, the effect of stretching is to weaken or even destroy the side linkages between the chains, so that wool is more vulnerable to chemical attack when stretched than when unstretched. Companion With Silk. "Another point which has been brought out during the course of this work is the similarity between the X-ray photographs of stretched wool and natural silk. Taken in conjunction with the facts that silk does not show any pronounced elasticity, and that it may, by treatment with suitable re-agents, be made to decrease considerably in length, this suggests that silk is already in an extended state, a hypothesis quite in keeping with the observation that the silk-worm pulls the fibre from its silk-glands by the motion of its head. „ r , . " In addition to the X-ray work, detailed investigations of the elasticity and swelling of wool and its behaviour under the action of steam and of various reagents, have been carried out in conjunction with the textile chemical laboratory of ilio university. The results obtained in this section of the work, not only support the above hypothesis as to the structure of the wool fibre, but also have brought to light many features hitherto unsuspected. Much research still remains to be done, but there is no doubt that, once tho structure of this extraordinary fibre is understood, its utility, great as it is to-day, will be enormously enhanced."