Abstract

The curvature and diameter of fibres influence the core bulk of raw wool, which in turn is used as an indicator of yarn bulk. The compressional properties of fibre masses are difficult to predict from first principles, therefore the direct effect of fibre diameter and curvature on the bulk of semi-worsted yarn was investigated. Wools with similar core bulk (28 cm³/g) in which fibre diameter ranged from 18.5 to 40 mm were processed into semi-worsted yarn and measured for yarn bulk. Contrary to popular belief, fine wool of the same core bulk produced yarn with higher bulk than stronger wool. However, with a correlation coefficient of -0.9 between mean fibre diameter and mean fibre curvature the influence of these two attributes on yarn bulk cannot be separated. Closer examination of the data shows that for these wools, which were selected to have constant core bulk, the variation in yarn bulk can be predicted slightly more accurately by the variation in mean diameter than the variation in mean fibre curvature between the samples. Rather low R² values and the size of the coefficients in the regression equations indicate that the influence either fibre diameter or fibre curvature has on yarn bulk at 28 cm³/g core bulk is small. Wool type also had little effect on the relationship between core bulk and yarn bulk at this level of core bulk.

D, Maddever, and A Bray

Proceedings of the New Zealand Society of Animal Production, Volume 58, , 288-290, 1998