The minimum diameter distribution and strength variation of top dyed wool

Wool fibres are well known for their diameter variations, and the minimum d iameter usually determines the strength of the fibre. This paper first exam ines the distributions of the minimum fibre diameters and the breaking forc e of wool from a dyed wool top. The quantitative relations between the coef ficient of variation (CV) of breaking force and that of minimum diameter at different gauge lengths are then corroborated with experimental data. The results suggest that after top making and dyeing of the wool, its breaking force variation can still be predicted from the variation in minimum fibre diameters, even though the top making and dyeing processes would have cause d some damage to the fibres. The results also imply that most processed fib res break at their thinnest position, particularly when the gauge length is long. This is similar to early findings concerning un-processed wool. The effect of strain rates on the results is also briefly discussed in this pap er.