The Chemical Composition of Wool

Abstract

SummaryA study is made of the disruption of wool by ultrasonic disintegration and the separation and identification by microscopy of the major components of the fibre. The ultrasonic disintegration process is investigated empirically in order to establish the conditions under which maximum rates of disruption occur. Of a large number of liquids examined it is found, in confirmation of earlier work, that the rate of disintegration of wool is very slow in water but usually increases in amount as the swelling of the fibre increases. The several exceptions to this rule show that there are other factors of secondary importance in determining the rate of disruption. The amount of disruption is sufficient for preparative purposes and increases in amount in the series dimethyl sulphoxide, formic acid, and dichloroacetic acid.Cortical cells, cuticle, and disrupted cortical cells can be separated on the basis of their different sizes by a combination of screening and sedimentation methods. The histological purity of the fractions is established by light and electron microscopy. It is also shown that the random nature of the ultrasonic disruption process results in the production of components of a continuous range of sizes from cortical cells down to needle· like components of size approaching that of microfibrils.

The Chemical Composition of Wool II. Analysis of the Major Histological Components Produced by Ultrasonic Disintegration

“…These liquids had been shown previously to give the most rapid rates of disruption of wool (Bradbury and Chapman 1964). The amino acid analyses of Merino 64's wool and the wool components produced from it are given in Tables 2 and 3.…”

“…The suspension was poured through a coarse sieve to remove short wool fibres; these were washed with water which was added to the suspension. The wool components were then sedimented, washed with water and ethanol, and screened by the method described by Bradbury and Chapman (1964). The histological purity of the separated components was always checked by light microscopy and that of the cuticle preparations by light and electron microscopy.…”

“…The same sample of Lincoln 36's wool processed to "top" form as that used previously by Bradbury (1960a) was extracted with detergent by the method of Bradbury and Chapman (1964).…”

“…The Merino wool was cut into short lengths and samples (1 g) were subjected to ultrasonic treatment for the appropriate time interval in 50 ml of either 98% formic acid, dichloroacetic acid, or dimethyl sulphoxide, the conditions described for maximum breakdown being used (see Table 4 of Bradbury and Chapman 1964). The suspension was poured through a coarse sieve to remove short wool fibres; these were washed with water which was added to the suspension.…”

“…In an attempt to overcome these difficulties we have studied the ultrasonic disruption of wool (Bradbury 1960b;Bradbury, Rogers, and Filshie 1963), and in Part I of this series (Bradbury and Chapman 1964) have shown that disruption can be achieved and the histological components separated from one another. This paper is concerned with the amino acid analysis of the various components and the related important consideration of the possibility of chemical modification of the components during ultrasonic treatment in formic acid, dichloroacetic acid, and dimethyl sulphoxide.…”