The micelle structure of the wool fibre

During the past few years, the elastic properties of wool have been studied in some detail, not simply on account of their intrinsic interest, but rather as an aid to the elucidation of the intimate structure of the fibre. The earlier of these investigations were concerned with the changes produced by the action of water at various partial pressures and different temperatures under widely different conditions of loading and reloading. More recently, the scope of the research was extended to include an examination of the elastic properties of wool in organic liquids of a relatively inert type. It was postulated that any particular liquid might fail to react with wool for one of two reasons: either that the compound is inherently incapable of reaction on chemical grounds or because it is unable to penetrate the fine capillary structure of the fibre. Both expectations were realised. In general, it was found that organic reagents with hydroxyl groups in the molecule were able to modify the elastic properties of wool to a striking degree, provided that the molecule was sufficiently small to gain admittance to the fibre. Other reagents were by comparison remarkably inert. The high order of reactivity of the normal aliphatic alcohols was utilised to give a measure of the size of the capillary spaces in the dry wool fibre. It is well known that the work required to stretch wool fibres is at a maximum in dry air and a minimum in water. Similarly, the work required to stretch fibres in methyl-or ethyl-alcohols was found to be of the same order as that required in water, whereas wool fibres in butyl-or amyl-alcohols showed a resistance to extension precisely similar to that of the dry fibre. Propyl alcohol was intermediate in type between the two extremes and from the graph of the work required to stretch fibres 30 per cent. of their length, against the molecular weight of the corresponding reagent, it was concluded that the size of the capillary spaces in the dry wool fibre is of the same order as the length of then -propyl alcohol molecule.